Abstract
In the semiconductor industry, positioning accuracy and acceleration are critical parameters. To improve the acceleration speed of a motor, this paper proposes the moving-coil maglev planar motor with a concentric winding structure. The coordinate system has been built for the multiple degrees of freedom movement system. The Lorenz force method has been applied to solve its electromagnetic model. The real-time solving of the generalized inverse matrix of factors can realize the decoupling of the winding current. When the maglev height changes, the electromagnetic force and torque decreases exponentially with the increase of the air gap. To decrease the influence on control system performance by the internal model change and the external disturbance, this paper proposes an improved active disturbance rejection control (ADRC) to design the controller. This new controller overcomes the jitter phenomenon due to the turning point for the traditional ADRC, thus it is more suitable for the maglev control system. The comparison between ADRC and the improved ADRC has been conducted, the result of which shows the improved ADRC has greater robustness.
Highlights
Lithography is the most important and complicated aspect in integrated circuit manufacturing; the manufacturing accuracy determines the integration degree and performance of the manufactured chip.The highly-accurate two-dimensional stepper is the core element of lithography
active disturbance rejection control (ADRC) mainly consists of a tracking differentiator (TD), based extended the nonlinear mainly consists of a tracking differentiator (TD), extended state observer (ESO), and nonlinear states error feedback (NLSEF)
To compare the performance under external disturbance of the improved ADRC and the traditional ADRC controller, a random disturbance with the amplitude of 10 N or 1 N·m is put into the control system
Summary
Lithography is the most important and complicated aspect in integrated circuit manufacturing; the manufacturing accuracy determines the integration degree and performance of the manufactured chip. The two-dimensional stepper driven directly by the maglev permanent magnet planar motor has many advantages, such as quick response, high accuracy, and simple structure [1,2,3,4] It can work in a vacuum environment, which can meet the requirement of next-generation ultraviolet lithography technology [5,6]. The square structure leads to a more complex electromagnetic model and, the decoupling control of the current in the concentric winding is important for realizing the high-precision control of the whole drive system It has to be controlled in six degrees of freedom because of the active magnetic bearing, even though the planar motor mover can only move relatively small distances in the x-y plane. The disturbance is imposed on the traditional and advanced controllers, respectively, to test their robustness to random disturbance
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