TRAFFIC RESPONSIVE SPEED CONTROL SYSTEM

• US 3,725,921 A
• Filed: 11/04/1970
• Issued: 04/03/1973
• Est. Priority Date: 11/04/1970
• Status: Expired due to Term

• Current Assignee: Siemens-Bendix Automotive Electronics LP
• Original Assignee: Henry C. Yee, Jack G. Elliott, Joseph S. Weidman, Zaven Margosian
• Inventors: Weidman, Joseph S., Yee, Henry C., Elliott, Jack G., Margosian, Zaven
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Montone, G. E.
• Application Number:
  US05/086,922
• Time in Patent Office: 881 Days
• Field of Search: 343/7ED 180/82.1,98,105 354/4
• US Class Current: 342/71
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60K 31/045 in a memory, e.g. a capacitor
• CPC Class Codes: B60W 2554/801 Lateral distance
• CPC Class Codes: B60W 2710/0605 Throttle position
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/93185 Controlling the brakes
• CPC Class Codes: G01S 2013/9319 Controlling the accelerator
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/9323 Alternative operation using light waves
• CPC Class Codes: G01S 2013/9325 for inter-vehicle distance regulation, e.g. navigating in platoons
• CPC Class Codes: Y02T 10/60 Other road transportation technologies with climate change mitigation effect

Abstract

A system for automatically adjusting the speed of a vehicle to existing traffic conditions is described. The system functions in conjunction with an automatic speed control system to maintain a safe following distance between vehicles traveling in the same direction. A range and range-rate sensor generates signals which are indicative of the distance between the vehicles, as well as the closing or opening velocity of the vehicles. These signals are used to accelerate or decelerate the trailing vehicle to maintain a safe and optimum distance between the vehicles in accordance with the speed of the lead vehicle. The system is noncooperative, so that the lead vehicle need not be similarly equipped in order for the system to operate. The system is capable of overriding the speed control system within the vehicle but can be overridden by the driver when a deceleration or acceleration decision is executed. Although the system can override the speed control system, the speed set into the speed control system can not be exceeded except by driver override. However, overriding of the speed control system by the invention system or by driver override does not destroy the speed set by the driver.

Claims

1. An adaptive system for maintaining an optimum spacing between a lead vehicle and a trailing vehicle and for causing said trailing vehicle to assume the velocity of said lead vehicle, said adaptive system operating in cooperation with an automatic speed control system which maintains said trailing vehicle at a driver selected speed;

said adaptive system comprising;

means for measuring the range and range-rate between said vehicles;

means for generating a throttle error signal and a brake error signal in response to the output of said means for measuring range and range-rate, said means for generating including means for preventing said adaptive system from accelerating said trailing vehicle to a speed above said driver selected speed;

said means for generating yielding said throttle error signal when the difference in speed between said vehicles can be reduced to zero by changing the throttle deflection of said trailing vehicle, and said means for generating yielding said brake error signal when the difference in velocity between said vehicles is a closing velocity which requires actuation of the brake system of said trailing vehicle.

2. The system of claim 1 wherein said means for generating includes means for storing a voltage representative of said driver selected speed;

and means for preventing said throttle error signal and said brake error signal from affecting said voltage representative of velocity so that said selected speed is automatically resumed when said throttle error signal and said brake error signal do not control said trailing vehicle.

3. The system of claim 1 wherein said means for preventing includes first signal summing means, said first summing means receiving signal representative of said trailing vehicle velocity and a signal representative of said throttle error signal and generating a sum output;

and means for subtracting said sum output from a voltage representative of said selected speed;

means for maintaining a constant polarity of said signal representative of said throttle error signal, so that said signal representative of said trailing vehiCle speed never exceeds said signal representative of said selected speed; and

the output of said means for subtracting is a throttle deflection signal which accelerates and decelerates said trailing vehicle to maintain said optimum spacing and assume said lead vehicle speed.

4. The system of claim 3 wherein said means for subtracting includes an inverter for inverting said sum output and a second summing means receiving the output of said inverter and said voltage representative of said selected speed so that the output of said second summing means is said throttle deflection signal.

5. The system of claim 1 wherein said means for preventing includes a storage circuit for receiving said throttle error signal and generating said signal representative of said throttle error signal in accordance with the magnitude of said throttle error signal;

and first signal summing means receiving the output of said storage circuit and a voltage representative of the velocity of said trailing vehicle.

6. The system of claim 3 wherein said means for preventing further includes signal storage means for receiving said throttle error signal and generating said signal representative of said throttle error signal;

and means for inhibiting the output of said storage means from going below zero volts.

7. The system of claim 3 wherein said signal representative of said selected velocity is fed to a memory circuit, said memory circuit including a velocity set control so that the driver of said trailing vehicle can set said memory circuit at any selected speed;

the output of said memory circuit serving as the signal representative of said selected speed input to said means for subtracting so that the signal stored in said memory circuit is unaffected by changes in said throttle error signal and said brake error signal.

8. The system of claim 1 further including a signal comparator circuit receiving said throttle error signal and a reference throttle signal, said reference throttle signal being correlative of a maximum level of said throttle error signal, said signal comparator generating an inhibit output when said throttle error signal exceeds said reference throttle signal;

throttle control means responsive to said throttle error signal to control the velocity of said trailing vehicle, said throttle control means receiving said inhibit output so that said throttle control means is inhibited when said throttle error signal exceeds said reference throttle signal.

9. The system of claim 7 further including a signal comparator circuit receiving said throttle error signal and a reference throttle signal, said reference throttle signal being correlative of a maximum level of said throttle error signal, said signal comparator generating an inhibit output when said throttle error signal exceeds said reference throttle signal;

throttle control means responsive to said throttle error signal to control the velocity of said trailing vehicle, said throttle control means receiving said inhibit output so that said throttle control means is inhibited when said throttle error signal exceeds said reference throttle signal.

