Development and control of 7-DOF artificial muscle manipulator considering redundancy

Recently, a robot´s activity has been spreading into the care setting and homes. For these robots to work alongside humans requires them to have the same flexibility as that of the human muscle and ensure safety even if they collide with humans. To satisfy these requirements, we examined pneumatic artificial muscles-which are not only provide high output but are also light, flexible, and safe-as robot actuators. However, the commonly used McKibben-type artificial muscles have several drawbacks. Therefore, we developed straight-fiber-type artificial muscles, which have a contraction ratio and force that surpasses those of McKibben-type artificial muscles. We also developed a 6-DOF manipulator that is actuated by straight-fiber-type artificial muscles. However, since the DOF of this manipulator is less than that of the human arm, it is difficult for the end effector to make detailed movements. To solve this problem, we developed a 7-DOF manipulator, introducing a new mechanism in the joints. In this paper, we introduce a new restraint condition to the inverse kinematic computation of this manipulator and propose the method of redundancy use. Finally, we conduct an experiment following the trajectory and verify the effectiveness of the proposed method.