Dynamic monitoring of vehicle separation

• US 6,268,804 B1
• Filed: 03/13/2000
• Issued: 07/31/2001
• Est. Priority Date: 12/18/1997
• Status: Expired due to Fees

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Smith, Derek Steven, Janky, James M., Schipper, John F.
• Primary Examiner(s): Tong, Nina
• Application Number:
  US09/523,830
• Time in Patent Office: 505 Days
• Field of Search: 340/903, 340/435, 340/436, 340/901, 340/904, 180/169, 180/167, 180/168, 180/170, 342/70, 342/71, 342/72, 367/909, 367/112, 367/96, 367/97, 367/107
• US Class Current: 340/903
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/081 using distance control
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
• CPC Class Codes: G01S 2013/9316 combined with communication equipment with other vehicles or with base stations
• CPC Class Codes: G01S 2013/93185 Controlling the brakes
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9322 using additional data, e.g. driver condition, road state or weather data
• 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: G01S 2013/93274 on the side of the vehicles
• CPC Class Codes: G01S 5/0072 Transmission between mobile stations, e.g. anti-collision systems
• CPC Class Codes: G08G 1/164 Centralised systems, e.g. external to vehicles
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes
• CPC Class Codes: Y10S 367/909 Collision avoidance

Abstract

A system for monitoring operation and location of a first moving vehicle relative to a second moving vehicle. A minimum separation distance between the first and second vehicles is estimated, based on the first vehicle velocity, and optionally on the second vehicle velocity, using location determination (LD) signals received from satellite-based transmitters from GPS, GLONASS and LEO satellites, or from ground-based signal sources such as LORAN signal towers, and using ranging signals from SONAR, RADAR or a similar system. The minimum separation distance is compared with the actual separation distance at selected times, and a vehicle driver is advised if the actual separation distance is too small, if the separation distance is decreasing too quickly, or if the second vehicle velocity is decreasing too quickly. The second vehicle may travel in the same traffic lane, in an adjacent lane, or on a road that intersects the road used by the first vehicle. Where the first and second vehicles travel on separate roads that will intersect, the system estimates whether the second vehicle will stop, or will be able to stop, at the intersection. The second vehicle may be a railroad car, such as a locomotive, or a road vehicle. A maximum vehicle clear-view velocity, consistent with vehicle stopping within a selected distance, is estimated. Road conditions are estimated and compensated for in estimating the minimum separation distance and/or the maximum vehicle clear-view velocity.

Claims

1. A method of monitoring operation of a first moving vehicle relative to a second moving vehicle on a road, the method comprising the steps of:

estimating the present velocity of said first moving vehicle using location determination (LD) signals received from two or more LD signal sources;

estimating a separation distance between said first and second moving vehicles, said second moving vehicle adjacent to and moving in the same general direction as said first moving vehicle in a selected road lane, using ranging signals received from a ranging signal source;

estimating a minimum separation distance between said first moving vehicle and said second moving vehicle, said minimum separation distance based on said present velocity of said first moving vehicle;

comparing said separation distance and said minimum separation distance; and

providing a signal indicating that said separation distance between said first and second moving vehicles is less than said minimum separation distance, when said separation distance is no greater than said minimum separation distance;

providing a second signal indicating that s aid separation distance between said first and second moving vehicles will ultimately become less than said minimum separation distance when said separation distance is greater than said minimum separation distance and said separation distance while initially negative is becoming more positive at a greater than a selected threshold rate with respect to time.

2. The method of claim 1, wherein said step of estimating said minimum separation distance comprises the steps of:

estimating a braking distance required to bring said first moving vehicle to a stop from said present velocity;

estimating a driver perception-reaction time;

estimating a driver perception-reaction distance by multiplying the driver perception-reaction time by said present velocity of said first vehicle; and

including the sum of the estimated braking distance and the estimated driver perception-reaction distance in said minimum separation distance for said first vehicle.

