An Adaptive Robust Control Method for Electro-hydraulic Servo System Based on Low Frequency Learning

Abstract

The invention discloses an adaptive robust control method of an electro-hydraulic servo system based on low-frequency learning. The steps of the method are as follows: First, establish a mathematical model of the hydraulic system, and make the following assumptions: the total disturbance of the system is smooth enough to exist and bounded; the expected position trajectory is third-order derivable and bounded; the uncertainty of the parameters changes The range is bounded; the absolute value and integral of the subtraction function about time are less than the predetermined value; secondly, construct an adaptive robust low-frequency learning controller, based on the traditional backstepping control method, and integrate the idea of ​​adaptive control and expectation compensation, in the controller A correction item is added to the parameter self-adjustment law; finally, the stability is proved by using Lyapunov stability theory, and the global asymptotic stability of the system is obtained by using Barbalat's lemma. The invention effectively avoids the high-frequency tremor caused by high gain and the influence of measurement noise on the high tracking performance of the system, and obtains better tracking performance.

Description

technical field [0001] The invention relates to the technical field of electromechanical servo control, in particular to an adaptive robust control method of an electro-hydraulic servo system based on low-frequency learning. Background technique [0002] In modern industrial production, hydraulic systems are widely used in many heavy-duty mechanical equipment such as cranes and truck-mounted cranes to ensure fast and heavy-duty operation. Hydraulic (such as hydraulic motor and hydraulic cylinder) system eliminates some mechanical transmission problems related to gears, such as backlash, strong inertial load, etc., and these nonlinear problems are the main factors affecting system performance, and their existence will affect the system. Therefore, the advanced controller design of the hydraulic system can obtain high-precision control performance. However, in the actual design of the controller for the hydraulic system, it is necessary to face many modeling uncertainties, su...

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Problems solved by technology

However, the discontinuous controller designed by the classical sliding mode control is likely to cause the flutter problem of the sliding mode surface, thereby deteriorating the tracking performance of the system; the adaptive control method is a very effective method for dealing with parameter uncertainty, and can obtain gradual Steady-state performance for close tracking

But for uncertain nonlinearity such as external load disturbance, it seems powerless. When the uncertain nonlinearity is too large, the system may be unstable.

However, there are uncertain nonlinearities in the actual hydraulic system, so the adaptive control method cannot obtain high-precision control performance in practical applications; the adaptive robust control method is proposed, and the control method is uncertain in two kinds of modeling. The system can obtain definite transient and steady-state performance under the condition that the characteristics exist at the same time. To obtain high-precision tracking performance, it is necessary to increase the feedback gain to reduce the tracking error. However, too large feedback gain will increase the frequency of the closed-loop system. Wide, which may stimulate the high-frequency tremor of the system to destabilize the system, thereby deteriorating the control performance, and even causing system instability. Therefore, the traditional adaptive robust control method has certain engineering limitations.

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