System for automatic vehicle location

• US 4,107,689 A
• Filed: 06/07/1976
• Issued: 08/15/1978
• Est. Priority Date: 06/07/1976
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: RCA Corporation (General Electric Company)
• Inventors: Jellinek, Ernest
• Primary Examiner(s): Engle, Samuel W.
• Assistant Examiner(s): Cangialosi, S. A.
• Application Number:
  US05/694,042
• Time in Patent Office: 799 Days
• Field of Search: 340/23, 340/24, 343/6.5 LC, 343/112 TC, 325/53, 235/150.24
• US Class Current: 340/991
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G08G 1/207 with respect to certain areas, e.g. forbidden or allowed areas with possible alerting when inside or outside boundaries

Abstract

An automatic vehicle location system wherein the position of a mobile unit is at any time (on a "real-time" basis) defined by a stored predetermined location code communicated to the mobile unit from a remote unit at a predetermined location and dead reckoned location coordinates relative to such stored location. When the mobile unit passes into the vicinity of a different remote unit, a new predetermined location code is communicated to the mobile unit from such remote units, and the dead reckoned coordinates are reset to zero. A novel dead reckoning system for use in conjunction with a specific deployment of the remote units is also disclosed.

Claims

1. A system for monitoring the position of a mobile unit within a predetermined area comprising:

dead reckoning means, within said mobile unit, for generating an output signal indicative of the instantaneous location coordinates of said mobile unit on a predetermined coordinate system;

a plurality of remote unit means, each means comprising a unit positioned at a respective predetermined location within said area, for communicating to said mobile unit information signals indicative of said respective predetermined locations as said mobile unit passes each remote unit at the respective locations;

each of said units representing a separate coordinate system wherein the location of each of said units represents the reference coordinates for its associated coordinate system,

storage means, in said mobile unit, receptive of said remote unit location signals, for storing thereby the information signal indicative of the location of the last communicating unit;

resetting means, cooperating with said storage means, for generating a reset signal in response to changes in said stored information, said reset signal being applied to said dead reckoning means to reset said dead reckoning means output signal to zero, whereby said coordinate system is changed in accordance with the stored information corresponding to the last passed remote unit; and

utilization means, receptive of said stored information signals and said dead reckoning means output signal, for determining therefrom said position of said mobile unit relative to the coordinate system of the last communicating remote unit.

2. The system of claim 1 wherein said dead reckoning means comprises:

reference detection means for generating a direction signal indicative of the direction of travel of said mobile unit as said mobile unit passes said last communicating remote unit;

said direction signal being further stored by said storage means;

relative heading sensor means, cooperating with said reference detection means, for generating a signal indicative of the instantaneous heading of said mobile unit relative to said direction;

odometer means, for generating a signal indicative of the distance traveled by said mobile unit from said last communicating remote unit; and

conversion means, responsive to said distance signal, said relative heading signal and said reset signal, for resettably generating a first output signal indicative of the component in said direction of the vectorial position of said mobile unit with respect to the location of said last communicating remote unit, and a second output signal indicative of the component in a direction perpendicular to said direction of the vertical position of said mobile unit with respect to the location of said last communicating remote unit, said conversion means output signals being reset in response to changes in said stored information.

3. The system of claim 2 wherein said relative heading sensor means comprises a digital change means in heading sensor, said change means in heading sensor generating a pulse indicative of a predetermined quantum of change in heading by said mobile unit and

a counter, responsive to said change in heading pulses and said reset signal, for generating a heading count indicative of cumulative changes in heading of said mobile unit since said counter was last reset, said counter being reset in response to changes in said stored information.

4. The system of claim 3 wherein said predetermined quantum of change is 90°

.

