Research On The Control Technology Of Combined Current And Pressure Braking For Magnetorheological Fluid Brake

Magnetorheological fluid brake(MRF brake)is a new type of brake developed based on its distinctive rheological property,transmitted via the mediator of magnetorheological fluid(MRF).The brake boasts a wide range of industrial application prospects because of its characteristic advantages of rapid response,as well as its adjustable and controllable torque.In view of the problems in current braking system,such as a low output torque,a limited range of torque adjustment and the complicated control,this paper researches into following aspects of questions:(1)The design theory of MRF brake is analyzed,the MRF brake is designed,with the maximum braking torque of 240 N·m which can realize the current-pressure combined braking.And the materials and magnetic circuits of the brake are analyzed and designed in detail.The excitation coil is designed based on the analytical computation of the magnetic circuit.Addtionally,the finite element simulation analysis and the test of the electromagnetic field of the MRF brake are completed.(2)The theory of magnetic domains is introduced,the mechanical transfer characteristic of shear yield stress in the compression-shear mode of MRF is analyzed;and the calculation model of shear yield stress of MRF under compression-shear working mode is established.The torque calculation model and transfer subsystem model of MRF brake are deduced.Moreover,the performance test-bed of MRF brake is built,and the experiments of no-load characteristics,constant torque characteristics,brake torque regulation characteristics and dynamic response characteristics are conducted.(3)The basic concept of fuzzy control is introduced,the reasonable distribution of the target torque of the brake subsystem is realized by using fuzzy rules and fuzzy reasoning.According to the characteristics of the MRF brake,the transfer functions of the current brake subsystem and the pressure brake subsystem are solved,and the control strategies of the regular PID control and the fruit fly optimization algorithm(FOA)PID control are designed respectively and analyzed simulatedly.The simulation results show that the FOA PID controller has the advantages of fast response,no overshoot,stable system and good dynamic performance.(4)The experiment platform of current pressure combined brake control of MRF brake is built;the hardware and software of the experiment platform are introduced in detail;and the experimental research of brake torque output control is carried out.The results suggest that both the conventional PID control and FOA PID control have good effects on the combined brake control,but the combination of the combined brake control and the FOA PID control has a better control effect.There are 55 figures,16 tables and 102 references in this paper.