Active electromagnetic suspension system for ground vehicles

Application of a new control strategy on actuators used in electromagnetic vehicle suspension systems has been studied in this paper. The vehicle is modeled as a quarter car in which the unsprung mass is supported by two vertically arranged electromagnetic actuators having a nonlinear behavior. The nonlinear actuators, having forces proportional to the square of the electric current and inversely proportional to the square of their distances from the mass, are controlled using a simple and feasible control strategy named "Performance Based Time-Delay". It is shown that this control strategy can result in excellent system performance compared to the conventional passive suspension system or other control strategies implemented in active suspension systems. The vibrations due to road roughness are controlled by changing magnetic fluxes of the actuators. Less required computational steps, use of an on-line digital computer, overall system simplicity, and achievement of a better response to larger high frequency disturbances are among the advantages of the system controller.