Posture control of redundant manipulators based on the task oriented stiffness regulation

This paper investigates the posture of a manipulator that has redundant DOF similar to human upper extremity. The human arm naturally takes a posture with no wandering although it has some redundant DOF. The authors consider that the posture will be determined task-oriented, which means that human unconsciously takes posture of his/her upper extremities, which is suitable for the task that the endpoint about to do. This study also assumes that all or some joints are capable to adjust the joint stiffness so that the stiffness of the endpoint in the task space is also adjustable. Hence our study aims to establish the way to make the manipulator take a posture that provides a stiffness of the endpoint suitable for the task. The new control formula for shaping the manipulator´s posture to provide a desired stiffness of the endpoint is presented followed by the simulation study to verify it.