Method for populating motor vehicle yaw gain tables for use in an electronic stability control system
An automated and algorithmic method utilizing motor vehicle steering geometry knowledge, applicable to small and large turn angles, along with knowledge of motor vehicle understeer gradient, for determining motor vehicle yaw gain by which a motor vehicle yaw gain table is populated for use by an electronic stability control system of the motor vehicle. The method may utilize either a recursive methodology of population or an open loop methodology of population.
1. A recursive method for populating values of a yaw gain table for an electronic stability control system of a motor vehicle, comprising the steps of:
providing a motor vehicle having an electronic stability control system, wherein the electronic stability control system has a yaw gain table requiring population;
determining geometry of the motor vehicle;
determining a plurality of front steer angles as a function of a plurality of turn radii of the motor vehicle responsive to said step of determining geometry;
determining for each turn radii a large angle geometry correction factor as a function of the plurality of turn radii responsive to said step of determining a plurality of front steer angles;
providing an understeer gradient for the motor vehicle; and
recursively populating the values of the yaw gain table as a function of predetermined reference speeds of the motor vehicle and predetermined front steer angles of the motor vehicle responsive to said determined plurality of front steer angles, the determined large angle geometry correction, and the provided understeer gradient, whereupon the yaw gain table has acquired the required population.
2. The method of claim 1 , wherein said step of providing comprises performing a plurality of step steer tests on the motor vehicle.
3. The method of claim 1 , wherein:
the values populating the yaw gain table have a predetermined correspondence to lateral acceleration of the motor vehicle, and wherein the values are limited in correspondence to a predetermined maximum lateral acceleration of the motor vehicle; and
the predetermined maximum lateral acceleration exceeds a maximum lateral acceleration capability of the motor vehicle.
4. The method of claim 3 , wherein said step of providing comprises performing a plurality of step steer tests on the motor vehicle.
5. A recursive method for populating values of a yaw gain table for an electronic stability control system of a motor vehicle, comprising the steps of:
providing a motor vehicle having an electronic stability control system, wherein the electronic stability control system has a yaw gain table requiring population;
determining geometry of the motor vehicle to thereby obtain a first table, wherein each entry of the first table denotes a front steer angle of the motor vehicle as a function of vehicle turn radius;
determining at least one large angle geometry correction factor as a function of at least one vehicle turn radius using at least one entry of the first table;
providing an understeer gradient of the motor vehicle; and
recursively populating the yaw gain table, wherein each entry of the yaw gain table represents a unique vehicle yaw gain as a function of at least a vehicle reference speed and a front steer angle derived from at least the vehicle large geometry correction factor and the vehicle understeer gradient, whereupon the yaw gain table has acquired the required population.
6. The method of claim 5 , wherein the understeer gradient is a function of, at least, a desired vehicle lateral acceleration.
7. The method of claim 6 , wherein:
the values populating the yaw gain table have a predetermined correspondence to lateral acceleration of the motor vehicle, and wherein the values are limited in correspondence to a predetermined maximum lateral acceleration of the motor vehicle; and
the predetermined maximum lateral acceleration exceeds a maximum lateral acceleration capability of the motor vehicle.
8. The method of claim 7 , wherein said step of providing comprises performing a plurality of step steer tests on the motor vehicle.
9. An open loop method for populating values of a yaw gain table for an electronic stability control system of a motor vehicle, comprising the steps of:
providing a motor vehicle having an electronic stability control system, wherein the electronic stability control system has a yaw gain table requiring population;
determining geometry of the motor vehicle;
determining a plurality of front steer angles as a function of a plurality of turn radii of the motor vehicle responsive to said step of determining geometry;
providing an understeer gradient for the motor vehicle;
populating a steer angle table as a function of predetermined yaw rates of the motor vehicle and predetermined vehicle speed vectors of the motor vehicle responsive to the determined plurality of front steer angles and the provided understeer gradient; and
populating the values of the yaw gain table as a function of predetermined reference speeds of the motor vehicle and predetermined yaw rates of the motor vehicle responsive to the populated steer angle table, whereupon the yaw gain table has acquired the required population.
10. The method of claim 9 , wherein said step of providing comprises performing a plurality of step steer tests on the motor vehicle.
11. The method of claim 9 , wherein the understeer gradient is a function of, at least, a desired vehicle lateral acceleration.
12. The method of claim 9 , wherein:
the values populating the yaw gain table have a predetermined correspondence to lateral acceleration of the motor vehicle, and wherein the values are limited in correspondence to a predetermined maximum lateral acceleration of the motor vehicle; and
the predetermined maximum lateral acceleration exceeds a maximum lateral acceleration capability of the motor vehicle.
13. The method of claim 12 , wherein the understeer gradient is a function of, at least, a desired vehicle lateral acceleration.
14. The method of claim 13 , wherein said step of providing comprises performing a plurality of step steer tests on the motor vehicle.