Estimation method of movement state variable in turning of automotive vehicle

• US 5,765,118 A
• Filed: 03/28/1996
• Issued: 06/09/1998
• Est. Priority Date: 03/30/1995
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Fukatani, Katsumi
• Primary Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US08/623,095
• Time in Patent Office: 803 Days
• Field of Search: 364/426.016, 364/424.051, 303/146, 701/72, 701/41
• US Class Current: 701/72
• CPC Class Codes: B60G 17/0162 mainly during a motion involving steering operation, e.g. cornering, overtaking B60G17/0164 takes precedence
• CPC Class Codes: B60G 17/0182 involving parameter estimation, e.g. observer, Kalman filter
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B62D 6/00 Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

An estimation method of estimating a lateral slip angle and a yaw rate or a wheeled vehicle on a basis of a state equation of an observer to be applied with a real yaw rate as a reference input, the observer being designed on a basis of a turning movement model which defines a steer-angle of the vehicle as an input variable and defines the lateral slip angle and the yaw rate as a state variable, wherein a forward speed, a steer-angle, a yaw rate and a lateral acceleration of the vehicle are detected to estimate a lateral acceleration based on the lateral slip angle and yaw rate calculated on a basis of the state equation of the observer and the detected forward speed, a correction coefficient is calculated on a basis of a ratio of the detected lateral acceleration and the estimated lateral acceleration, and a factor of a cornering power defined in the state equation of the observer is multiplied by the calculated correction coefficient.

Claims

1. An estimation method of estimating first and second movement state variables in turning of a wheeled vehicle on a basis of a state equation of an observer to be applied with a first real movement state variable corresponding with the first movement state variable as a reference input, said observer being designed on a basis of a turning movement model which defines a real physical variable indicative of a steer-angle of the vehicle as an input variable and defines the first and second movement state variables each as a state variable, wherein the estimation method comprises the steps of:

detecting the real physical variable and the first real movement state variable for estimating the first and second movement state variables and further detecting a third real movement state variable in turning of the vehicle, different from the first and second movement state variables;

estimating a third movement state variable corresponding with the detected third real movement state variable on a basis of either one of the estimated first and second movement state variables;

calculating a correction value for correction of a cornering power defined in the state equation of said observer on a basis of a difference between the detected third real movement state variable and the estimated third movement state variable; and

correcting a factor of the cornering power by the calculated correction value.

2. An estimation method of estimating a lateral slip angle and yaw rate of a wheeled vehicle on a basis of a state equation of an observer to be applied with a real yaw rate corresponding with the yaw rate as a reference input, said observer being designed on a basis of a turning movement model which defines a real steer-angle of the vehicle as an input variable and defines the lateral slip angle and the yaw rate each as a state variable, wherein the estimation method comprises the steps of:

detecting the real yaw rate and the real steer-angle for estimating the lateral slip angle and yaw rate and further detecting a real forward speed and a real lateral acceleration of the vehicle;

estimating a lateral acceleration of the vehicle based on the estimated lateral slip angle and yaw rate and the detected forward speed of the vehicle;

calculating a correction coefficient based on a ratio of the detected real lateral acceleration to the estimated lateral acceleration; and

multiplying a factor of a cornering power defined in the state equation of said observer by the calculated correction coefficient.

3. An estimation method of estimating a lateral slip angle and yaw rate of a wheeled vehicle based on a state equation of an observer to be applied with a real yaw rate corresponding with the yaw rate as a reference input, said observer being designed on a basis of a turning movement model which defines a real steer-angle of the vehicle as an input variable and defines the lateral slip angle and the yaw rate as a state variable, wherein the estimation method comprises the steps of;

detecting the real yaw rate and the real steering-angle for estimating the lateral slip angle and yaw rate and further detecting a real forward speed and a real lateral acceleration of the vehicle,

calculating a cornering force based on the detected real forward speed, yaw rate and lateral acceleration;

estimating a cornering force based on the estimated lateral slip angle and yaw rate and the detected real forward speed;

calculating a correction coefficient based on a ratio of the calculated cornering force relative to the estimated cornering force; and

multiplying a factor of the estimated cornering force by the calculated correction coefficient.

4. An estimation method of estimating first and second movement state variables in turning of a wheeled vehicle based on a state equation of an observer to be applied with a first real movement state variable corresponding with the first movement state variable as a reference input, said observer being designed on a basis of a turning movement model which defines a real physical variable indicative of a steer-angle of the vehicle as an input variable and defines the first and second movement state variables each as a state variable, wherein the estimation method comprises the steps of:

detecting the real physical variable and the first real movement state variable for estimating the first and second movement state variables;

calculating a correction value for correction of a cornering power defined in the state equation of said observer on a basis of a difference between the detected first real movement state variable and the estimated first movement state variable; and

correcting a factor of the cornering power on the basis of the calculated correction value.

5. An estimation method of estimating a movement state variable including at least a lateral acceleration in turning a wheeled vehicle on a basis of a state equation of an observer to be applied with a real lateral acceleration corresponding with the movement state variable as a reference input, said observer being designed on a basis of a turning movement model which defines a real steer-angie of the vehicle as an input variable and defines the movement state variable as the state variable, wherein the estimation method comprises the steps of:

detecting the real steer-angle speed and the real lateral acceleration of the vehicle for estimating the movement state variable;

calculating a correction coefficient based on a ratio of the detected real lateral acceleration to the lateral acceleration estimated on a basis of the state equation of said observer; and

multiplying a factor of a cornering power defined in the state equation of said observer by the calculated correction coefficient.