Patent ID: 8538635
Filing Date: 2013-09-17
Classification: B60T,B60W,G06F,Y10T

Abstract:
1. A vehicle speed estimator that estimates a vehicle speed of an all-wheel-drive construction vehicle, comprising: a rotation speed detector that detects a rotation speed of each of wheels at every predetermined time; and a reference wheel-speed calculator that selects a minimum rotation speed among the rotation speeds of the wheels detected by the rotation speed detector, calculates a reference wheel speed of the construction vehicle at every predetermined time, and output the reference wheel speed, wherein the reference wheel-speed calculator comprises: a minimum wheel-speed calculator that calculates a minimum wheel speed at every predetermined time based on the rotation speeds detected by the rotation speed detector; a variable filter processor that performs a low-pass filter processing to the minimum wheel speed calculated by the minimum wheel-speed calculator, the variable filter processor having a variable time constant; and a time constant changer that changes the time constant of the variable filter processor in accordance with travel conditions of the construction vehicle, and the time constant changer comprises an acceleration and deceleration time constant changer that sets the time constant of the variable filter processor for the low-pass filter processing to be smaller than a predetermined value when the minimum wheel speed calculated from the rotation speed of the one of the wheels having the minimum rotation speed detected by the rotation speed detector is decelerating, and sets the time constant of the variable filter processor for the low-pass filter processing to be larger than the predetermined value when the minimum wheel speed is accelerating.