Feedback control of a pneumatically driven soft finger using a photoelastic polyurethane bending sensor

摘要

In recent years, pneumatically driven soft-fingered hands constructed from polymer materials have been developed to grasp variously shaped objects. In general, the motion-control ability of these hands is limited to grasping objects. A dexterous manipulation requires pinching and in-hand manipulation. However, this is difficult because soft-fingered hands face two major problems of low positioning accuracy and vibration during high-speed motion. These problems can be solved with feedback control by using a soft sensor that does not impair finger softness. This study proposes a pneumatically driven soft-finger system with a soft-position sensor formed from photoelastic polyurethane that measures the soft-finger curvature through changes in the light intensity. A sensor feedback control for the soft finger is also established in this paper. Consequently, in a series of basic experiments, the sensor feedback control achieved precise positioning and continuous accurate path tracking. Finally, pinching motions and object orientation control were achieved by accurate continuous-path control of two soft fingers.