Fractional order sliding mode optimization control method for flexible joint mechanical arm

Abstract

The invention discloses a fractional order sliding mode optimization control method for a flexible joint mechanical arm. In order to solve the problem that in flexible integer order sliding mode dynamics control over joints of a mechanical arm, chattering and trail tracking control exist, in combination with the advantages of sliding mode variable structure control, a fractional order calculus theory is introduced, based on the features of the rapid convergence, information memorability and heritability of a fractional differential operator and on the basis of a common fractional order indirection discretization Qustaloup algorithm, the approximate precision of the fractional differential operator is optimized and promoted, and therefore a novel fractional order sliding mode variable structure controller which is better in strong robustness, interference resistance and effect of weakening clattering is provided. A joint flexible dynamics control system of the mechanical arm has bettercontinuity, rapidness and robustness and good interference resistance, and finally design of the fractional order sliding mode variable structure control method is realized.

Description

technical field [0001] The invention relates to a control method for a flexible joint mechanical arm, in particular to a fractional-order sliding mode optimization control method for a flexible joint mechanical arm, which belongs to the field of robot control. Background technique [0002] In terms of dynamic control and trajectory tracking control of flexible joint manipulators, the integer-order sliding mode variable structure control method has the advantages of strong robustness to parameter time-varying and external disturbances, but the traditional integer-order sliding mode control system There is a problem with large chattering [1] . At present, the commonly used methods to reduce sliding mode chattering are: the positive lateralization method in the boundary layer [2] , Observer-Based Adjustment Method [3,4] , high-order sliding mode control algorithm and other methods [5] Chattering can be weakened to a certain extent. The first two methods do not have the robu...

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Problems solved by technology

[0003] There are still certain shortcomings in the existing fractional-order sliding mode control method. For example, the Chinese invention patent application document "A Fractional-order Sliding Mode Control Method for a Flexible Joint Manipulator" (publication number CN108181813A) discloses a flexible joint manipulator system The fractional-order sliding mode control method, aiming at the problem of chattering and trajectory tracking control in the integer-order sliding mode dynamics control of manipulator joint flexibility, combined with the advantages of sliding mode variable structure control, introduces fractional-order calculus theory, and Using the fast convergence, information memory and heredity of the fractional differential operator, a fractional sliding mode variable structure controller is proposed to realize the design of the fractional sliding mode variable structure control method

The method of the invention adopts the traditional indirect discretization method, which has better robustness and anti-interference characteristics compared with the traditional integer-order sliding mode variable structure control, and can weaken the chattering of the sliding mode motion to a certain extent phenomenon, but the indirect discretization of the conventional fractional differential operator has certain defects in the low-frequency and high-frequency band processing of the control signal, so the control effect of this method is still not ideal in the occasion where the application requires high control precision

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