WHEEL BEHAVIOR DETECTION DEVICE

PURPOSE:To prevent a vehicle from oscillating and pitching by providing a filter means delivering a waveform which is nearer to an original shape of a control variable as the bad road index indicating the roughness of a road surface is smaller, and by instructing an increase and a decrease in brake force or the like in accordance with an output from the filter means. CONSTITUTION:At first, a bad road index computing circuit 5 delivers the degree of a bad road having a great roughness or the like as a bad road index, and a control variable computing circuit 6 calculates control variables for right and left wheels. Further, a third filter 7 smoothes the control variables in accordance with the bad road index. For example, when the bad road index is small, waveforms having near original shapes of the control variables are delivered. Meanwhile, when a bad road index is large, waveforms from which abrupt variations in the index is removed, are delivered. The control variables having been smoothed by the third filter 7 are transmitted to a brake control section 8 to be used for judgment to decrease, increase or hold the brake force. With this arrangement, it is possible to prevent a vehicle from oscillating, pitching and lowering its acceleration and deceleration.