VEHICLE DRIVE FORCE DISTRIBUTION CONTROL SYSTEM

• US 20080071451A1
• Filed: 09/19/2007
• Published: 03/20/2008
• Est. Priority Date: 09/20/2006
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: DEGUCHI, Yoshitaka, YAMAGUCHI, Ichiro
• Granted Patent: US 9,132,731 B2
• Time in Patent Office: Days
• US Class Current: 701/69
• CPC Class Codes: B60K 17/356 having fluid or electric motor, for driving one or more wheels disposition of motor in, or adjacent to, traction wheel B60K7/00
• CPC Class Codes: B60K 23/0808 for varying torque distribution between driven axles, e.g. by transfer clutch
• CPC Class Codes: B60K 6/52 Driving a plurality of drive axles, e.g. four-wheel drive
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 3/102 of individual wheels
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 2050/0028 Mathematical models, e.g. for simulation
• CPC Class Codes: B60W 2300/18 Four-wheel drive vehicles
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2540/18 Steering angle
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2720/14 Yaw
• CPC Class Codes: B60W 2720/30 Wheel torque
• CPC Class Codes: B60W 30/045 Improving turning performance
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

A controller (8) controlling a drive force distributed to each wheel (1-4) of a vehicle sets dynamic drive force target values (Fxf**, Fx₃**, Fx₄**) to the wheels, and determines a variation amount target ratio related to variation amounts (ΔM, ΔFx, ΔFy) of a vehicle yaw moment (M), a vehicle front/aft force (Fx), and a vehicle lateral force (Fy) such that a vehicle behavior generated by the dynamic drive force target values does not vary. The controller (8) determines sets of the drive forces (Fxf(j, k), Fx₃(j, k), Fx₄(j, k)) realizing the variation amount target ratio, selects drive force command values from these sets such that each drive force command value is within a drive force limiting range, and controls a drive force regulating mechanism (20, 12, 13, 15,16) according to the selected drive force command values.

Claims

1. A driving/braking force control system for a vehicle having at least a pair of a right wheel and a left wheel which are independently controlled, comprising:

a driving/braking force regulating mechanism which applies a wheel driving/braking force to each of the wheels; and

a programmable controller programmed to;

set dynamic wheel driving/braking force target values on the basis of a present operation state;

calculate a vehicle front/aft force, a vehicle lateral force and a vehicle yaw moment as parameters representing vehicle behavior generated by the wheel dynamic driving/braking force target values;

calculate a wheel driving/braking force limiting range for each of the dynamic wheel driving/braking force target values;

determine, when one of the dynamic wheel driving/braking force target values is not within the wheel driving/braking force limiting range, a vehicle behavior variation amount target value which is represented by a ratio of variation amount target values of the vehicle front/aft force, the vehicle lateral force, and the vehicle yaw moment;

calculate a variation in a tire lateral force of each wheel accompanying a variation in the wheel driving/braking force of each wheel on the basis of a sensitivity of the tire lateral force of each wheel;

calculate sets of the wheel driving/braking forces that achieve the vehicle behavior variation amount target value even when a variation in the tire lateral force of each wheel accompanying a variation in the wheel driving/braking force of each wheel occurs;

select a set of the wheel driving/braking forces from the sets of the wheel driving/braking forces as wheel driving/braking force command values such that each of the wheel driving/braking forces in the selected set is within the driving/braking force limiting range; and

control the driving/braking force regulating mechanism to apply wheel driving/braking forces to the right wheel and the left wheel according to the wheel driving/braking force command values.

2. The driving/braking force control system as defined in claim 1, wherein the controller is further programmed to determine the vehicle behavior variation amount target value which can suppress a variation in the vehicle lateral force and a variation in the vehicle yaw moment generated by the dynamic driving/braking target values.

3. The driving/braking force control system as defined in claim 1, wherein the controller is further programmed to determine the vehicle behavior variation amount target value which can suppress a variation in the vehicle front/aft force and a variation in the vehicle yaw moment generated by the dynamic driving/braking target values.

4. The driving/braking force control system as defined in claim 1, wherein the controller is further programmed to determine the vehicle behavior variation amount target value which can suppress a variation in the vehicle skid angle and a variation in the vehicle yaw moment generated by the dynamic driving/braking target values.

