Consideration of PAM actuator in Robotic Systems through Mimicking Human Shoulder Complex

Abstract

The shoulder complex is often presented as the system that has the highest degree of freedom(DoF) in the human body. It consists of the clavicle, scapula, and thorax allowing the arm to perform a large range of the motion. However, in case of the robotic systems, the shoulder complex is often kinematically simplified or substituted to other mechanisms because a complexity of musculoskeletal system compromises engineering plausibility. Nevertheless, in the muscular systems, the shoulder complex allows the muscle overcome its contraction ratio.

Moreover, the pneumatic artificial muscles(PAMs) has been evaluated as the most similar actuators to the human muscles. When pressurized air is applied, it swells up and contracts. The PAM is faster and lighter than other actuators because the power source is air. For this reason, the PAM actuator obviously has advantages to utilize to robotic system.

In this thesis, an upper body that mimics the musculoskeletal system was designed including the shoulder complex. To emphasize the lightness, opened-ball joints and deformable membrane are chosen instead of bearing and validated driving by the PAMs arranged similarly to muscles in human body.