Accelerometers and gyroscopes are both motion-detecting devices.
Accelerometers detect linear motion (acceleration along an axis).
Gyroscopes detect angular velocity (how quickly an object is turning) using the Coriolis effect.
Neither device reports current speed or angle, only acceleration or rate of turn, requiring integration over time for those values.
Inertial Measurement Unit (IMU)
Both accelerometers and gyroscopes are typically packaged together in an Inertial Measurement Unit (IMU).
IMUs may include additional sensors beyond just accelerometers and gyroscopes.
IMUs utilize Microelectromechanical Systems (MEMS) for compact sensor integration.
Components of Accelerometers
Accelerometers using capacitive sensing consist of:
Proof Mass (Seismic Mass): An H-shaped structure that can move back and forth.
Electrodes: Stationary structures fixed in the substrate that do not touch the proof mass, forming a comb-like structure with it.
Principle of Capacitive Sensing
Capacitance occurs when two objects are close but not touching.
Factors influencing capacitance include the distance between the plates.
A differential capacitor is formed by a middle plate (proof mass) and two stationary plates (electrodes):
Changes in charge due to movement lead to variations in capacitance.
As the accelerometer moves, capacitance on one side increases while it decreases on the opposite side.
Signal Processing
Changes in differential capacitance are:
Recorded.
Passed through:
Charge amplification
Signal conditioning
Low pass filtering
Converted to a digital signal using an Analog-to-Digital Converter (ADC).
Multi-Directional Sensing
To detect motion in multiple directions, sensors must be oriented at 90-degree angles to each other.
This configuration enables detection of motion in all three dimensions.
Practical Application
Demonstration with an MPU6050 attached to an Arduino Uno:
Outputs acceleration data to a laptop.
Shows acceleration due to gravity and responses to movement.
Data processing logic is essential for real analysis.
Impact of Technology
Microscopic sensors are:
Small.
Low power.
Inexpensive.
Accurate.
Now integrated into a wide range of devices, originally in robotics and automobiles, now in most smart devices.
Conclusion
Understanding accelerometers and gyroscopes, their physics principles, and real-life outputs allows greater insight into their functionalities and applications.
For further resources, visit CircaBread.com for study guides and engineering content.