EP0444772A2
Expired / Lapsed
EP
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An apparatus and a method for estimating the friction coefficient of a road surface
Assignee: Mitsubishi Motors Corp
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Filing: 1991-01-23
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Granted: —
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Expires: 2011-01-23
Abstract
Abstract An apparatus for effecting a method for estimating the friction coefficient of a road surface according to the present invention comprises front- and rear-wheel rotation sensors(118, 120, 122, 124) for detecting the running speed of a vehicle, a linear G sensor(130) for detecting an actual transverse acceleration(GY) of the vehicle, a steering angle sensor(126) for detecting the steering angle(δ) of front wheels, and a torque calculating unit(112) supplied with the vehicle speed, actual transverse acceleration, and steering angle detected by means of these sensors. In the torque calculating unit(112), which takes account of an assumed value of the stability factor of the vehicle in addition to the vehicle speed, actual transverse acceleration, and steering angle, a target transverse acceleration required by a driver is calculated, for example, and whether or not the friction coefficient of the road surface is low is then estimated according to the relationship between the calculated target transverse acceleration and the actual transverse acceleration.
Inventors
- 👤 Masayoshi Ito
- 👤 Kiichi Yamada
- 👤 Masayuki Hashiguchi
- 👤 Keiji Isoda
- 👤 Toshio Shigehara
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 07:30
CPC Classifications
B; B62; B62D; B62D6/00; B62D6/002; B62D6/006; B60; B60K; B60K28/00; B60K28/10; B60K28/16; B60T; B60T8/00; B60T8/17; B60T8/172; B60T8/175; G; G01; G01N; G01N19/00; G01N19/02; B60T2201/00; B60T2201/16; B60T2210/00; B60T2210/10; B60T2210/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
155 words
An apparatus for estimating the friction coefficient of a road surface while a vehicle is running, comprising means(112, 118, 120, 122, 124) for detecting the running speed(V) of said vehicle and calculating means(112) for calculating the friction coefficient of said road surface according to said vehicle speed(V), characteruzed in that : said calculating means(112) includes means for obtaining an actual transverse acceleration(GY) acting on said vehicle at right angles to the running direction thereof, means for detecting the steering angle(δ) of steerable wheels(FWL, FWR) of said vehicle, estimating means for estimating the friction coefficient of said road surface or a road surface condition indicative of said friction coeificient by arithmetically processing the stability factor(A) of said vehicle in addition to said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ) obtained with use of said individual means, and means for producing a predetermined output in accordance with the result obtained with use of said estimating means.
Claim 2
Dependent Claim
118 words
An apparatus according to claim 1, characterized in that said apparatus previously has an assumed value(AL) indicative of the upper limit value of the stability factor(A) of said vehicle on a road surface having a low friction coefficient, and said estimating means includes means for calculating a target transverse acceleration(GYO) of said vehicle required by a driver, on the basis of said vehicle speed(V), steering angle(δ), and assumed values(AL) of stability factor, and means for comparing said calculated target transverse acceleration(GYO) and said actual transverse acceleration(GY), whereby the friction coefficient of said road surface is determined to be low if the value of said actual transverse acceleration(GY) is smaller than the value of said calculated target transverse acceleration(GYO).
Claim 3
Dependent Claim
93 words
An apparatus according to claim 1, characterized in that said apparatus has a limit value(AG) of the stability factor(A) predetermined for stable turning of said vehicle, and said estimating means includes means for calculating said stability factor(A) on the basis of said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ), and means for comparing said calculated stability factor(A) and said limit value(AG), whereby said road surface condition is determined to be so severe that the limit of vehicle steering capacity is reached if said calculated stability factor((A) is greater than said limit value(AG).
Claim 4
Dependent Claim
44 words
An apparatus according to claim 3, characterized in that said output producing means(138) includes means for giving an alarm on receiving the result of estimation by said estimating means that said road surface condition is so severe that said steering limit capacity is reached.
Claim 5
Dependent Claim
69 words
An apparatus according to claim 3, characterized in that said estimating means includes means for calculating said stability factor(A) on the basis of said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ), and means for comparing said calculated stability factor(A) and said limit value(AG), whereby the value of said transverse acceleration(GY) obtained when said calculated stability factor((A) is equal to said limit value(AG) is set as said friction coefficient.
