Research On New Super-twisting Sliding Mode Control Strategy And Its Application To Multi-cylinder Hydraulic Press

Because the multi-cylinder hydraulic press has strong nonlinearity,over actuated characteristics and non-synchronization caused by partial load,the modeling of the multi-cylinder hydraulic press is complex and the controller design is difficult.Therefore,at present,there is little in-depth research on the control strategy of multicylinder hydraulic press,and the performance of the control system still needs to be improved.In view of the above problems,this paper focuses on the control method of the five-cylinder hydraulic press.Firstly,the dynamic equations of the moving beam of the multi-cylinder hydraulic press are refined as a general set of second-order nonlinear differential equations.On this basis,a new boundary layer super-twisting sliding mode control strategy is proposed,and the stability analysis method is given.Then the control strategy is applied to the virtual layer control of multi-cylinder hydraulic press,and the simulation results show the superiority of the proposed method.Secondly,in view of the shortcomings of the previous super-twisting algorithm,the super-twisting algorithm is improved by introducing a linear term,and a new boundary layer fast super-twisting sliding mode algorithm is formed.This algorithm not only has smaller steady-state chattering,but also has stronger anti-interference ability and faster convergence speed.On this basis,aiming at the general second-order nonlinear differential equations extracted in the third chapter,a new fast supertwisting sliding mode control strategy based on extended state observer(ESO)is proposed.The stability of the strategy is verified by the dynamic stability analysis of the system.Then the virtual layer controller and executive layer controller of multicylinder hydraulic press are designed by using the proposed control strategy.The simulation and comparison results verify the superiority of the method.Finally,the joint debugging of MATLAB and Lab VIEW is used to test the real object of the five-cylinder hydraulic press,which proves the effectiveness of the proposed control strategy in the actual system.In summary,the control strategy proposed in this paper can not only improve the fast leveling performance of the five-cylinder hydraulic press under partial load,increase the synchronization of the diagonal cylinder,but also make the hydraulic press have stronger anti-interference ability and higher control precision.In addition,a detailed proof of stability is given,which confirms the feasibility of the algorithm and expands the research scope of the super-twisting algorithm.