A Pneumatically Driven Arm Muscle Training System Realizing Wide Motion Range and Large Moment Arm

Machine-human interaction training systems have been proposed to improve muscle workout efficiency by guiding the user with an ideal motion trajectory to maximize the exercise result while applying appropriate load. However, most of these systems have flaws such as unnatural movement, additional weight through the device, bulky, or usage environmental constraints. This study proposes a novel pneumatically driven arm muscle training system. It uses pneumatic artificial muscles (PAMs) to induce an elbow flexion moment which loads on the trainee's triceps during exercise. A rail system is installed on the lower arm to allow for adapting position change of the PAM's anchor point to increase the device's motion range and moment arm. This mechanism increases the applied moment on the lower arm and the system's effectiveness. We confirmed the developed device's performance through the experiments. As a result, the system shows to resemble a reference exercise, the push-down workout, in many ways. The proposed mechanism has been confirmed to provide periodic loads of up to 21 Nm to the target triceps, effectively activating muscle activity over a wide range of motion from 0 to 80 deg. This study can serve as a basis for further improvement of the soft exoskeletal training device.