Research On Nonlinear Compensation Control Of Rigid-flexible Composite Transmission System

With the rapid development of industrial robots,the transmission accuracy,reliability and life expectancy of the reducer are put forward higher requirements.In view of the problems existing in the traditional rigid reduction mechanism,Professor Wang Jiaxu of Chongqing University invented a kind of precise filter reducer.The core idea of the filter reducer is the deformation coordination.With the rigid-flexible composite gear instead of the traditional rigid gear pair,the transmission performance is greatly improved.However,the rigid-flexible composite transmission has strong nonlinearity,which increasing the difficulty of modeling and control.In this paper,rigid-flexible composite transmission is used as the research object,the nonlinear dynamic model of rigid-flexible composite transmission is established for the nonlinear factors such as flexible deformation,hysteresis effect and nonlinear friction in the system.Then,nonlinear compensation control methods are designed for the dynamic model.Finally,it is verified by off-line numerical simulation and hardware in the loop simulation.The main contents of the paper are as follows:(1)Based on the kinematic relation of the rigid-flexible composite drive and the Lagrange energy equation,the dynamic model suitable for rigid-flexible composite transmission is deduced.Experiments show that the traditional friction model can't fit the experimental data well,and a Stribeck friction model with improved viscosity is proposed.Based on the traditional hysteresis model,a hysteresis model for rigid-flexible compound transmission system is deduced.The model can describe the hysteresis characteristic of rigid-flexible composite transmission system and the parameter identification is simple.(2)A nonlinear compensation control method based on PD control is proposed.The feed forward compensation term and the hysteresis inverse model compensation term are designed for the determined friction model and the hysteresis model respectively.And the transfer function of the system is analyzed.The closed-loop characteristic of the system is analyzed by the root locus method,and it is proved that the system can be stable in the wide gain range.The simulation results show that the nonlinear compensation control method can effectively improve the position tracking accuracy of rigid-flexible composite transmission system.(3)In order to improve the tracking accuracy of the system,a neural network adaptive compensation control method is proposed to solve the nonlinear factors such as flexible deformation,friction parameter uncertainty and external disturbance in the dynamic model of rigid-flexible composite transmission system.The uncertainties of model are approximated and compensated by RBF neural network.The Lyapunov theory proves that all errors of the system are bounded.The simulation results show that the method can further improve the position tracking accuracy of rigid-flexible composite transmission system.(4)In order to test the actual control effect of the nonlinear compensation control algorithm of rigid-flexible composite transmission in this paper,a hardware-in-the-loop simulation scheme of rigid-flexible composite drive control based on LabVIEW and Simulink is proposed.Real-time simulation of LabVIEW and Simulink is realized by S function,using the LabVIEW SIT toolbox for LabVIEW and Simulink data communication,give full play to the advantages of both,the experimental results show that the proposed nonlinear compensation control method of effectiveness.