Enhanced Quad Tuning Techniques Overview

hi there everyone and welcome to the second video in my betaflight 4.5 tuning masterclass the first video in this series covered filters so if you haven't watched that yet I would go and watch that one first because you need to have a good filter tune as a foundation for the pit tuning that we're going to be doing in this video this video is carefully structured so we're going to start with the more simple and basic parts of pit tuning and then we're going to move to the more advanced sections later on the goal with this is that you can follow through the video and stop at any stage p and be confident that your quad is going to be better tuned the further you get along the video with that said let's not waste any more time let's dive right into it and start looking at pit tuning in betaflight 4.5 I really hope you're enjoying this tuning series if you'd like access to all of this information in PDF format so that you can work through it at your own pace while you're tuning your quad then you can find that on my patreon you can join from just a few dollars a month and you'll get access to the entire guide including filters pids and rates as a workbook that you can use when you're tuning any quad we're going to start with a quick look at the betaflight pit F controller so you can see where all the sections are and how they connect to each other the inputs to the pit controller are the set point which is the position of your sticks and the gyro which is the sensor measuring the rotational rate of the Quad on all three axes the set point minus the gyro is the PID error so that's the difference between what you're telling the quad to do and what it's actually doing and that PID error is fed into the propor proportional term and the integral term which we're going to talk about more in a second the derivative of the gyro so that's the rate of change of the rotation of the Quad or the rotational acceleration of the Quad is fed into the derivative term and the differential of the set point so that's the velocity of your sticks is fed into the feed forward term all of these terms are combined together with different amounts of gain in the PID F gains section and the result of that is What's called the pidm that's the push that the flight controller is asking the quad to make on all three axes roll pitch and your that is passed to the motor mixer which turns that request into a change in throttle of all of the different Motors when this system works it simply tries to minimize this pit error to as little as possible so your quad follows what you're telling it to do with your sticks as closely as possible let's look at how each of the terms Works individually starting with the proportional term or the P term the P term acts like the spring in a spring and damper in a suspension strut the goal of the P term is to push back against pit error and try and reduce that pit error to zero so as the pit error increases on each pit Loop the P term gets bigger and bigger and it always pushes the quad against that pit error so it's trying to reduce it the bigger the pit error gets the larger the P term gets and the harder it pushes the quad back to try and reduce that error to to zero the derivative term or the D term acts like the shock absorber in a suspension strut the D term looks at the rate of change of the gyro so how much the gyro is changing each PID Loop and it wants that gyro value to stay the same so the D term pushes back against changes in the gyro and it tries to slow the quad down now this is very important because this helps avoid overshoots and oscillations because that D term getss very big and pushes very hard if the quad is oscillating or trying to move very very quickly it acts like that shock absorber slowing the quad down and making sure we get a nice damped response just like in a suspension strut the balance between that spring strength which is the P term and the size of the shock absorber the D term is really really important for getting a nice damped response the betaflight default PD balance is pretty good for 5-in quads but the right balance for quads that are a bit smaller or a bit larger or that are more powerful than normal or less powerful is always going to be a bit different and so we're going to be looking in detail at how we tune that PD balance but the ratio between those terms is what's important not their absolute size so if you double both the p and the D term they will both have the same relationship with each other you'll get a similar response now let's take a look at the integral term the integral term is again looking at the PID error so the difference between the set point and the gyro and it's adding up that error over over time and the more that error adds up over time the harder the integral term is pushing back to bring the quad back into line so this means if we have a small amount of pit error over a long period of time the I term will start pushing back harder and harder until that error reduces to zero and this is really useful for dealing with a sort of fixed offset a systematic offset in the uh in the pit error that can't be removed by just the P term alone eventually the I term is going to build up to the point where it can minimize that error to zero in the same way that we have a PD balance we also have a pi balance the D term prevents the P term from oscillating and in the same way the P term actually prevents the I term from oscillating as a result there is an ideal pi ratio and an ideal PD ratio for a particular quad that allows the maximum i p and d terms without getting any oscillations and this gives us the relationship or the tuning flow which starts with the D term then the P term then the I term and then finally other terms like the feed forward term and this guides us through the tuning to make sure that we're going to get a quad that is going to fly really nicely without oscillations from any of the terms in the pit control ER the feed forward term is a little different from p i and D Feed forward is looking at the set point so it's looking at your sticks the rate of change of movement of your sticks if the feed forward term is correctly set it effectively eliminates any delay between the set point and the gyro which improves stick tracking particularly through fast moves and it's one of the terms that is present in betaflight but is not present in every other flight Control software and that has a big impact on how accur and how precise betaflight can be when it's tracking your sticks now that we've covered the theory behind all of the main terms in the betaflight pit controller it's time to talk a little about tuning flights tuning flights for pit tuning consist of sharp moves on the roll pitch and your axes and making sure you do those moves correctly is going to be important to getting the correct data getting really clean data which you can use to make decisions when you're pit tuning there are two things to bear in mind when you're doing your tuning flights the first is make sure to keep hold of the stick as you're doing your sharp moves so a sharp move out and back to Center is okay a sharp move left and right where you Wobble the stick like this is also good but don't do this don't release the stick and let it bounce back to Center because that is going to create all kinds of oscillations and totally mess up your data for making decisions on your pit tuning so make sure to keep hold of the stick the second is consider tuning in angle mode tuning in angle mode is a lot easier because when you do wobbles like this left to right you actually get really sharp inputs to the pit controller and the quad is sort of just wobbling in midair and that's nice and easy to control so I would definitely recommend doing most of your pit tuning in angle mode before we dive into pit tuning there's an optional setting that you might want to change in order to get even more responsiveness and Authority out of the pit controller this is to increase your pitm limit to do this you can go into the CLI and type set pitm limit equals 1,000 and set pitum limit your equals 1,000 then you type save and hit enter and that will save the setting what this will do is it'll increase the authority the pit controller has it'll enable it to push harder through the motor mixer and that can help with responsiveness through particularly fast moves the tuning process we're going to follow in this video is to start with the master multiplier and this is similar to tuning the volume on a music track you have to get the volume right otherwise no matter what you do with anything else it's just not going to sound right the tune isn't going to be good so we need to get the right Master m multiplier and get that volume level correct then we're going to be looking at the PD balance which is the high frequency quick response of the pit controller so that's similar to the treble and then we're going to move on to the I term which is looking at the low frequency slow response of the flight controller making sure that's correct and that's like tuning the bass the foundation of a great pit tune is the right Master multiplier setting and the right setting is as much as your build can tolerate without getting hot Motors or oscillations in dterm trilling while you're flying the more Master multiplier you have the better the final tune is going to be in terms of its responsiveness to your stick inputs and its tolerance of windy conditions but you don't want to overdo the master so before tuning make sure that your build is in a representative state so if you commonly fly with a GoPro make sure the GoPro is on there and if you usually fly with slightly damaged nicked or bent props make sure that those are the props you're using for the tune and that will make sure that you get your master multiplier as high as you can without risking any Hot Motors or oscillations while you're actually flying now I have to warn you that some speed freaks like this guy are producing more and more powerful motors with higher KV and these motors are going to require a lower Master multiplier because the effect of having a powerful motor with high KV is to multiply up the pit gain values props with a steeper pitch also have this effect but typically powerful Motors tend to have more of an effect than just steeper pitch props a lower Master multiplier with powerful Motors is going to perform better than a higher Master multiplier with weaker Motors and that's all to do with how fast the motor responds so if you have a low master with powerful Motors it's going to respond nice and quickly a higher Master multiplier with weaker Motors will still respond to the same level but it's just going to take longer to get there because the motor doesn't generate as much torque that faster response of the motor is going to give you a quad that's more responsive to your sticks and better able to handle windy conditions so so don't worry if you have to run a lower Master multiplier with more powerful Motors because you are getting better performance than if you had a higher Master multiplier but we're