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 with the conventional skyhook control, using a laboratory implementation on a heavy truck seat suspension that represents a base-excited system with a semiactive suspension. An evaluation of the damping force, seat acceleration, and the electrical currents supplied to a magneto-rheological (MR) damper that 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.

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