Which sensor type is used to measure motion or orientation in assistive devices?

• A. EMG sensors
• B. IMUs
• C. Pressure mapping sensors
• D. Force sensors

Answer: (B)

Understanding motion and orientation in assistive devices relies on sensing how things move and rotate. An IMU, or inertial measurement unit, is the sensor that does this by combining a accelerometer (measures linear acceleration) and a gyroscope (measures angular rate), and often a magnetometer to help determine absolute orientation. Together, these measures let the device track tilt, rotation, and movement in three dimensions, which is essential for controlling a powered prosthesis, tracking posture, or enabling dynamic wheelchair or exoskeleton responses.

EMG sensors measure electrical activity of muscles, not movement itself. Pressure mapping sensors reveal how pressure is distributed across a surface, useful for seating and load distribution but not motion. Force sensors measure contact force or torque at a point, not the overall motion or orientation. So the sensor type that best provides motion and orientation data is the IMU.