Research Of Internal Model Control To Vehicle Stability Control

With the development of society and economy, passenger vehiclesare more and more necessary in daily life, and the active safety controlfor vehicles become more and more urgent consequently. Vehiclehandling stability control is a key point for vehicle active safety control.It will prevent vehicle from accidents while fulfilling obstacle avoidancemaneuvers at high speeds.Vehicle handling stability control system is mainly composed ofthree parts which are sensors, ECU and actuators, of which the controlalgorithm is the core for ECU. The control algorithm directly decidesperformance of vehicle handling stability congrol system and then thedriving safety. This dissertation is mainly focus on the research of controlalgorithm, and firstly solves the nonlinearity involved in controls fordifferent actuators, and then introduces internal model control (IMC) todesign different IMC vehicle handling and stability control system whoseperformance is verified under different driving conditions. At last,prototype vehicle is equipped with an IMC vehicle handling and stabilitycontroller, and fulfils the experiments designed according to FMVSS-126(Federal Motor Vehicle Safety Standard No.126).The main contents of this dissertation are summarized as follows.Firstly, a simple, applicable and accurate model to estimate vehiclevelocity and side slip angle is put forward. Based on the on-board sensorsand vehicle dynamics equations, the relationship between vehicle speedand sideslip angle and the measurable ones are deduced, and then the estimation model is established. The accuracy of the estimated variales istestified in CarSim, and the model can meet the controller requirement ofvehicle handling and stability control system.Secondly, a linear multi-input-multi-output (MIMO) IMC controllerwas proposed. A four-wheel-steering (4WS) vehicle is selected first forhandling and stability controller design. Based on tyre characteristicsanalysis, the linear control theory is used for the stability control for4WSvehicle within linear regions. Then, according to the characteristics of4WS vehicle, the MIMO IMC controller is designed based on the internalmodel of a linear three-degree-of-freedom vehicle model. At last, in orderto investigate the controller’s effect, linear quadratic regulator (LQR) isintroduced as reference algorithm. In simulations, different drivingmaneuvers including both open-looped and close-loop are carried out andresults well show the effect effectivenes of the designed IMC.Thirdly, a nonlinear MIMO IMC controller was introduced. Tofurther examine the robustness of the IMC, a vehicle with active frontwheel steering and active braking exhibiting strong nonlinearity isselected. The nonlinearity of the active front wheel steering and activebraking vehicle is firstly analyzed. Then, the combination of internalmodel control and the inverse system theory is proposed for the first time,and the pseudo linear MIMO IMC controller is designed. At last, bothopen and close-looped driving maneuvers are introduce to testify thedesigned controller, and the simulation results are compared with linearMIMO IMC showing the good response rate, accuracy and robustness ofthe pseudo linear MIMO IMC controller.Fourthly, a pseudo linear MISO (multi-input-single-output) IMCcontroller was applied. Based on the pseudo linear MIMO IMC, active braking vehicle which is a multi-input-single-output nonlinear system ismodeled for handling and stability control. The unbanlanced MISOcharacteristic, which decided by the optimization of braking wheelsaccording to detaile analysis, for four wheel active braking vehicleworsenes handling and stability control. To solve this problem, properadjustment based on combination of IMC and inverse system theory isproposed, and then the pseudo linear MISO IMC controller is set up. Inthe end, comprehensive comparisons are made for all designed IMCcontrollers under both open-looped and close-looped driving condtions.Fively, an experiment is designed and performed. This dissertationdesigns and accomplishes experiments for an experimental vehicleequipped with the hydraulic actuators produced by Jiaoda Shenzhouaccording to FMVSS-126. The experiment results show that with the helpof pseudo linear MISO IMC controller, the experimental successfullypasses the test.