A Pneumatically Driven Arm Motion Teaching System Using Visual and Torque Feedback

Machine-human interaction systems have been proposed to improve motion learning efficiency by providing feedback on motion misalignment between a learner and an instructor. Conventional motion teaching systems based on haptic information presentation generally use electrical sensors and motors, which causes the exoskeleton suit weight and the scale of the entire system to become large. In this study, we proposed a pneumatic-driven motion teaching system that provides feedback to the learner by simultaneously presenting visual and torque information to the learner. 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. We conducted a motion teaching experiment to verify the effectiveness of the proposed method. Specifically, we performed motion instruction on eight subjects using three patterns: a visual-only presentation method, a conventional method that simultaneously presents visual and vibrotactile presentation, and the proposed method that simultaneously presents visual and torque. The experimental results showed that the proposed method reduced the angle and angular velocity tracking errors compared to the visual-only method and visual-vibrotactile method.