Key Parameter Estimation Method Of Lightweight Electric Vehicle With Payload

As the lightweight and miniaturization of in-wheel motor and power battery are the major development directions of pure electric vehicle (PEV), the lightweight design on PEV triggers a wave of research around the world. But it brings the problems that the total mass has a significant reduction, and the payload parameter variation may affect the vehicle handling stability. Besides, the most vehicle controllers are based on the parameters calibration and can not estimate and update the parameters in time.The main contents in this paper are summed as follows:1. Based on vehicle dynamic characteristic,3-DOF vehicle dynamic model and simulation model with payload variation is estabilished. Through the simulation tests of front wheel step steer input and double lane change, the effects of payload on vehicle steady and transient state response are compared.2. According to the characteristic of 4 wheels independent drive (4-WID), design the novel parameter estimation method based on the longitudinal dynamics in the vehicle starting stage. Convergence tolerance and recursive least squares method with exponential forgetting factors are used for real-time estimation.3. The adaptive parameter update law and controllers are designed by using 3-DOF independent driving vehicle model. Equality constrained quadratic programming is used to allocate the driving torque of 4-WID. The direct state tracking method, the state observation method and the parameter error convergence characteristic method are designed for compensating adaptive parameter update and estimation. Simulation tests show the effectiveness of the proposed adaptive update laws.