NSGA-II-TLQR Control of Semi-active Suspension System with Magnetorheological Damper Considering Response Time Delay

With the advantages of simple structure, low energy consumption, and wide controllable damping range of magnetorheological (MR) damper, semi-active suspension with MR damper has become a promising application in the existing vehicle suspension system. However, the response time of MR fluid, the operation time of control system and the driving time of MR damper will result in response time delay together, which severe affect the vibration attenuating performance of the vehicle semi-active suspension system with MR damper. In this paper, a LQR controller incorporating NAGA-II algorithm considering response time delay (NSGA-II-TLQR) was developed to compensate for the response time delay of vehicle semi-active suspension system.

Firstly, the mechanical property experiments of MR damper were carried out, and the direct model and the inverse model of MR damper were established by using genetic algorithm, respectively. Secondly, the model of a two-degree-of-freedom (2DOF) quarter vehicle semi-active suspension system with MR damper was built. Subsequently, the NSGA-II algorithm was introduced to optimize the weighting coefficient matrix of the LQR controller. Then the first-order Taylor series expansion was applied to the NSGA-II-LQR controller to predict the control force, which compensate for the response time delay. Finally, the performance was verified by simulation and experimental tests.

The results show that the body acceleration RMS values with NSGA-II-TLQR controller are decreased by 15.5% and 4.48%, the suspension deflection RMS values are decreased by 22.54% and − 1.22%, and the tire dynamic load RMS values are decreased by 10.32% and 5.38% compared with the passive suspension and the suspension with NSGA-II-LQR controller, respectively.

The semi-active suspension with NSGA-II-TLQR controller has better performance in the ride comfort and handling stability.