| Mask aligner double stage is a very important precision equipment in the field of chip manufacturing,in which the motor driver is the core component of the double stage to meet the requirements of running speed,acceleration and precision performance.It is of great significance to study the disturbance analysis and current closed-loop control of the high-performance motor driver for mask aligner double stage.Because there are many uncertain changes in the parameters of load and control loop during on-line operation,the current performance of the motor of the workpiece table is reduced,which has a negative impact on the motor thrust and the motion performance of the motion table.In order to ensure that the current loop of the driver can still maintain the expected performance under the negative influence of the above changes,the uncertainty in the current loop of the mask aligner dual-stage driver and the design of the corresponding current closed-loop controller are studied in this thesis.The main work includes:Aiming at the current open-loop system of mask aligner dual stage driver,the nominal system modeling and model parameter identification are studied.Without considering uncertain factors,the information criterion and generalized least squares recursive algorithm are used to model the nominal model of current open-loop system,determine the model order,and identify the model parameters systematically.Aiming at the uncertainty existing in the open-loop system of driver current,the uncertainty modeling research is carried out and the specific description of uncertainty is obtained.Using rational function approximation method,a set of rational functions is used to represent the error between the actual system and the nominal model,and the set of rational functions converges to the actual upper bound of uncertainty in frequency domain,thus,a complete mathematical model of the controlled system composed of nominal system and uncertainty is obtained.The relationship between control performance index and system model parameters of current open-loop system is theoretically deduced,and an algorithm for controller design based on performance index is proposed.Considering that the mask aligner dualstage driver is a complex and precise system,in order to meet its accuracy requirements,its mathematical model is usually of high order.Because the corresponding relationship between performance index and model parameters of high-order system is unknown,this thesis deduces the corresponding relationship in detail,which provides a theoretical basis for the next controller design method and solves the problem that the previous controller design method based on performance index relies too much on engineering experience,thus giving an algorithm for controller design based on performance index.In order to suppress the influence of uncertainty on the closed-loop performance of the driver current loop,based on the controller design method according to the expected control performance index and the idea of robust control,an uncertain robust controller design algorithm based on dividing robust forbidden zone and feasible region is proposed.By drawing the amplitude-frequency characteristic curve of the expected closed-loop system and the robust forbidden zone and feasible region of the system,the algorithm selects an optimal expected closed-loop frequency curve,and then deduces the concrete mathematical model of the controller.The effectiveness of the controller design algorithm is verified by the physical test. |
