DEVICE FOR ESTIMATING STATE QUANTITY OF SKID MOTION OF VEHICLE

• US 20120016646A1
• Filed: 03/26/2010
• Published: 01/19/2012
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Takenaka, Toru
• Granted Patent: US 8,855,885 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 2270/86 Optimizing braking by using ESP vehicle or tire model
• 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
• CPC Class Codes: B60T 8/17551 determining control parameters related to vehicle stability used in the regulation, e.g. by calculations involving measured or detected parameters
• CPC Class Codes: B60W 2050/0024 Variable gains
• CPC Class Codes: B60W 2050/0025 Transfer function weighting factor
• CPC Class Codes: B60W 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 2050/0054 Cut-off filters, retarders, delaying means, dead zones, threshold values or cut-off frequency
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 2520/30 Wheel torque
• CPC Class Codes: B60W 2720/125 Lateral acceleration
• CPC Class Codes: B60W 40/076 Slope angle of the road
• CPC Class Codes: B60W 40/101 Side slip angle of tyre

Abstract

A device for estimating the state quantity of a skid motion of a vehicle is provided with an element which finds road surface reaction force model values of respective wheels and a skid motion state quantity model value using a vehicle model including a friction characteristic model between the wheels and the road surface, an element which finds the deviation between the lateral acceleration model value generated in a predetermined position of the vehicle by the resultant force of the road surface reaction force model values and the lateral acceleration detected value indicated by the output of an actual lateral acceleration detecting means, and an element which determines, as the estimated value of the skid motion state quantity, a value obtained by adding a value obtained by passing the deviation through a filter having a high-cut characteristic to the skid motion state quantity model value.

Claims

1. A device for estimating a state quantity of a skid motion of a vehicle, the device sequentially estimating a value of a skid motion state quantity with a skid angle or a skid speed in a predetermined position of the vehicle defined as the skid motion state quantity to be estimated and the device comprising:

a vehicle model computing element, which finds road surface reaction force model values, each of which is a value of a road surface reaction force including at least a lateral force out of the road surface reaction force acting on each wheel of the vehicle from a road surface on a vehicle model, by performing arithmetic processing of the vehicle model while inputting an observed value of a predetermined type of quantity to be observed related to a behavior of an actual vehicle, which is required to identify at least a slip of the wheel of the vehicle on the vehicle model, into the vehicle model by using the vehicle model, which includes a friction characteristic model representing a relationship between the slip between the wheel of the vehicle and the road surface and the road surface reaction force acting on the wheel from the road surface and represents the dynamics of the vehicle, and which finds a new value of a skid motion state quantity model value, which is a value of the skid motion state quantity generated in the vehicle on the vehicle model due to a resultant force of the road surface reaction force model values by using the road surface reaction force model values and a past calculated value of the skid motion state quantity model value;

a predetermined position actual lateral acceleration detecting element, which includes at least a lateral acceleration sensor sensing actual acceleration in the lateral direction of the vehicle and generates an output based on predetermined position actual lateral acceleration, which is the actual acceleration in the lateral direction in the predetermined position of the vehicle;

a lateral acceleration model value computing element, which finds a predetermined position lateral acceleration model value, which is a value of the acceleration in the lateral direction of the vehicle generated in the predetermined position of the vehicle on the vehicle model by the resultant force of the road surface reaction force model values, by using the road surface reaction force model values;

a lateral acceleration deviation computing element, which finds a lateral acceleration deviation, which is a deviation between a detected value of the predetermined position actual lateral acceleration indicated by the output from the predetermined position actual lateral acceleration detecting element and the predetermined position lateral acceleration model value; and

a skid motion state quantity estimated value determining element, which determines, as a correction manipulated variable, a value obtained by passing the lateral acceleration deviation through a filter having a high-cut characteristic or a value obtained by passing the lateral acceleration deviation through the filter and a gain multiplication element, which multiplies an input value by a predetermined gain, and which determines a value obtained by adding the correction manipulated variable to the skid motion state quantity model value as an estimated value of the skid motion state quantity of the actual vehicle.

2. The device for estimating the state quantity of the skid motion of the vehicle according to claim 1, wherein the predetermined position of the vehicle is the position of the center of gravity of the vehicle.

