Research on Self-adaptive Fuzzy Control for Keeping Engine Speed Constant During Vehicle Starting
Keeping engine speed constant during vehicle starting is an effective control method, but how to make engine speed vary with the target speed curve so as to improve starting quality is a difficult issue. To solve the problem, a new clutch control principle was proposed, and a control system comprised of a self-adaptive fuzzy controller constructed by engine speed and its target speed and clutch displacement and rule harmonizing controller was devised. The simulation experiment show that engine can reach its target speed with little overshot under diversiform situation and vehicle starts successfully with constant engine speed and small friction loss as well. The start quality is proved to be improved through applying the strategy.
AbstractThe numerical analysis of two-dimensional laminar vortex shedding from a rectangular cylinder within a confined channel flow is presented. This study, carried out using a computational fluid dynamics (CFD) code based on the SIMPLEST algorithm, considers the influence of numerical diffusion on the prediction of the vortex shedding frequency. The computational analysis compares the commonly used first-order accurate UPWIND scheme with the well-known third-order scheme QUICK and its derivative SMART, used for the discretization of convective transport. For the temporal differencing, a fully implicit scheme has been adopted. Plots of Strouhal number against Reynolds number suggest that the implementation of a higher-order scheme is beneficial for the accurate capture of the vortex shedding transient in unsteady flows of this nature.