Vehicle speed estimator and traction control device
First Claim
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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, whereinthe 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;
a time constant changer that changes the time constant of the variable filter processor in accordance with travel conditions of the construction vehicle; and
a gear-shift state determiner that determines a state of a transmission of the construction vehicle, whereinthe time constant changer comprises a lockup switch time constant changer that changes the time constant of the variable filter processor when the gear-shift state determiner determines that a predetermined time does not pass after a lockup-release command has been output in the transmission.
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Abstract
A vehicle speed estimator includes a unit that selects a minimum rotation speed among rotation speeds of wheels detected by a rotation speed detector and calculates a reference wheel speed of a construction vehicle at every predetermined time. The unit includes: a variable filter processor that performs a low-pass filter processing to the minimum rotation speed, 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.
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Citations
6 Claims
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1. A vehicle speed estimator that estimates a vehicle speed of an all-wheel-drive construction vehicle, comprising:
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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; a time constant changer that changes the time constant of the variable filter processor in accordance with travel conditions of the construction vehicle; and a gear-shift state determiner that determines a state of a transmission of the construction vehicle, wherein the time constant changer comprises a lockup switch time constant changer that changes the time constant of the variable filter processor when the gear-shift state determiner determines that a predetermined time does not pass after a lockup-release command has been output in the transmission. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification