Wearable sensors

Advances in sensor-based technologies have led to the widespread use of wearable sensors, like accelerometers, gyroscopes and inertial measurement units, for the assessment of human biomechanics and equipment design. Accelerometers are devices that directly measure linear accelerations and, hence, overcome the problems associated with using displacements or forces to indirectly derive these data. Gyroscopes are another common sensor type and are designed to specifically measure angular velocity. In many applications, biomechanists may also be interested in using the angular velocities that are measured with gyroscopes to mathematically derive angular positions (orientations). Accelerometers and gyroscopes are available as uni-axial, bi-axial or tri-axial devices, meaning that they can measure linear acceleration and angular velocity along or about one, two or three axes of motion. Rapid miniaturisation of such technologies has now made it possible to combine tri-axial accelerometers, gyroscopes and magnetometers (sensors that detect and measure magnetic fields) in a single, yet small, wearable measuring unit. Such wearable units are collectively known as inertial measurement units or IMUs and are fast becoming an alternative means for assessing the biomechanics of human motion and equipment design.