Armor-Based Stable Force Pneumatic Artificial Muscles for Steady Actuation Properties

In this article, a novel actuator called armor-based stable force pneumatic artificial muscle (AS-PAM) is presented. AS-PAM has a sealed chamber made of polygonal parts and film, which helps the actuator to be lightweight (similar to 100 g) and achieve a large contraction ratio (>60%). It has an armor and a constraint to guide its motion, which keeps its force output [6.25 N/(cm(2)center dot bar)] stable over its operating range (<10% deviation). An analytical model is presented to predict and control the behavior of the actuator, and various experiments were conducted to show the validity of the model. Afterward, a gripper using the actuators is presented to illustrate how it can be used in real applications. With its characteristics, the actuator shows interesting behaviors that cannot be found in other soft pneumatic actuators, and it would allow AS-PAM to expand the range of applications in which soft robots cooperate with humans.