Sensorizing Flexible Joints for Soft Robots: A Feasibility Study

This paper presents the development and feasibility study of a supernumerary sixth finger, an assistive device designed to restore grasping capabilities in individuals with paretic hands, enhanced by proprioceptive feedback. The prototype incorporates soft joints equipped with highly reliable and linear sensors to monitor the bending angle of the artificial finger, allowing precise trajectory tracking and improved grasping functionality. The robotic device incorporates accurate sensor-equipped joints (SJ) for bending angle measurement, with measurement errors consistently below 2 degrees, and high durability, with a drift of less than 1 degrees per 1000 cycles and a lifespan exceeding 3500 cycles. The sensing mechanism employs a layered structure with two metal strain gauges positioned on a nylon screen mesh (SM), forming a Wheatstone bridge configuration for optimal measurement. This design approach ensures reliable sensor performance, enhanced durability, and minimized mechanical creep, making the sixth finger a promising solution for improving assistive grasping technology