Vehicle control device, vehicle control method, and vehicle control system

1 . A vehicle control device, which is configured to be provided in a vehicle including a friction brake configured to generate a friction braking force in the vehicle and a motor configured to generate a driving force in the vehicle, the vehicle control device comprising:

a controller configured to output a result of calculation based on input information,

wherein the controller is configured to:

acquire a first physical quantity relating to a speed of the vehicle;

acquire a second physical quantity relating to a requested braking force required to stop the vehicle;

estimate a road surface gradient based on: (i) a difference between a derivative of the first physical quantity and a sensor value acquired from an acceleration sensor configured to detect an acceleration of the vehicle; and (ii) another value acquired from the acceleration sensor and stored when the vehicle has stopped at the road surface gradient; and

output a control command for generating the driving force by the motor, immediately before the vehicle stops, under a state in which the friction braking force based on the second physical quantity is being generated, so that the driving force decreases as the road surface gradient increases in a downward direction when the vehicle is being decelerated.

2 . The vehicle control device according to claim 1 , wherein the controller is configured to output the control command when the first physical quantity falls below a predetermined speed.

3 . The vehicle control device according to claim 2 , wherein the controller is configured to output the control command so that the driving force increases as the first physical quantity decreases and a third physical quantity relating to a deceleration of the vehicle decreases.

4 . The vehicle control device according to claim 3 , wherein the controller is configured to output the control command so that a maximum value of the driving force is held until a predetermined time elapses after the vehicle is determined to have stopped.

5 . The vehicle control device according to claim 4 , wherein the controller is configured to output the control command so that the driving force decreases after the maximum value of the driving force is held.

6 . The vehicle control device according to claim 2 , wherein the controller is configured to output the control command so that a maximum value of the driving force is held until a predetermined time elapses after the vehicle is determined to have stopped.

7 . The vehicle control device according to claim 2 , wherein the controller is configured to output the control command so that the driving force decreases after a maximum value of the driving force is held.

8 . The vehicle control device according to claim 2 , wherein the controller is configured to output the control command so that a sum of the driving force and a force caused by a creep phenomenon occurring in the vehicle is prevented from exceeding the friction braking force.

9 . The vehicle control device according to claim 1 , wherein the motor is an electric motor.

10 . A vehicle control method of controlling a vehicle including a friction brake configured to generate a friction braking force in the vehicle and a motor configured to generate a driving force in the vehicle, the vehicle control method comprising:

acquiring a first physical quantity relating to a speed of the vehicle;

acquiring a second physical quantity relating to a requested braking force required to stop the vehicle;

estimating a road surface gradient based on: (i) a difference between a derivative of the first physical quantity and a sensor value acquired from an acceleration sensor configured to detect an acceleration of the vehicle; and (ii) another value acquired from the acceleration sensor and stored when the vehicle has stopped at the road surface gradient; and

outputting a control command for generating the driving force by the motor, immediately before the vehicle stops, under a state in which the friction braking force based on the second physical quantity is being generated, so that the driving force decreases as the road surface gradient increases in a downward direction when the vehicle is being decelerated.

11 . A vehicle control system, comprising:

a friction brake configured to generate a friction braking force in a vehicle;

a motor configured to generate a driving force in the vehicle; and

a controller configured to output a result of calculation based on input information, wherein the controller is configured to:

acquire a first physical quantity relating to a speed of the vehicle;

acquire a second physical quantity relating to a requested braking force required to stop the vehicle;

estimate a road surface gradient based on: (i) a difference between a derivative of the first physical quantity and a sensor value acquired from an acceleration sensor configured to detect an acceleration of the vehicle; and (ii) another value acquired from the acceleration sensor and stored when the vehicle has stopped at the road surface gradient; and

output a control command for generating the driving force by the motor, immediately before the vehicle stops, under a state in which the friction braking force based on the second physical quantity is being generated, so that the driving force decreases as the road surface gradient increases in a downward direction when the vehicle is being decelerated.

12 . The vehicle control device according to claim 5 , wherein the controller is configured to output the control command so that the driving force decreases at a constant rate after the maximum value of the driving force is held.

13 . The vehicle control device according to claim 7 , wherein the controller is configured to output the control command so that the driving force decreases at a constant rate after the maximum value of the driving force is held.