3. The method of claim 2, wherein said step of estimating said minimum separation distance further comprises the steps of:

estimating a road condition of said road, where said road condition is drawn from a class of conditions comprising dry road pavement, slightly wet road pavement, totally wetted road pavement, ice present on the road pavement, and snow present on the road pavement; and

compensating in said estimation of said braking distance for said road condition.

4. The method of claim 3, wherein said step of compensating for said road condition comprises;

estimating said braking distance for said dry road pavement; and

when said road condition is not said dry road pavement, increasing said braking distance by a selected fraction of said braking distance for said dry road pavement, where said fraction depends upon said road condition.

5. The method of claim 1, wherein said step of estimating said minimum separation distance comprises the steps of:

estimating a rate, dependent upon said present velocity, at which said present velocity will decrease when a braking action is applied to said first moving vehicle; and

estimating said minimum separation distance as the distance required to bring said first moving vehicle to a stop after said braking action is first applied to said first moving vehicle based upon said rate.

6. A method of monitoring operation of a first moving vehicle relative to a second moving vehicle on a road, the method comprising the steps of:

estimating a first present velocity of said first moving vehicle using location determination (LD)signals received from two or more LD signal sources;

estimating a second present velocity of a second moving vehicle that moves in the same general direction as said first moving vehicle using ranging signals received from a ranging signal source;

estimating a separation distance between said first moving vehicle and said second moving vehicle using said ranging signals;

estimating a minimum separation distance between said first moving vehicle and said second moving vehicle, said minimum separation distance based on said first and second present velocities;

comparing said separation distance and said minimum separation distance; and

providing a signal indicating that said separation distance between said first and second moving vehicles is less than said minimum separation distance, when said separation distance is no greater than said minimum separation distance;

providing a second signal indicating that said separation distance between said first and second moving vehicles will ultimately become less than said minimum separation distance when said separation distance is greater than said minimum separation distance and said separation distance while initially negative is becoming more positive at a greater than a selected threshold rate with respect to time.

7. The method of claim 6, wherein said step of estimating said minimum separation distance comprises the steps of:

estimating a first driver perception-reaction time;

estimating a first driver perception-reaction distance by multiplying said first driver perception-reaction time by said first present velocity;

estimating a first braking distance required to bring said first moving vehicle to a stop from said first present velocity;

estimating a second braking distance required to bring said second moving vehicle to a stop from said said present velocity; and

computing the difference of said first driver perception-reaction distance plus said first braking distance minus said second braking distance, and interpreting this difference as said minimum separation distance.

8. The method of claim 7, wherein said step of estimating said minimum separation distance further comprises the steps of:

estimating a first rate, dependent upon said first present velocity, at which said first present velocity will decrease when a first braking action is applied to said first moving vehicle;

estimating said second rate, dependent upon said second present velocity, at which said second present velocity will decrease when a second braking action is applied to said second moving vehicle;

estimating said first braking distance required to bring said first moving vehicle to a stop after said first braking action is first applied to said first moving vehicle, based upon said first rate;

estimating a second braking distance required to bring said second moving vehicle to a stop after said second braking action is first applied to said second moving vehicle, based upon said second rate; and

estimating said minimum separation distance as the sum of said first driver perception-reaction distance plus said first braking distance minus said second braking distance.

9. The method of claim 6, wherein said step of estimating said minimum separation distance further comprises the steps of;

estimating a road condition of said road, where said road condition is drawn from a class of conditions comprising dry road pavement, slightly wet road pavement, totally wetted road pavement, ice present on the road pavement, and snow present on the road pavement; and

compensating in at least one of said estimation of said first braking distance and said second braking distance for said road condition.

10. The method of claim 9, wherein said step of compensating for said road condition comprises:

estimating said first braking distance and said second braking distance for said dry road pavement; and

when said road condition is not said dry road pavement, increasing at least one of said first braking distance and said second braking distance by a selected fraction of said respective first and second braking distances for said dry road pavement, where said fraction depends upon said condition.

