Study On The Control Methords Of Nonlinear Electromechanical Position Servo System With Uncertainties

Electromechanical Position Servo System (EPSS) is a kind of automatic system used widely. Based on the state of the nonlinear EPSS with uncertainties, the exiting problems and the practical requirements, this dissertation deeply investigates the theories and applications of the system for its structure and control, and succeeds in constructing a systematic design structure. Moreover, the theoretical results are applied to an actual nonlinear EPSS with uncertainties successfully. The main contributions of the dissertation are summarized as follows:1. Bulid a model with which agrees an actual nonlinear EPSS with uncertainties well. The dissertation analyzes the key factors such as non-linear friction, electromechanical coupling resonance, clearance of dynamic train of gearings and modulating wave frequency of PWM that affect the system badly, and then some methods such as friction identification and compensation, gapless drive and control output nonlinear modulating are introduced to solve those problems.2. Three different approaches of designing controller and system framework for an actual nonlinear EPSS with uncertainties are discussed respectively:(1) Based on PID and SMC control method and engineering approximation, a double model controller with three closed loops is designed. An algorithm that can produce any triangular wave with finite amplitude and finite frequency is proposed. A nonlinear control method is given to control a type of linear system.(2) An adaptive controller is designed for system velocity loop. Parameters' optimizing on-line method is used for eliminating non-linearity, uncertain disturbance and model predigesting factors that affect system. A novel model reference adaptive control method is proposed.(3) Two different controllers are designed based on VSC and adaptive method for two different system work modules of EPSS with uncertainties. A modified exponential approach method is built based on the sliding model control.3. The author develops simple computer software that can help the servo engineer designing an EPSS, which satisfied the user's requirements easily.