Sensor-equipped Joint Design for Accurate Trajectory Tracking in Soft Robots

This study presents the design and experimental validation of a novel sensorized joint (SJ), specifically developed for soft robotics applications, including robotic fingers, manipulators, and synthetic limbs based on rigid segments connected by flexible joints. The proposed joint integrates highly accurate bending sensors while incorporating a structural design that minimizes unwanted movements such as buckling and torsional deformation, favoring pure in-plane bending. A dedicated test bench was used to evaluate the joint mechanical stability, durability and robustness under cyclic loading and external disturbances. Experimental results confirmed that the joint maintains in-plane pure bending, drifting during repeated measurements drift was estimated to be less than 1/1000 cycles and measurement standard deviation remained within a ± 2° range, primarily due to test bench induced uncertainties rather than sensor inaccuracies. These findings indicate that the new joint design enhances trajectory tracking reliability, making it a robust solution for precisiondriven soft robotic applications.