11. The method of claim 6, further comprising the steps of:

estimating a deceleration rate of said second moving vehicle;

comparing said deceleration rate with a selected threshold deceleration rate; and

providing a third signal indicating that said second vehicle is decelerating rapidly when the deceleration rate is less than said selected threshold deceleration rate.

12. A system for monitoring operation of a first moving vehicle relative to a second moving vehicle on a road, the system comprising:

a location determination (LD) module, carried on said first moving vehicle, that receives LD signals from at least two LD signal sources and estimates a present location and present velocity of said first moving vehicle and a separation distance between said first moving vehicle and said second moving vehicle that precedes and moves in the same general direction as said first moving vehicle;

a computer, connected to or a part of said LD module, that is programmed to;

estimate a minimum separation distance between said first and second moving vehicles; and

compare said separation distance and said minimum separation distance; and

a display that provides a signal, in at least one of visually perceptible form and audibly perceptible form, indicating that said separation distance between said first and second moving vehicles is less than said minimum separation distance, when said separation distance is no greater than said minimum separation distance;

wherein said computer is programmed to cause said display to provide a second signal indicating that said separation distance between said first and second moving vehicles will ultimately become less than said minimum separation distance when said separation distance is greater than said minimum separation distance, but the difference between said minimum separation distance and said separation distance while initially negative is becoming more positive at greater than a selected threshold rate with respect to time.

13. The system of claim 12, wherein said computer estimates said minimum separation distance by including the steps of:

estimating a braking distance required to bring said first moving vehicle to a stop from said present velocity;

estimating a driver perception-reaction time;

estimating a driver perception-reaction distance by multiplying said driver perception-reaction time by said present velocity of said first vehicle; and

including the sum of said estimated braking distance and the estimated driver perception-reaction distance in said minimum separation distance for said first moving vehicle.

14. The system of claim 13, wherein said computer estimates said minimum separation distance by including the further steps of:

estimating a road condition of said road, where said road condition is drawn from a class of conditions comprising dry road pavement, slightly wet road pavement, totally wetted road pavement, ice present on the road pavement, and snow present on the road pavement; and

compensating in said estimation of said braking distance for said road condition.

15. The system of claim 14, wherein said computer compensates for said road condition by including the steps of:

estimating said braking distance for said dry road pavement; and

when said road condition is not said dry road pavement, causing said computer to increase said braking distance by a selected fraction of said braking distance for said dry road pavement, where said fraction depends upon said road condition.

16. The system of claim 15, further comprising a road pavement sensor, connected to said computer, that:

examines a selected portion of road pavement adjacent to said first moving vehicle as said first moving vehicle moves along said road pavement; and

estimates whether said selected portion of said road pavement is dry, slightly wet, wet, substantially covered with ice or substantially covered with snow.

17. The system of claim 12, wherein said computer estimates said minimum separation distance by including the steps of:

estimating a rate, dependent upon said present velocity, at which said present velocity will decrease when a braking action is applied to said first moving vehicle; and

estimating said minimum separation distance as the distance required to bring said first moving vehicle to a stop after said braking action is first applied to said first moving vehicle, based upon said rate.

18. The system of claim 12, wherein said computer is installed in said first moving vehicle and performs at least one function that is not related to monitoring said separation distance and said minimum separation distance.

19. The system of claim 12, wherein said system includes a data/command entry module, connected to said computer, that allows entry of at least one of an item of data and a command for said system to perform a selected task related to monitoring said separation distance and said minimum separation distance.

20. The systems of claim 12, further comprising at least one of the following, connected to said computer:

a CD ROM player, carried on said first moving vehicle;

a radio receiver that receives at least one of AM signals and FM signals, carried on said first moving vehicle;

a fuel usage monitor, carried on said first moving vehicle; and

a temperature monitor carried on said first moving vehicle.

