No-Jerk Skyhook Control Methods for Semiactive Suspensions

Abstract

This paper presents two alternative implementations of skyhook control, named “skyhook function” and “no-jerk skyhook,” for reducing the dynamic jerk that is often experienced with conventional skyhook control in semiactive suspension systems. An analysis of the relationship between the absolute velocity of the sprung mass and the relative velocity across the suspension are used to show the damping-force discontinuities that result from the conventional implementation of skyhook control. This analysis shows that at zero crossings of the relative velocity, conventional skyhook introduces a sharp increase (jump) in damping force, which, in turn, causes a jump in sprung-mass acceleration. This acceleration jump, or jerk, causes a significant reduction in isolation benefits that can be offered by skyhook suspensions. The alternative implementations of skyhook control included in this study offer modifications to the formulation of conventional skyhook control such that the damping force jumps are eliminated. The alternative policies are compared to the conventional skyhook control in the laboratory, using a base-excited semiactive system that includes a heavy-truck seat suspension. An evaluation of the damping force, seat acceleration, and the electrical currents supplied to a magnetorheological damper, which is used for this study, shows that the alternative implementations of skyhook control can entirely eliminate the damping-force discontinuities and the resulting dynamic jerks caused by conventional skyhook control.

High frequency energy transfer in semi-active suspension

“…In this case, Eq. (9) can be rewritten in the form yðtÞ ¼ AðtÞcos½o 2 t þ yðtÞ (11) where A(t) and yðtÞ are the amplitude and phase of the process. As we would like that c(t) varies between C min and C max with a constant amplitude (i.e.…”

Cost-Effective Skyhook Control for Semiactive Vehicle Suspension Applications

“…(5) shows that the composition of these three equations can well represent this MR damper. In the model, A= 186.5, B=1, C=0, and the other parameters are shown in Fig.…”

“…(7) and (8), the one-sensor based skyhook control policy can be expressed (similar to no-jerk skyhook [5]) as:…”

“…Since the advent of this two-sensor based skyhook control, a significant number of studies have discussed how to improve and effectively implement this damping control [2][3][4][5][6][7][8][9]. However, there has not been much study about the implementation cost, which actually is sensitive and essential for market success in the competitive automotive industry.…”

Vibration isolation of a feedback linearized model for a contactless Electromagnetic Isolator by Virtually Varying Mass control

“…S. Rakheja [6] introduces another onoff damping control, in which, the damper is turned on only when the absolute velocity and the relative displacement had the opposite signs. Mehdi Ahmadian [2] proposes the nojerk on-off skyhook control which removes the discontinuity of the damping force. Yanqing Liu [3] proposes the on-off stiffness control, in which, the spring stiffness should be as small as possible when the relative displacement had an opposite sign with the absolute velocity.…”