Fractional order sliding mode control method of flexible joint mechanical arm

Abstract

The invention discloses a fractional order sliding mode control method of a flexible joint mechanical arm. To overcome buffeting and problems on trace tracking control about integral order sliding mode dynamics control of flexibility of a mechanism arm, the method is as follows: through advantages of sliding mode variable structure control, a fractional order calculus theory is introduced, and a novel fractional order sliding mode variable structure controller high in robustness and interference resistance and having a better buffeting weakening effect is provided by means of quick convergence, information memory and heredity of fractional order differential operators, so a joint flexibility dynamics control system of the mechanical arm exhibits better continuity, rapidity, robustness andgood interference resistance. Finally, the design of a fractional order sliding mode variable structure control method is realized.

Description

technical field [0001] The invention relates to a control method of a flexible joint mechanical arm, in particular to a fractional-order sliding mode control method of a flexible joint mechanical arm, belonging to the field of robot control. Background technique [0002] The modern manufacturing industry has higher and higher requirements for the performance of the manipulator. The components of the manipulator are moving towards lightweight and the performance of the drive system is developing towards high speed, high precision and heavy load. For the motion control system of the manipulator, the precise control of the joint Driving force is an important method to improve the flexibility and safety of robots. In this context, the flexible drive control of manipulators has become a research hotspot in academia and industry. [0003] The mechanical arm realizes the motion control of the end through the rotation and movement of each joint. During the movement of the mechanica...

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Problems solved by technology

The flexibility of the connecting rod can be reduced through reasonable material and structural design; the flexible joint is a typical rigid-flexible coupling nonlinear system, and it is also a system in which the dynamic characteristics and control characteristics are coupled with each other, that is, the electromechanical coupling system. Flexibility, although it can also be reduced by reasonable material and structural design, but the effect is not obvious, and the cost is high

Non-linear, strongly coupled flexible joints are difficult to control, prone to end-jitter during movement, and difficult to quickly attenuate, thus having a serious impact on the fast and precise positioning and trajectory control performance of the manipulator, and the excited vibrations will affect the accuracy of the joints and lifespan

[0004] Conventional rigid manipulator control algorithms are difficult to achieve stable and accurate control of such flexible joint manipulators. In order to achieve the control goals of high precision, high stability and strong robustness of flexible joint manipulators, it is necessary to consider the manipulator body at the same time. The dynamic coupling of each joint, the structural parameters of the manipulator body and the uncertainty of external load disturbance

In terms of the dynamic control and trajectory tracking control of the flexible joints of the manipulator, the integer-order sliding mode control technology has been used to be robust to time-varying parameters and external disturbances, such as Hu Yueming's "Variable Structure Control Theory and Application" (Beijing : Science Press, 2003:157-164), the traditional integer-order sliding mode control system has a large chattering problem, and the commonly used methods to reduce sliding mode chattering are: the positive lateralization method in the boundary layer (Baik I C, Kim K H, Youn M J.Robust nonlinear speedcontrol of PM synchronous motor using boundary layer integral sliding modecontrol technique[J].IEEE Transactions on Control Systems Technology,2000,8(1):47-54), observer-based regulation method (Edwards Christopher, Spurgeon Sarah K, Parron Ron J. Sliding mode observers for fault detection and isolation [J]. Automatica, 2000, 36(4): 541-553, and Lin Da, Wang Xinyuan. Observer-based decentralized fuzzychaotic systems via network structure adaptation[J].Fuzzy Sets and Systems,2010,161(15):2066-2080), high order sliding mode control algorithm (Dinuzzo Francesco,FerraraAntonella.Higher order sliding mode controllers with optimal reaching[J].IEEETransactions on Automatic Control, 2009, 54(9): 2126-2136) and other methods can weaken chattering to a certain extent, and the first two methods do not have the robustness of traditional sliding mode controllers, which makes the system have steady-state errors. The latter algorithm is more complicated, and there is coupling between the control output signal and its derivative in the first-order or second-order low-order system, which is not conducive to the design of sliding mode control law

Although the fuzzy sliding mode control has strong robustness and does not depend on the system model, although it can make full use of expert information and other advantages, there is a large static error in the fuzzy control system.

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