Model-free control method in intelligent control

Abstract

The invention discloses a model-free control method in intelligent control. The model-free control method comprises the steps of: carrying out model order reduction on a controlled object; and designing a model-free sliding-mode controller, which is composed of a model-free intelligent PID control rate based on time delay estimation and a sliding-mode correction sub-controller. The model-free control method combines the advantages of model order reduction and modern intelligent control, utilizes a computer sampling mechanism and adopts a time delay estimation technology to for reducing the order of a high-order system, and performing online estimation on real-time local dynamic characteristics; in addition, a circulative iteration controller is designed for correcting errors caused by time delay estimation, thereby further improving following control precision; and the model-free control method can effectively overcome influence of a series of uncertain factors such as unmodeled dynamics of the complex controlled object and external interference, and has the advantages of being simple in controller design structure, few in calculation workload, independent of mathematical model and parameters of a controlled system, good control performance and effect and the like.

Description

technical field [0001] The invention belongs to the field of intelligent control, in particular to a model-free control method in intelligent control. Background technique [0002] Since the 20th century, modern control theory has developed rapidly, and the design of most controllers needs to be based on the mathematical model of the controlled object. According to the type of the mathematical model of the controlled object, the controller can be divided into control methods based on linear systems, such as LQR, H∞; and control methods based on nonlinear systems, such as backstepping, sliding mode control, adaptive control, etc. . [0003] The control method based on linear system linearizes the nonlinear system, which simplifies the mathematical model of the controlled system and facilitates the design of the controller. However, with this linear control method, the controlled object can only be controlled stably near the operating point, and it is difficult to achieve st...

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Problems solved by technology

Although this kind of controller can guarantee the stability of the system in many occasions, it is difficult to guarantee the control accuracy, especially in the case of strong disturbance, strong nonlinearity and external disturbance.

For this reason, many experts at home and abroad have proposed a model-free control that does not depend on the model of the controlled object and ensures the control accuracy of the system: Hou Zhongsheng et al. proposed a model-free adaptive controller design, the control method consists of two parts Composition (Control Theory and Application, 2006 (04), 586-592): basic algorithm and combination algorithm; the basic algorithm and combination algorithm are stored in the computer program and the memory of the model-free controller, and the combination algorithm is composed of a series of special Algorithm composition, each algorithm module has corresponding parameters, the parameters can be adjusted through online self-adaptation, but its disadvantage is that there are too many controller parameters

M.Fliess et al. proposed a model-free intelligent PID control method based on algebraic estimation (International Journal of Control, Vol.86, 2013, 2228-2252; IEEE / ASME Trans.on Mechatronics, Vol.20, No.2, 2014,1-11.), this method has a simple controller structure, and has good anti-interference and model uncertainty processing capabilities, but the estimation method of the local model is relatively complicated

The above two kinds of model-free control do not need to know the mathematical model of the controlled object. The control structure is simple and can ensure the stability of the system. However, there are high requirements for the computing power of the main controller, which is not conducive to engineering implementation.

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