Theoretical analysis and evaluation of an optimally controlled full-car vehicle model with a variable-damping semi-active vehicle suspension forced by measured road inputs

摘要

This study aims to obtain the optimal control algorithm for a full-car model with a variable-damping semi-active suspension, such as a magnetorheological damper, by solving the linear quadratic regulator problem, and then to evaluate the system performance if the control inputs are constrained and delayed, and the vehicle is subjected to measured road inputs. A seven-degree of freedom full-car vehicle model was considered, and the state equations of the system were obtained in bilinear form. An integral performance index involving a weighted combination of the mean squares of average sprung mass acceleration and suspension deflections was defined. Trade-off curves were obtained between the sprung mass acceleration and suspension deflections of the optimally controlled system which is subjected to a measured road profile input. Performance of the optimally controlled system was compared to the performance of the corresponding optimum passive suspension system. For the vehicle parameters and the road input profile considered in this study, a reduction of 6.4% in the average vertical acceleration and 2.8% in the average suspension deflection was achieved by the semi-active suspensions. The response of the system to an initial condition has shown that its transient oscillations are damped out effectively by the semi-active suspension