US Patent 7333882 Suspension control apparatus

In a suspension control system a sky-hook command signal (B) obtained from velocity data obtained by integrating a sprung mass acceleration (αu) from a sprung mass acceleration sensor (9u) and an unsprung mass vibration damping command signal (C) obtained on the basis of an unsprung mass acceleration (αd) detected by an unsprung mass acceleration sensor (9d) are added together to obtain a control signal (A) for a damping characteristic inverting type shock absorber (6). The control signal (A) reflects the unsprung mass acceleration (αd) that leads in phase by 90° the piston speed. Accordingly, it is possible to compensate for a response delay due to an actuator (11), etc.