Laser based tracking device for detecting the distance between a vehicle and a roadway marker

• US 5,293,162 A
• Filed: 03/09/1992
• Issued: 03/08/1994
• Est. Priority Date: 03/09/1992
• Status: Expired due to Fees

• Current Assignee: Aerometrics, Inc. (TSI Incorporated)
• Original Assignee: William D. Bachalo
• Inventors: Bachalo, William D.
• Primary Examiner(s): Swarthout, Brent
• Application Number:
  US07/847,378
• Time in Patent Office: 729 Days
• Field of Search: 340/901, 340/904, 340/905, 340/425.5, 340/436, 340/438, 340/439, 340/457, 340/933, 340/942, 340/435, 250/202, 250/236, 250/235, 250/561, 356/5
• US Class Current: 340/905
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: G05D 1/0248 in combination with a laser lasers per se H01S

Abstract

A laser tracking device for the warning of vehicle weaving and steering assistance of vehicles, includes a laser generation apparatus for generating and transmitting a laser beam. A mirror is provided for sweeping the laser beam across a roadway surface. The mirror also receives a reflection of the laser beam back from a roadway marker located on the roadway surface and directs it to a receiver. A master clock is coupled to the mirror for generating a first timing signal when the laser beam starts to sweep across the roadway surface. The receiver generates a second timing signal when the reflected laser beam is incident on it. A processor is coupled to the receiver and the master clock. The processor compares the first timing signal with the second timing signal. The processor uses the results of that comparison to calculate the distance between the vehicle and the roadway marker. That information can be used to control the direction and steering of the vehicle in order to prevent weaving, unintentional lane changes as well as other problems leading to accidents and collisions.

Claims

1. A laser tracking device for determining the distance between a vehicle and a roadway marker on the surface of a roadway, comprising:

a laser diode for generating and transmitting a laser beam;

a rotating polygonal mirror coupled to a controllable motor, said mirror being located within an optical path of said laser beam, for sweeping said laser beam across said roadway surface, said mirror also receiving a reflection of said laser beam back from said roadway surface, and directing said reflected laser beam to a receiver means;

master clock means coupled to said controllable motor for generating a first timing signal and issuing a series of timing pulses when said laser beam starts to sweep across said roadway surface;

counter means coupled to said master clock means, said counter means beginning to count said timing pulses when said master clock means generates said first timing signal, said counter means continuing to count said timing pulses concurrently as said laser beam sweeps across said roadway surface;

wherein said receiver means generates a second timing signal when said reflected laser beam is incident on it, and wherein said counter ceases counting upon said generation of said second timing signal; and

microprocessor means coupled to said receiver means and said master clock means for analyzing the number of said timing pulses counted by said counter means between generation of said first and second timing signals so as to calculate a distance between said tracking device and said roadway marker.

2. The device of claim 1 wherein said tracking device is mounted on a vehicle.

3. A method for determining the distance between a vehicle and a roadway marker, comprising the steps of:

(a) generating a laser beam;

(b) sweeping said laser beam across a roadway surface;

(c) generating a first timing signal and a series of timing pulses when said laser beam starts to sweep across said roadway surface;

(d) counting said timing pulses concurrently as said laser beam sweeps across said roadway surface;

(e) receiving a reflection of said laser beam from said roadway marker on said roadway surface;

(f) generating a second timing signal when said reflection is received;

(g) stopping the count of said timing pulses when said second timing signal is generated;

(h) analyzing the number of said timing pulses counted between generation of said first and second timing signals so as to determine the distance between said vehicle and said roadway marker.

4. A laser tracking device, comprising:

laser generation means for generating and transmitting a laser beam;

laser steering means for sweeping said laser beam across a roadway having at least one roadway marker located thereon, said laser beam being reflected by said roadway marker, said laser steering means also receiving said reflection of said laser beam back from said surface, and directing said reflected laser beam to a receiver means;

master clock means coupled to said laser steering means for generating a first timing signal and issuing a series of timing pulses when said laser beam starts to sweep across said surface;

counter means coupled to said master clock means, said counter means beginning to count said timing pulses when said master clock means generates said first timing signal, said counter means continuing to count said timing pulses concurrently as said laser beam sweeps across said roadway surface;

wherein said receiver means generates a second timing signal when said reflected laser beam is incident on it, and wherein said counter ceases counting upon said generation of said second timing signal; and

processor means coupled to said receiver means and said master clock means for analyzing the number of said timing pulses counted by said counter means between generation of said first and second timing signals so as to calculate a distance between said laser tracking device and said roadway marker.