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 tyreroad 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.
To improve fuel economy and reduce emissions, direct injection technology with precise fuel injections is widely used for gasoline engines, because quantitative precise fuel injection, as well as multi injection during one combustion revolution, is fit for the whole engine speed range. This paper designs a PID controller of fuel injection quantity for gasoline direct injection (GDI). Firstly, a mathematical model of an injector, which is used for controller validation, is established mainly based on fluid dynamic; Secondly, a map of fuel injection quantity corresponding with engine demands (according to engine speed and rail pressure) is calibrated by using the high-fidelity engine software enDYNA through experiments. Then, a PID controller is aimed to track the given value of fuel injection quantity. Tuning controller parameters are chosen by randomized algorithm according to the criteria of performance. Simulation results show that the designed control scheme is effective.
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