Experimental setup of a novel 4 DoF parallel manipulator

Abstract

Parallel manipulators (PM) started with the introduction of architectures with 6 Degree of Freedom (DoF), but a vast of applications require less than 6 DoF. In this respect, architectures for 3 and 4 DoF PM have been proposed. With respect to the 4 DoF most of the robots that have become prototypes are the kind of three translation and one rotation (3T1R) or 3R1T, yet relatively 4 DoF manipulators of the class 2R2T have been built. In this paper the stages for designing and prototyping, including the control architecture design of a 4 DoF PM with 2R2T are put forward. The choice of the DoF is based on the necessary motion for fulfilling the tasks for diagnosis and rehabilitation of human lower-limbs. First, the robot design including the inverse and forward kinematics equation is presented. Then, the prototype is described, and the hardware and control architecture are developed. A control scheme is implemented and the result showing the tracking accuracy of the proposed controller have been included, showing accurate response in terms of position error.