Synthesizing robust control systems for mechatronic objects with digital state controllers and observers

Abstract

Currently, digital controllers with state observers are widely applied in automatic control systems for mechatronic objects, which great potential abilities are caused by structural flexibility and developed methods of synthesis. However, during design and practical implementation of the systems there is problem of robustness, associated with parametrical uncertainty of typical mechatronic objects. Most methods for synthesis of robust control systems are based on application of continuous mathematical models and do not take into account specific of digital realization of controllers with state observers. Methods of state space, modal control, digital system design, numerical optimization algorithms and simulation in MatLab environment were used. We propose a method of synthesizing robust digital modal control systems with state observers based on generating dynamic system characteristics within the areas of parametric robustness. Further, low sensitivity of the system to changes in controlled object parameters is ensured by the minimal phase character of the complex controller transfer function, while low sensitivity to changing parameters of the controller itself is ensured by excluding positive feedback in both control and adjustment circuits. Developed recommendations of choosing dynamic characteristics of state controller with observer loops within robustness areas and of forming rational state observer structure allow us to synthesize digital automatic control system with low sensitivity for variation of both control object parameters and inherent controller parameters.