running less powerful Motors finding the right Master multiplier is a lot easier if the dterm isn't dynamically changing while you're flying to avoid the dterm dynamically changing we're going to set Dynamic damping to Zero by sliding this slider all the way down to zero if you can't see these sliders here then you need to enable expert mode in betaflight configurator and there's a setting in the top right once you've enabled expert mode you should see all of these extra sliders including the dynamic damping slider and slide that to zero then we're going to start tuning the master slider and we're going to start with the master a little bit below one so maybe 0.5 or so and starting to increase it up from there as you're doing that and doing your tuning flights pay attention to the motor temperature after you've flown around for a bit the sound of the motors when you're flying the motors should sound nice and smooth you shouldn't be hearing any oscillations or trilling or rough sounding Motors while you're doing your tuning flights those are indications that you've raised the master multiplier too high initially you're going to find that increasing the master multiplier improves the feel of the Quad it's going to improve prop wash handling um the sticks are going to feel more responsive everything is going to be just improving as you increase that Master multiplier then you're going to get to a point where those improvements kind of seem to slow down or maybe even stop and that indicates that you're getting close to the optimum position of the master multiplier and then if you keep going and you should keep going to learn what the effect is if you keep going you're going to start hearing the motors sounding a little bit rough maybe hearing some uh trilling oscillations During certain moments when you're flying those are indications that your master multiplier is now a bit too high and when the quad lands and you feel the motors they will probably feel a little bit warm or hot and that's another indication that the master might be a bit too high once you've figured out where the optimum position is you're going to just leave it there and that's going to be perfect and it's not going to make much difference whether it's like 0.1 higher or 0.1 lower so don't worry too much about it just find that position where everything seems to be working the best and that's where you should set your master the magic of Master multiplier is that if you're doing just a quick and dirty tune it may be the only slider you need to touch just increase that Master multiplier a few notches that'll get the quad feeling really nice and responsive and you can leave it there you don't need to go through all of the of PD balance and iterm if you don't want to particularly if your quad is a pretty typical 5-in freestyle build now let's talk about Dynamic idle Dynamic idle is absolutely critical for minimizing prop wash especially on smaller quads and especially if you're using steeper pitch props I have a whole video on Prop wash how it occurs and how Dynamic idle addresses it but here are my recommendations for dynamic idle in betaflight 4.5 you can see that it depends on the pitch of your prop and also on the prop size size and the reason for this is it to do with blade stool and it's to do with two things the steepness of your prop the steepness of the pitch and the tip speed of the prop so as your prop size gets smaller you need to increase your Dynamic idle RPM to get the same tip speed and as your prop pitch increases you need a higher RPM to prevent blade stall hopefully this table is going to give you the values that you need and obviously if you're running a prop that's somewhere in the middle you can pick a value between the two values in the table when you have a really tightly tuned quad throttle pit attenuation or TPA is a setting that it's really useful to know about what TPA does is it reduces the dains with increasing throttle and this helps avoid High throttle oscillations where you might have a really good tune at low throttle but then when you increase the throttle the whole Quad starts oscillating TPA rate is the attenuation at Full Throttle so a default value of 65 means that your pids are going to be attenuated to 35% of what they are at zero throttle by the time you get to Max throttle the TPA break point is the throttle value where attenuation starts to kick in and this is set between 1,000 and 2,000 for historical reasons so a value of 1350 is 35% throttle a value of a th000 is 0% throttle and a value of 2,000 is 100% throttle if you're getting high throttle oscillations but you're not getting oscillations at medium and low throttle then set your TPA break point just below the throttle level where oscillations are starting to kick in then increase your TPA rate until the oscillations are nicely eliminated for you and if the logs show that you have high throttle P term oscillations as well as dterm oscillations then you can fix that by setting your TPA mode to PD to attenuate the P term as well as the D term but that's not usually required once you're ready to move on it's time to find the ideal PD balance for the quad and to do this we first need to disable feed forward and gain in the pit Loop because they can mess with the PD response so we're going to turn feed forward gains all the way down to zero and I gains all the way down to zero we should leave Dynamic damping off as well at this point then we're going to want to take some logs so we're going to start with the p&i slider a little bit below 1.0 so I typically start around 0.5 and then work upwards in steps of .125 something like that and keep going until you start hearing oscillation um during sharp moves and they should be slightly audible when you're flying once you have some logs at a range of different PD balance values it's time to load them all into pit toolbox when you're loading in a multi-art file pit Toolbox will show you all of the sub files within your log and you can just select the ones that are useful that were useful flights for you so five here was not a useful flight so I'm not going to select that and then we hit okay to load them in once they're all loaded in you'll see a Trace like this which is showing one of the flights we're going to go over here to the step response tool which is what we're going to use to check our PD balance and we see our logs in the top right if I hit run I'm going to show you a log with a PD balance of 0.5 on the slider so this is significantly less than one and you can see the response is quite slow it gets up to 1.0 but it takes a little while and on Pitch it kind of tries to get to one and then it drifts away and that's an example of not having enough PD balance you can also see that we have these small wobbles here these are not oscillations this is just noise in the log and it's not worth worrying about you'll see that all of the logs have this type of wobble whether or not the quad is actually oscillating if I now load in a log with 0.75 PD balance you can see immediately it's a much more responsive log we've got the uh quad responding up to 1.0 much more quickly and it stays at 1.0 on both uh the rooll and on Pitch again we have these little wobbles but that's nothing to worry about if I now show you 1.0 1.0 is even faster but you can see that we're now getting diminishing returns where we're not getting a much much faster response with a higher slider value so we're starting to get towards the peak of that curve if I now load in 1.25 now we have something that looks more illary you can see that these are not just small wobbles anymore these are quite significant wobbles and they continue for a long time at a reasonable amplitude so this is an example of too much PD balance we've got too much P term and we've got oscillations we can also see that while we've got oscillations on Roll we don't really have much in the way of oscillations on pitch and it's not always going to be the same slider value that's correct for roll and Pitch sometimes you'll need different ones and we're going to talk about how we correct for that in a second if I now go way too far you can see that with way too much PD balance so way too much P term um we've got a lot of oscillation particularly on roll and also some oscillation which is dying away on Pitch looking at all of these different values we can sort of pick the slider values that we think are best and I've also included a run at 1.1 PD balance which is sort of halfway between 1 and 1.25 because I think that's going to be pretty much Optimum and I can see that certainly on Roll I've got uh a choice of maybe one or perhaps 1.1 that's going to give me the best PD balance I think one and that's log number three with a p term of 67 and then when I'm looking at the pitch response it's a little bit different I'm thinking 1.1 is probably the best here and so that's going to be a p term of 77 so 67 and 77 based on looking at a range of different slider values now if I jump into betaf flight configurator I need to set 67 and 77 as the two values that I want for my P term so to do that I'm going to slide the slider up to 1.0 that's going to give me 67 on the roll P term which is what I want and now I need to adjust the pitch P term separately and we have this pitch tracking p i and FF slider and that's what I'm going to use to adjust the pitch term separate from Roll I'm going to just move that up to 1.1 and that gives me my 67 on roll and 77 on Pitch that I found from looking at my step responses I find this image to be a really good reference for tuning PD balance if you have got the PD balance right it should look something like the red line where it's very very quick to reach 1.0 you maybe have just a tiny bit of overshoot just a hair of overshoot but you don't see any oscillation so you're just getting it up to that response line as quickly as possible and then it's flat if you've got an under damped response you're going to get a big oscillation like this green curve is showing and if you've got an overdamped response you're going to see something like the blue where it's very sluggish and slow to get up to 1.0 neither of those are good you want something that looks like the red line obviously taking into account the real step responses always have just a little bit of noise a little bit of wobble on them which is nothing to worry about but you do need to be aware that it's always going to be there and it doesn't necessarily mean you've got oscillation now that we've got the PD balance sorted it's time to look at the itemm and tuning the I term in betaflight is a little bit easier than tuning the P and D terms because the tuning window is much wider the beta flight default pi ratio is pretty good for most quads particularly quads that are similar to typical 5-in freestyle or racing builds but you can still get some significant improvements in flight performance from tuning the itm especially if you have a smaller or larger build than 5 in the pi ratio behaves similarly to the PD ratio in that as you in increase the ey gain slider the responsiveness of the Quad gets