21. The system of claim 12, wherein said first moving vehicle has a dashboard and at least one of said LD module, said computer, and said display is installed in said dashboard.

22. A system for monitoring operation of a first moving vehicle relative to a second moving vehicle on a road, the system comprising:

a location determination (LD) module, carried on a first moving vehicle, that receives LD signals from at least two LD signal sources and estimates a first resent location and a first present velocity of said first vehicle;

a ranging signal source located on said LD module that transmits and receives ranging signals to estimate a second present location and second present velocity v(t;

2) of said second moving vehicle that precedes and moves in the same general direction as said first moving vehicle, and a separation distance between said first moving vehicle and said second moving vehicle;

a computer, connected to or a part of said LD module, that is programmed to;

estimate a minimum separation distance between said first and moving vehicles; and

compare said separation distance and said minimum separation distance; and

a display that provides a signal, in at least one of visually perceptible form and audibly perceptible form, indicating that said separation distance between said first and second moving vehicles is less than said minimum separation distance, when said separation distance is no greater than said minimum separation distance;

wherein said computer is programmed to cause said display to provide a second signal indicating that said separation distance between said first and second moving vehicles will ultimately become less than said minimum separation distance when said separation distance is greater than said minimum separation distance, but the difference between said minimum separation distance and said separation distance while initially negative is becoming more positive at greater than a selected threshold rate with respect to time.

23. The system of claim 22, wherein said computer estimates said minimum separation distance by including the steps of:

estimating a first driver perception-reaction time;

estimating a first driver perception-reaction distance by multiplying said first driver perception-reaction time by said first resent velocity;

estimating a first braking distance required to bring said first moving vehicle to a stop from said first present velocity;

estimating a second braking distance required to bring said second moving vehicle to a stop from said second present velocity; and

computing the difference of said first driver perception-reaction distance plus said first braking distance minus said second braking distance, and interpreting this difference as said minimum separation distance.

24. The system of claim 23, wherein said computer further estimates said minimum separation distance by including the steps of:

estimating a first rate, dependent upon said first present velocity, at which said first present velocity will decrease when a first braking action is applied to said first moving vehicle.

estimating a second rate, dependent upon said second present velocity, at which said second present velocity will decrease when a second braking action is applied to said second moving vehicle;

estimating said first braking distance required to bring said first moving vehicle to a stop after said first braking action is first applied to said first moving vehicle, based upon said first rate;

estimating said second braking distance required to bring said second moving vehicle to a stop after said second braking action is first applied to said second moving vehicle, based upon said second rate; and

estimating said minimum separation distance as the sum of said first driver perception-reaction distance plus said first braking distance minus said second braking distance.

25. The system of claim 23, wherein said computer estimates said minimum separation distance by including the steps of:

estimating a road condition of said road, where said road condition is drawn from a class of conditions comprising dry road pavement, slightly wet road pavement, totally wetted road pavement, ice present on the road pavement, and snow present on the road pavement; and

compensating in at least one of said estimation of said first braking distance and said second braking distance for said road condition.

26. The system of claim 25, wherein said computer compensates for said road condition by including the steps of:

estimating said first braking distance and said second braking distance for said dry road pavement; and

when said road condition is not said dry road pavement, increasing at least one of said first braking distance and said second braking distance by a selected fraction of said respective first and second braking distances for said dry road pavement, where said fraction depends upon said road condition.

27. The system of claim 22, wherein said computer is further programmed to:

estimate a deceleration rate of said second moving vehicle;

comparing said deceleration rate with a selected threshold deceleration rate; and

providing a signal indicating that said second vehicle is decelerating rapidly when the deceleration rate is less than said selected threshold deceleration rate.

28. The system of claim 22, wherein said first moving vehicle has a dashboard and at least one of said LD module, said computer, and said display is installed in said dashboard.