Automated highway tracking and communication system and method

• US 6,219,596 B1
• Filed: 09/18/1997
• Issued: 04/17/2001
• Est. Priority Date: 09/18/1997
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Tani, Toyofumi, Ishigami, Tadatomi, Utsui, Yoshihiko, Fukae, Tadamasa, Tamiya, Norihiro
• Primary Examiner(s): Chin, Gary
• Application Number:
  US08/933,107
• Time in Patent Office: 1,307 Days
• Field of Search: 701/23, 701/117, 701/207, 342/42, 342/44, 342/51, 342/52, 342/56, 342/450, 342/451, 180/167, 180/168, 180/169, 340/991, 340/992, 340/993, 340/901
• US Class Current: 701/23
• CPC Class Codes: G01S 17/74 Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe

Abstract

A vehicle borne transmitter transmits a spread spectrum transmit signal which is pseudo (PN) encoded. The transmitted signal is reflected off of a reflector on known position which may be a highway guardrail, tunnel wall, or the like. The reflected signal is detected by a receiver in the vehicle and a pseudo noise code (PN code) is synchronized to the reflected signal to accomplish maximum correlation. The phase delay between the transmitted PN code and received PN code is thereby utilized to determine the distance between the vehicle and reflector to maintain the vehicle in the center of a roadway lane. Roadway transponders may be periodically located adjacent the roadway and will be responsive to the vehicle borne interrogation signal. The periodically located transducers produce a reply signal including a PN code and imbedded data which data may represent transponder ID and position, roadway or map data, or other data which is desirable to transmit between the transducer and the vehicle travelling the highway.

Claims

1. A system for measuring a lateral position of a vehicle along a roadway, comprising:

a wave reflector mounted adjacent to and a known distance from the roadway;

a vehicle mounted transmitter transmitting a vehicle originated interrogation signal containing a spread spectrum code toward said reflector;

a vehicle mounted receiver receiving a reflection signal containing said spread spectrum code when said vehicle originated signal is reflected from said reflector;

a comparator circuit for measuring the time difference between transmission of said vehicle originated signal by said transmitter and receipt of said reflection signal by said receiver, said comparator circuit determining the lateral distance between said vehicle and said wave reflector from said time difference.

2. The system of claim 1, further comprising;

plural transponders disposed along said roadway and transmitting information in response to interrogation;

said vehicle mounted transmitter interrogating a transponder when adjacent thereto, said vehicle mounted receiver receiving information transmitted by said interrogated transponder.

3. The system of claim 2, wherein said information transmitted by said interrogated transponder includes the vehicle time of passing said interrogated transponder.

4. The system of claim 3, wherein said system further includes a passing time detector for determining the time at which the vehicle is closest to said interrogated transponder.

5. The system of claim 2 wherein said information transmitted by said interrogated transponder includes transponder position which is representative of vehicle longitudinal position.

6. The system of claim 2, wherein each of said transponders transmits a transponder ID code uniquely identifying the transponder and its position.

7. The system of claim 1, wherein said vehicle originated spread spectrum signal having a pseudo-random noise code imbedded therein.

8. The system of claim 7 wherein said pseudo-random noise code is different for each said vehicle.

9. The system of claim 1, wherein said wave reflector also functions as a highway guardrail.

10. A system for measuring a lateral position of a vehicle along a roadway having a wave reflector disposed a known distance adjacent thereto, comprising:

a vehicle mounted transmitter transmitting a vehicle originated interrogation signal containing a spread spectrum code toward the wave reflector;

a vehicle mounted receiver receiving a reflection signal containing said spread spectrum code, which is obtained when said vehicle originated signal is reflected from the wave reflector;

a comparator circuit for measuring the time difference between transmission of said vehicle originated signal by said transmitter and receipt of said reflection signal by said receiver, said comparator circuit determining the lateral distance between said vehicle and the wave reflector from said time difference.

