Self-adaptive Fuzzy Integrated Control And Optimization Design Of Vehicle Semi-active Suspension And Electric Power Steering System

The steering system and the suspension system are two big essential systems of the vehicle chassis system which affect the vehicle body attitude, which is the important composition part to guaranteed the vehicles smooth running, the operation stability and the security. Therefore the research related improvement the structure of suspension to enhances the suspension dynamic performance, as well as uses the power steering technical to enhance the handiness and the stable while steering is one of the vehicle project area of technology hot spot topics. This both all had the relatively mature theory in respective research area, but because the suspension system and the steering system are not the two isolated systems, but has certainly mutually the coupling function,Therefore the simple superimposition control cannot obtain the most superior performance of the two systems, therefore as obtain the more superior entire vehicle overall performance to have to rely on the two system control coordinated, namely integrated control. This article has conducted the thorough research to the semi-active suspension shock absorber development, the semi-active suspension system and the electric power steering system integrated control method, and the road test has carried on.Firstly, the half vehicle suspension model based on steering is established, Also had established the entire vehicle multi-degree of freedom dynamics integration model including the electric power steering model, the semi-active suspension model, the tire model and the road surface model, and the influence of semi-active suspension and the electric power steering system to the vehicle body attitude is analyzed.Secondly, the fuzzy control theory is carried on to the integrated control of the semi-active suspension system and the electric power steering system, an adjustable gene is introduced, a self-adaptive fuzzy method with parameter is put forward, has provided foundation for semi-active suspension and the electric power steering and the control system with good robust.Thirdly, based on a car shock absorber foundation, uses the design mentality of the adjustment orifice opening to change the shock absorber damping, one kind of new adjustable damping shock absorber is designed and developed, and through the bench test to obtained the relations between the corner and the adjustable damping force. Some gist for designing the control system was supplied especially for damping control rule.Fourthly, The self-adaptive fuzzy control method is carried on the integrated control of the semi-active suspension and the electric power steering system,The research has developed based on LPC2131 micro controller semi-active suspension and electric power steering controller hardware, It is sustainment to design the semi-active suspension and electric power steering and its control system.Fifthly, based on the simulation calculate, carried on the road test of the integration control system, including the smooth random input experiment, the serpentuate experiment, the steering wheel corner step more inputs experiment and so on. And the results are analyzed contrast with the simulation.At last,considering traditional design method of vehicle semi-active suspension system and electric power steering always design control parameters following structure parameters and it can not obtain the global optimum performance for the system, the multi-objectives optimization using the ameliorated genetic algorithm to the semi-active suspension and the electric power steering entire vehicle dynamics system integration system is carried on to optimize, caused the design parameter and the controlled variable of the integrative system achieves superiorly simultaneously.It was showed that the simulation results were coped with the experiments. In contrast with the passive system, The center of mass acceleration, the pitch rate, yaw rate and roll rate were all reduced obviously after self-adaptive fuzzy integrated control. The peak decreased in average 7.8%-10% for the center of mass acceleration, 14.7% for roll rate and 55.6% for steering torque. The former standard deviation decreased by 8.3%-23.4%,the latter was decreased 12.7% and 53.8%. In human sensitive frequency range,the power spectrum of the center of mass acceleration was reduced obviously. The entire vehicle dynamic performances of integrated system are more excellent than the semi-active suspension and EPS system controlled unattached. In contrast with the passive system, under the integrated control the entire vehicle dynamic. performances had effective improvement, coordinated the vehicles among the smooth running, secure and the operation handiness while steering, under each kind of driving condition guaranteed the entire vehicle to be possible smoothness, the security and the operation stable are well matched.