Driving assist apparatus for vehicle

Patent metadata

Field	Value
Publication number	US-10889299-B2
Application number	US-201916284176-A
Country	US
Kind code	B2
Filing date	Feb 25, 2019
Priority date	Feb 26, 2018
Publication date	Jan 12, 2021
Grant date	Jan 12, 2021

Abstract

This driving assist apparatus for a vehicle sets target wheel speed of an inside rear wheel in turning to substantially zero when a state of a center differential apparatus is a locked state in a case where the vehicle is turned in an extremely low speed traveling control. Further, the apparatus sets target wheel speed of each of wheels other than the inside rear wheel in turning such that a mean value of target wheel speeds of front wheels is equal to a mean value of target wheel speeds of rear wheels and the mean value of target wheel speeds of front wheels is equal to target vehicle body speed. Furthermore, the apparatus adjusts driving force and braking force such that wheel speed of each of the wheels becomes equal to the target wheel speed set for each of the wheels.

First claim

What is claimed is:

1. A driving assist apparatus for a vehicle, applied to a vehicle comprising:
a plurality of wheels including a front left wheel, a front right wheel, a rear left wheel, and a rear right wheel,
a driving device which generates driving force for the vehicle,
a rotating shaft for front wheels for transmitting the driving force to the front left wheel and the front right wheel,
a differential gear for front wheels which is disposed between the front left wheel and the front right wheel and the rotating shaft for front wheels, and allows differential between the front left wheel and the front right wheel,
a rotating shaft for rear wheels for transmitting the driving force to the rear left wheel and the rear right wheel,
a differential gear for rear wheels which is disposed between the rear left wheel and the rear right wheel and the rotating shaft for rear wheels, and allows differential between the rear left wheel and the rear right wheel,
a center differential apparatus configured to be enable to selectively realize at least two states of a free state that is a state where differential between the rotating shaft for front wheel and the rotating shaft for rear wheels is allowed and a locked state that is a state where the rotating shaft for front wheels and the rotating shaft for rear wheels are directly connected, and configured such that a ratio of rotational speed of the rotating shaft for rear wheels to rotational speed of the rotating shaft for front wheels becomes a predetermined ratio in the locked state, and
a brake apparatus which gives braking force to each of the plurality of the wheels, and
the driving assist apparatus for a vehicle comprises:
a wheel speed detector which detects wheel speed of each of the plurality of the wheels, and
a control part which performs extremely low speed traveling control in which the driving force generated by the driving device and the braking force given to each of the plurality of the wheels by the brake apparatus are adjusted such that vehicle body speed of the vehicle is in agreement with a predetermined target vehicle body speed, without requiring an accelerator operation and a brake operation by a driver of the vehicle;
wherein:
the control part is configured to perform turning assist control in which:
when a predetermined turning assist control request occurs and the state of the center differential apparatus is the locked state in a case where the vehicle is turned by the front left wheel and the front right wheel being steered in a state where the extremely low speed traveling control is performed, target wheel speed of an inside rear wheel in turning among the plurality of the wheels is set to wheel speed lower than wheel speed of the inside rear wheel in turning in a case where the vehicle is turned by steering, and target wheel speed of each of wheels other than the inside rear wheel in turning among the plurality of the wheels are respectively set such that a ratio of a target rear wheel mean value that is a mean value of target wheel speed of the rear left wheel and target wheel speed of the rear right wheel to a target front wheel mean value that is a mean value of target wheel speed of the front left wheel and target wheel speed of the front right wheel is equal to the predetermined ratio and the target front wheel mean value becomes equal to the target vehicle body speed, and
the driving force generated by the driving device and the braking force given respectively to the plurality of the wheels by the brake apparatus are adjusted such that the wheel speed detected for each of the plurality of the wheels becomes equal to the target wheel speed set for each of the plurality of the wheels.

2. The driving assist apparatus for a vehicle, according to claim 1 , wherein:
the control part is configured to set the target wheel speed of the inside rear wheel in turning in the turning assist control to zero.

3. The driving assist apparatus for a vehicle, according to claim 2 , wherein:
the control part is configured to, when the predetermined ratio is 1,
set the target wheel speed of an outside rear wheel in turning in the turning assist control to a value (2ωa) that is twice as much as the target vehicle body speed (ωa),
set the target wheel speed of an inside front wheel in turning in the turning assist control to a value (ωa−ωb) obtained by subtracting a predetermined value (ωb) from the target vehicle body speed (ωa), and
set the target wheel speed of an outside front wheel in turning in the turning assist control to a value (ωa+ωb) obtained by adding the predetermined value (ωb) to the target vehicle body speed (ωa).

Assignees

• Toyota Motor Co Ltd

Inventors

• Yasutomi Taisuke

Classifications

• B60T7/12 Primary

  for automatic initiation; for initiation not subject to will of driver or passenger {(limiting speed of vehicles other than rail vehicles B60K31/00)} · CPC title

• B60W30/18145 Primary

  Cornering · CPC title

• B60W2540/18

  Steering angle · CPC title

• B60W2520/28

  Wheel speed · CPC title

• B60T2201/16

  Curve braking control, e.g. turn control within ABS control algorithm · CPC title