Verification of linear approximation model of McKibben Pneumatic Actuator

A McKibben-type pneumatic actuator (MPA) has been widely used for various robots, and dynamic motion with MPA has been realized with a simple control method. However, motion analysis of robot using MPA has not been done enough yet due to complicated output characteristics of MPA. The purpose of our research is to establish a motion analysis method of a robot using MPA to realize more dynamic and stable movement. For that purpose, in this paper, we propose a new model of MPA suitable for motion analysis which is not too complicated. The proposed model is derived from linearly approximating the model proposed in our previous study about the length of MPA, and its coefficient can be theoretically obtained. First, verification experiments of the proposed model were performed on MPA of three lengths, and it was confirmed that the correlation coefficient between the proposed model and experimental results was sufficiently large. Next, we verified the effectiveness of the proposed model when the model was applied to an actual robot.MPA was mounted on a two-dimensional leg robot, realizing bending and stretching exercise was performed. It is confirmed that high tracking performance could be realized by pressure inputs design based on the proposed model. The results of these verification experiments indicate that the proposed model is sufficiently effective.