Design of Orthotic Devices Presenting Tick-Tick Feedback through Periodic and Discrete Braking Force

Abstract

Sensory cues regarding body movement are crucial for motor learning, such as skill acquisition and rehabilitation. Accurately and precisely grasping the cues is challenging for learners with limited somatosensory, especially when the vision is obstructed. This study presents an orthotic device that provides rotary switch-like clicking (tick-tick) feedback according to knee joint flexion to augment the sensory capability. We design the 2-link 1-joint device with an electromagnetic brake to generate the frictional force of the joint according to the angle formed by the links. The first experiment showed up to 4-N of the friction force. The second experiment studied the effects of the tick-tick feedback on motor learning, in which participants remember and regenerate the knee motor task visually displayed. Although no statistically significant effects were found, the results suggested several insights and future directions for device and experiment designs, including suppression mechanism of the device misalignment, task difficulty level adjustment, and adoption of skeletal detection methods using optical tracking.