Vehicle classification and axle counting sensor system and method

• US 6,304,321 B1
• Filed: 01/07/2000
• Issued: 10/16/2001
• Est. Priority Date: 11/23/1992
• Status: Expired due to Term

• Current Assignee: OSI Defense Systems LLC (OSI Systems Incorporated)
• Original Assignee: Schwartz Electro-Optics Incorporated
• Inventors: Gustavson, Robert L., Wangler, Richard J., Myers, John T., McConnell, Robert E. II
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US09/479,517
• Time in Patent Office: 648 Days
• Field of Search: 356/376, 356/398, 356/4.01
• US Class Current: 356/4.01
• CPC Class Codes: A01M 7/0089 Regulating or controlling systems the delivery being related to the movement of a vehicle B05B9/06
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/50 Systems of measurement based on relative movement of target
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/486 Receivers
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G08G 1/015 with provision for distinguishing between two or more types of vehicles, e.g. between motor-cars and cycles
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors

Abstract

A vehicle detection and classification sensor provides accurate 3D profiling and classification of highway vehicles for speeds up to 100 mph. A scanning time-of-flight laser rangefinder is used to measure the distance to the highway from a fixed point above the road surface and then measure the distance to the surfaces of any vehicle that is viewed by the sensor. A rotating polygon scans a beam laser into two beams projected across the road surface at a fixed angle between them. The beam is pulsed at a high repetition rate for determining vehicle speeds with a high accuracy and uses the calculated speed and consecutive range measurements as the vehicle moves past the sensor to develop a three-dimensional profile of the vehicle. An algorithm is applied to the three-dimensional profile for providing a vehicle-classification.

Claims

1. A method for determining a vehicle profile useful in classifying the vehicle, the method comprising the steps of:

scanning a laser range finder beam transversely across a vehicle traveling through a sensing zone of the sensor for determining the range for a plurality of points on the vehicle;

determining an orientation of the beam for each of the plurality of points on the vehicle;

determining a vehicle speed;

processing the ranges and corresponding beam orientations for forming a set of two dimensional cross-sectional profiles of the vehicle;

positioning the profiles based on the vehicle speed; and

providing a three-dimensional representation of the vehicle for classification thereof.