Design and Experiment of Model-free Output-feedback Control for Vehicle Active Suspensions

A practical output-feedback control strategy using saturated super-twisting algorithm was proposed for the model-free vibration control problem of vehicle active suspension systems. Sensor noises and perturbed unknown dynamics were considered in the control design, and a higher order sliding mode observer was employed to estimate the total disturbance term and system states. To achieve second-order sliding mode using continuous control on the chosen sliding surface in finite time, a novel saturated super-twisting algorithm was used to design the closed-loop regulator. The exact feedback linearization was no longer required, and only one sensor was used to measure the output variable so as to decrease the control cost and complexity in the proposed control scheme. The asymptotical stability and boundedness of the system could be guaranteed by tuning the controller gains. Finally, the experimental validation based on hardware-in-loop test was implemented to demonstrate the effectiveness of the proposed method. The simulation and experimental results for different road excitations showed the proposed control could achieve better ride comfort than the traditional proportion-differentiation (PD) and linear quadratic regulator (LQR) control methods, and the vibration damping performance was accomplished with less control chattering. The frequency response results showed that the maximum acceleration gain of passive control was 44.7 dB, and that of the LQR control was 29.4 dB, whereas that of the proposed control method was decreased to 13.5 dB, thus the ride comfort was significantly improved. © 2019, Chinese Society of Agricultural Machinery. All right reserved.