3. The device for estimating the state quantity of the skid motion of the vehicle according to claim 1, wherein the filter is a band-pass filter having a high-cut characteristic and a low-cut characteristic.

4. The device for estimating the state quantity of the skid motion of the vehicle according to claim 1, wherein a gain having the predetermined value is set to a value equal to a time constant, which defines a cutoff frequency on the high-frequency side in the high-cut characteristic of the filter.

5. A device for estimating a state quantity of a skid motion of a vehicle, the device sequentially estimating a value of a skid motion state quantity with a skid angle or a skid speed in a predetermined position of the vehicle defined as the skid motion state quantity to be estimated and the device comprising:

a vehicle model computing element, which finds road surface reaction force model values, each of which is a value of a road surface reaction force including at least a lateral force out of the road surface reaction force acting on each wheel of the vehicle from a road surface on a vehicle model, by performing arithmetic processing of the vehicle model while inputting an observed value of a predetermined type of quantity to be observed related to a behavior of an actual vehicle, which is required to identify at least a slip of the wheel of the vehicle on the vehicle model, into the vehicle model by using the vehicle model, which includes a friction characteristic model representing a relationship between the slip between the wheel of the vehicle and the road surface and the road surface reaction force acting on the wheel from the road surface and represents the dynamics of the vehicle, and which finds a skid motion state quantity model value, which is a value of the skid motion state quantity generated in the vehicle on the vehicle model due to a resultant force of the road surface reaction force model values;

a predetermined position actual lateral acceleration detecting element, which includes at least a lateral acceleration sensor sensing actual acceleration in the lateral direction of the vehicle and generates an output based on predetermined position actual lateral acceleration, which is the actual acceleration in the lateral direction in the predetermined position of the vehicle;

a lateral acceleration model value computing element, which finds a predetermined position lateral acceleration model value, which is a value of the acceleration in the lateral direction of the vehicle generated in the predetermined position of the vehicle on the vehicle model by the resultant force of the road surface reaction force model values, by using the road surface reaction force model values;

a lateral acceleration deviation computing element, which finds a lateral acceleration deviation, which is a deviation between a detected value of the predetermined position actual lateral acceleration indicated by the output from the predetermined position actual lateral acceleration detecting element and the predetermined position lateral acceleration model value;

a yaw angular acceleration detecting element, which generates an output based on angular acceleration about a predetermined yaw axis of the actual vehicle;

a yaw angular acceleration model value computing element, which finds a yaw angular acceleration model value, which is a value of the angular acceleration generated about the predetermined yaw axis of the vehicle on the vehicle model by the resultant force of the road surface reaction force model values, by using the road surface reaction force model values;

a yaw acceleration deviation computing element, which finds a yaw angular acceleration deviation, which is a deviation between a detected value of angular acceleration indicated by the output from the yaw angular acceleration detecting element and the yaw angular acceleration model value; and

a skid motion state quantity estimated value determining element, which determines a value obtained by correcting the skid motion state quantity model value according to the lateral acceleration deviation and the yaw angular acceleration deviation, as an estimated value of the skid motion state quantity of the actual vehicle.

6. The device for estimating the state quantity of the skid motion of the vehicle according to claim 5, wherein the predetermined position of the vehicle is the position of the center of gravity of the vehicle.

7. The device for estimating the state quantity of the skid motion of the vehicle according to claim 5, wherein:

the vehicle model computing element includes an element which sequentially finds a new value of the skid motion state quantity model value by using the road surface reaction force model values and a past calculated value of the skid motion state quantity model value;

the skid motion state quantity estimated value determining element includes;

a linear-combined value calculating element, which finds a linear-combined value (α