10. The system of claim 3 further including a signal comparator circuit receiving said throttle error signal and a reference throttle signal, said reference throttle signal being correlative of a maximum level of said throttle error signal, said signal comparator generating an inhibit output when said throttle error signal exceeds said reference throttle signal;

throttle control means responsive to said throttle error signal to control the velocity of said trailing vehicle, said throttle control means receiving said inhibit output so that said throttle control means is inhibited when said throttle error signal exceeds said reference throttle signal.

11. The system of claim 1 wherein said means for measuring range and range-rate is a Doppler radar system, the Doppler signal being zero when the relative velocity between said lead vehicle and said trailing vEhicle is zero;

and further including means for preventing said adaptive system from losing control of said trailing vehicle when said Doppler signal is zero.

12. The system of claim 11 wherein said means for preventing includes a range memory;

timing means for actuating said range memory to store the latest range input when said Doppler goes to zero; and

means for generating a small throttle control signal after a prescribed period of time so that said trailing vehicle increases slightly in speed to produce another range input and thereby enable said adaptive system to retain control of said trailing vehicle.

13. The system of claim 12 where said means for generating a small throttle control signal is a resume circuit actuated by said timer, said timer actuating said resume circuit a preselected period of time after said Doppler goes to zero so that said resume circuit generates said small throttle signal and thereby actuates said range memory.

14. The system of claim 1 wherein said means for measuring range and range-rate is a Doppler radar system, said radar system generating an approach/ recede signal indicative of the opening or closing relative velocity of said vehicles.

15. The system of claim 14 further including a polarity circuit receiving said range-rate signal;

said polarity circuit receiving said approach/recede signal so that the polarity of the output of said polarity circuit is changed from positive for a receding relationship of said vehicles to negative for a closing relationship of said vehicles by said approach/recede signal.

16. The system of claim 7 wherein said means for maintaining further includes signal storage means for receiving said throttle error signal and generating said signal representative of said throttle error signal;

and means for inhibiting the output of said storage means from going below zero volts.

17. The system of claim 13 wherein said means for measuring range and range-rate is a Doppler radar system, said radar system generating an approach/recede signal indicative of the opening or closing relative velocity of said vehicles.

18. The system of claim 17 further including a polarity circuit receiving said range-rate signal;

said polarity circuit receiving said approach/recede signal so that the polarity of the output of said polarity circuit is changed from positive for a receding relationship of said vehicles to negative for a closing relationship of said vehicles by said approach/recede signal.

19. The system of claim 1 wherein said brake error signal actuates a brake actuator circuit through brake error processing means.

20. The system of claim 19 wherein said brake error processing means includes signal polarity responsive means, said polarity responsive means passing only positive signals so that said throttle error signal and brake error signal individually control said trailing vehicle.

21. The system of claim 8 wherein said brake error signal actuates a brake actuator circuit through brake error processing means, and wherein said brake error processing means includes signal polarity responsive means, said polarity responsive means passing only positive signals so that said throttle error signal and brake error signal individually control said trailing vehicle.

22. The system of claim 21 further including brake error signal storage means;

and means for rapidly discharging said brake error storage means, said means for discharging receiving said inhibit output to rapidly discharge said brake error storage means when said brake error signal falls below said reference throttle signal.

23. The system of claim 21 wherein said means for measuring range and range-rate produces a target absent signal when the difference in speed between said vehicles is zero;

and further including brake error storage means; and

means for slowly discharging said brake error storage means;

said means for slowly discharging receiving said target absent signal so that said Brake error signal is discharged from said brake error storage means.

24. The system of claim 23 further including brake error signal storage means;

and means for rapidly discharging said brake error storage means, said means for discharging receiving said inhibit output to rapidly discharge said brake error storage means when said brake error signal falls below said reference throttle signal.

25. The system of claim 21 further including a brake error summing circuit receiving said range and range-rate signals and the output of a nonlinear amplifier;

the output of said brake error summing circuit actuating said polarity sensitive circuit.

26. The system of claim 25 wherein said nonlinear amplifier receives the speed of said trailing vehicle as an input, and the output of said amplifier is constant for all speeds below a selected speed and linearly increases above said selected speed.

27. The system of claim 26 wherein said polarity responsive circuit is a half-wave rectifier.

28. A noncooperative adaptive speed control system for maintaining a safe trailing distance between a lead vehicle and a following vehicle and for maintaining said trailing vehicle at the velocity of said lead vehicle comprising:

means for transmitting energy to said lead vehicle and receiving energy reflected from said lead vehicle;

means for processing said reflected energy to generate a throttle control function (E) and brake control function (Eb), said throttle control function being defined as;

E R - Ro + 11/3 R and said brake control function being defined as;

Eb (55 - R - 3R)/25 X 100% when the velocity (V2) of said trailing vehicle is less than 30 miles per hour, and Eb ( 55 - R - 3R + 0.7(V2 -

     30))/25 X 100% when the velocity (V2) of said trailing vehicle exceeds 30 miles per hour, where;

E said throttle control function Eb said brake control function R range to lead car in feet R range-rate between said vehicles Ro desired range V2 speed of said trailing car.

29. The system of claim 28 wherein the desired range (Ro) is defined by:

Ro 55 + V2 where;

55 is a constant, in feet, minimum spacing between said vehicles, and V2 is the speed, in miles per hour, of said trailing car.

30. The system of claim 28 wherein said means for transmitting and receiving is a Gunn diode Doppler radar system.