The Control Strategy And Simulation Of ESP On Vehicle Turning

In recent years, with the advancing of Science Technology and the improving of people's living standard, besides comfort, customer require more and more about vehicle safety, so nowadays, the key research of Automotive Technology is how to improve the safety of Vehicle.ESP(Electronic Stability Program) has a hot research in the domain of current international vehicle initiative safety, at abroad, the ESP interrelated products have been equipped on the middle-grade and top-grade cars at a large number.But in China, the research of ESP is still in infancy stage.ESP(Electronic Stability Program) was developed from ABS(Anti-lock Brake Stytem) and TCS(Traction Control System) which has another name of ASR(Acceleration Slip Regulation).ESP mainly work through adjusting the size and distribution of the longitudinal tire force, in case of the tire slips, at the same time, ESP can make Vehicle produces effective yaw moment to restain oversteering or understeering, prevent Vehicle to become unstable, make vehicle follow the instruction of driver, so that to improve the maneuverability and stability of vehicle.In this paper, how to develop and research ESP system are discussed, the proposed analysis of ESP work principle is based on the foreign achievement and reference, the mainly work is research vehicle turning, aiming at the oversteering or understeering of vehicle is easily produced during vehicle turning.Design control strategy of controlling the four wheels separately, using vehicle sideslip angle and yaw rate which are the mainly two parameters of vehicle runing condition as the control variable.The designed PID controller and Fuzzy controller can adapt themselves to different vehicle velocity, different steering angle, different road friction, then finally through the simulation of simulink validate the effectiveness of the two controllers.There are six chapters altogether.In chapter one, the conception, effection, characteristic of ESP are given, introduce the signification of researching ESP, the history and present situation, the framework and working principle of ESP, and the effection of real time monitor, assisted driver and pre-reminder of ESP, definite assiste driving which is one of the three characteristics as the key part of researching.In chapter two, contruct the vehicle dynamic modles which are used to analysis the vehicle stability performance.Take track maintenance and stability as the two problems of vehicle movement researching, analyze the main movement and the approach to improve vehicle stability.Contruct the two degree of freedom and eight degree of freedom vehicle model for the analysis and simulation using.Introduce the tire modle and the braking force distributer modle.In chapter three, mainly design the control system of ESP, firstly, analyze the basic work principle of control system, which includes the basic idea, basic process and the control methed.Secondly, introduce the work principle of ABS and ASR separately, and make a comparison between ESP, ABS and ASR.Finally, proposed the using of the two parameters of vehicle movement, vehicle sideslip angle and yaw rate, which are also the main control variable, contruct the structural drawing of the control system, lay the root for the simulation.In chapter four, design two controllers, PID controller and Fuzzy controller.In PID controller, simply introduced the PID control method and parameters setting.PID controller using the deviation of vehicle actual yaw rate and desired yaw rate as its input, and the yaw moment is the output, through the judgement of braking force distributer and dicide to control which tire of the four wheels is optimal.In Fuzzy controller, introduced the control method and make Fuzzy linguistic control rules, the input of the Fuzzy controller is two dimension, the deviation of actual and desired sideslipe angle and yaw rate are inputs separately, and the yaw moment is the output, so the following is similiar to PID control, through the judgement of braking force distributer and decide to control which tire of the four wheels is optimal.In chapter five, mainly are test simulations of the two controllers working in different working environment.Firstly, introduce simulink simply, propose the simulation structual drawing and corresponding parameters.Secondly, mountains of test simulation processed at modified and J-turn car steering angle, under the velocity of 20m/s and 30m/s, at different road friction(from 0.4 to 0.9), write down the simulation effection graph each, and make a comparison of the two controller's working performance, from the results, we find the two controller can both achieve to the expected working effectiveness in most cases, PID controller and Fuzzy controller has their own advantage, but Fuzzy controller has a wider use and stable performance than PID controller.In chapter six, there are summary and prospect.Summarize aiming the oversteering and understeering of vehicle turning through four wheels control each is available theoretically, and test the two controller proposed in this paper are effective and can assist driving during vehicle turning especially in unextreamly complicated working environment.In prospect, I sincerely hope the scholars who are intereated in this domain make a further research in the six parts as follows:vehicle modle, hydraulic components, Fuzzy linguistic rules, PID parameters setting equipments, braking and driving, actual vehicle test.