Motion and Position Sensors

• MEMS accelerometer — measures acceleration including gravity, so it gives tilt when still.
• Gyroscope — measures rotation rate (°/s); integrating it gives angle but drifts.
• Magnetometer — senses Earth's field for heading (compass).
• An IMU combines them (MPU-6050, ICM-20948, BNO055); a sensor-fusion filter (complementary or Kalman) merges fast gyro data with drift-free accelerometer/magnetometer data.
• Rotary encoders — incremental (A/B quadrature pulses) or absolute.
• Hall-effect sensors — detect magnetic fields: motor commutation, speed sensing, contactless current sensing.

Complementary filter:

angle = 0.98 * (angle + gyro_rate * dt) + 0.02 * accel_angle;