scholarly journals Practical Fractional-Order Variable-Gain Super-Twisting Control with Application to Wafer Stages of Photolithography Systems

2021 ◽  
pp. 1-1
Author(s):  
Zhian Kuang ◽  
Liting Sun ◽  
Huijun SE Gao ◽  
Masayoshi Tomizuka
Keyword(s):  
Fractional Order ◽  
Variable Gain ◽  
Order Variable ◽  
Twisting Control ◽  
Super Twisting Control

Fractional-Order Variable-Gain Super-Twisting Control With Application to Wafer Stages of Photolithography Systems

2020 ◽  
Author(s):  
Zhian Kuang ◽  
Liting Sun ◽  
Huijun Gao ◽  
Masayoshi Tomizuka
Keyword(s):  
Fractional Order ◽  
Sliding Mode ◽  
Response Speed ◽  
Tracking Performance ◽  
Sliding Surface ◽  
Variable Gain ◽  
Equivalent Control ◽  
Order Variable ◽  
Twisting Control ◽  
Super Twisting Control

Abstract In this paper, a novel fractional-order variable-gain super-twisting control (FVSTC) scheme is proposed and applied to improve the tracking performance of wafer stages in the photolithography systems. The FVSTC overcomes the drawbacks of the super-twisting control (STC) such as slow response speed and incomplete compensation to disturbances. First, to improve the dynamics of the states on the sliding surface, a fractional-order sliding surface is designed. Moreover, to improve the dynamics of the sliding mode variable, an equivalent-control-based method is utilized, and a switching controller based on a variable-gain super-twisting algorithm is deployed. Via such designed schemes, the proposed controller is robust against external disturbances and model uncertainties. Stability proof of the closed-loop system is provided. Numerical simulations to track a sinusoidal signal and experiments on a wafer stage testbed are conducted. The results show that the proposed FVSTC scheme can achieve much better tracking performance than conventional methods.

Variable Gain Super-Twisting Control of GMAW Process for Pipeline Welding

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Manas Kr. Bera ◽  
Bijnan Bandyopadhyay ◽  
A. K. Paul
Keyword(s):  
Finite Time ◽  
Sliding Mode ◽  
Gas Metal Arc Welding ◽  
Control Effort ◽  
Variable Gain ◽  
Output Tracking ◽  
Pipeline Welding ◽  
The Stability ◽  
Twisting Control ◽  
Super Twisting Control

Quality control is the key issue that needs to be addressed in any gas metal arc welding (GMAW) system, especially in robotic pipeline welding system. This paper explores a second-order sliding mode control (SMC) strategy—a variable gain super-twisting control, to maximize the productivity, consistency in welding quality. This is achieved by the robust finite time output tracking of GMAW system. A nonlinear multi-input multi-output (MIMO) model of GMAW system has been considered here for the design of variable gain super-twisting (VGST) controller by which complete rejection of the bounded uncertainties/disturbances is possible and the adaptive characteristic of its gains help to use the control effort effectively. The stability of internal dynamics of the system is studied to establish the feasibility of solving the robust finite time output tracking problem. The stability of the overall system has been analyzed using Lyapunov stability criterion. The performance of the controller is demonstrated using the model of the system emulating the realistic conditions of operation. The simulation results are presented to illustrate the efficacy of the controller.

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