Observer-Based Control System Design of High Performance Motion System with Parallel Kinematics

摘要

This paper deals with a multi-axis control system of a precision air bearing motion stage with parallel kinematics. The air bearing motion stages offers high precision positioning resolution and accuracy due to frictionless motion, usage of high resolution optical encoders and temperature stable materials. The achievement of a nanometer positing resolution requires the highest feedback resolution and servo stiffness. A design of the extended state observer combined with a position sensor processing is presented for a multi-axis motion control in a plane. The proposed observer structure is presented in a form of a third order acceleration observer. The application of the observed acceleration disturbance helps to increase the servo stiffness. The simulation and experimental results confirms the efficiency of proposed solution. There are achieved 20 nm positioning resolution and 50 nm tracking error at a velocity of 0.5 mm/s using the optical encoder with a period of 20 μ m.