Design And Research Of Magnetorheological And Hydraulic Combined Braking System

Mature design,reliable performance and low cost is the traditional hydraulic brake system characteristics.The excellent reaction speed and control precision are the advantages of the magnetorheological braking system.However,due to the existence of the viscous resistance of the magnetorheological fluid,whether the braking system is working or not,the magnetorheological braking system provide some certain braking torque all the time,which will affect the car's fuel economy and power,so the magnetorheological braking system is not widely used.In this thesis,an emergency braking test is carried out on a test vehicle with a logic threshold anti-lock control system.After analyzing the test data,I have combined the advantages of the two braking systems together to design a new type of compound brake system for hydraulic brake to bear the main braking torque and the magnetorheological brake to adjust the slip rate.The system has the following advantages: the compound brake is small in size and easy to install.The new compound braking system has better performance than the traditional hydraulic braking system for the control of the wheel slip rate.The magnetorheological brake only provides a small torque,which makes the viscous resistance torque smaller and reduces the magnetorheological brake module on the fuel economy and dynamic impact.Based on a test vehicle brake system layout space and performance requirements,the structure,size parameters and performance indexes of the compound brake are designed.The fuzzy self-tuning PID anti-lock control strategy is designed for the magnetorheological braking module in the compound braking system,and the logic threshold control strategy is designed for the hydraulic braking system.The model of compound braking system,traditional hydraulic braking system and vehicle dynamics is designed,and the model and logic control algorithm are modeled in Matlab /Simulink software.In the high adhesion coefficient,low adhesion coefficient and Muejump road,two kinds of systems are involved in anti-lock control comparison simulation test.Finally,the performance of the new compound braking system in the braking distance is similar to the traditional hydraulic braking system on the high adhesion coefficient road.On the low adhesion coefficient road,the compound braking system is not only the braking process is smooth,but also the braking distance are better than the traditional hydraulic braking system.On the Mue-jump road,the braking distance performance and ride comfort of the compound brake are slightly better than those of the traditional hydraulic braking system.