Adaptive Control of Four Motor Servo Systems Based on Characteristic Model and Gradient Projection Estimator

For multi-motor servo system, its complex system model makes controller design difficult and hard to realize in practical situation. To solve this problem, an easily realized adaptive control scheme based on characteristic modeling method and gradient projection estimator is proposed in this article. Firstly, characteristic modeling method is applied into servo systems to obtain a simplified system model, which makes controller design much easier. Also, system's uncertainties will be integrated into three time-varying characteristic parameters, which will be estimated online through gradient projection method. With this estimator, characteristic model can reflect real-time system status accurately but in a simple format. Then, based on characteristic model and parameter estimator, an adaptive controller is proposed to guarantee high track precision and enhance system robustness. The stability of the estimator's updating law and adaptive control law is analyzed, and the effectiveness of the proposed control scheme is proved through simulation and experiments.