Vehicle speed estimation using inductive vehicle detection systems

• US 20040056778A1
• Filed: 09/17/2003
• Published: 03/25/2004
• Est. Priority Date: 09/17/2002
• Status: Active Grant

• Current Assignee: Inductive Signature Technologies Incorporated
• Original Assignee: Inductive Signature Technologies Incorporated
• Inventors: Hilliard, Steven R.
• Granted Patent: US 6,999,886 B2
• Time in Patent Office: Days
• US Class Current: 340/933
• CPC Class Codes: G08G 1/042 using inductive or magnetic detectors

Abstract

A method and apparatus for communicating estimated vehicular speed and length using data obtained from a single wire-loop. The detector card connected to a single wire-loop produces a first bivalent output based on the actual measurement of a vehicle at the wire-loop sensor and synthesizes a second bivalent output to mimic the output of a two wire-loop speed trap. By simulating a second bivalent output at the detector card level, a conventional field controller is capable of estimating the vehicular speed from a single wire-loop sensor.

Claims

1. A method for communicating at least one of vehicle speed and vehicle length information gathered from a vehicle detector, said method comprising the steps of:

a) measuring at least one of vehicle speed and a vehicle length using a first vehicle detector during a first vehicle detection event;

b) constructing a first output pulse corresponding to said first vehicle detection event;

c) outputting said first output pulse on a first output channel corresponding to said first vehicle detector;

d) inferring from at least one of said speed and said vehicle length information a second vehicle detection event for a second vehicle detector;

e) constructing a second output pulse corresponding to said second vehicle detection event;

f) outputting said second output pulse on a second output channel corresponding to said second vehicle detector.

2. The method of claim 1 wherein said first output pulse comprises a first pulse-width, and wherein said second output pulse comprises a second pulse-width;

and wherein said second pulse-width is substantially equal to said first pulse-width.

3. The method of claim 1 wherein said first output pulse comprises a first start-time, and wherein said second output pulse comprises a second start-time;

and wherein the difference between said second start-time and said first start-time is chosen to be substantially correspond to the quotient of a hypothetical offset distance between said first and second vehicle detectors divided by said vehicle speed.

4. The method of claim 3 wherein said hypothetical offset distance is chosen to substantially correspond to a measured offset distance between one or more pairs of real vehicle detectors.

6. The apparatus of claim 1 wherein said first output pulse comprises a first pulse-width, and wherein said second output pulse comprises a second pulse-width;

and wherein said second pulse-width is substantially equal to said first pulse-width.

7. The apparatus of claim 1 wherein said first output pulse comprises a first start-time, and wherein said second output pulse comprises a second start-time;

and wherein the difference between said second start-time and said first start-time is chosen to be substantially correspond to the quotient of a hypothetical offset distance between said first and second vehicle detectors divided by said vehicle speed.

8. The apparatus of claim 3 wherein said hypothetical offset distance is chosen to substantially correspond to a measured offset distance between one or more pairs of real vehicle detectors.

5. An apparatus for communicating at least one of vehicle speed and vehicle length information gathered from a vehicle detector, said apparatus comprising:

a) a means for measuring at least one of vehicle speed and a vehicle length during a first vehicle detection event;

b) a means for constructing a first output pulse corresponding to said first vehicle detection event;

c) a means for outputting said first output pulse on a first output channel corresponding to said first vehicle detector;

d) a means for inferring from at least one of said speed and said vehicle length information a second vehicle detection event for a second vehicle detector;

e) a means for constructing a second output pulse corresponding to said second vehicle detection event;

f) a means for outputting said second output pulse on a second output channel corresponding to said second vehicle detector.