1*A+α

2*B) obtained by linearly combining two weighting factors (α

1) and (α

2) by which the lateral acceleration deviation (A) and the yaw angular acceleration deviation (B) are multiplied, respectively;

a correction basic value determining element, which determines a basic value of a correction manipulated variable for use in correcting the skid motion state quantity model value; and

a correction computing element, which determines a value obtained by adding the correction manipulated variable to the skid motion state quantity model value as an estimated value of the skid motion state quantity of the actual vehicle by using a value obtained by passing the basic value through a first filter having a high-cut characteristic or a value obtained by passing the basic value through the first filter and a gain multiplication element, which multiplies an input value by a gain having a predetermined value, as the correction manipulated variable;

the two weighting factors (α

1) and (α

2) in the linear-combined value (α

1*A+α

2*B) are set, on the assumption that the left direction in a state of facing forward of the vehicle is defined as the positive direction of lateral acceleration of the vehicle and the counterclockwise direction viewed from the above of the vehicle is defined as the positive direction of angular acceleration about the yaw axis of the vehicle, so that the two weighting factors (α

1) and (α

2) have mutually the same polarity in the case where the neutral steer point (hereinafter, referred to as “

NSP”

) of the actual vehicle lies on a rear side beyond the center of gravity of the vehicle and so that the two weighting factors (α

1) and (α

2) have polarities different from each other in the case where the NSP lies on a front side beyond the center of gravity of the vehicle; and

the correction basic value determining element determines the basic value to be zero in the case where the linear-combined value (α

1*A+α

2*B) has a different polarity from the term (α

1*A) including the lateral acceleration deviation (A) in the linear-combined value and determines the basic value to be a value closer to zero out of the linear-combined value (α

1*A+α

2*B) and the lateral acceleration deviation (A) in the case where the linear-combined value (α

1*A+α

2*B) has the same polarity as the term (α

1*A) including the second filtering value (A).

8. The device for estimating the state quantity of the skid motion of the vehicle according to claim 5, wherein:

the vehicle model computing element includes an element which sequentially finds a new value of the skid motion state quantity model value by using the road surface reaction force model values and a past calculated value of the skid motion state quantity model value;

the skid motion state quantity estimated value determining element includes;

a linear-combined value calculating element, which finds a linear-combined value (α

1*A+α

2*B) obtained by linearly combining two weighting factors (α

1) and (α

2) by which a second filtering value (A), which is obtained by passing the lateral acceleration deviation through a second filter having a low-cut characteristic, and a third filtering value (B), which is obtained by passing the yaw angular acceleration deviation through a third filter having a low-cut characteristic, are multiplied, respectively;

a correction basic value determining element, which determines a basic value of a correction manipulated variable for use in correcting the skid motion state quantity model value; and

a correction computing element, which determines a value obtained by adding the correction manipulated variable to the skid motion state quantity model value as an estimated value of the skid motion state quantity of the actual vehicle by using a value obtained by passing the basic value through a first filter having a high-cut characteristic or a value obtained by passing the basic value through the first filter and a gain multiplication element, which multiplies an input value by a gain having a predetermined value, as the correction manipulated variable;

the two weighting factors (α

1) and (α

2) in the linear-combined value (α

1*A+α

2*B) are set, on the assumption that the left direction in a state of facing forward of the vehicle is defined as the positive direction of lateral acceleration of the vehicle and the counterclockwise direction viewed from the above of the vehicle is defined as the positive direction of angular acceleration about the yaw axis of the vehicle, so that the two weighting factors (α

1) and (α

2) have mutually the same polarity in the case where the neutral steer point (hereinafter, referred to as “

NSP”

) of the actual vehicle lies on a rear side beyond the center of gravity of the vehicle and so that the two weighting factors (α

1) and (α

2) have polarities different from each other in the case where the NSP lies on a front side beyond the center of gravity of the vehicle; and

the correction basic value determining element determines the basic value to be zero in the case where the linear-combined value (α

1*A+α

2*B) has a different polarity from the term (α

1*A) including the second filtering value (A) in the linear-combined value and determines the basic value to be a value closer to zero out of the linear-combined value (α

1*A+α

2*B) and the lateral acceleration deviation (A) in the case where the linear-combined value (α

1*A+α

2*B) has the same polarity as the term (α

1*A) including the second filtering value (A).