5. The system of claim 3 wherein said predetermined area contains a plurality of intersecting drivable surfaces, said remote units are respectively positioned proximate to said drivable surfaces to communicate thereby with said mobile unit as said mobile unit passes said remote unit on said drivable surfaces, and a remote unit is positioned at each substantially non-perpendicular intersection of said drivable surfaces, wherein further:

said dead reckoning means comprises;

a turn sensor, coupled to said mobile unit, for generating output signals respectively indicative of perpendicular turns in left and right hand directions by said mobile unit; and

heading register means, responsive to said turn sensor output signals, for generating a two bit binary count indicative of changes in the heading of said mobile unit in increments of 90°

, said count being incremented in response to each turn in one of said directions, decremented in response to each turn in the other of said directions; and

said conversion means comprises;

first and second counters, and

gating means, responsive to said binary heading count and said distance signal, for selectively incrementing or decrementing the contents of said first and second counters in accordance with said heading count and said distance signal, whereby the contents of said first register is representative of the position of said mobile unit from said stored location in said original direction and the contents of said second register are representative of the position of said mobile unit from said stored location in a direction perpendicular to said original direction;

said heading register means, and said first and second counters being responsive to said reset signal and reset in response to each change in said stored information.

6. The system of claim 5, wherein said mobile unit is coupled to a vehicle having longitudinal and transverse axes, and said reference detection means comprises:

a first antenna having a radiation pattern disposed to communicate with remote units positioned on one transverse side of said vehicle;

a second antenna having a radiation pattern disposed to communicate with remote units positioned on a second transverse side of said vehicle, said second side being opposite said first side; and

detector means, coupled to said first and second antennas, for generating a signal indicative of which said first and second antennas communicate with said remote unit, said detector means signal being indicative of said direction, and applied to said storage means.

7. The system of claim 1, wherein:

said dead reckoning means comprises;

absolute heading sensor means for producing an output signal indicative of the heading of said mobile unit with respect to a fixed reference direction;

odometer means, for generating a signal indicative of the distance traveled by said mobile unit;

conversion means, responsive to said heading signals, signals, said distance signals and said reset signal, for resettably generating a first output signal indicative of the component of the vectorial position of said mobile unit with respect to the location of said stored location in said reference direction and a second output signal indicative of the component of the vectorial location of said mobile unit with respect to said stored location in a direction perpendicular to said reference direction;

said conversion means output signals being reset in response to changes in said stored location.

8. A method for monitoring the position of a mobile unit within a predetermined area comprising the steps of:

(a) positioning a plurality of remote units at predetermined locations within said area for communicating information indicative of the respective locations of said remote units when said mobile unit comes within the vicinity of said respective remote units;

(b) receiving and storing within said mobile unit information indicative of the predetermined location of a first remote unit when said mobile unit comes into the vicinity of said first remote unit;

(c) dead reckoning the instantaneous location coordinates of said mobile unit from said stored predetermined location;

whereby the instantaneous position of said mobile unit within said area is defined by said stored predetermined location and said dead reckoned location coordinates;

(d) when said mobile unit comes into the vicinity of a second remote unit, receiving information indicative of the predetermined location of said second remote unit and replacing in storage said first remote unit location information with said second remote unit location information;

(e) detecting the condition when said second remote unit location information is different from said first remote unit location information; and

(f) upon detection of said condition, resetting said dead reckoned instantaneous location coordinates to zero.

9. The method of claim 8, further including the step of:

(g) generating and storing information indicative of the initial direction of travel of said mobile unit with respect to said respective remote units at the time said mobile unit comes into the vicinity of said respective remote units; and

wherein said dead reckoning step (c) comprises the steps of;

(h) generating a signal indicative of the heading of said mobile unit with respect to said initial direction of travel;

(i) generating a signal indicative of increments of distance traveled by said mobile unit;

(j) generating, from said heading signal and said distance signal, first and second signals respectively indicative of the component of the instantaneous vectorial location of said mobile unit with respect to said stored location in a direction substantially parallel to said initial direction and of the component of the vectorial location of said mobile unit with respect to said stored location in a direction substantially perpendicular to said initial direction.

10. The method of claim 9 for a predetermined area containing intersecting drivable surfaces, wherein said positioning step (a) includes the following step of:

(k) positioning a remote unit at each non-perpendicular intersection of said drivable surfaces; and

wherein further;

said generation of a heading signal step (h) includes the steps of;

(l) generating signals respectively indicative of perpendicular turns by said mobile unit in right and left directions; and

(m) incrementing and decrementing a resettable two-bit bidirectional counter in response to said turn signals to generate said heading signal.