METHOD AND DEVICE FOR CALCULATING MAGNITUDE OF CORNERING FORCE GENERATED IN WHEEL

• US 20090043517A1
• Filed: 07/18/2006
• Published: 02/12/2009
• Est. Priority Date: 07/19/2005
• Status: Active Grant

• Current Assignee: Yokohama Rubber Company Limited
• Original Assignee: Yokohama Rubber Company Limited
• Inventors: Miyashita, Naoshi, Matsuda, Jun, Kitazaki, Tsuyoshi
• Granted Patent: US 7,822,563 B2
• Time in Patent Office: Days
• US Class Current: 702/41
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/64 Wheel forces, e.g. on hub, spindle or bearing
• CPC Class Codes: B60G 2400/824 Travel path sensing; Track monitoring
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60T 2240/04 Tire deformation
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2530/20 Tyre data
• CPC Class Codes: B60W 2556/50 of positioning data, e.g. GPS [Global Positioning System] data
• CPC Class Codes: B60W 30/02 Control of vehicle driving stability
• CPC Class Codes: B60W 30/095 Predicting travel path or likelihood of collision
• CPC Class Codes: B60W 30/18172 Preventing, or responsive to skidding of wheels
• CPC Class Codes: B60W 40/00 Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
• CPC Class Codes: B60W 40/064 Degree of grip
• CPC Class Codes: B60W 40/101 Side slip angle of tyre

Abstract

A method of calculating a cornering force to be applied to each wheel provided to a vehicle which is cornering, comprising the steps of: obtaining a magnitude of a centrifugal force to the vehicle in a direction substantially orthogonal to a vehicle traveling direction, a contact length of each wheel during the cornering of the vehicle, and an amount of deformation in a wheel width direction at the contact portion of each wheel of the vehicle, calculating a difference between the obtained amount of the deformation and an amount of deformation in the wheel width direction under a straight forward travel condition of the vehicle for each wheel, and calculating a cornering force for each wheel based on the magnitude of the centrifugal force, the contact length, and the difference between amounts of deformation in the wheel width direction.

Claims

1. A cornering force calculating method of calculating a magnitude of a cornering force to be applied to each of a plurality of wheels provided to a vehicle when the vehicle is cornering, the plurality of wheels being each assembled with a tire, the cornering force calculating method comprising:

a centrifugal force measuring step of measuring a magnitude of a centrifugal force to be applied to the vehicle which is cornering, the centrifugal force being in a direction substantially orthogonal to a vehicle traveling direction;

a contact length deriving step of determining a contact length in a wheel circumferential direction, at a contact portion of each of the plurality of wheels of the vehicle which is cornering;

a width direction deformation amount deriving step of determining an amount of deformation in a wheel width direction, at the contact portion of each of the plurality of wheels of the vehicle which is cornering; and

a cornering force calculating step of calculating a magnitude of a cornering force generated in each of the plurality of wheels provided to the vehicle, based on the magnitude of the centrifugal force, the contact length, and the amount of the deformation in the wheel width direction.

2. The cornering force calculating method according to claim 1, further comprising a width direction deformation deviation calculating step of calculating, prior to the cornering force calculating step, a difference between the amount of the deformation in the wheel width direction during when the vehicle is cornering determined in the width direction deformation amount deriving step and the amount of deformation in the wheel width direction during when the vehicle is traveling straight, for each of the plurality of wheels, wherein:

the amount of the deformation in the wheel width direction of the contact portion of each of the plurality of wheels during when the vehicle is traveling straight is determined in advance; and

the cornering force calculating step includes calculating a magnitude of a cornering force generated in each of the plurality of wheels, respectively, by using the magnitude of the centrifugal force, the contact length, and the difference between the amounts of the deformation in the wheel width direction.

