Motion Sensors

Using accelerometers, gyroscopes, PIR sensors, and ultrasonic rangefinders.

Motion sensors detect movement, acceleration, rotation, and proximity. From MEMS accelerometers in smartphones to PIR sensors in security systems, motion sensing enables countless applications.

Objectives

  • Understand MEMS accelerometer and gyroscope operation
  • Interface accelerometers for tilt and vibration sensing
  • Use gyroscopes for rotation rate measurement
  • Design PIR-based motion detection circuits
  • Implement ultrasonic distance measurement

Key Takeaways

  • Accelerometers measure acceleration including gravity
  • Gyroscopes measure rotation rate, integrate for angle
  • Sensor fusion combines strengths of both sensors
  • PIR detects warm moving objects
  • Ultrasonic measures distance via echo timing