Sensor evaluation for soft robotic hand rehabilitation devices

Developing a compact sensing system is important for controlling the joint coordination of wearable soft robotic hand rehabilitation devices. Flexible skin attachable sensors allow compact measurement of the finger and distal thumb joint (interphalangeal joint and metacarpophalangeal joint) angles. For accurate and reliable measurement of the joint angles, appropriate flexible sensors should be selected, which give stable measurements and have sensitive response with respect to the joint angle. In this study, the performance indices of two types of flexible stretchable sensors (carbon nano-tube pattern sensor and silver-nano sensor) and two type of commercial bending sensors (Bend Sensor® and Flex Sensor®) are compared. A plastic test bed was designed to collect the sensor signal respect to the bending angle. The sensitivity, relaxation, repeatability and hysteresis of each sensor were investigated and compared, and eventually a suitable sensor for soft robotic hand rehabilitation device is proposed.