Device for controlling running behavior of vehicle by mathematical tire model with compensation for brake malfunction

• US 6,266,601 B1
• Filed: 12/22/1999
• Issued: 07/24/2001
• Est. Priority Date: 02/01/1999
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Soga, Masayuki, Hattori, Yoshikazu
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Donnelly, Arthur D.
• Application Number:
  US09/469,267
• Time in Patent Office: 580 Days
• Field of Search: 701/70, 701/72, 701/74, 701/77, 701/78, 701/83, 303/140, 303/146, 180/197
• US Class Current: 701/74
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence

Abstract

A control device for controlling the running behavior of a four wheeled vehicle has a mathematical tire model of each wheel defining a relationship between longitudinal and lateral forces vs. slip ratio, synthesizes the mathematical tire model at zero slip and a control input from an outside running behavior controller such as a spin controller or a driftout controller to generate nominal values of longitudinal force, lateral force and yaw moment of the vehicle body, and controls the slip ratio of the wheels through cyclic adjustment so as to approach the differences between the nominal values and the actual values in the longitudinal force, lateral force and yaw moment of the vehicle body to the corresponding differences of those parameters due to differentiation thereof by the slip ratio based upon the mathematical tire model, wherein when an uncontrollable braking force is applied to any one of the wheels due to a malfunction of the brake system, the nominal values of the longitudinal force and the yaw moment are modified to be decreased as much as an additional longitudinal force and an additional yaw moment corresponding respectively to a longitudinal force and a yaw moment generated in the vehicle by a difference between the uncontrollable braking force and a braking force to be applied to the one wheel according to the slip control.

Claims

1. A device for controlling a running behavior of a vehicle based upon a force-slip performance of a tire, the vehicle having a vehicle body, a pair of front wheels and a pair of rear wheels, brake means for selectively applying a controlled braking force to each of the front pair and the rear pair of the wheels bearing the tires, and means for detecting a braking force applied to each of the front and rear pairs of wheels adapted to be applied with the controlled braking force, comprises:

first means for cyclically calculating by a minute cycle period longitudinal force and lateral force of each of the front and rear pairs of wheels in reference to slip ratio thereof according to a mathematical tire model of a relationship therebetween, so as to obtain a first longitudinal force and a first lateral force corresponding to a first slip ratio and a second longitudinal force and a second lateral force corresponding to zero slip ratio;

second means for cyclically calculating by the minute cycle period longitudinal force, lateral force and yaw moment of the vehicle body based upon the longitudinal forces and the lateral forces of the front pair and rear pairs of wheels, so as to obtain a first longitudinal force, a first lateral force and a first yaw moment of the vehicle body corresponding to the first longitudinal forces and the first lateral forces of the front and rear pairs of wheels and a second longitudinal force, a second lateral force and a second yaw moment of the vehicle body corresponding to the second longitudinal forces and the second lateral forces of the front and rear pairs of the wheels;

third means for cyclically modifying by the minute cycle period the second longitudinal force, the second lateral force and the second yaw moment of the vehicle body calculated by the second means with a longitudinal force, a lateral force and a yaw moment corresponding to an output of an outside running behavior controller, so as to obtain a nominal longitudinal force, a nominal lateral force and a nominal yaw moment, respectively;

fourth means for cyclically calculating by the minute cycle period a difference between the nominal longitudinal force and the first longitudinal force, a difference between the nominal lateral force and the first lateral force and a difference between the nominal yaw moment and the first yaw moment;

fifth means for cyclically calculating by the minute cycle period differentials of the longitudinal and lateral forces of each of the front and rear pairs of wheels on the basis of the slip ratio thereof according to the mathematical tire model;

sixth means for cyclically calculating by the minute cycle period differentials of the longitudinal force, lateral force and yaw moment of the vehicle body based upon differentials of the longitudinal and lateral forces of each of the front and rear pairs of wheels on the basis of the slip ratio;