better the quad gets more precise and accurate up until it starts to cause oscillations so again we're going to be moving that slider up until we get oscillations when we're tuning the it term it's important to remember that the I term is an integrating term this means that it's always going to wind up to the same value and push just as hard to remove systematic pit error the eye gain affects how quickly the eye term can wind up if we have low eye gain it's going to take a long time to wind up to remove systematic pit error and then if we flip the quad over and the systematic error is in the other direction it's going to take a long time for the eye gain to wind up in the other direction with a higher eye gain it winds up quickly and when the systematic pit error changes the item corrects nice and quickly this makes the Quad feel more precise and more accurate particularly when you're flying in close proximity to objects obviously bearing in mind that if you have too much it term it's going to cause oscillations and we want to avoid that to to tune the item you want to start with the ey gain slider turn down nice and low that's going to give you very little eye gain and the quad should feel a little bit loose a little bit sort of um imprecise with not enough eye gain as you increase that ey gain slider the quad is going to be feeling more accurate more precise more predictable and it's going to be nicer to fly and you're going to feel more confident with it as you keep going with the eye gain slider and you turn that it term up higher and higher you will then start to see oscillations bounce backs slow wobbles on fast moves that's an indication that you've gone too far you now have too much ey gain and to turn it back down now that we've got the ey term nicely tuned I want to take you through some of the tools betaflight gives you to modify its performance for certain situations starting with iterm relax the purpose of iterm relax is to prevent the iterm accumulating building up during fast stick moves and the reason for this is that when you move the stick very fast often the is not going to be able to follow your stick perfectly through that very fast move it's going to lag behind it a bit when that happens the item can wind up to a big value and cause a bounce back at the end of that move things that help avoid this happening are having enough feed forward so that your drone can track your stick movement nice and closely and also having a drone that's very responsive in general you can leave iter relax at default but if you have a very responsive drone like a racing drone drone and you've got plenty of feed forward then you can increase that cut off significantly to 30 to 40 if you have a very slow drone that cannot track your sticks tightly through sharp moves you need to reduce that cut off and the best way to do that is by looking at logs and making sure that the iterm isn't winding up and causing a bounce back during a fast move iterm wind up is very similar to iterm relax but rather than being based on how fast you're moving the sticks it's based on how close the motors are to being maxed out so if you've commanded a fast move and the motors have maxed out to try and turn the quad as quickly as possible it turn wind up will prevent the iterm accumulating in that situation and it adds on top of iterm relax so it has a stronger effect when the motors are nearly maxed out the default value of 85 says that whenever the motors are above 85% start reducing the ierm accumulation and the ierm accumulation will always be zero when the motors are maxed out with ier wind up where itm relax and iterm wind up reduce the accumulation of the iterm anti-gravity does the opposite anti-gravity boost the accumulation of the item during fast throttle changes and this can be helpful for drones where the center of gravity is far away from the center of thrust because they tend to nod or Bob during fast throttle changes particularly when you cut the throttle quickly to zero the default is8 which boosts itm accumulation by eight times during a very rapid throttle change reduce this value if you see wobbles during fast throttle changes that you think are caused by ierm oscillation particularly if you've turned the eye gain up a bit when you've tuned the quad an eight times boost is quite a lot and that can push the eye term to oscillate if you reduce it to four or five and you see that oscillation go away then that's going to be perfect if you have a quad where the center of gravity and Centro Thruster coincident then you may not need anti-gravity and so you can turn the gain down or even turn it off and you may not see any wobbles anti-gravity has some advanced settings in the CLI that it's worth knowing about even if you don't actually adjust them if you're seeing oscillations in the P term during fast throttle changes that is going to be due to the anti-gravity boost on the P term so anti-gravity boosts p and I so you can adjust the P component of the anti-gravity boost individually by using set anti-gravity P gain to some value 100 is default if you're getting P oscillations you're going to want to reduce that value anti-gravity also has a cutof frequency so for very small or very large quads anti-gravity May react too quickly or too slowly it may boost the ey term too fast or it may not boost the ey term quickly enough if that's the problem and you can see that in the logs there is a cutof frequency for the anti-gravity that's a set anti-gravity cutof Hertz five is the default less than five is going to slow and smooth the anti-gravity response and lengthen it out more than five is going to speed up and shorten the anti-gravity response and make it sharper item rotation and absolute control are both settings which add some mathematics into the pit Loop to calculate a rotation of the iterm vector with the quad this means that when you do fast your spins the itemm on the pitch axis will be transferred to the roll axis and while this can sound good in theory I've done some testing of this and I've found that in general these settings don't reduce pit error and in fact in some cases they actually increase it so I wouldn't recommend using either of these settings um particularly for ordinary freestyle flying some line of sight Pilots use iterm rotation absolute control um and find them beneficial but certainly in my testing I can't see anything in the logs that suggests that they're doing anything to help the tracking of the set point all right now it's time to move into some of the more advanced tuning topics including feed forward and dynamic damping don't forget that this information is available as a PDF document on my patreon you can join from just a few dollars a month and you'll get access to the entire guide for filters pids and rates as a PDF which you can then refer back to whenever you're tuning quads in the future I'd really appreciate it if you consider joining up even if it's just for a couple of months to get hold of that guide and there's a link down in the video description now that we've tuned Pi I and D it's time to take a look at feedforward but before we dive into tuning feed forward we have to make sure it's set up correctly and the best way to do that is using the the presets for all the different radio links so if you go into the presets Tab and you search for your radio link so I'm on Express lrs so I'm going to search for Express lrs you can see we've got all of these different presets for the different Express lrs radio links I'm using 250 HZ so I'm going to select this one and I'm going to go through the options I want to do HD freestyle I have a separate elrs receiver and I want single cell values for my voltage Telemetry and I'm not going going to change my rates because I want to do my rates later that's another video once you've got all those selected you can click pick and then save and reboot and that will apply the presets and will adjust all of the settings for both your radio link and for your feed forward settings which is what we want to adjust if you jump now into the pit tuning tab you'll see that in the feed forward settings all of these have changed the Jitter reduction smoothness averaging they've all changed and Boost Max rate and transition have all stayed the same once you've set up your radio preset correctly you can start to tune feed forward and to do that just return the stick response slider to about 0.5 or so and then gradually increase it and you're wanting to pay attention for a couple of things when your stick response slider of feed forward gains are far too low the quad is going to feel a little sluggish it's not going to feel like it responds to your sticks as quickly as you'd like it to as you increase that feed forward slider the quad is going to feel more and more responsive and more and more locked to your sticks if you go too far and I mean you really do have to go quite far with feed forward you will start to see and hear an overshoot particularly at the start of a Sharp move and perhaps also you'll be able to see an overshoot at the end of a Sharp move as well that indicates that you've gone too far and then you need to work the slider back it's much easier to see all of these effects in a blackbox log so what we have here is we're looking at stick tracking for a particular flight with two two little feed forward we have the gyro Trace in light blue and the set point in green so you can see the set point increases up to a level and the gyro sort of lags behind it we can also see that the motors are nowhere near maxing out at the start of the move so the quad isn't really trying to follow our sticks particularly hard because the feed forward isn't pushing into the move hard enough if we look at the end of a move you can see that at the end of the move the gyro also lags behind the set point significantly so the set points coming down our sticks are moving back to Center but the gyro isn't following that very closely it's lagging behind and that's because the p term and the D term they are all operating after the fact only feed forward knows what your sticks are doing when you're doing it if we increase feed forward too much we turn feed forward up to a really high level and you have to go you really have to go some to have too much feed forward you can see that the feed forward is spiking up really high at the start of a move and actually we're getting quite good tracking at the start of a move with feed forward that high and the motors are pushing a lot harder they're a lot closer to maxing out with feed forward that high but at the end of a move we have all sorts of problems at the end of a move we can see the motor is maxing out but then the gyro is sort of careering past the set point and we have this big overshoot and bounce back and that's because even when the uh the gyro is passing the set point feed is still pushing way too hard and the gyro is sailing past the set point and then we're getting a bit of overshoot and bounce back if we look at just the right amount of feed forward we can see what it should look like when it's absolutely perfect we have