Process for determining a safety margin for a traveling motor vehicle
First Claim
1. A process for determining a safety margin with respect to adhesion between tires and roadway of a motor vehicle travelling along a direction of travel under all conditions of travel comprisingdetecting by means of at least one acceleration sensor located on said motor vehicle longitudinal and transverse acceleration values (ax, ay) for said motor vehicle along directions which are longitudinal and transverse to the direction of travel and producing signals indicative thereof,detecting by means of a rotational wheel sensor a rotational wheel acceleration (Phi) for said motor vehicle and producing a signal indicative thereof,detecting by means of a steering angle sensor a dynamic steering angle for said motor vehicle and producing a signal indicative thereof,receiving all of said signals in an electronic processor under all conditions of travel and by means of said electronic processor determining a transverse adhesion value (Siy) as a function of said transverse acceleration value (ay) and said dynamic steering angle,by means of said electronic processor determining a longitudinal adhesion value (Six) as a function of said longitudinal acceleration value (ax) and said rotational wheel acceleration (Phi),by means of said electronic processor determining a maximum attainable longitudinal acceleration value (axLIM) and a maximum attainable transverse acceleration value (ayLIM) by multiplying said longitudinal acceleration value (Six) and said transverse acceleration value (Siy) by vehicle specific coefficients (Kx, Ky) respectively,establishing a limit curve (aLIM) from the maximum attainable acceleration values (axLIM, ayLIM),forming a current vehicle movement state vector (AF) from a vectorial combination of the longitudinal acceleration (ax) and the transverse acceleration (ay) values,by means of said electronic processor determining a safety margin value (SAFLIM) under all conditions of travel by comparing the lengths of said vehicle movement state vector (AF) with a collinear limit vector (AMAX) which reaches said limit curve (aLIM), andon a display device displaying said safety margin value (SAFLIM) under all conditions of travel.
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Accused Products
Abstract
A process for determining a safety margin with respect to adhesion between tires and roadway of a travelling motor vehicle comprises, detecting longitudinal and transverse acceleration values (ax, ay), a rotational wheel acceleration value (Phi), and a dynamic steering angle value, and producing signals indicative thereof. A longitudinal adhesion value (Six) is determined as a function of the longitudinal acceleration (ax) and the rotational wheel acceleration (Phi), while a transverse adhesion value (Siy) is determined as a function of the transverse acceleration (ay) and the dynamic steering angle. Maximum attainable longitudinal and transverse acceleration values (axLIM, ayLIM) are next determined by multiplying the longitudinal and transverse acceleration values (Six, Siy) by vehicle specific coefficients (Kx, Ky) and a limit curve (aLIM), e.g., an ellipse, is established. Next a current vehicle movement state vector (AF) is formed by a vectorial combination of the longitudinal and transverse acceleration values (ax, ay). A safety margin value (SAFLIM) is obtained by comparing the lengths of the vehicle movement state vector (AF) with a collinear limit vector (AMAX) which reaches the limit curve (aLIM), and the safety margin value (SAFLIM) is displayed to the driver. Desirably, if the safety margin value (SAFLIM) exceeds predetermined threshold values, perceptible warning signals, e.g., a yellow light and then a red light, are triggered.
50 Citations
10 Claims
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1. A process for determining a safety margin with respect to adhesion between tires and roadway of a motor vehicle travelling along a direction of travel under all conditions of travel comprising
detecting by means of at least one acceleration sensor located on said motor vehicle longitudinal and transverse acceleration values (ax, ay) for said motor vehicle along directions which are longitudinal and transverse to the direction of travel and producing signals indicative thereof, detecting by means of a rotational wheel sensor a rotational wheel acceleration (Phi) for said motor vehicle and producing a signal indicative thereof, detecting by means of a steering angle sensor a dynamic steering angle for said motor vehicle and producing a signal indicative thereof, receiving all of said signals in an electronic processor under all conditions of travel and by means of said electronic processor determining a transverse adhesion value (Siy) as a function of said transverse acceleration value (ay) and said dynamic steering angle, by means of said electronic processor determining a longitudinal adhesion value (Six) as a function of said longitudinal acceleration value (ax) and said rotational wheel acceleration (Phi), by means of said electronic processor determining a maximum attainable longitudinal acceleration value (axLIM) and a maximum attainable transverse acceleration value (ayLIM) by multiplying said longitudinal acceleration value (Six) and said transverse acceleration value (Siy) by vehicle specific coefficients (Kx, Ky) respectively, establishing a limit curve (aLIM) from the maximum attainable acceleration values (axLIM, ayLIM), forming a current vehicle movement state vector (AF) from a vectorial combination of the longitudinal acceleration (ax) and the transverse acceleration (ay) values, by means of said electronic processor determining a safety margin value (SAFLIM) under all conditions of travel by comparing the lengths of said vehicle movement state vector (AF) with a collinear limit vector (AMAX) which reaches said limit curve (aLIM), and on a display device displaying said safety margin value (SAFLIM) under all conditions of travel.
Specification