PowerGrasp: Concept for a novel Soft-Robotic Arm Support System

This paper presents a novel concept and first modules for a soft-robotic arm support system for application in overhead assembly in automotive industry. Repetitive manual tasks and associated body movements are still typical in industrial assembly jobs. Even without an additional load or tool, such tasks are monotonous and often lead to stress in the musculoskeletal system, which frequently causes pain and injuries. In light of ageing industrial workforce, solving this problem becomes a major challenge for ergonomics researchers and engineers. In this paper we present a novel active soft orthotic device which is not an exoskeleton, even though there are some similarities. It is designed to induce only moderate external forces into the human skeleton for muscle fatigue compensation, without causing harm. The concept involves different soft-robotic actuators, depending on the human arm joints to be supported, as well as concepts for control, energy storage and sensors. By detecting muscle fatigue of the worker we created an active assist-as-needed system, which has advantages in energy consumption on the one hand and prevents muscle atrophy of the worker on the other hand. To fulfill these requirements we developed pneumatic actuators, which adjust themselves to the user without external calibration. This automatic calibration process requires no special knowledge of the employees and takes place only by using separated pneumatic chambers and adjustable straps and buckles. By using strain gauges and inertial measurement units, as well as pressure sensors and force sensors we measure and analyze all necessary information for the position related force control in real time. We also present first evaluation results with static overhead retaining tasks.