the correct stick tracking at the start of the move so the gyro is lagging slightly behind the set point maybe at the start of a move but it's not too bad and at the end of the move you can see we still have the motors maxing out but now the gyro returns nicely to the set point and then continues on so the performance overall is much much better that's kind of what we want to see when feed forward is correctly tuned when we're looking at a black box log there are some extra tools that we have available to us to help improve the performance of feed forward even a bit more the first is feed forward boost now what this does is it adds an element to feed forward based on the acceleration of your sticks and this helps get feed forward moving even more quickly at the start of a fast move if you're seeing in your log that the gyro is lagging behind the set point at the start of the move but then catching up later on it's definitely worth adding some additional feed forward boost to help correct that a bit more feed forward boost will accelerate how quickly feed forward ramps up and therefore help the gyro track the set point at the very start of a fast move if you're seeing the gyro getting ahead of the set point at the start of a fast move but it corrects later on that is definitely an indication that you have too much feedforward boost and you should reduce it a bit that will kind of tame the start of the move and allow feed forward to ramp up at just the right rate to give you good stick tracking the default of 15 for feed forward boost is pretty good for most cases but if you do see your gyro lagging boost it up a bit increase it and if you do see your gyro getting ahead of your set point but then it's correcting later on then it's worth decreasing feed forward boost feed forward has another tool called Max rate limit and what this does is it cuts feed forward to zero as your sticks approach maximum deflection this helps avoid the situation where feed forward is pushing all the way up until your sticks hit their limits and then your quad overshoots because you've got this sudden stop where the stick is hitting its maximum deflection what this is really useful for is if you're in the situation where you've got the right amount of feed forward so that the end of a move looks really nice you've got the motors maxing out and then it returning nicely to the set point so this is looking really good but you've still got a bit of lag at the start of a move and you can see that feed forward is being cut off before the uh before the gyro has quite track the set point all the way increasing the max limit can allow you to have this feed forward keep pushing for a bit longer help keep that gyro tracking a bit close to the set point and then it'll back off just before the uh the gyro needs to track the set point through this transition where it goes from increasing to Flat the more responsive your quad is the higher you can increase the max rate limit to tighten up the start of a Sharp move like this um the default 90 is fine but you can definitely try increasing that to 92 95 and that will help tighten up the start of a really sharp move if you've got a responsive quad now let's talk about Dynamic damping Dynamic damping is an advanced feature in betaflight that allows you to dynamically boost or increase the dterm on Sharp moves while keeping the DM at a lower value during normal flying this can help you to tame overshoot caused by high feed forward allowing you to push your feed forward gains higher and get better stick tracking or it can be used to reduce the dterm during normal flying to help reduce motor heating you need to tune the dynamic damping gain so that the dterm boosts up to maximum on Sharp moves but sits at its minimum value during normal flight and this can only really be tuned with blackbox logs the gain of 37 which is default is a pretty good starting point Dynamic damping advanced should always under all circumstances be set to zero we know that in the PID controller the derivative term is based on the gyro the signal for the derivative term comes from the gyro and the signal for the feed forward term comes from the set point Dynamic damping Advanced for some reason that I do not understand adds some component of the set point into the derivative term you don't want this you want to keep the derivative term based only on the gyro so leave Dynamic damping Advance set to zero to tune Dynamic damping you'll want to set your blackbox logging debug mode to D Min and then in the logs in blackbox Explorer you're going to see the actual D term on roll and pitch and also the gyro factor which is determining how the dterm is boosting up and down you're also going to want to return your Dynamic damping slider to 1.0 when you're doing a tuning flight do some normal flying and then do some moderate and sharper moves you want to set your Dynamic damping gain so that the dterm does not boost up at all during normal flight so it's just sitting there at its base value you want to see your dterm Boost a little bit on moderate moves and you want to see your dterm max out on the sharpest moves and that shows that you've got your Dynamic damping gain set just right once you have your Dynamic damping gain set right there are two ways that you can use it the first is to enable higher feed forward gains for more responsive flight feel and better stick tracking to do that you're going to use Dynamic damping to boost the dterm in situations like this so here's an example where we have high feed forward we've got the gyro coming back towards the set point and overshooting because we've got too much feed forward and the gyro is just flying past the set point you can use Dynamic damping here to boost this dterm to help tame this overshoot and bring the gyro back to the set point without it over shooting and bouncing back that's one way you can use it it's going to allow you to push your feed forward gains higher to do this what you're going to want to do is you're going to want to increase this Dynamic damping slider until the dterm is boosting high enough to tame that overshoot what you're going to want to listen for is dterm oscillations on fast moves which is showing that your dterm is boosting so high that it's amplifying noise and causing oscillations but provided you're not hearing any of that and your Motors are staying reasonably cool then it's okay to increase this Dynamic damping slider to tame that overshoot on fast moves the second way to use Dynamic damping is to use it to reduce your dterm during normal flying so you want your dterm boosting up to a good value during fast moves but sitting at a lower value during normal flying and the way you're going to do that is you're going to look at what your derivative value is that you found from your PD balance tuning and you're going to want to reduce your damping gains your Dain gains and increase your Dynamic damping so that your dmax is equal to your derivative term that you had before so here we have Dynamic damping at zero and a dmax of 45 and a derivative term of 45 we turn our dains down a bit we turn our Dynamic damping up and now we have a dmax that's still 45 but our normal derivative term during normal flying is only 33 so we've reduced that Dain during normal flying that's going to help reduce motor heating keep Motors cooler this is particularly useful for applications like racing where you're high in the throttle all the time and you need to do everything you can to keep your Motors cool now let's take a look at some of the other settings starting with throttle boost now this works similarly to feed forward boost it adds a component to the throttle value based on the acceleration of your throttle stick so if you move the throttle stick very very fast throttle boost will add a bit to the throttle to help the quad pick up more quickly and reduce the delay when you suddenly get on the throttle if you're feeling like there's a bit of lag when you hit the throttle then it might be worth increasing throttle boost and seeing if that helps resolve the issue the next setting is motor output limit and what this does is it reduces the maximum motor Drive value that betaflight can ever send to your ESC and this allows you to use 4S motors with a 6S battery and to do that you would set your motor output limit to 66% because you're running a 4S motor on a 6S Pack 4 over 6 is 66% if you're running 3s Motors on a 4S battery that motor output limit should be set to 75% vbat sag compensation is a pretty interesting setting what it does is it reduces the maximum motor drive when the battery is fully charged and increases it gradually as the battery voltage Falls this gives a very consistent flight performance over the entire life of the battery but it does it by reducing the performance when the battery is fully charged to the same level that it's going to be at when the battery is empty this makes it very very difficult to know that your battery is discharging because the quad feels exactly the same so use this with caution as it's very easy to over discharge your batteries you'll want to set up some other warning that your battery voltage is low typically if you're going to use vbat sag compensation you're going to set it to 100% thrust linearization is another interesting setting this boosts the motor drive at low throttle values so if your ESC doesn't provides much torque at low throttle thrust linearization boosts it up this is very useful for improving responsiveness and stick tracking at low throttle particularly for small quads like tiny whoops that are using ESC pwms of 48 khz or higher and they typically have low torque at low throttle if you're going to turn thrust linearization on the default value of 20% is usually pretty good for tiny whoops all right so that brings us to the end of the pit tuning section of my betaflight 4.5 tuning guide you should now have a quad that is really tightly locked to your sticks and might even feel a bit too sharp if that's the the case don't worry because we are going to address that in the next video where we're going to be looking at our rates if you want to make sure that you see that video as soon as it comes out make sure you like this video subscribe and hit the notification Bell and then follow along with me while we get our rates tuned to Perfection so that you have that buttery smooth stick feel that's all I have for you for today so until next time I wish you all very very happy [Music] flying