3. The cornering force calculating method according to claim 2, wherein the cornering force calculating step comprises:

determining, for each of the plurality of wheels, a deformation area equivalent indicating a deformation area of the contact portion of each of the plurality of wheels during when the vehicle is cornering, the deformation area equivalent being obtained by multiplying the contact length with the difference of the amounts of the deformation in the wheel width direction; and

multiplying each ratio of the deformation area equivalent of each of the plurality of wheels with respect to a sum of the deformation area equivalents of the plurality of wheels, with the magnitude of the centrifugal force to calculate, for each of the plurality of wheels, a magnitude of a cornering force generated in the contact portion of each of the plurality of wheels.

4. The cornering force calculating method according to claim 1, further comprising an acceleration data acquiring step of acquiring time series acceleration data at a predetermined portion of the tire, the time series acceleration data being generated due to an external force applied from the road surface to the tire in rotation,

wherein the contact length deriving step comprises using the time series acceleration data of the tire acquired in the acceleration data acquiring step to determine a contact length of a wheel to which the tire is assembled.

5. The cornering force calculating method according to claim 4, wherein the contact length deriving step comprises:

determining displacement data by extracting, from the time series acceleration data, time series acceleration data due to deformation of a tire and by subjecting the time series acceleration data due to deformation of a tire to time integration of second order, to calculate an amount of the deformation at a predetermined portion of the tire; and

calculating the contact length, by using the amount of deformation at the predetermined portion of the tire.

6. The cornering force calculating method according to claim 4, wherein:

the time series acceleration data acquired in the acceleration data acquiring step includes acceleration data in a radial direction which is orthogonal to a circumferential direction of the tire; and

an amount of deformation at the predetermined portion of the tire calculated in the contact length deriving step includes an amount of deformation in the radial direction of the tire.

7. The cornering force calculating method according to claim 1, further comprising an acceleration data acquiring step of acquiring time series acceleration data in the wheel width direction at a predetermined portion of the tire, the time series acceleration data being generated due to an external force applied from the road surface to the tire in rotation,

wherein the width direction deformation amount deriving step comprises using the time series acceleration data of the tire acquired in the acceleration data acquiring step to determine an amount of the deformation in the wheel width direction of each of the plurality of wheels.

8. The cornering force calculating method according to claim 7, wherein the width direction deformation amount deriving step comprises:

determining displacement data by extracting, from the time series acceleration data, time series acceleration data due to deformation of a tire and by subjecting the time series acceleration data due to deformation of a tire to time integration of second order, to calculate an amount of the deformation in the wheel width direction of the tire.

9. The cornering force calculating method according to claim 1, further comprising a vehicle acceleration measuring step of measuring, through a vehicle acceleration sensor provided to the vehicle, a magnitude of acceleration of the vehicle in a direction substantially orthogonal to the vehicle travelling direction during when the vehicle is cornering,

wherein the centrifugal force deriving step derives a magnitude of the centrifugal force based on the magnitude of acceleration of the vehicle measured in the vehicle acceleration measuring step and a weight of the vehicle which is determined in advance.

10. A cornering force calculating device for calculating a magnitude of a cornering force to be applied to each of a plurality of wheels provided to a vehicle when the vehicle is cornering, the plurality of wheels being each assembled with a tire, the cornering force calculating device comprising:

a centrifugal force measuring means for measuring a magnitude of a centrifugal force to be applied to the vehicle which is cornering, the centrifugal force being in a direction substantially orthogonal to a vehicle traveling direction;

a contact length deriving means for determining a contact length in a wheel circumferential direction, at a contact portion of each of the plurality of wheels of the vehicle which is cornering;

a width direction deformation amount deriving means for determining an amount of deformation in a wheel width direction, at the contact portion of each of the plurality of wheels of the vehicle which is cornering; and

a cornering force calculating means for calculating a magnitude of a cornering force generated in each of the plurality of wheels provided to the vehicle, based on the measured magnitude of the centrifugal force, the derived contact length, and the amount of the deformation in the wheel width direction.