Patent ID: 7783580
Filing Date: 2010-08-24
Classification: G05B

Abstract:
1. A control method combining fuzzy logic control with sliding mode control, comprising: receiving an input signal and obtaining an output signal corresponding to the input signal through sliding mode parameter definition and fuzzy logic inference, wherein the input signal is denoted as e(t) representing an error between a practically measured stage displacement and a desired displacement, a signal ce(t) representing an error change amount is obtained from the input signal e(t), sliding variables are defined as s(t)=ce(t)+λe(t) and are used as input control variables for fuzzy control prior to fuzzification, the output signal is servo mechanism drive power u(t) driving the servo mechanism to move the stage, and wherein the value of λ is designed according to convergence rate of the two variables e(t) and ce(t); selecting different membership function gains according to a value of the control variables, wherein the sliding variable s(t) defined by the sliding mode is corrected by corresponding function gain gs(t), and the drive power u(t) inferred by the fuzzy logic is corrected by corresponding function gain gu(t); and wherein initially the sliding variable s(t) is relatively large, the function gains gs(t) and gu(t) are in exponential decay to rapidly narrow a scope of the membership function gains, and as the sliding variable s(t) approaches a target value, the function gains gs(t) and gu(t) fall to a minimum according to a linear function.