hi there everyone and welcome to the second video in my betaflight 4.5 tuning masterclass the first video in this series covered filters so if you haven&#39;t watched that yet I would go and watch that one first because you need to have a good filter tune as a foundation for the pit tuning that we&#39;re going to be doing in this video this video is carefully structured so we&#39;re going to start with the more simple and basic parts of pit tuning and then we&#39;re going to move to the more advanced sections later on the goal with this is that you can follow through the video and stop at any stage p and be confident that your quad is going to be better tuned the further you get along the video with that said let&#39;s not waste any more time let&#39;s dive right into it and start looking at pit tuning in betaflight 4.5 I really hope you&#39;re enjoying this tuning series if you&#39;d like access to all of this information in PDF format so that you can work through it at your own pace while you&#39;re tuning your quad then you can find that on my patreon you can join from just a few dollars a month and you&#39;ll get access to the entire guide including filters pids and rates as a workbook that you can use when you&#39;re tuning any quad we&#39;re going to start with a quick look at the betaflight pit F controller so you can see where all the sections are and how they connect to each other the inputs to the pit controller are the set point which is the position of your sticks and the gyro which is the sensor measuring the rotational rate of the Quad on all three axes the set point minus the gyro is the PID error so that&#39;s the difference between what you&#39;re telling the quad to do and what it&#39;s actually doing and that PID error is fed into the propor proportional term and the integral term which we&#39;re going to talk about more in a second the derivative of the gyro so that&#39;s the rate of change of the rotation of the Quad or the rotational acceleration of the Quad is fed into the derivative term and the differential of the set point so that&#39;s the velocity of your sticks is fed into the feed forward term all of these terms are combined together with different amounts of gain in the PID F gains section and the result of that is What&#39;s called the pidm that&#39;s the push that the flight controller is asking the quad to make on all three axes roll pitch and your that is passed to the motor mixer which turns that request into a change in throttle of all of the different Motors when this system works it simply tries to minimize this pit error to as little as possible so your quad follows what you&#39;re telling it to do with your sticks as closely as possible let&#39;s look at how each of the terms Works individually starting with the proportional term or the P term the P term acts like the spring in a spring and damper in a suspension strut the goal of the P term is to push back against pit error and try and reduce that pit error to zero so as the pit error increases on each pit Loop the P term gets bigger and bigger and it always pushes the quad against that pit error so it&#39;s trying to reduce it the bigger the pit error gets the larger the P term gets and the harder it pushes the quad back to try and reduce that error to to zero the derivative term or the D term acts like the shock absorber in a suspension strut the D term looks at the rate of change of the gyro so how much the gyro is changing each PID Loop and it wants that gyro value to stay the same so the D term pushes back against changes in the gyro and it tries to slow the quad down now this is very important because this helps avoid overshoots and oscillations because that D term getss very big and pushes very hard if the quad is oscillating or trying to move very very quickly it acts like that shock absorber slowing the quad down and making sure we get a nice damped response just like in a suspension strut the balance between that spring strength which is the P term and the size of the shock absorber the D term is really really important for getting a nice damped response the betaflight default PD balance is pretty good for 5-in quads but the right balance for quads that are a bit smaller or a bit larger or that are more powerful than normal or less powerful is always going to be a bit different and so we&#39;re going to be looking in detail at how we tune that PD balance but the ratio between those terms is what&#39;s important not their absolute size so if you double both the p and the D term they will both have the same relationship with each other you&#39;ll get a similar response now let&#39;s take a look at the integral term the integral term is again looking at the PID error so the difference between the set point and the gyro and it&#39;s adding up that error over over time and the more that error adds up over time the harder the integral term is pushing back to bring the quad back into line so this means if we have a small amount of pit error over a long period of time the I term will start pushing back harder and harder until that error reduces to zero and this is really useful for dealing with a sort of fixed offset a systematic offset in the uh in the pit error that can&#39;t be removed by just the P term alone eventually the I term is going to build up to the point where it can minimize that error to zero in the same way that we have a PD balance we also have a pi balance the D term prevents the P term from oscillating and in the same way the P term actually prevents the I term from oscillating as a result there is an ideal pi ratio and an ideal PD ratio for a particular quad that allows the maximum i p and d terms without getting any oscillations and this gives us the relationship or the tuning flow which starts with the D term then the P term then the I term and then finally other terms like the feed forward term and this guides us through the tuning to make sure that we&#39;re going to get a quad that is going to fly really nicely without oscillations from any of the terms in the pit control ER the feed forward term is a little different from p i and D Feed forward is looking at the set point so it&#39;s looking at your sticks the rate of change of movement of your sticks if the feed forward term is correctly set it effectively eliminates any delay between the set point and the gyro which improves stick tracking particularly through fast moves and it&#39;s one of the terms that is present in betaflight but is not present in every other flight Control software and that has a big impact on how accur and how precise betaflight can be when it&#39;s tracking your sticks now that we&#39;ve covered the theory behind all of the main terms in the betaflight pit controller it&#39;s time to talk a little about tuning flights tuning flights for pit tuning consist of sharp moves on the roll pitch and your axes and making sure you do those moves correctly is going to be important to getting the correct data getting really clean data which you can use to make decisions when you&#39;re pit tuning there are two things to bear in mind when you&#39;re doing your tuning flights the first is make sure to keep hold of the stick as you&#39;re doing your sharp moves so a sharp move out and back to Center is okay a sharp move left and right where you Wobble the stick like this is also good but don&#39;t do this don&#39;t release the stick and let it bounce back to Center because that is going to create all kinds of oscillations and totally mess up your data for making decisions on your pit tuning so make sure to keep hold of the stick the second is consider tuning in angle mode tuning in angle mode is a lot easier because when you do wobbles like this left to right you actually get really sharp inputs to the pit controller and the quad is sort of just wobbling in midair and that&#39;s nice and easy to control so I would definitely recommend doing most of your pit tuning in angle mode before we dive into pit tuning there&#39;s an optional setting that you might want to change in order to get even more responsiveness and Authority out of the pit controller this is to increase your pitm limit to do this you can go into the CLI and type set pitm limit equals 1,000 and set pitum limit your equals 1,000 then you type save and hit enter and that will save the setting what this will do is it&#39;ll increase the authority the pit controller has it&#39;ll enable it to push harder through the motor mixer and that can help with responsiveness through particularly fast moves the tuning process we&#39;re going to follow in this video is to start with the master multiplier and this is similar to tuning the volume on a music track you have to get the volume right otherwise no matter what you do with anything else it&#39;s just not going to sound right the tune isn&#39;t going to be good so we need to get the right Master m multiplier and get that volume level correct then we&#39;re going to be looking at the PD balance which is the high frequency quick response of the pit controller so that&#39;s similar to the treble and then we&#39;re going to move on to the I term which is looking at the low frequency slow response of the flight controller making sure that&#39;s correct and that&#39;s like tuning the bass the foundation of a great pit tune is the right Master multiplier setting and the right setting is as much as your build can tolerate without getting hot Motors or oscillations in dterm trilling while you&#39;re flying the more Master multiplier you have the better the final tune is going to be in terms of its responsiveness to your stick inputs and its tolerance of windy conditions but you don&#39;t want to overdo the master so before tuning make sure that your build is in a representative state so if you commonly fly with a GoPro make sure the GoPro is on there and if you usually fly with slightly damaged nicked or bent props make sure that those are the props you&#39;re using for the tune and that will make sure that you get your master multiplier as high as you can without risking any Hot Motors or oscillations while you&#39;re actually flying now I have to warn you that some speed freaks like this guy are producing more and more powerful motors with higher KV and these motors are going to require a lower Master multiplier because the effect of having a powerful motor with high KV is to multiply up the pit gain values props with a steeper pitch also have this effect but typically powerful Motors tend to have more of an effect than just steeper pitch props a lower Master multiplier with powerful Motors is going to perform better than a higher Master multiplier with weaker Motors and that&#39;s all to do with how fast the motor responds so if you have a low master with powerful Motors it&#39;s going to respond nice and quickly a higher Master multiplier with weaker Motors will still respond to the same level but it&#39;s just going to take longer to get there because the motor doesn&#39;t generate as much torque that faster response of the motor is going to give you a quad that&#39;s more responsive to your sticks and better able to handle windy conditions so so don&#39;t worry if you have to run a lower Master multiplier with more powerful Motors because you are getting better performance than if you had a higher Master multiplier but we&#39;re running less powerful Motors finding the right Master multiplier is a lot easier if the dterm isn&#39;t dynamically changing while you&#39;re flying to avoid the dterm dynamically changing we&#39;re going to set Dynamic damping to Zero by sliding this slider all the way down to zero if you can&#39;t see these sliders here then you need to enable expert mode in betaflight configurator and there&#39;s a setting in the top