9. The device for estimating the state quantity of the skid motion of the vehicle according to claim 5, wherein:

the vehicle model computing element includes an element which sequentially finds a new value of the skid motion state quantity model value by using the road surface reaction force model values and a past calculated value of an estimated value of the skid motion state quantity;

the skid motion state quantity estimated value determining element includes;

a linear-combined value calculating element, which finds a linear-combined value (α

1*A+α

2*B) obtained by linearly combining two weighting factors (α

1) and (α

2) by which the lateral acceleration deviation (A) and the yaw angular acceleration deviation (B) are multiplied, respectively;

a correction basic value determining element, which determines a basic value of a correction manipulated variable for use in correcting the skid motion state quantity model value; and

a correction computing element, which determines a value obtained by adding the correction manipulated variable to the skid motion state quantity model value as an estimated value of the skid motion state quantity of the actual vehicle by using the basic value or a value obtained by passing the basic value through a fourth filter having a low-cut characteristic as the correction manipulated variable;

the two weighting factors (α

1) and (α

2) in the linear-combined value (α

1*A+α

2*B) are set, on the assumption that the left direction in a state of facing forward of the vehicle is defined as the positive direction of lateral acceleration of the vehicle and the counterclockwise direction viewed from the above of the vehicle is defined as the positive direction of angular acceleration about the yaw axis of the vehicle, so that the two weighting factors (α

1) and (α

2) have mutually the same polarity in the case where the neutral steer point (hereinafter, referred to as “

NSP”

) of the actual vehicle lies on a rear side beyond the center of gravity of the vehicle and so that the two weighting factors (α

1) and (α

2) have polarities different from each other in the case where the NSP lies on a front side beyond the center of gravity of the vehicle; and

the correction basic value determining element determines the basic value to be zero in the case where the linear-combined value (α

1*A+α

2*B) has a different polarity from the term (α

1*A) including the lateral acceleration deviation (A) in the linear-combined value and determines the basic value to be a value closer to zero out of the linear-combined value (α

1*A+α

2*B) and the lateral acceleration deviation (A) in the case where the linear-combined value (α

1*A+α

2*B) has the same polarity as the term (α

1*A) including the lateral acceleration deviation (A).

10. The device for estimating the state quantity of the skid motion of the vehicle according to claim 5, wherein:

the vehicle model computing element includes an element which sequentially finds a new value of the skid motion state quantity model value by using the road surface reaction force model values and a past calculated value of an estimated value of the skid motion state quantity;

the skid motion state quantity estimated value determining element includes;

a linear-combined value calculating element, which finds a linear-combined value (α

1*A+α

2*B) obtained by linearly combining two weighting factors (α

1) and (α

2) by which a fifth filtering value (A), which is obtained by passing the lateral acceleration deviation through a fifth filter having a low-cut characteristic, and a sixth filtering value (B), which is obtained by passing the yaw angular acceleration deviation through a sixth filter having a low-cut characteristic, are multiplied, respectively;

a correction basic value determining element, which determines a basic value of a correction manipulated variable for use in correcting the skid motion state quantity model value; and

a correction computing element, which determines a value obtained by adding the correction manipulated variable to the skid motion state quantity model value as an estimated value of the skid motion state quantity of the actual vehicle by using the basic value or a value obtained by passing the basic value through a fourth filter having a low-cut characteristic as the correction manipulated variable;

the two weighting factors (α

1) and (α

2) in the linear-combined value (α

1*A+α

2*B) are set, on the assumption that the left direction in a state of facing forward of the vehicle is defined as the positive direction of lateral acceleration of the vehicle and the counterclockwise direction viewed from the above of the vehicle is defined as the positive direction of angular acceleration about the yaw axis of the vehicle, so that the two weighting factors (α

1) and (α

2) have mutually the same polarity in the case where the neutral steer point (hereinafter, referred to as “

NSP”

) of the actual vehicle lies on a rear side beyond the center of gravity of the vehicle and so that the two weighting factors (α

1) and (α

2) have polarities different from each other in the case where the NSP lies on a front side beyond the center of gravity of the vehicle; and

the correction basic value determining element determines the basic value to be zero in the case where the linear-combined value (α

1*A+α

2*B) has a different polarity from the term (α

1*A) including the fifth filtering value (A) in the linear-combined value and determines the basic value to be a value closer to zero out of the linear-combined value (α

1*A+α

2*B) and the second filtering value (A) in the case where the linear-combined value (α

1*A+α

2*B) has the same polarity as the term (α

1*A) including the fifth filtering value (A).