Optimal velocity based control of a parallel manipulator with fixed linear actuators

Abstract

High speed motion and positioning accuracy are the most important performance requirements of robot manipulators for the pick and place and assembly tasks. This paper focuses on the kinematic central system applied to a new parallel manipulator (NPM) with fixed linear direct drive actuators specially designed for high-speed trajectory applications. An optimal velocity based control method for high speed straight line trajectory of the NPM is proposed. The method is based on the maximum velocity zones analysis consisting of algebraic inequalities describing the constraints on the kinematics model. The proposed control algorithm is then implemented in off-line trajectory planning and in real time position servoing for kinematic control in the sense of achieving optimal trajectory performance. Digital PD control structure of the NPM is presented in order to satisfy the requirements in the actual manufacturing automation. The experimental straight line trajectory is satisfactorily controlled at a speed of 1.5 m/s with no reduction in accuracy.