Cost-Effective Skyhook Control for Semiactive Vehicle Suspension Applications

Skyhook control, which is now widely applied to vehicle suspension control, requires two sensors to measure sprung mass acceleration and relative displacement, respectively. In the practical implementation, these two measurement signals are converted into corresponding velocities; then per the skyhook control policy the velocities are employed to decide the desired damping level; finally the damping control signal will be sent to a controllable damper to reduce vibration. For automotive application, the cost as well as reliability is always one of the primary concerns. In this paper, a new scheme is proposed to simplify skyhook control implementation by eliminating one sensor instead of traditionally using two. This design can reduce cost and improve system reliability by reducing the semiactive system complexity. According to a quarter car model, the idea is expatiated on through analysis of the phase relationship between the two velocities that are essential for skyhook control. Then the estimation of the relative velocity from the sprung mass acceleration is formulated. A cost effective skyhook control is derived from using only one accelerometer, and the effectiveness of this new skyhook control approach is demonstrated with ride control through a simulation study of a full car suspension system with application of magneto-rheological (MR) dampers.