<p>A pair of electrodes are provided between which the electroviscous fluid is disposed. A control applies pulses of positive and negative voltages alternately across the electrodes to control viscosity of the electroviscous fluid. The control applies each pulses of positive voltage and negative voltage gradually so that the positive and negative voltages are applied as nearly-trapezoidal pulse signal waveforms. The control applies the pulses of the positive voltage of a frequency greater than one Hz. The control maintains a ratio between the time the positive voltage and the negative voltage are applied to an intermediate ratio from between 8.2 to 2.8. The control applies each pulse of positive and negative voltages with a voltage value that changes at a rate of between 3 and 15 V/mm/micron sec.</p>
