Abstract:

As the core component of the precision positioning platform, the control accuracy of the macro micro composite driver directly affects the performance of the platform. To improve the control accuracy of macro micro composite drivers, a dual loop composite control strategy with a master-slave structure is proposed. In the design of the macro motion control loop, a dynamic model is established based on the principle of electromagnetic force drive. The PSO-LQR controller tuned by particle swarm optimization algorithm (PSO) and the traditional LQR controller are used to construct the controller. Through comparative analysis of numerical simulation and experimental testing, it is verified that the PSO-LQR controller has higher displacement positioning accuracy in the outer loop control. In the design of micro motion control loop, a dynamic model was established based on linear pressure magnetic equation, and a non singular terminal sliding mode controller was designed as the inner loop by integrating exponential convergence law and hyperbolic tangent function, effectively suppressing the system chattering phenomenon. To verify the effectiveness of the proposed control strategy, a macro micro composite positioning experimental platform was built using a laser interferometer, and its positioning performance was tested. The experimental results show that under the same conditions, compared with the traditional LQR controller, the PSO-LQR controller has superiority in step positioning and displacement tracking; The micro motion part can achieve a step size of 1 μ m without generating displacement overshoot. When the positioning target is 15 μ m, the displacement error under the control of the non singular terminal sliding mode controller is about 0.24 μ m, effectively suppressing system chattering. In terms of macro micro composite positioning, a laser interferometer was used for closed-loop calibration of the grating displacement sensor, and repeated experiments were conducted. The final positioning accuracy was 370 nm.

Key words: macro-micro composite actuator, dynamics, particle swarm optimization, LQR control, sliding mode control, laser interferomete, control strategy