Claim 6
Dependent Claim
156 words
An apparatus according to claim 1, characterized in that said apparatus has a limit value(AL) of the stability factor(A) predetermined for stable turning of said vehicle and a discrimination value(GYTH) intermediate between a first maximum transverse acceleration of said vehicle obtainable on a road surface having a predetermined high friction coefficient and a second maximum transverse acceleration of said vehicle obtainable on a road surface having a predetermined low friction coefficient, and said estimating means includes means for calculating said stability factor(A) on the basis of said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ), and means for comparing said calculated stability factor(A) and said limit value(AL) and comparing said actual transverse acceleration(GY) and said discrimination value(GYTH), whereby the friction coefficient of the road surface is determined to be low if said calculated stability factor(A) is greater than said limit value(AL) and if the value of said actual transverse acceleration(GY) is smaller than said discrimination value(GYTH).
Claim 7
Independent Claim
146 words
A method for estimating the friction coefficient of a road surface while a vehicle is running, comprising a process for obtaining the running speed(V) of said vehicle and a calculating process for calculating the friction coefficient of said road surface according to said vehicle speed(V), characterized in that : said calculating process includes a process for obtaining the steering angle(δ) of steerable wheels(FWL, FWR of said vehicle, and an actual : transverse acceleration acting(GY) on said vehicle at right angles to the running direction thereof, an estimating process for estimating the friction coefficient of said road surface or a road surface condition indicative of said friction coefficient by arithmetically processing the stability factor(A) of said vehicle in addition to said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ), and a process for producing a predetermined output in accordance with the result obtained in said estimating process.
Claim 8
Dependent Claim
119 words
A method according to claim 7, characterized in that said method further comprises a process for preparing an assumed value(AL) indicative of the upper limit value of the stability factor(A) of said vehicle on a road surface having a low friction coefficient, and said estimating process includes calculating a target transverse acceleration(GYO) of said vehicle required by a driver, on the basis of said vehicle speed, steering angle(δ), and assumed values(AL) of stability factor(A), and then comparing said calculated target transverse acceleration(GYO) and said actual transverse acceleration(GY), whereby the friction coefficient of said road surface is determined to be low if the value of said actual transverse acceleration(GY) is smaller than the value of said calculated target transverse acceleration(GYO).
Claim 9
Dependent Claim
94 words
A method according to claim 7, characterized in that said method further comprises a process for preparing a limit value(AG) of the stability factor(A) for stable turning of said vehicle, and said estimating process includes calculating said stability factor(A) on the basis of said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ), and then comparing said calculated stability factor(A) and said limit value(AG), whereby said road surface condition is determined to be so severe that the limit of vehicle steering capacity is reached if said calculated stability factor is greater than said limit value.
Claim 10
Dependent Claim
45 words
A method according to claim 9, characterized in that said output producing process includes giving an alarm when the result of estimation in said estimating process that said road surface condition is so severe the limit of that said steering capacity is reached is obtained.
Claim 11
Dependent Claim
66 words
A method according to claim 9, characterized in that said estimating process includes calculating said stability factor(A) on the basis of said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ), and then comparing said calculated stability factor(A) and said limit value(AG), whereby the value of said transverse acceleration(GY) obtained when said calculated stability factor(A) is equal to said limit value(AG) is set as said friction coefficient.
Claim 12
Dependent Claim
157 words
A method according to claim 7, characterised in that said method further comprises a process for preparing a limit value(AL) of the stability factor(A) for stable turning of said vehicle and a discrimination value(GYTH) intermediate between a first maximum transverse acceleration of said vehicle obtainable on a road surface having a predetermined high friction coefficient and a second maximum transverse acceleration of said vehicle obtainable on a road surface having a predetermined low friction coefficient, and said estimating process includes calculating said stability factor(A) on the basis of said vehicle speed(V), actual transverse acceleration(GY), and steering angle(δ), and then comparing said calculated stability factor(A) and said limit value(AL) and comparing said actual transverse acceleration(GY) and said discrimination value(GYTH), whereby the friction coefficient of the road surface is determined to be low if said calculated stability factor(A) is greater than said limit value(AL) and if the value of said actual transverse acceleration(GY) is smaller than said discrimination value(GYTH).
References Cited (Backward Citations)
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