Analysis of Autonomous Coordination Between Actuators in the Antagonist Musculoskeletal Model

Abstract

The McKibben Pneumatic Actuator (MPA) is well-known as a type of soft actuator. As MPA generates tension only in the direction of compression, it is necessary to construct an antagonistic structure to drive a joint by MPAs and to coordinate antagonized MPAs. Similar to MPA, muscles in animals also generate tension only in the direction of contraction. Some studies have reported that animals utilize tension information to coordinate muscles for various autonomous movements. The purpose of this study is to realize autonomous cooperation between antagonized MPAs by applying tension feedback control and analyzing the mechanism of coordination. For this purpose, we verify the effect of tension feedback control on the 1-DOF pendulum model with antagonized MPAs. First, through numerical simulations, it is confirmed that the tension feedback generates various coordinated movements of antagonized MPAs, and the pendulum exhibits a bifurcation phenomenon based on the phase difference of the inputs of MPAs. Thereafter, we develop an actual experimental machine based on the model and confirm the autonomous cooperation between actual MPAs through verification experiments similar to the numerical simulations.