Research On Some Key Problems For Vehicle Handling Inverse Dynamics

Research on the character of vehicle handling dynamics is an important approach determining safe running for high speed vehicle. Vehicle driving safety is the urgent key problem to be solved of automobile independent development while encountering emergency collision avoidance with high speed. And it is also the premise and one of the necessary conditions of vehicle active safety. In the case of vehicle high speed turning, driver model parameters are not easy to determine, which makes driver model difficult to bulid. In order to avoid the problem, driver handling input is calculated by the handling inverse dynamics method.Some theories are researched in this paper aiming at vehicle inverse handling dynamics. Several high efficient and accurate algorithms are proposed for the handling inverse dynamics, and an available estimation method for the vehicle handling dynamics is executed.(1) A simulation research method for solving vehicle handling inverse dynamics problem of vehicle status is proposed. Based on optimal control theory, the torque of steering wheels was set as the control variable. The minimum distance required to complete the collision avoidance process was determined as the control object. By using a new optimal control method-Gauss Pseudospectral Method(GPM), the optimal control problem is converted into a nonlinear programming problem that is then solved by means of the sequential quadratic programming. Matlab simulation results are obtained for a vehicle performing given boundarys by the method. The correctness of the model is verified through real vehicle test.(2) A simulation research method for solving vehicle minimum time maneuver problem is proposed. Based on optimal control theory, steering angle input and traction/brake force imposed by driver are control variables, the minimum time required to complete the double lane change and slalom is control object. By using a new optimal control method-Gauss Pseudospectral Method(GPM), the optimal control problem is converted into a nonlinear programming problem that is then solved by means of the sequential quadratic programming. Matlab simulation results are obtained for two different vehicles performing similar given path boundary by the method. The simulation results show that the proposed method is not sensitive to the initial value and the optimization efficiency is higher compared with indirect methods and traditional direct methods. When solving the vehicle minimum time maneuver problem with the method, boundary constrains and path constrains are well satisfied. Utilizing the method the maneuverability of two different vehicles that complete double lane change with minimum time can be evaluated objectively. The correctness of the model is verified through real vehicle test.(3) A new technique for vehicle handling inverse dynamics which can evaluate the emergency collision avoidance performance was proposed. The collision avoidance of lane-change steering maneuver has to deal with many constraints, so that traditional direct methods are not suitable for this problem. Based on Model Predictive Control(MPC), the steering angle input was the control variable, the optimal trajectory of completing the collision avoidance process of lane-change steering maneuver was the control object. By using the Model Predictive Control, the optimal control problem was converted into a secondary plan problem that was then solved by the algorithm called active set method. The simulations results show that the proposed method has potential advantage in calculation for optimal steering input of vehicle trajectory involves too heavy computational complexity. And the proposed method can solve the vehicle handling inverse dynamics problem of the lane-change steering maneuver successfully.(4) Based on multiple linear regression method, a simulation research method of driver’s psychological burden under emergency for traffic safety is put forward. Test of driver’s physiological responses was established using holter analyzer, Frecord data collection system and GPS. Multiple linear regression model of the distance between vehicle and obstacle in the same lane, the vehicle speed, the maximum braking pedal speed and the maximum steering wheel angle speed was proposed. The relationship between the five factors above was analyzed. The results indicate that the distance between the vehicle and the obstacle has more important influence on the maximum steering wheel angle speed and the maximum braking pedal speed than that of the vehicle speed. The driver’s psychological burden will increase according with the bigger vehicle speed and the smaller distance between the vehicle and the obstacle. The study can provide a new theoretical method for the further drivers’ behavior analysis under emergency.(5) Based on improved Fuzzy-AHP, a simulation research method of subjective evaluation of vehicle handling stability is put forward. A certain vehicle was evaluated and weights of subjective evaluation indexes were obtained through real vehicle evaluation test. Cooperated with the weights and the subjective evaluation the overall performance result was given. The result shows that the proposed method can provide a scientific reference for the vehicle designer to control the structure parameters.