Study on Force Control of Pneumatically Driven Arm Motion Assist Suit

Machine-human interaction systems have been proposed to improve motion learning efficiency by providing feedback on motion misalignment between a learner and an instructor. We developed a pneumatic-driven motion teaching system that provides feedback to the learner by simultaneously presenting visual and torque information. We achieved a lightweight, soft, and user-safety haptic system using pneumatic artificial muscles (PAMs) as actuators. PAMs’ shrink force generates external torque on the learner’s joint to correct the elbow flexion and extension motion misalignment between the instructor and the learner. However, accurate force control is difficult due to loosening of the suit and modeling errors of the PAMs. In this study, a novel 2-DOF force tracking control method using a force sensor was developed for PAM-driven assistive suits. The proposed method compensated the driving delay of PAMs and improved the accuracy of the force tracking control of the assistive suit compared to the only feedback control methods.