Study Of Control Algorithm For Steer By Wire

With the rapid development of control technology, more and more electronic control devices applied to the car. Under such a background, steer-by-wire(for short SBW) system appears, The difference from traditional mechanical steering system is that the mechanical connection between steering wheel and steering wheel is replaced by control signal. Currently, there is no mature theory or products, but the variable steering ratio and other advantages of steer-by-wire system can't be surpassed by traditional mechanical steering system.The technology is the research direction in the future, is the highest form for development of steering system. So far,Almost all the major car manufacturers and research institutions In the world have invested an amount of human and material resources to the study on Steer by Wire.Based on domestic and foreign research results, this paper has completed the following works with focus on study of control algorithm about front-wheel corner for SBW system.Research status and development prospects at home and abroad on steer-by-wire technology is Introduced. System structure, performance characteristics and key technologies of SBW system are briefly described. On this basis, information about system principles of steer-by-wire system is given, including the steering wheel assembly, steering actuator, the main controller, fail-safe systems, power supply and so on.Established a SBW system dynamic model and ADAMS vehicle model.SBW system dynamics model:Based on force analysis about SBW system,this paper establishs dynamic model of steering wheel assembly and the steering actuator. Then,we introduce dugoff tire model, derive a mathematical expression of the tire aligning moment. Finally found a moderate complex four degrees of freedom (longitudinal, lateral, yaw and roll of a vehicle) dynamic model of automobile. ADAMS vehicle model:We build a vehicle model for the experimental simulation throught ADAMS software, Under modeling process, we simplify some structural which don't affect the performance of steering system. Based on the ADAMS vehicle model, we conducted a simulation test by joining a pilot model and road information, And the Feasibility of the model has been verified by the simulation test.Study of control algorithm about front-wheel corner for SBW system. In order to meet the demand of a operational stability of a vehicle,after analysing the factors of a angle transmission ratio of steering system, we made the ideal angle transmission ratio of steering system.Based on the theory of the ideal angle transmission ratio,control algorithm about front-wheel corner for SBW system is designed, And we conducted simulation test. The results shows that control algorithm about front-wheel corner is helpful for improving the steering characteristics.PID control algorithm for the SBW system. To improve a car's steering characteristics, we propose PID control algorithm, combined with the characteristics of SBW,and conducted simulation test. the result shows that the algorithm is good for SBW, can enhance the vehicle's operation stability and security.