Road condition discriminating system
First Claim
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1. A rough road discriminating system for a vehicle having a wheel system comprising:
- vehicle speed sensor means, adapted to be mounted on a part of said wheel system of said vehicle, for generating a vehicle speed signal in response to revolutions of a wheel thereof;
processing means for performing the following functions;
(a) computing a value of wheel acceleration/deceleration as a rate of change of wheel speed representing a differentiated value of wheel speed, based on said vehicle speed signal, (b) generating a change degree signal by computing an amount of change in a magnitude of said wheel acceleration/deceleration during a predetermined period of time, and (c) comparing said change degree signal with a set value and generating a rough road decision signal indicating that said vehicle is running on a rough road when said change degree signal exceeds said set value; and
actuating means for controlling actuating means of said vehicle in accordance with the rough road decision signal from said processing means.
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Abstract
A road surface condition discriminating system is disclosed, in which a vehicle speed signal produced from a vehicle speed sensor mounted on a part of the wheel system of an automobile running on a road is analyzed to decide the road surface conditions on the basis of the variations in the wheel revolutions. The system computes the acceleration from the derivative of the measured speed and then various actuating devices of the vehicle, such as, height control, shock absorber control, power steering control and skid control are controlled from the decision on the road condition.
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Citations
22 Claims
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1. A rough road discriminating system for a vehicle having a wheel system comprising:
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vehicle speed sensor means, adapted to be mounted on a part of said wheel system of said vehicle, for generating a vehicle speed signal in response to revolutions of a wheel thereof; processing means for performing the following functions;
(a) computing a value of wheel acceleration/deceleration as a rate of change of wheel speed representing a differentiated value of wheel speed, based on said vehicle speed signal, (b) generating a change degree signal by computing an amount of change in a magnitude of said wheel acceleration/deceleration during a predetermined period of time, and (c) comparing said change degree signal with a set value and generating a rough road decision signal indicating that said vehicle is running on a rough road when said change degree signal exceeds said set value; andactuating means for controlling actuating means of said vehicle in accordance with the rough road decision signal from said processing means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A rough road discriminating system for a wheeled vehicle, comprising:
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first means for detecting a speed of a wheel of said vehicle and producing a signal indicative thereof; and second means for performing the following; (1) calculating a rate of change of said detected wheel speed; (2) determining a change amount in said rate of change over a first predetermined time; (3) determining whether said change amount is greater than a predetermined rough road setting; (4) indicating a rough road if said amount is greater than said rough road setting; and (5) indicating a non-rough road only after said amount has been less than said rough road setting for time greater than a second predetermined time. - View Dependent Claims (12, 13, 14)
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15. A device for calculating a roughness of a road being traversed by a wheeled vehicle, comprising:
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first means for detecting a speed of a wheel of the vehicle; and second means for; (1) calculating a rate of change of said wheel speed, (2) computing a variance of said rate of change as a sum of squares of different wheel rates of change, divided by a number of factors making up the sum, and (b
3) looking up a road surface coefficient in a table as a function of said computed variance.
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16. A device for calculating a roughness of a road being traversed by a wheeled vehicle, comprising:
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first means for detecting a speed of a wheel of the vehicle; and second means for; (1) calculating a value of rate of change of said wheel speed, (2) determining when said rate of change value exceeds a predetermined threshold, (3) counting occurrences of said threshold being exceeded in a predetermined time, and (4) looking up a road surface coefficient in a table as a function of said counted occurrences per predetermined time.
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17. A device for calculating a roughness of a road being traversed by a wheeled vehicle, comprising:
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first means for detecting a speed of a wheel of the vehicle; and second means for; (1) calculating a rate of change of said wheel speed, (2) determining whether said rate of change is one of positive and negative; (3) determining if a current positive rate of change value is greater than a previous maximum rate of change, and increasing said previous maximum to said current value when said current value is greater; (4) determining if a current negative rate of change value is less than a previous minimum rate of change, and decreasing said previous minimum to said current value when said current value is less; (5) repeating said functions (1)-(4) for a predetermined time interval; (6) determining a difference between said maximum and minimum; and (7) looking up a road surface coefficient in a table as a function of said difference.
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18. A method of discriminating a rough road being traversed by a vehicle, comprising the steps of:
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generating a vehicle speed signal in response to revolutions of a wheel; computing a rate of change of wheel speed as a value of wheel acceleration representing a differentiated value of wheel speed based on said vehicle speed signal; generating a change degree signal by computing a degree of change in a magnitude of said wheel acceleration during a predetermined period of time; comparing said change degree signal with a set value; generating a rough road decision result indicating that road running of said vehicle is running on a rough road when said change degree signal exceeds said set value; and controlling an aspect of said vehicle in accordance with the rough road decision result. - View Dependent Claims (19, 20, 21, 22)
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Specification