Patent ID: 6400452
Filing Date: 2002-06-04
Classification: G01S,H04B

Abstract:
A method for obtaining three dimensional positional information by a mobile unit employing a three dimensional laser system; said three dimensional multi-unit laser control and tracking system comprising: a light beacon generating a rotating and scanning beam of laser light to cover a three-dimensional site area; said rotating and scanning beam of laser light being rotated and scanned in accordance with a set of predetermined rotating and scanning data; and at least one mobile unit located in said three-dimensional site area; each said mobile unit having an identification number (ID); each said mobile unit being illuminated by said rotating and scanning beam of laser light; each said mobile unit being capable of providing its identification number (ID) upon sensing and reflecting said rotating and scanning beam of laser light; each said mobile unit further including an intelligent reflector (IR) including: a laser reflector; a memory chip, said memory chip including said ID of said mobile unit; a clock; a processor; and a first communication system; wherein said processor using said clock is capable of determining an exact time instance when said rotating and scanning laser beam illuminated said intelligent reflector; and wherein said first communication system transmits said ID of said mobile unit and said exact timing data describing when said rotating and scanning laser beam, illuminated said intelligent reflector back to said light beacon; said method comprising:(a) reflecting a rotating laser beam; (b) determining an exact time of illumination by said laser beam; (c) transmitting said identification number (ID) and said exact time of illumination to a signal system; (d) using a first encoder for measuring a horizontal angular coordinate of said mobile unit; (e) using a second encoder for measuring a vertical angular coordinate of said mobile unit; (f) using a signal system clock for measuring an exact time when said reflected from said mobile unit laser beam reaches said laser beacon; wherein said signal system includes said signal system clock; (g) determining a distance between said laser beacon and said one mobile unit at the time when said one mobile unit is illuminated by said laser beam; said distance being equal to a traveling time period divided by two and multiplied by the speed of light; wherein said traveling time period comprises a time period that laser beam spent traveling between said laser beacon and said mobile unit back and forth; wherein said traveling time period is equal to the time difference between said exact time when said laser beam reaches said laser beacon and said exact time of illumination of said mobile unit by said laser beam that is transferred back to said signal system; (h) generating a set of three dimensional data by said signal system by processing said horizontal angular coordinate of said mobile unit; said vertical angular coordinate of said mobile unit; and said distance between the laser beacon and the mobile unit at the time said one mobile unit is illuminated; (i) transmitting said set of three dimensional positional data from said signal system to said one mobile unit; and (k) receiving by said one mobile unit said set of three dimensional positional data generated and transmitted by said signal system.