High Specific Power Actuators for Robotic Manipulators

Recent advances in actuator technology suggest that the implementation of reliable, high power-to-weight ratio pneumatic actuation systems is now possible for robotic platforms. Current robotic manipulator arms for casualty extraction and patient placement use hydraulic actuation, whereas related robotic prosthetic devices use large, heavy actuator motors. We have developed an alternative solution to robotic manipulation that employs pneumatic artificial muscles (PAMs) to generate desired joint torque and range of motion. The goal of this study is to determine the size and configuration of a robotic manipulator for battlefield casualty extraction. Following characterization and comparison of different-sized PAM actuators, a prototype of a PAM robotic manipulator arm was constructed. A quasi-static model for the PAM actuators is applied to system modeling. This model includes the Gaylord force from pressure effects on the braid, as well as a nonlinear Mooney-Rivlin term that considers the elastic energy of the bladder. Experiments are performed to measure joint torque over the manipulator range of motion. The model developed here is experimentally validated.