Implementation of a 6-DOF Precision Positioning Platform for a Injection Molded Part

Abstract

This paper propose a six degree-of-freedom (DOF) compact positioner with high resolution and large travel range for the manufacture of injection molded part application. The precise positioner is composed of monolithic parallel flexure mechanism, horizontal and vertical electromagnetic actuators, and optical displacement sensors to achieve the 6-DOF motion. The concept of the system intends to achieve three goals: 1) large travel range, 2) high precision positioning, and 3) fast response. In our system, there are eight sets of permanent magnets attached to the moving platform, and eight sets of electromagnets mounted on the bottom platen. The whole control architecture is to take the six posture data measured by the six optical displacement sensors first and then to control the 6-DOF motion by regulating the current in the electromagnetic actuators. For the purpose of system robustness and stability, an adaptive sliding-mode controller is proposed to validate the system performance. The developed robust adaptive control architecture consists of two components: 1) sliding mode controller, 2) adaptive law. From the simulation and experimental results, satisfactory performances of the hereby developed system, including stiffness and precision, have been successfully demonstrated.