seventh means for cyclically calculating by the minute cycle period a difference in the longitudinal force, a difference in the lateral force and a difference in the yaw moment of the vehicle body based upon the differentials thereof;

eighth means for cyclically calculating by the minute cycle period a first difference between the difference in the longitudinal force calculated by the fourth means and the difference in the longitudinal force calculated by the seventh means, a second difference between the difference in the lateral force calculated by the fourth means and the difference in the lateral force calculated by the seventh means, and a third difference between the difference in the yaw moment calculated by the fourth means and the difference in the yaw moment calculated by the seventh means;

ninth means for calculating by the minute cycle period differences in the slip ratio of each of the front and rear pairs of wheels which minimize a weighted sum of squares of the first, second and third differences; and

tenth means for selectively operating the brake means to change the slip ratio of each of the front and rear pairs of wheels according to the difference thereof calculated by the ninth means,

wherein the third means further cyclically modify the nominal longitudinal force and the nominal yaw moment to be decreased as much as an additional longitudinal force and an additional yaw moment, respectively, the additional longitudinal force and the additional yaw moment corresponding respectively to a sum of a longitudinal force and a sum of a yaw moment generated in the vehicle by a difference between an uncontrollable braking force detected by the braking force detection means with respect to each of the front and rear pairs of wheels and a braking force to be applied thereto according to the change of the slip ratio thereof effected by the tenth means.

2. A device according to claim 1, further comprising:

eleventh means for cyclically calculating by the minute cycle period a weighted sum of a square of each of the differences in the slip ratio calculated by the ninth means;

wherein the ninth means are modified to calculate the differences in the slip ratio so that a sum of the weighted sum calculated by the ninth means and the weighted sum calculated by the eleventh means is minimized.

3. A device according to claim 1, further comprising:

twelfth means for cyclically calculating by the minute cycle period a weighted sum of a square of each of respective sums of the slip ratio and the change thereof calculated by the ninth means;

wherein the ninth means are modified to calculate the differences in the slip ratio so that a sum of the weighted sum calculated by the ninth means and the weighted sum calculated by the twelfth means is minimized.

4. A device according to claim 2, further comprising:

twelfth means for cyclically calculating by the minute cycle period a weighted sum of a square of each of respective sums of the slip ratio and the change thereof calculated by the ninth means;

wherein the ninth means are modified to calculate the differences in the slip ratio so that a sum of the weighted sum calculated by the ninth means, the weighted sum calculated by the eleventh means and the weighted sum calculated by the twelfth means is minimized.

5. A device according to claim 1, wherein the third means modify the second longitudinal force, the second lateral force and the second yaw moment of the vehicle body calculated by the second means with the longitudinal force, the lateral force and the yaw moment corresponding to the output of the outside running behavior controller, so as to obtain the nominal longitudinal force, the nominal lateral force and the nominal yaw moment, respectively, by adding the longitudinal force, the lateral force and the yaw moment corresponding to the output of the outside running behavior controller to the second longitudinal force, the second lateral force and the second yaw moment, respectively.

6. A device according to claim 5, wherein the third means substantially cancel the lateral force corresponding to the output of the outside running behavior controller in obtaining the nominal lateral force.

7. A device according to claim 2, wherein the ninth means apply a variable weighting factor on each of the difference in the slip ratio of each of the front pair of wheels calculated thereby before outputting the calculated slip ratio difference such that a slip ratio difference applied with a larger weighting factor affects less in the running behavior control than a slip ratio difference applied with a smaller weighting factor, the weighting factor being varied such that, when the nominal yaw moment calculated by the third means is directed to assist a turn of the vehicle, the weighting factor on the slip ratio difference of one of the pair of front wheels serving at the inside of a turn is made larger.

8. A device according to claim 1, wherein the tenth means are adapted to cancel a braking of the rear wheels by overriding the difference of the slip ratio calculated by the ninth means when the yaw rate of the vehicle has changed its direction from a first direction conforming to a turning of the vehicle to a second direction opposite to the first direction during a turn running of the vehicle.