5. The driving/braking force control system as defined in claim 4, wherein the controller is further programmed to determine the vehicle behavior variation amount target value which can suppress the variation in the vehicle yaw moment while maintaining a ratio between the variation amount of the vehicle front/aft force and the variation amount of the vehicle lateral force maintained at cos β

/sin β

, where β

is a vehicle skid angle,

6. The driving/braking force control system as defined in claim 1, wherein the controller is further programmed to determine the wheel driving/braking force command values by multiplying the dynamic wheel driving/braking force target values by a positive decreasing constant when one of the wheel driving/braking force command values is not within the wheel driving/braking force limiting range,

7. The driving/braking force control system as defined in claim 1, wherein the controller is further programmed to determine the vehicle behavior variation amount target value on the basis of an operation state of the vehicle.

8. The driving/braking force control system as defined in claim 1, wherein the controller is further programmed to select a set of the wheel driving/braking forces such that a deviation of the wheel driving/braking forces in the selected set from the dynamic wheel driving/braking force target values is minimal when plural sets of the wheel driving/braking forces exist within the driving/braking force limiting range.

9. A driving/braking force control system for a vehicle having at least a pair of a right wheel and a left wheel which are independently controlled, comprising:

means for regulating a wheel driving/braking force which is applied to each of the wheels;

means for setting dynamic wheel driving/braking force target values on the basis of a present operation state;

means for calculating a vehicle front/aft force, a vehicle lateral force and a vehicle yaw moment as parameters representing vehicle behavior generated by the wheel dynamic driving/braking force target values;

means for calculating a wheel driving/braking force limiting range for each of the dynamic wheel driving/braking force target values;

means for determining, when one of the dynamic wheel driving/braking force target values is not within the wheel driving/braking force limiting range, a vehicle behavior variation amount target value which is represented by a ratio of variation amount target values of the vehicle front/aft force, the vehicle lateral force and the vehicle yaw moment;

means for calculating a variation in a tire lateral force of each wheel accompanying a variation in the wheel driving/braking force of each wheel on the basis of a sensitivity of the tire lateral force of each wheel;

means for calculating sets of the wheel driving/braking forces that achieve the vehicle behavior variation amount target value even when a variation in the tire lateral force of each wheel accompanying a variation in the wheel driving/braking force of each wheel occurs;

means for selecting a set of the wheel driving/braking forces from the sets of the wheel driving/braking forces as driving/braking force command values such that each of the wheel driving/braking forces in the selected set is within the driving/braking force limiting range; and

means for controlling the driving/braking force regulating mechanism to apply wheel driving/braking forces to the right wheel and the left wheel according to the wheel driving/braking force command values.

10. A driving/braking force control method for a vehicle having at least a pair of a right wheel and a left wheel which are independently controlled, and a driving/braking force regulating mechanism which applies a wheel driving/braking force to each of the wheels, the method comprising:

setting dynamic wheel driving/braking force target values on the basis of a present operation state;

calculating a vehicle front/aft force, a vehicle lateral force and a vehicle yaw moment as parameters representing vehicle behavior generated by the wheel dynamic driving/braking force target values;

calculating a wheel driving/braking force limiting range for each of the dynamic wheel driving/braking force target values;

determining, when one of the dynamic wheel driving/braking force target values is not within the wheel driving/braking force limiting range, a vehicle behavior variation amount target value which is represented by a ratio of variation amount target values of the vehicle front/aft force, the vehicle lateral force and the vehicle yaw moment;

calculating a variation in a tire lateral force of each wheel accompanying a variation in the wheel driving/braking force of each wheel on the basis of a sensitivity of the tire lateral force of each wheel;

calculating sets of the wheel driving/braking forces that achieve the vehicle behavior variation amount target value even when a variation in the tire lateral force of each wheel accompanying a variation in the wheel driving/braking force of each wheel occurs;

selecting a set of the wheel driving/braking forces from the sets of the wheel driving/braking forces as driving/braking force command values such that each of the wheel driving/braking forces in the selected set is within the driving/braking force limiting range; and

controlling the driving/braking force regulating mechanism to apply wheel driving/braking forces to the right wheel and the left wheel according to the wheel driving/braking force command values.