right once you&#39;ve enabled expert mode you should see all of these extra sliders including the dynamic damping slider and slide that to zero then we&#39;re going to start tuning the master slider and we&#39;re going to start with the master a little bit below one so maybe 0.5 or so and starting to increase it up from there as you&#39;re doing that and doing your tuning flights pay attention to the motor temperature after you&#39;ve flown around for a bit the sound of the motors when you&#39;re flying the motors should sound nice and smooth you shouldn&#39;t be hearing any oscillations or trilling or rough sounding Motors while you&#39;re doing your tuning flights those are indications that you&#39;ve raised the master multiplier too high initially you&#39;re going to find that increasing the master multiplier improves the feel of the Quad it&#39;s going to improve prop wash handling um the sticks are going to feel more responsive everything is going to be just improving as you increase that Master multiplier then you&#39;re going to get to a point where those improvements kind of seem to slow down or maybe even stop and that indicates that you&#39;re getting close to the optimum position of the master multiplier and then if you keep going and you should keep going to learn what the effect is if you keep going you&#39;re going to start hearing the motors sounding a little bit rough maybe hearing some uh trilling oscillations During certain moments when you&#39;re flying those are indications that your master multiplier is now a bit too high and when the quad lands and you feel the motors they will probably feel a little bit warm or hot and that&#39;s another indication that the master might be a bit too high once you&#39;ve figured out where the optimum position is you&#39;re going to just leave it there and that&#39;s going to be perfect and it&#39;s not going to make much difference whether it&#39;s like 0.1 higher or 0.1 lower so don&#39;t worry too much about it just find that position where everything seems to be working the best and that&#39;s where you should set your master the magic of Master multiplier is that if you&#39;re doing just a quick and dirty tune it may be the only slider you need to touch just increase that Master multiplier a few notches that&#39;ll get the quad feeling really nice and responsive and you can leave it there you don&#39;t need to go through all of the of PD balance and iterm if you don&#39;t want to particularly if your quad is a pretty typical 5-in freestyle build now let&#39;s talk about Dynamic idle Dynamic idle is absolutely critical for minimizing prop wash especially on smaller quads and especially if you&#39;re using steeper pitch props I have a whole video on Prop wash how it occurs and how Dynamic idle addresses it but here are my recommendations for dynamic idle in betaflight 4.5 you can see that it depends on the pitch of your prop and also on the prop size size and the reason for this is it to do with blade stool and it&#39;s to do with two things the steepness of your prop the steepness of the pitch and the tip speed of the prop so as your prop size gets smaller you need to increase your Dynamic idle RPM to get the same tip speed and as your prop pitch increases you need a higher RPM to prevent blade stall hopefully this table is going to give you the values that you need and obviously if you&#39;re running a prop that&#39;s somewhere in the middle you can pick a value between the two values in the table when you have a really tightly tuned quad throttle pit attenuation or TPA is a setting that it&#39;s really useful to know about what TPA does is it reduces the dains with increasing throttle and this helps avoid High throttle oscillations where you might have a really good tune at low throttle but then when you increase the throttle the whole Quad starts oscillating TPA rate is the attenuation at Full Throttle so a default value of 65 means that your pids are going to be attenuated to 35% of what they are at zero throttle by the time you get to Max throttle the TPA break point is the throttle value where attenuation starts to kick in and this is set between 1,000 and 2,000 for historical reasons so a value of 1350 is 35% throttle a value of a th000 is 0% throttle and a value of 2,000 is 100% throttle if you&#39;re getting high throttle oscillations but you&#39;re not getting oscillations at medium and low throttle then set your TPA break point just below the throttle level where oscillations are starting to kick in then increase your TPA rate until the oscillations are nicely eliminated for you and if the logs show that you have high throttle P term oscillations as well as dterm oscillations then you can fix that by setting your TPA mode to PD to attenuate the P term as well as the D term but that&#39;s not usually required once you&#39;re ready to move on it&#39;s time to find the ideal PD balance for the quad and to do this we first need to disable feed forward and gain in the pit Loop because they can mess with the PD response so we&#39;re going to turn feed forward gains all the way down to zero and I gains all the way down to zero we should leave Dynamic damping off as well at this point then we&#39;re going to want to take some logs so we&#39;re going to start with the p&amp;i slider a little bit below 1.0 so I typically start around 0.5 and then work upwards in steps of .125 something like that and keep going until you start hearing oscillation um during sharp moves and they should be slightly audible when you&#39;re flying once you have some logs at a range of different PD balance values it&#39;s time to load them all into pit toolbox when you&#39;re loading in a multi-art file pit Toolbox will show you all of the sub files within your log and you can just select the ones that are useful that were useful flights for you so five here was not a useful flight so I&#39;m not going to select that and then we hit okay to load them in once they&#39;re all loaded in you&#39;ll see a Trace like this which is showing one of the flights we&#39;re going to go over here to the step response tool which is what we&#39;re going to use to check our PD balance and we see our logs in the top right if I hit run I&#39;m going to show you a log with a PD balance of 0.5 on the slider so this is significantly less than one and you can see the response is quite slow it gets up to 1.0 but it takes a little while and on Pitch it kind of tries to get to one and then it drifts away and that&#39;s an example of not having enough PD balance you can also see that we have these small wobbles here these are not oscillations this is just noise in the log and it&#39;s not worth worrying about you&#39;ll see that all of the logs have this type of wobble whether or not the quad is actually oscillating if I now load in a log with 0.75 PD balance you can see immediately it&#39;s a much more responsive log we&#39;ve got the uh quad responding up to 1.0 much more quickly and it stays at 1.0 on both uh the rooll and on Pitch again we have these little wobbles but that&#39;s nothing to worry about if I now show you 1.0 1.0 is even faster but you can see that we&#39;re now getting diminishing returns where we&#39;re not getting a much much faster response with a higher slider value so we&#39;re starting to get towards the peak of that curve if I now load in 1.25 now we have something that looks more illary you can see that these are not just small wobbles anymore these are quite significant wobbles and they continue for a long time at a reasonable amplitude so this is an example of too much PD balance we&#39;ve got too much P term and we&#39;ve got oscillations we can also see that while we&#39;ve got oscillations on Roll we don&#39;t really have much in the way of oscillations on pitch and it&#39;s not always going to be the same slider value that&#39;s correct for roll and Pitch sometimes you&#39;ll need different ones and we&#39;re going to talk about how we correct for that in a second if I now go way too far you can see that with way too much PD balance so way too much P term um we&#39;ve got a lot of oscillation particularly on roll and also some oscillation which is dying away on Pitch looking at all of these different values we can sort of pick the slider values that we think are best and I&#39;ve also included a run at 1.1 PD balance which is sort of halfway between 1 and 1.25 because I think that&#39;s going to be pretty much Optimum and I can see that certainly on Roll I&#39;ve got uh a choice of maybe one or perhaps 1.1 that&#39;s going to give me the best PD balance I think one and that&#39;s log number three with a p term of 67 and then when I&#39;m looking at the pitch response it&#39;s a little bit different I&#39;m thinking 1.1 is probably the best here and so that&#39;s going to be a p term of 77 so 67 and 77 based on looking at a range of different slider values now if I jump into betaf flight configurator I need to set 67 and 77 as the two values that I want for my P term so to do that I&#39;m going to slide the slider up to 1.0 that&#39;s going to give me 67 on the roll P term which is what I want and now I need to adjust the pitch P term separately and we have this pitch tracking p i and FF slider and that&#39;s what I&#39;m going to use to adjust the pitch term separate from Roll I&#39;m going to just move that up to 1.1 and that gives me my 67 on roll and 77 on Pitch that I found from looking at my step responses I find this image to be a really good reference for tuning PD balance if you have got the PD balance right it should look something like the red line where it&#39;s very very quick to reach 1.0 you maybe have just a tiny bit of overshoot just a hair of overshoot but you don&#39;t see any oscillation so you&#39;re just getting it up to that response line as quickly as possible and then it&#39;s flat if you&#39;ve got an under damped response you&#39;re going to get a big oscillation like this green curve is showing and if you&#39;ve got an overdamped response you&#39;re going to see something like the blue where it&#39;s very sluggish and slow to get up to 1.0 neither of those are good you want something that looks like the red line obviously taking into account the real step responses always have just a little bit of noise a little bit of wobble on them which is nothing to worry about but you do need to be aware that it&#39;s always going to be there and it doesn&#39;t necessarily mean you&#39;ve got oscillation now that we&#39;ve got the PD balance sorted it&#39;s time to look at the itemm and tuning the I term in betaflight is a little bit easier than tuning the P and D terms because the tuning window is much wider the beta flight default pi ratio is pretty good for most quads particularly quads that are similar to typical 5-in freestyle or racing builds but you can still get some significant improvements in flight performance from tuning the itm especially if you have a smaller or larger build than 5 in the pi ratio behaves similarly to the PD ratio in that as you in increase the ey gain slider the responsiveness of the Quad gets better the quad gets