Vehicle velocities estimation based on mixed EKF

Longitudinal and lateral vehicle velocities are the important information for active vehicle stability control. But for both technical and economical reasons, these vehicle states can not be measured directly in a standard car. In order to provide high precision vehicle velocities information for active stability control system, a mixed EKF is presented to estimate the longitudinal and lateral vehicle velocities, which is suitable for continuous state variables with discrete observation. To offer the necessary tyre-road forces information for estimating vehicle velocities, a random walk model is proposed to model the tyre-road forces. It could avoid the complex tyre-road force model effectively. In order to evaluate the performance of the proposed mixed EKF, the simulation are carried out in the ISO double lane change condition and slalom condition with the parameters of Hongqi vehicle CA7180A3E. Meanwhile, estimation results are compared with the vehicle dynamics software veDYNA. Simulation results show that the introduced mixed EKF method has perfectly high precision and could satisfy the requirement of active vehicle stability control system.