To provide a grade inferring device and its method for inferring a grade of a road surface from acceleration and driving force of a vehicle body without requiring an additional device for measuring grade.
This grade inferring device is provided with a driving force computing means for calculating an inferred value of driving force Fd of a motor vehicle and a grade computing means for calculating a grade of the road surface detected by an acceleration sensor from the force acting on the motor vehicle and the driving force Fd generated by the acceleration ax of the vehicle body of the motor vehicle in the horizontal direction and gravity acceleration (g) of the motor vehicle for the road surface, respectively. The grade is calculated by using the sum of a horizontal component for the road surface of the gravity acceleration (g) and a horizontal component for the road surface of the acceleration (a) of the vehicle body of the motor vehicle due to the driving force of the motor vehicle in the vertical direction to the gravity acceleration as the acceleration ax of the vehicle body and using the sum of the driving force Fd and the force acting on the motor vehicle generated by the horizontal component for the road surface of the gravity acceleration (g) as the force acting on the motor vehicle generated by the horizontal component for the road surface of the acceleration (a) of the vehicle body.
SATO SHINSUKE
SUZUKI TORU
Kazuo Abe
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