The low-power consumption, high reliability, and cost advantages of the semi-active magnetorheological actuator have contributed to her wide application prospects. However, the system performance is not comparable with active systems. Taking the vehicle ride comfort as an example, in the full frequency domain of road excitation, the RMS of semi-active suspension systems is about 20% lower than that of active ones. The essential reason is that the output force of the magnetorheological actuator and the excitation velocity are always in the same direction. Semi-active systems using magnetorheological actuators can only achieve the first- and third-quadrant mechanical characteristics in the force-velocity diagram, while the active actuator-based system provides excellent performance, to a great extent, thanks to its adjustment capability within the four-quadrant diagram.
Inspired by the “four-quadrant operation” of active actuators such as motors, retaining the advantages of both semi-active and active actuators, this paper uses semi-active actuators to realize the four-quadrant controllable semi-active actuators of active-actuator performance. Such actuators are defined as pseudo-active actuators. The basic design principle of the pseudo-active actuator using semi-active actuators to realize the performance of active actuators is presented. Further, a specific pseudo-active actuator employing magnetorheological dampers is designed and developed. It is composed of two secondary magnetorheological dampers and a mechanical compensation mechanism. Through the mechanical compensation mechanism, the output force of the first magnetorheological damper is in the same direction as the excitation, and the output force of the second magnetorheological damper is in the opposite direction. In sequence, a control strategy of the vehicular pseudo-active suspension is proposed, and the system performance is analyzed.
 

Magnetorheological damper,pseudo-active,semi-active,four quadrants,suspension control