| The magnetorheological damper(MRD)is a device with semi-active control characteristics,whose output damping force can be adjusted by changing the magnetic field.It has the advantages of quick response,high energy absorption efficiency,and pollution-free properties,making it a promising candidate for use in buffering systems under continuous impact conditions.However,under impact conditions,especially when subjected to continuous impact forces,changes in control current,temperature,and other factors can lead to changes in the liquid properties of the MRD,resulting in serious interference from both internal and external factors,and making it difficult to maintain stable damping performance,thereby affecting the buffering effect of the control system.In this paper,we focus on disturbances such as temperature and hysteresis under impact buffering conditions,and study control strategies from theoretical analysis,simulation experiments,and other aspects to enable the system to maintain good buffering control performance under continuous impact.We validate the effectiveness of the control method through physical simulation experiments.The specific research content is as follows:(1)The motion equation of the magnetorheological impact buffering system was established by analyzing the force situation of the magnetorheological damper.The "platform effect" was taken as the control objective of the impact buffering system,so that the output damping force can reach a minimum within a limited displacement.After comparing several classic mechanical models of the magnetorheological damper,the Bingham model was selected as the mechanical model for the magnetorheological damper used in impact buffering.To realize magnetic field feedback control,a dual-rod magnetorheological damper with an embedded Hall sensor was designed for impact buffering,which facilitates the detection of magnetic field changes in the internal channel of the damper.(2)The working environment and nonlinear characteristics of the magnetorheological damper under continuous impact conditions were analyzed,and the main sources of disturbance were determined to be temperature and hysteresis.To apply suitable disturbance signals in the numerical simulation system,the Jiles-Atherton hysteresis model was established based on the theory of ferromagnetic domain walls,and a temperature model was established based on the temperature rise characteristics of the magnetorheological fluid.The hysteresis characteristic curve was obtained through Hall sensor measurements,and genetic algorithms were used for parameter identification of the five parameters in the J-A model.(3)The control algorithm of the magneto-rheological shock absorber system considering disturbance factors was studied.Three traditional control algorithms,namely,open-loop,PID,and fractional-order PID control algorithms,were designed and simulated to implement the shock absorption control system.A self-disturbance rejection control algorithm based on a linear extended observer and tracking differentiator was proposed.Simulation results showed that,compared with open-loop control,the PID and fractional-order PID control algorithms reduced the peak value of the damping force by 20% and had a certain buffering control effect when there was no disturbance input.Under the conditions of considering temperature and hysteresis disturbances,the self-disturbance rejection control had the best buffering effect and the damping forcedisplacement was closest to the "platform effect" compared with other algorithms.Simulation verification under continuous shock conditions showed that the self-disturbance rejection control effect was still stable,further proving the effectiveness of the proposed self-disturbance rejection control method.(4)The hardware and software system design of the magneto-rheological shock absorber system self-disturbance rejection controller based on the STM32 development board was carried out.The hardware part of the designed controller includes the conditioning circuits of various sensors and the PWM output conversion circuit,and was debugged and verified.The software part designed the initialization program of each circuit module,the self-disturbance rejection control algorithm program,and the timer output PWM wave program.The magneto-rheological shock absorber system control was physically simulated and verified using the development board and controller,and the results were consistent with the Simulink simulation experiment results. |