more precise and accurate up until it starts to cause oscillations so again we&#39;re going to be moving that slider up until we get oscillations when we&#39;re tuning the it term it&#39;s important to remember that the I term is an integrating term this means that it&#39;s always going to wind up to the same value and push just as hard to remove systematic pit error the eye gain affects how quickly the eye term can wind up if we have low eye gain it&#39;s going to take a long time to wind up to remove systematic pit error and then if we flip the quad over and the systematic error is in the other direction it&#39;s going to take a long time for the eye gain to wind up in the other direction with a higher eye gain it winds up quickly and when the systematic pit error changes the item corrects nice and quickly this makes the Quad feel more precise and more accurate particularly when you&#39;re flying in close proximity to objects obviously bearing in mind that if you have too much it term it&#39;s going to cause oscillations and we want to avoid that to to tune the item you want to start with the ey gain slider turn down nice and low that&#39;s going to give you very little eye gain and the quad should feel a little bit loose a little bit sort of um imprecise with not enough eye gain as you increase that ey gain slider the quad is going to be feeling more accurate more precise more predictable and it&#39;s going to be nicer to fly and you&#39;re going to feel more confident with it as you keep going with the eye gain slider and you turn that it term up higher and higher you will then start to see oscillations bounce backs slow wobbles on fast moves that&#39;s an indication that you&#39;ve gone too far you now have too much ey gain and to turn it back down now that we&#39;ve got the ey term nicely tuned I want to take you through some of the tools betaflight gives you to modify its performance for certain situations starting with iterm relax the purpose of iterm relax is to prevent the iterm accumulating building up during fast stick moves and the reason for this is that when you move the stick very fast often the is not going to be able to follow your stick perfectly through that very fast move it&#39;s going to lag behind it a bit when that happens the item can wind up to a big value and cause a bounce back at the end of that move things that help avoid this happening are having enough feed forward so that your drone can track your stick movement nice and closely and also having a drone that&#39;s very responsive in general you can leave iter relax at default but if you have a very responsive drone like a racing drone drone and you&#39;ve got plenty of feed forward then you can increase that cut off significantly to 30 to 40 if you have a very slow drone that cannot track your sticks tightly through sharp moves you need to reduce that cut off and the best way to do that is by looking at logs and making sure that the iterm isn&#39;t winding up and causing a bounce back during a fast move iterm wind up is very similar to iterm relax but rather than being based on how fast you&#39;re moving the sticks it&#39;s based on how close the motors are to being maxed out so if you&#39;ve commanded a fast move and the motors have maxed out to try and turn the quad as quickly as possible it turn wind up will prevent the iterm accumulating in that situation and it adds on top of iterm relax so it has a stronger effect when the motors are nearly maxed out the default value of 85 says that whenever the motors are above 85% start reducing the ierm accumulation and the ierm accumulation will always be zero when the motors are maxed out with ier wind up where itm relax and iterm wind up reduce the accumulation of the iterm anti-gravity does the opposite anti-gravity boost the accumulation of the item during fast throttle changes and this can be helpful for drones where the center of gravity is far away from the center of thrust because they tend to nod or Bob during fast throttle changes particularly when you cut the throttle quickly to zero the default is8 which boosts itm accumulation by eight times during a very rapid throttle change reduce this value if you see wobbles during fast throttle changes that you think are caused by ierm oscillation particularly if you&#39;ve turned the eye gain up a bit when you&#39;ve tuned the quad an eight times boost is quite a lot and that can push the eye term to oscillate if you reduce it to four or five and you see that oscillation go away then that&#39;s going to be perfect if you have a quad where the center of gravity and Centro Thruster coincident then you may not need anti-gravity and so you can turn the gain down or even turn it off and you may not see any wobbles anti-gravity has some advanced settings in the CLI that it&#39;s worth knowing about even if you don&#39;t actually adjust them if you&#39;re seeing oscillations in the P term during fast throttle changes that is going to be due to the anti-gravity boost on the P term so anti-gravity boosts p and I so you can adjust the P component of the anti-gravity boost individually by using set anti-gravity P gain to some value 100 is default if you&#39;re getting P oscillations you&#39;re going to want to reduce that value anti-gravity also has a cutof frequency so for very small or very large quads anti-gravity May react too quickly or too slowly it may boost the ey term too fast or it may not boost the ey term quickly enough if that&#39;s the problem and you can see that in the logs there is a cutof frequency for the anti-gravity that&#39;s a set anti-gravity cutof Hertz five is the default less than five is going to slow and smooth the anti-gravity response and lengthen it out more than five is going to speed up and shorten the anti-gravity response and make it sharper item rotation and absolute control are both settings which add some mathematics into the pit Loop to calculate a rotation of the iterm vector with the quad this means that when you do fast your spins the itemm on the pitch axis will be transferred to the roll axis and while this can sound good in theory I&#39;ve done some testing of this and I&#39;ve found that in general these settings don&#39;t reduce pit error and in fact in some cases they actually increase it so I wouldn&#39;t recommend using either of these settings um particularly for ordinary freestyle flying some line of sight Pilots use iterm rotation absolute control um and find them beneficial but certainly in my testing I can&#39;t see anything in the logs that suggests that they&#39;re doing anything to help the tracking of the set point all right now it&#39;s time to move into some of the more advanced tuning topics including feed forward and dynamic damping don&#39;t forget that this information is available as a PDF document on my patreon you can join from just a few dollars a month and you&#39;ll get access to the entire guide for filters pids and rates as a PDF which you can then refer back to whenever you&#39;re tuning quads in the future I&#39;d really appreciate it if you consider joining up even if it&#39;s just for a couple of months to get hold of that guide and there&#39;s a link down in the video description now that we&#39;ve tuned Pi I and D it&#39;s time to take a look at feedforward but before we dive into tuning feed forward we have to make sure it&#39;s set up correctly and the best way to do that is using the the presets for all the different radio links so if you go into the presets Tab and you search for your radio link so I&#39;m on Express lrs so I&#39;m going to search for Express lrs you can see we&#39;ve got all of these different presets for the different Express lrs radio links I&#39;m using 250 HZ so I&#39;m going to select this one and I&#39;m going to go through the options I want to do HD freestyle I have a separate elrs receiver and I want single cell values for my voltage Telemetry and I&#39;m not going going to change my rates because I want to do my rates later that&#39;s another video once you&#39;ve got all those selected you can click pick and then save and reboot and that will apply the presets and will adjust all of the settings for both your radio link and for your feed forward settings which is what we want to adjust if you jump now into the pit tuning tab you&#39;ll see that in the feed forward settings all of these have changed the Jitter reduction smoothness averaging they&#39;ve all changed and Boost Max rate and transition have all stayed the same once you&#39;ve set up your radio preset correctly you can start to tune feed forward and to do that just return the stick response slider to about 0.5 or so and then gradually increase it and you&#39;re wanting to pay attention for a couple of things when your stick response slider of feed forward gains are far too low the quad is going to feel a little sluggish it&#39;s not going to feel like it responds to your sticks as quickly as you&#39;d like it to as you increase that feed forward slider the quad is going to feel more and more responsive and more and more locked to your sticks if you go too far and I mean you really do have to go quite far with feed forward you will start to see and hear an overshoot particularly at the start of a Sharp move and perhaps also you&#39;ll be able to see an overshoot at the end of a Sharp move as well that indicates that you&#39;ve gone too far and then you need to work the slider back it&#39;s much easier to see all of these effects in a blackbox log so what we have here is we&#39;re looking at stick tracking for a particular flight with two two little feed forward we have the gyro Trace in light blue and the set point in green so you can see the set point increases up to a level and the gyro sort of lags behind it we can also see that the motors are nowhere near maxing out at the start of the move so the quad isn&#39;t really trying to follow our sticks particularly hard because the feed forward isn&#39;t pushing into the move hard enough if we look at the end of a move you can see that at the end of the move the gyro also lags behind the set point significantly so the set points coming down our sticks are moving back to Center but the gyro isn&#39;t following that very closely it&#39;s lagging behind and that&#39;s because the p term and the D term they are all operating after the fact only feed forward knows what your sticks are doing when you&#39;re doing it if we increase feed forward too much we turn feed forward up to a really high level and you have to go you really have to go some to have too much feed forward you can see that the feed forward is spiking up really high at the start of a move and actually we&#39;re getting quite good tracking at the start of a move with feed forward that high and the motors are pushing a lot harder they&#39;re a lot closer to maxing out with feed forward that high but at the end of a move we have all sorts of problems at the end of a move we can see the motor is maxing out but then the gyro is sort of careering past the set point and we have this big overshoot and bounce back and that&#39;s because even when the uh the gyro