AUTOMATIC HEADWAY CONTROL SYSTEM
First Claim
1. An automatic headway control system for controlling a vehicle having a braking means and an accelerating means comprising ranging means mounted on the controlled vehicle for determining the actual headway between said vehicle and a preceding vehicle, speed sensing means mounted on the controlled vehicle for sensing the magnitude of its actual speed, speed computing means for determining the actual speed of the preceding vehicle and the smaller of the actual vehicle speeds, headway computing means coupled to said speed sensing means for computing the safe headway between said controlled vehicle and said preceding vehicle as a function of the smaller of the actual vehicle speeds, and command computing means for actuating the braking means and the accelerating means to equalize said actual headway and said safe headway.
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Accused Products
Abstract
An electronic system coupled to a ranging device and a vehicle speed measuring device automatically controls vehicle braking and acceleration according to available vehicle headway and vehicle speed. The system provides acceleration, coasting, or braking according to the position and speed of its vehicle relative to a preceding vehicle. Significant improvements in roadway capacity and vehicle safety result from the use of the system.
15 Citations
12 Claims
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1. An automatic headway control system for controlling a vehicle having a braking means and an accelerating means comprising ranging means mounted on the controlled vehicle for determining the actual headway between said vehicle and a preceding vehicle, speed sensing means mounted on the controlled vehicle for sensing the magnitude of its actual speed, speed computing means for determining the actual speed of the preceding vehicle and the smaller of the actual vehicle speeds, headway computing means coupled to said speed sensing means for computing the safe headway between said controlled vehicle and said preceding vehicle as a function of the smaller of the actual vehicle speeds, and command computing means for actuating the braking means and the accelerating means to equalize said actual headway and said safe headway.
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2. The system of claim 1 in which the command computing means comprises speed control means for maintaining the speed of the controlled vehicle at a preselected desired value whenever actual headway exceeds a preselected maximum.
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3. The system of claim 2 comprising means for determining the relative speed of the vehicles, said command computing means including means for applying maximum braking when the speed of the controlled vehicle exceeds the speed of the preceding vehicle and actual headway is less than a predetermined amount that increases with said relative speed.
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4. The system of claim 3 in which the command computing means includes means for providing proportional braking when the speed of the controlled vehicle exceeds the speed of the preceding vehicle and actual headway is greater than the predetermined amount of claim 3 but less than a second predetermined amount that also increases with relative vehicle speed.
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5. The system of claim 4 in which the command computing means includes means for closing the vehicle throttle when the speed of the controlled vehicle exceeds the speed of the preceding vehicle and actual headway is greater than said second predetermined amount.
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6. The system of claim 5 in which the command computing means includes means for closing the vehicle throttle when the speed of the controlled vehicle is less than the speed of the preceding vehicle and actual headway is less than said safe headway.
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7. The system of claim 6 in which the command computing means includes means for opening the vehicle throttle to accelerate the controlled vehicle when the speed of the controlled vehicle is less than the speed of the preceding vehicle and actual headway exceeds said safe headway.
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8. The system of claim 1 comprising means for determining the relative speed of the vehicles, said command computing means including means for applying maximum braking when the speed of the controlled vehicle exceeds the speed of the preceding vehicle and actual headway is less than a predetermined amount that increases with said relative speed.
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9. An automatic headway control system for controlling a vehicle having a braking means and an accelerating means comprising signal sending means mounted on the vehicle for projecting a signal forward of the controlled vehicle, signal receiving means mounted on the controlled vehicle for receiving reflections of said signal from a preceding vehicle, said signal sending means and said signal receiving means determining the actual headway between the controlled vehicle and a preceding vehicle less than a predetermined distance ahead of the controlled vehicle, speed sensing means mounted on the controlled vehicle for sensing the magnitude of its speed, brake actuating means for actuating the braking means of the controlled vehicle, throttle actuating means for actuating the accelerating means of the controlled vehicle, speed computing means for determining the actual speed of the preceding vehicle and the smaller of the actual vehicle speeds, headway computing means coupled to said speed sensing means for computing the safe headway between said preceding vehicle and said controlled vehicle as a function of the smaller of the actual vehicle speeds, and command computing means coupled to said signal sending means and said signal receiving means for controlling said brake actuating means and said accelerating means to modify the speed of the controlled vehicle so the actual headway approaches the safe headway.
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10. The system of claim 9 in which the speed sensing means comprises voltage generating means for generating a voltage representative of the actual speed of the controlled vehicle, and a desired speed means for producing a voltage representative of the desired speed of the controlled vehicle, said desired speed means including a field effect transistor having its gate terminal connected by a switch to said voltage generating means for receiving said voltage and its source terminal connected to said command computing means, said field effect transistor providing an output voltage at its source terminal representative of the actual speed of the controlled vehicle when said switch was actuated momentarily.
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11. The system of claim 10 comprising activating circuitry for the command computing means, said activating circuitry including switches for deactivating the command computing means upon manual actuation of the vehicle brakes or the vehicle accelerator.
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12. The system of claim 11 in which the command computing means comprises means for producing a voltage representative of the difference between the speed of the preceding vehicle and the speed of the controlled vehicle when the preceding vehicle is less than a predetermined distance ahead of the controlled vehicle, and means for producing accelerating or decelerating proportional to said difference when said difference is less than about 5 mph, actual headway is within about 15 feet of the safe headway, and the desired speed of the controlled vehicle exceeds the actual speed of the preceding vehicle.
Specification