Retrofitting Soft Assistive Robots with Sew-Free Sensing Garments for Joint Motion Tracking and Kinematic Feedback

Tracking human movement is essential during robot-assisted rehabilitation to provide kinematic feedback for monitoring range of motion, counting repetitions of a certain movement, or achieving closed-loop control. Current strategies for tracking and analyzing human motion, however, are costly, not easily accessible, or challenging to integrate with existing soft assistive robots. In this work, we present skin-tight sensing garments using commercial flex sensors that can be rapidly manufactured using a sew-free lamination strategy. We designed and fabricated sensing garments that can be worn underneath an existing soft robotic wrist orthosis to provide kinematic feedback on flexion and extension of the wrist. We conducted preliminary experiments and demonstrated that our sensing garment can track the position of the wrist with less than 5° of root mean squared error (RMSE) when compared to motion capture. We also demonstrated that our garment design and fabrication approach can be easily extended to other joints and rehabilitation devices to track uniaxial motions by developing a sensing garment for the index finger to provide kinematic feedback when used with a commercial soft rehabilitation glove. Our sensing garments are easy to manufacture, consist of inexpensive and readily available materials, and show promise as a method for providing real-time kinematic feedback of the user during robot-assisted rehabilitation activities.