Increasing Payload Capacity of Wearable Robots Using Linear Actuators

Wearable robots for carrying heavy loads in an industrial field should be able to carry a load over their entire range of motion. The payload capacity of a wearable robot employing rotary actuators or linear actuators at the knee joints decreases drastically in the knee-flexion posture, because the moment arm of gravity increases and the moment arm of the force generated by the linear actuators at the knees decreases after a certain point. To resolve this issue, this study proposes two types of sublink mechanisms for the knee joints. With only a few modifications to the existing knee-joint configuration, the moment arm in the knee-flexion posture is increased and the payload capacity is effectively increased, and thus, enabling robot pilots to squat down and stand up with heavy loads. The proposed mechanisms were simulated and tested with a wearable robot, and their effectiveness was verified.