hi welcome back to engineers escape my name is Jake and today or on part 2 of our build a camera drone series how it flies flight mechanics and components of a quadcopter unmanned aerial system let's go [Music] if you haven't already make sure you check out part 1 the introduction and overview and also be on the lookout for part 3 where we're going to be ordering the components before we start building our quadcopter it's a good idea to have some basic understanding of how I work so let's go over to the white board and get started so what is a drone a drone could also be called a UAV which stands for unmanned aerial vehicle an aircraft piloted by remote control or on-board computers so we know what a UAV is what is a UAS UAS stands for unmanned aerial system so basically includes the drone and everything else like the radio and the goggles what's a rotor a rotor is a generic term for something that spins or rotates in our case they will be the propellers that will create thrust and lift so what's a quadcopter a quad quadcopter quadrotor is a specific case of a multi rotor that has four propellers thrust lift and torque thrust thrust is a pushing force and can be acting in any direction lift is a force that directly opposes the weight of the aircraft so gravity will try and bring it down the force of weight and lift will keep it up in the air torque is a twisting force that tends to cause rotation and I think people might not have as good of an understanding of torque as they do these other two so let's talk about that a little bit more Newton's third law says that for every action there is an equal and opposite reaction an example of this would be holding an eraser for every action the weight of the eraser pushing down on my hand there is an equal and opposite reaction by hand pushing up on the eraser and this keeps it still Newton's third law also works for torques in this example we have a top-down view of a helicopter have you ever thought about why a helicopter has a tail rotor in this example the propellers are spinning this way that is the body is applying a rotational force on the propellers this way so according to Newton's third law the propellers will also be rotating the body the opposite direction so the body is going to want to try to rotate this way this is why we have the tail rotor the tail rotor will apply a force to the body of the helicopter to prevent it from spinning this concept of torques and balancing is going to be important in understanding how the quadcopter works the rusts lift and torque are all generated by spinning rotors more rpms create more thrust and torque for each rotor for simplicity we are going to be ignoring drag we're going to assume that the center of gravity CG is centered on the craft and we're going to assume that the quad is not moving at the start of all maneuvers or the velocity equals zero this is our quad X setup so here are our four motors you'll notice they're numbered 1 2 3 & 4 also notice that the red arrow in the middle is facing towards the front of the quad you'll also see the directions that the propellers are spinning so Motors number 4 and number 1 spin clockwise and motors number 2 and number 3 spin counterclockwise also note that the radio we're using is going to be a mode 2 radio the first move we'll talk about is hovering hovering means it's staying in the same place in the air and we're going to assume at a 50% throttle that our craft will be hovering the amount of RPMs each of the propellers is getting is going to be denoted by the fraction of the circle that's filled in with green each of the four motors are at 50% rpm the important thing about hovering is that a total lift generated by all four propellers is equal to the amount of weight of the copter the quadcopter will also not be rotating in any direct because the two clockwise motors are going the same speed as the two counterclockwise motors cancelling out the torques to ascend you'll increase the throttle to all four motors equally this will make the lift greater than the weight and the craft will rise into the air to descend you'll do the opposite pitch means when the copter tilts forward or backwards in this example we're going to have the copter pitching forwards so if we look over here at our diagram the front two motors have spun down and the back two motors have spun up since the two back motors have a greater lift than the front this will cause the craft to tilt forwards again the torques in this example also equal out so we will have no yawning since the quad is now tipped forward some of the lifts will be changed into forward thrust and propel the quad forward in order to pitch the craft forward use the right stick and push it upwards to pitch back use the right stick and push backwards roll means to tilt the copter left or right in this example we're going to be showing left roll you can see here that the left two motors have spun down and the right two motors have spun up the right two motors will be creating more lift than the left two motors this will cause the quad to roll left and again the torques cancel out now that the quad has rolled left some of the lift will be changed into thrust and cause the quad to travel to the left in order to roll we're going to be using the right stick you push that left to roll left or right to roll right yaw means to change the direction at the front of the craft is facing so you could lot yaw left or y'all right in this example we're going to be on to the left the two counterclockwise motors are spinning slower than the clockwise motors this creates an imbalance in torque and if you remember from Newton's third law if these ones have more torque and they're spinning this way then that means the body is going to want to try to rotate the opposite way and this will cause the body to yaw to the left to yaw to the left push the left stick to the left to y'alright push the left stick to the right now let's look at the drone components in the unmanned aerial system the flight controller is the brain of the drone it keeps it in the air and also talks to other components the radio transmitter or the remote control will send our commands from here over to our receiver abbreviated as our X and that will tell the receiver will tell the flight controller what we want to do the electronic speed controller or ESC takes the signal from the flight controller and tells the motor how fast to spin there are four esc s and motors on a quadcopter but for simplicity I'm only drawing one the GPS usually also has a compass module this sends location data to the flight controller and also heading data the first-person view camera will take video from the quadcopter in real time and send it to the flight controller which has a built-in on-screen display what the on-screen display does is it takes flight data and overlays it on the video so we can read it in real time it takes this video with the overlaid information and sends it to the video transmitter which transmits it through the air which is received by a power VR X or video receiver also known as goggles so that we can monitor it you can also have a DVR or digital video recorder if you want to save that real-time footage the battery supplies the flight controller and other components of power this little guy right here is the capacitor the capacitor cleans up dirty power signals to prevent interference this flight controller doubles as a power distribution board or PDB and what that means is that instead of having to solder all the components power to one pad there's spats throughout the flight controller to make it easier to solder what it also does is it takes the battery voltage say eleven point four volts and will reduce it down to different voltages for these smaller components such as five volts and maybe 3.3 volts when the battery needs recharge we'll put it on the charger the charger also has another task which is putting batteries in storage mode and we'll talk about that more later on our drone we're also going to have an HD camera and a gimbal the gimbal stabilizes the HD camera footage an HD camera of course is the video we're going to be showing everyone that looks nice we can also control the gimbal by hooking it up to the receiver we now have a basic understanding of some of the components so let's talk about some of the sensors that help the quad fly the first sensor is the IMU or inertial measurement unit this actually has two different sensors one is the accelerometer which measures the force exerted on the quad the linear force the next is the gyroscope which measures the rotational motion of the quad these two sensors only measure the linear and rotational forces on the quad in other words it doesn't currently know where it's at and it also doesn't know where it's currently rotated it doesn't know if it's straight up and down or upside down with those sensors barometer is the next sensor a bar is a unit of atmospheric pressure so this measures that miss feared pressure since atmospheric pressure decreases with an increase in altitude the barometer is actually used to tell us the altitude of our quadcopter the volt meter is used to measure the battery voltage the current sensor measures the current power equals current times voltage or if you want to think of it in terms of units watts equal one amp times one volt if you keep track of the power used over time you can also display watt hours which will tell you how much energy has been used from the battery or milliamp hours which will tell you how much charge has been used for the battery the compass or the magnetometer works by sensing Earth's weak magnetic field and that will tell us the heading of the drone in other words if it's facing north east south or west GNSS stands for global navigation satellite system this includes GPS from the United States and also GLONASS from Russia and there's also some other smaller ones like Galileo people usually call the GNSS just GPS because that's the one that's typically included and ours will have receivers for both GPS and GLONASS based upon its position of multiple satellites in the sky we can determine our position speed and to a lesser extent our altitude all right guys I hope you found that video helpful if you did I'd appreciate it if you left a like and if you'd like to see more videos like this be sure to subscribe also if you haven't already be sure to check out part 1 the intro a no review and be on the lookout for part 3 where we're going to be ordering the components thanks for watching [Music]