Research On Fractional Order PID Design And Disturbance Rejection Control Method For Flexible Transmission Systems

The flexible transmission is a new type of transmission with good buffer absorption capacity,and it has been used in equipment with low running speed and high torque.Since the most of the flexible transmission systems are low-damper high-order nonlinear systems,and traditional control methods are difficult to guarantee the performance of the systems.Therefore,research on flexible transmission system control has a positive effect on the promotion of flexible technology in industry.This dissert ation takes flexible transmission as the research object,proposed an improved Maxwell model to describe the hysteresis nonlinearity of a flexible transmission system;The main purpose is to solve the difficult problem of FOPID parameter setting in the pro cess of driving the motor speed of the system,and compensate the hysteresis nonlinearity in the flexible transmission system through the composite control to meet the requirements of system positioning and anti-interference.The main research contents of this paper are as follows:Combined with the Maxwell model,the structure of the flexible transmission system,the cause of hysteresis and its manifestation and description method are analyzed.A asymmetry Maxwell hysteresis model is proposed,which can describe more hysteresis shapes.For the drive control part of flexible transmission,to solve the complexity of FOPID parameter tuning,a parameter frequency domain tuning method is proposed for the conventional linear system and time-delay system.Taking the Bode ideal closed-loop reference model as the goal,the multi-parameter search problem is transformed into a single-variable search problem by model matching and frequency domain fitting.The search efficiency is improved and the response effect is approximated to the response of reference model,which enhances the stability,robustness and immunity of the controlled system.The simulation results show that the proposed method is excellent for linear,time-delay and high-order time-delay systems.The FOPID digital programming is realized by G-L definition and short memory method,and applied to the motor drive in the flexible transmission experimental system.The experiments verified that the system controlled by the method in this paper can achieve the desired effect.In terms of the position control of the transmission,a backstepping controller based on DOB is proposed.DOB is used to observe the uncertainty and interference of the model and compensation system,combined with the system decomposition idea of the backstepping control,The Lyapunov function of the closed-loop system is recursively obtained to construct the feedback controller,the numerical simulations of the systems with different disturbances is carried out to verify the effectiveness of the proposed method.Combined with the open-loop test results of the transmission system,the nonlinear expressions are analyzed.And the series model of the flexible transmission system is established.According to the application requirements of the flexible transmission platform,Experiments with the position loop control method demonstrate the effectiveness of the proposed method for the control of flexible transmission systems.