Design method of double-filter disturbance observer of non-minimum phase system

Abstract

The invention discloses a design method of a double-filter disturbance observer of a non-minimum phase system, and is used for solving the problems that the system is unstable and disturbance cannot be suppressed in the non-minimum phase system in a traditional disturbance observer method. According to the method, a forward model is introduced, and a new disturbance observer frame structure and double-filter design scheme is given. Starting from the frame structure of the new disturbance observer, stability constraint is carried out on the double filters, and the tracking characteristic and the disturbance suppression characteristic of the system are analyzed on the premise that the stability of the system is guaranteed. The first filter adopts the design of an original closed-loop controller, the second filter is designed according to the first filter, and the performance of the second filter is the same as that of the first filter. On the basis of not changing the tracking characteristic and the stability of the closed-loop non-minimum phase system, the disturbance suppression capability of the system can be doubled by independently using any filter, and the disturbance suppression capability of the system can be doubled by using the double filters at the same time.

Description

technical field [0001] The invention belongs to the field of control systems, and in particular relates to a design method of a double-filter disturbance observer for a non-minimum phase system, which is mainly used to improve the disturbance suppression capability of a closed-loop non-minimum phase system without changing the tracking characteristics and stability . Background technique [0002] In the control system, in addition to the common minimum phase system, there are also non-minimum phase systems that are inherently stable but contain non-minimum phase links, such as hysteresis systems, grinding circuit systems, and DC motors. Non-minimum phase systems are difficult to control because of the fundamental limitation of non-minimum phase links in their control performance. The disturbance suppression characteristic of the closed-loop non-minimum phase system is limited to the single closed-loop system itself, and the disturbance suppression ability is insufficient. ...

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Problems solved by technology

According to the document "A New DisturbanceObserver for Non-minimum Phase Linear Systems", when the traditional disturbance observer method is used in a non-minimum phase system, since the inverse model is indispensable, it will lead to unstable poles in the system, making the system unstable. Lose the disturbance suppression effect, and even cause system crash

In this paper, a disturbance observer method for non-minimum phase systems is also proposed, but the method is modified for non-minimum phase objects, which will inevitably affect the original tracking characteristics and stability of closed-loop non-minimum phase systems

In the document "An approximate inverse system for nonminimum-phase systems and its application to disturbance observer", the proposed disturbance observer is limited to the estimation of disturbance without considering the stability of the closed-loop system, which has great limitations

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