11. The system of claim 10 wherein said roadway is provided with plural transponders disposed adjacent to the roadway and transmitting information in response to interrogation;

said vehicle mounted transmitter interrogating a transponder when adjacent thereto, said vehicle mounted receiver receiving said information transmitted by the interrogated transponder.

12. A method of determining a vehicle'"'"'s lateral position along a roadway, comprising:

a. locating a highway guardrail substantially continuously adjacent to and a known distance from the roadway by issuing an interrogation signal containing a spread spectrum code from said vehicle to interrogate transponders disposed along said guardrail as the vehicle passes thereby; and

b. measuring the vehicle'"'"'s distance from the guardrail based on said spectrum code received from said transponders to determine the vehicle'"'"'s lateral distance along said roadway.

13. In an automated highway system having a reflector spaced a known distance adjacent a roadway, a method of controlling a vehicle to follow a desired track along the roadway comprising:

(a) determining a desired distance between the vehicle and said reflector by issuing an interrogation signal containing a spread spectrum code from said vehicle to interrogate said reflector as the vehicle passes thereby;

(b) measuring the vehicle'"'"'s distance from the reflector based on said spectrum code received from said reflector to determine the lateral distance between the vehicle and said reflector;

(c) comparing the lateral distance measured in said step (b) to the desired distance determined in said step (a) to define a tracking error value; and

(d) steering said vehicle based on said tracking error value to reduce said tracking error value to zero.

14. In an automated highway system usable along a roadway having transponders located adjacent thereto at intervals, each said transponder having a position identifying code, a method of communicating between the roadway system and a vehicle passing therealong and for determining the vehicle'"'"'s longitudinal position along a roadway, comprising

a. supplying each vehicle with a spread spectrum code identifying that vehicle;

b. issuing an interrogation signal containing said spread spectrum code from said vehicle to interrogate each transponder as the vehicle passes thereby;

c. said vehicle receiving said position identifying code transmitted by said transponder to receive roadway position information identifying the longitudinal position of said vehicle along said roadway; and

d. transmitting additional information with said interrogation signal.

15. A system for determining a vehicle'"'"'s lateral position along a roadway comprising:

(a) a highway guardrail substantially continuously adjacent to and a known distance from the roadway; and

(b) a spread spectrum transmitter/receiver measuring the vehicle'"'"'s distance from the guardrail by by transmitting an interrogation signal containing a spread spectrum code from said vehicle to interrogate transponders on said guardrail as the vehicle passes thereby, and by receiving said spread spectrum code from said transponders to determine the lateral distance between said vehicle and said continuously adjacent guardrail at an instant in time.

16. In an automated highway system having a reflector spaced a known distance adjacent the roadway, a system for controlling a vehicle to follow a desired track along a roadway, comprising:

means for measuring the vehicle'"'"'s distance from the reflector to determine the lateral distance between the vehicle and reflector, wherein said means for measuring transmits an interrogation signal containing a spread spectrum code from said vehicle to interrogate a reflector as the vehicle passes thereby, and receives said spread spectrum code from said reflector to determine said lateral distance;

means, operatively connected to said means for measuring, for comparing the lateral distance measured by said means for measuring to a desired distance from the reflector needed to keep the vehicle in a desired track along the roadway to define a tracking error value; and

means, responsive to the tracking error value, for steering said vehicle to reduce said tracking error value to zero.

17. In an automated highway system usable along a roadway having transponders located adjacent thereto at intervals, each said transponder having a position identifying code, a system for communicating between the roadway system and a vehicle passing therealong and for determining the vehicle'"'"'s longitudinal position along a roadway, a vehicle mounted system comprising:

a transmitter issuing an interrogation signal containing a spread spectrum code identifying the vehicle to interrogate each transponder as the vehicle passes thereby;

a receiver receiving said position identifying code transmitted by said transponder to receive roadway position information identifying the longitudinal position of said vehicle along said roadway, said receiver receiving additional information transmitted by said transponder.