Frequency Response Analysis of Macro-Micro Stages With Active Disturbance Reject Controller

Abstract

Under the disturbance of friction and the elastic deformation of motion stage, the positioning accuracy of traditional mechanical bearing high speed direct-drive motion stage can only reach the micron level, which is difficult to meet the requirement of higher speed precision positioning. Therefore, the macro-micro stages utilize the flexure hinges to compensate for displacement in the friction dead zone. However, due to the nonlinear elastic vibration of the flexure hinge during the action, the settling time of micro-platform is different with stiffnesses. Effect analysis of different stiffness on the settling time of the micro-platform is significant for the platform design. According to the motion characteristics of the macro-micro stages, this paper designs the cascade extended state observer (ESO) to estimate and compensate for the disturbance and combine the proportional–derivative (PD) controller as the active disturbance rejection control (ADRC) strategy of the micro-platform position loop. Through the frequency response analysis of the control system, the influence of different stiffness on the settling time of micro-platform is explored. The simulation results show that the ADRC strategy based on cascade ESO has better robustness, and the macro-micro stages have a shorter settling time when the flexure hinge have smaller stiffness during the positioning phase.