Adaptive cruise control system
First Claim
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1. An adaptive cruise control system for controlling a distance, R, between a source vehicle and a preceding vehicle, said system comprising:
- a sensor for sensing said distance, R;
a signal representing a predetermined time, TR;
means for determining a maximum headway, Dmax;
means for determining a desired headway, DFOLLOW based on said predetermined time, TR;
means for comparing DFOLLOW to Dmax; and
means for controlling said distance, R, to the smaller of said desired headway, DFOLLOW or said maximum headway, Dmax, thereby defining a controlled distance.
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Abstract
An adaptive cruise control system that provides a smooth following by limiting the headway to keep it lower than a predetermined maximum. The present invention accomplishes this objective through systematically limiting the headway. In particular, the present invention reduces a time related speed multiplier used in calculating the desired headway, to maintain a headway that is less than an effective maximum sensor range for the adaptive cruise control system.
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Citations
23 Claims
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1. An adaptive cruise control system for controlling a distance, R, between a source vehicle and a preceding vehicle, said system comprising:
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a sensor for sensing said distance, R;
a signal representing a predetermined time, T R ;
means for determining a maximum headway, Dmax;
means for determining a desired headway, D FOLLOW based on said predetermined time, TR ;
means for comparing D FOLLOW to Dmax; and
means for controlling said distance, R, to the smaller of said desired headway, D FOLLOW or said maximum headway, Dmax, thereby defining a controlled distance.- View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for limiting a following distance between a source vehicle and a preceeding vehicle in an adaptive cruise control system, said method comprising the steps of:
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relaying an actual source vehicle speed, a relative distance, a relative velocity, between the actual source vehicle speed and a preceeding vehicle speed, a desired source vehicle speed, a time related speed multiplier, and a maximum system range to an adaptive cruise computer;
determining a predetermined maximum headway;
calculating a desired headway by solving a desired distance equation;
limiting said time related speed multiplier;
setting a headway limited flag when said relative distance approaches said predetermined maximum headway;
determining a source vehicle command speed based on said limited time related speed multiplier;
limiting the following distance to be less than said predetermined maximum headway; and
controlling said desired source vehicle speed to said source vehicle command speed. - View Dependent Claims (9, 10, 12)
setting said relative velocity equal to zero;
setting said source vehicle speed equal to said preceding vehicle speed; and
setting said time related speed multiplier equal to a value pre-set by an operator of said source vehicle.
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11. The method as claimed in claim S wherein said step of setting a headway limited flag further comprises the step of activating an indicator.
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13. A method of controlling the headway between a preceding vehicle and a source vehicle operating at a controlled speed comprising the steps of:
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determining a maximum headway between the preceding vehicle and the source vehicle;
calculating a desired headway between the preceding vehicle and the source vehicle;
comparing the desired headway to the maximum headway; and
when the desired headway is greater than the maximum headway, setting the controlled speed to result in a limited headway at which the source vehicle follows the preceding vehicle wherein the limited headway is less than the desired headway. - View Dependent Claims (14, 15, 16, 17)
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18. A method of controlling the headway between a preceding vehicle and a source vehicle operating at a controlled speed comprising the steps of:
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reading input of a sensor to determine an actual headway spacing between the source vehicle and the preceding vehicle;
determining a maximum headway spacing between the source vehicle and the preceding vehicle as a function of a maximum effective range of the sensor;
reading driver spacing input from a manually adjustable unit;
determining a following headway spacing between the preceding vehicle and the source vehicle as a function of the driver spacing input;
comparing the following headway spacing to the maximum headway spacing; and
when the following headway spacing is greater than the maximum headway spacing, setting the controlled speed of the source vehicle to effect a limited headway spacing between the preceding vehicle and the source vehicle that is less than the following headway spacing. - View Dependent Claims (19, 20, 21, 22, 23)
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Specification