Task-Space Measurement and Control for a 6DOF Stewart Nanoscale Platform

A 6DOF Stewart platform driven by piezoelectric actuators was designed for nanoscale positioning. A measurement method to directly measure the pose (position and orientation) of the end-effector is investigated in this article. By means of the measured parameters task-space on-line control objective can thus achieve. The design of the sensor holder for sensor employment and the cuboid with referenced measure points as well as the computation method for obtaining the end-effector parameters is introduced. A control scheme in combination of feedforward and feedback is proposed. The feedforward controller is designed based on the hysteresis model derived by using a dynamic Preisach method. Hybrid control is designed for the feedback controller to improve the performance of both the positioning and force output for nano-cutting and nano-assembly applications. The optimal gain of the feedback controller is searched by using relay feedback test method and genetic algorithm.