is passing the set point feed is still pushing way too hard and the gyro is sailing past the set point and then we&#39;re getting a bit of overshoot and bounce back if we look at just the right amount of feed forward we can see what it should look like when it&#39;s absolutely perfect we have the correct stick tracking at the start of the move so the gyro is lagging slightly behind the set point maybe at the start of a move but it&#39;s not too bad and at the end of the move you can see we still have the motors maxing out but now the gyro returns nicely to the set point and then continues on so the performance overall is much much better that&#39;s kind of what we want to see when feed forward is correctly tuned when we&#39;re looking at a black box log there are some extra tools that we have available to us to help improve the performance of feed forward even a bit more the first is feed forward boost now what this does is it adds an element to feed forward based on the acceleration of your sticks and this helps get feed forward moving even more quickly at the start of a fast move if you&#39;re seeing in your log that the gyro is lagging behind the set point at the start of the move but then catching up later on it&#39;s definitely worth adding some additional feed forward boost to help correct that a bit more feed forward boost will accelerate how quickly feed forward ramps up and therefore help the gyro track the set point at the very start of a fast move if you&#39;re seeing the gyro getting ahead of the set point at the start of a fast move but it corrects later on that is definitely an indication that you have too much feedforward boost and you should reduce it a bit that will kind of tame the start of the move and allow feed forward to ramp up at just the right rate to give you good stick tracking the default of 15 for feed forward boost is pretty good for most cases but if you do see your gyro lagging boost it up a bit increase it and if you do see your gyro getting ahead of your set point but then it&#39;s correcting later on then it&#39;s worth decreasing feed forward boost feed forward has another tool called Max rate limit and what this does is it cuts feed forward to zero as your sticks approach maximum deflection this helps avoid the situation where feed forward is pushing all the way up until your sticks hit their limits and then your quad overshoots because you&#39;ve got this sudden stop where the stick is hitting its maximum deflection what this is really useful for is if you&#39;re in the situation where you&#39;ve got the right amount of feed forward so that the end of a move looks really nice you&#39;ve got the motors maxing out and then it returning nicely to the set point so this is looking really good but you&#39;ve still got a bit of lag at the start of a move and you can see that feed forward is being cut off before the uh before the gyro has quite track the set point all the way increasing the max limit can allow you to have this feed forward keep pushing for a bit longer help keep that gyro tracking a bit close to the set point and then it&#39;ll back off just before the uh the gyro needs to track the set point through this transition where it goes from increasing to Flat the more responsive your quad is the higher you can increase the max rate limit to tighten up the start of a Sharp move like this um the default 90 is fine but you can definitely try increasing that to 92 95 and that will help tighten up the start of a really sharp move if you&#39;ve got a responsive quad now let&#39;s talk about Dynamic damping Dynamic damping is an advanced feature in betaflight that allows you to dynamically boost or increase the dterm on Sharp moves while keeping the DM at a lower value during normal flying this can help you to tame overshoot caused by high feed forward allowing you to push your feed forward gains higher and get better stick tracking or it can be used to reduce the dterm during normal flying to help reduce motor heating you need to tune the dynamic damping gain so that the dterm boosts up to maximum on Sharp moves but sits at its minimum value during normal flight and this can only really be tuned with blackbox logs the gain of 37 which is default is a pretty good starting point Dynamic damping advanced should always under all circumstances be set to zero we know that in the PID controller the derivative term is based on the gyro the signal for the derivative term comes from the gyro and the signal for the feed forward term comes from the set point Dynamic damping Advanced for some reason that I do not understand adds some component of the set point into the derivative term you don&#39;t want this you want to keep the derivative term based only on the gyro so leave Dynamic damping Advance set to zero to tune Dynamic damping you&#39;ll want to set your blackbox logging debug mode to D Min and then in the logs in blackbox Explorer you&#39;re going to see the actual D term on roll and pitch and also the gyro factor which is determining how the dterm is boosting up and down you&#39;re also going to want to return your Dynamic damping slider to 1.0 when you&#39;re doing a tuning flight do some normal flying and then do some moderate and sharper moves you want to set your Dynamic damping gain so that the dterm does not boost up at all during normal flight so it&#39;s just sitting there at its base value you want to see your dterm Boost a little bit on moderate moves and you want to see your dterm max out on the sharpest moves and that shows that you&#39;ve got your Dynamic damping gain set just right once you have your Dynamic damping gain set right there are two ways that you can use it the first is to enable higher feed forward gains for more responsive flight feel and better stick tracking to do that you&#39;re going to use Dynamic damping to boost the dterm in situations like this so here&#39;s an example where we have high feed forward we&#39;ve got the gyro coming back towards the set point and overshooting because we&#39;ve got too much feed forward and the gyro is just flying past the set point you can use Dynamic damping here to boost this dterm to help tame this overshoot and bring the gyro back to the set point without it over shooting and bouncing back that&#39;s one way you can use it it&#39;s going to allow you to push your feed forward gains higher to do this what you&#39;re going to want to do is you&#39;re going to want to increase this Dynamic damping slider until the dterm is boosting high enough to tame that overshoot what you&#39;re going to want to listen for is dterm oscillations on fast moves which is showing that your dterm is boosting so high that it&#39;s amplifying noise and causing oscillations but provided you&#39;re not hearing any of that and your Motors are staying reasonably cool then it&#39;s okay to increase this Dynamic damping slider to tame that overshoot on fast moves the second way to use Dynamic damping is to use it to reduce your dterm during normal flying so you want your dterm boosting up to a good value during fast moves but sitting at a lower value during normal flying and the way you&#39;re going to do that is you&#39;re going to look at what your derivative value is that you found from your PD balance tuning and you&#39;re going to want to reduce your damping gains your Dain gains and increase your Dynamic damping so that your dmax is equal to your derivative term that you had before so here we have Dynamic damping at zero and a dmax of 45 and a derivative term of 45 we turn our dains down a bit we turn our Dynamic damping up and now we have a dmax that&#39;s still 45 but our normal derivative term during normal flying is only 33 so we&#39;ve reduced that Dain during normal flying that&#39;s going to help reduce motor heating keep Motors cooler this is particularly useful for applications like racing where you&#39;re high in the throttle all the time and you need to do everything you can to keep your Motors cool now let&#39;s take a look at some of the other settings starting with throttle boost now this works similarly to feed forward boost it adds a component to the throttle value based on the acceleration of your throttle stick so if you move the throttle stick very very fast throttle boost will add a bit to the throttle to help the quad pick up more quickly and reduce the delay when you suddenly get on the throttle if you&#39;re feeling like there&#39;s a bit of lag when you hit the throttle then it might be worth increasing throttle boost and seeing if that helps resolve the issue the next setting is motor output limit and what this does is it reduces the maximum motor Drive value that betaflight can ever send to your ESC and this allows you to use 4S motors with a 6S battery and to do that you would set your motor output limit to 66% because you&#39;re running a 4S motor on a 6S Pack 4 over 6 is 66% if you&#39;re running 3s Motors on a 4S battery that motor output limit should be set to 75% vbat sag compensation is a pretty interesting setting what it does is it reduces the maximum motor drive when the battery is fully charged and increases it gradually as the battery voltage Falls this gives a very consistent flight performance over the entire life of the battery but it does it by reducing the performance when the battery is fully charged to the same level that it&#39;s going to be at when the battery is empty this makes it very very difficult to know that your battery is discharging because the quad feels exactly the same so use this with caution as it&#39;s very easy to over discharge your batteries you&#39;ll want to set up some other warning that your battery voltage is low typically if you&#39;re going to use vbat sag compensation you&#39;re going to set it to 100% thrust linearization is another interesting setting this boosts the motor drive at low throttle values so if your ESC doesn&#39;t provides much torque at low throttle thrust linearization boosts it up this is very useful for improving responsiveness and stick tracking at low throttle particularly for small quads like tiny whoops that are using ESC pwms of 48 khz or higher and they typically have low torque at low throttle if you&#39;re going to turn thrust linearization on the default value of 20% is usually pretty good for tiny whoops all right so that brings us to the end of the pit tuning section of my betaflight 4.5 tuning guide you should now have a quad that is really tightly locked to your sticks and might even feel a bit too sharp if that&#39;s the the case don&#39;t worry because we are going to address that in the next video where we&#39;re going to be looking at our rates if you want to make sure that you see that video as soon as it comes out make sure you like this video subscribe and hit the notification Bell and then follow along with me while we get our rates tuned to Perfection so that you have that buttery smooth stick feel that&#39;s all I have for you for today so until next time I wish you all very very happy [Music] flying

Transcript for:Enhanced Quad Tuning Techniques Overview

Transcript for:
Enhanced Quad Tuning Techniques Overview