Position sensing system for surveying and grading

A position sensing apparatus comprising:

• a first laser beam transmitter operable for projecting a first laser beam that rotates at a constant angular velocity in a first plane, wherein said first plane defines a datum plane;
• a second laser beam transmitter operable for projecting a second laser beam that rotates at a constant angular velocity in a second plane substantially parallel to said first plane, wherein said first and second laser beam transmitters are positioned apart at known locations;
• a first laser beam detector mounted to said second laser beam transmitter and operable for detecting when said first laser beam strikes said first laser beam detector;
• a first radio transmitter coupled to said first laser beam detector and operable for broadcasting a first reference signal each time said first laser beam strikes said first laser beam detector;
• a second laser beam detector mounted to said first laser beam transmitter and operable for detecting when said second laser beam strikes said second laser beam detector;
• a second radio transmitter coupled to said second laser beam detector and operable for broadcasting a second reference signal each time said second laser beam strikes said second laser beam detector;
• a laser beam receiver that is placed at a location at which the position is to be determined and operable for detecting said first and second laser beams during each rotation thereof, wherein said laser beam receiver includes means for measuring the height at which said laser beam receiver receives said first laser beam;
• a radio receiver operable for receiving said first and second reference signals;
• and
• processing means coupled to said laser beam and radio receivers and responsive to the timing of the detection of said laser beams by said laser beam receiver relative to the receipt of said reference signals by said radio receiver for determining the position in the plane of the laser beams of said laser beam receiver relative to the known locations of said laser beam transmitters and for determining the elevation at each location according to said height measured by said laser beam receiver, wherein said processing means further includes means for recording the measured position and elevation of each location.

An apparatus comprising:

• first and second reference stations positioned apart at known locations during position sensing operations utilizing said apparatus, wherein each reference station includes a laser beam transmitter that projects a laser beam that periodically sweeps at a constant angular velocity in a plane across an area in which position sensing is to occur and that periodically strikes the other reference station and a portable receiver, includes a detector for detecting the laser beam from the other laser beam transmitter, and includes a radio transmitter coupled to said detector for broadcasting a reference signal upon each detection of the other laser beam by said detector, and wherein one of said laser beams is a datum laser beam that defines a datum plane;
• a portable receiver that is placed at a location at which the position is to be determined, wherein said portable receiver includes a laser beam receiver operable for detecting the two laser beams, includes a radio receiver operable for receiving the two reference signals, and includes means for measuring the height at which said datum laser beam strikes said laser beam receiver;
• and
• processing means coupled to said portable receiver and responsive to the timing of the detection of said laser beams by said laser beam receiver relative to the receipt of said reference signals by said radio receiver for determining the position in said datum plane of said portable receiver relative to the locations of said laser beam transmitters, and responsive to the height measured by said laser beam receiver for determining the elevation of each location relative to said datum plane.

A surveying apparatus for determining the position of one or more locations to be surveyed, said apparatus comprising:

• a first energy beam transmitter operable for projecting a first energy beam that sweeps in a plane across the area to be surveyed;
• first reference signal means for generating a first reference signal when said first energy beam is aligned with a first reference line;
• a second energy beam transmitter operable for projecting a second energy beam that sweeps in a plane across the area to be surveyed, wherein said first and second energy beam transmitters are positioned apart during a surveying operation;
• second reference signal means for generating a second reference signal when said second energy beam is aligned with a second reference line;
• an energy beam receiver operable for detecting said first and second energy beams, wherein said energy beam receiver is sequentially positioned at each location to be surveyed;
• a reference signal receiver operable for receiving said first and second reference signals;
• and
• processing means coupled to said energy beam and reference signal receivers and responsive to the timing of the detection of said energy beams relative to the receipt of said reference signals for determining the position of said energy beam receiver at each location to be surveyed relative to said reference lines and said energy beam transmitters, wherein said processing means further includes means for recording the measured position of each location to be surveyed.

An apparatus for positioning markers at one or more locations to be marked, said apparatus comprising:

• a first energy beam transmitter operable for projecting a first energy beam that sweeps in a plane across the area to be marked;
• first reference signal means for generating a first reference signal when said first energy beam is aligned with a first reference line;
• a second energy beam transmitter operable for projecting a second energy beam that sweeps in a plane across the area to be marked, wherein said first and second energy beam transmitters are positioned apart during a marking operation;
• second reference signal means for generating a second reference signal when said second energy beam is aligned with a second reference line;
• an energy beam receiver operable for detecting said first and second energy beams, wherein said energy beam receiver is sequentially positioned at each location to be marked;
• a reference signal receiver operable for receiving said first and second reference signals;
• processing means coupled to said energy beam and reference signal receivers and responsive to the timing of the detection of said energy beams relative to the receipt of said reference signals for determining the position of said energy beam receiver relative to said energy beam transmitters;
• data base means coupled to said processing means for defining the positions relative to said energy beam transmitters of the locations to be marked;
• and
• position error means coupled to said processing means for indicating a positional error of said energy beam receiver relative to a location to be marked, wherein the position of said energy beam receiver defines the location to be marked when said positional error is substantially equal to zero.

A reference station for use with another like reference station and one or more portable receivers for position sensing, wherein during a position sensing operation the reference stations are spaced apart at known positions and the portable receiver is placed at a location at which the position is to be determined, said reference station comprising:

• a housing;
• an energy beam transmitter mounted to said housing and operable for projecting a first energy beam that sweeps in a plane, wherein during a position sensing operation said first energy beam periodically strikes another reference station and a portable receiver;
• an energy beam detector mounted to said housing and operable for detecting when the energy beam from the other reference station strikes said energy beam detector during a position sensing operation;
• and
• reference signal means mounted to said housing and responsive to the detection of the energy beam of the other reference station by said energy beam detector for generating a reference signal to the portable receiver.

A portable sensing station for use with two or more reference stations for position sensing, wherein during a position sensing operation the reference stations are spaced apart at known positions, wherein each of the reference stations projects an energy beam that sweeps in a plane and periodically strikes the other reference station and said portable sensing station, and wherein each of the reference stations generates a reference signal when the energy beam from the other reference station strikes it, said portable sensing station comprising:

• an energy beam receiver operable for detecting energy beams striking said energy beam receiver, wherein said energy beam receiver is placed at a location at which the position is to be determined;
• a reference signal receiver operable for receiving each of the reference signals from the reference stations;
• and
• processing means coupled to said energy beam and reference signal receivers and responsive to the timing of the detection of the energy beams by said energy beam receiver relative to the receipt of the reference signals by said reference signal receiver for determining the position in the plane of the energy beams of said energy beam receiver relative to the reference stations.

An apparatus for sensing the position and elevation of a grading implement mounted on an earth-moving vehicle and for determining an elevation error of the grading implement relative to a desired elevation, wherein the desired elevation of the grading implement at a particular position is the elevation that would allow the earth-moving vehicle and attached grading implement to produce a desired graded surface at that position, said apparatus comprising:

• a first energy beam transmitter operable for projecting a first energy beam that sweeps in a plane across the area to be graded and forms a datum plane;
• first reference signal means for generating a first reference signal when said first energy beam is aligned with a first reference line;
• a second energy beam transmitter operable for projecting a second energy beam that sweeps in a plane across the area to be graded, wherein said first and second energy beam transmitters are positioned apart during operation of said apparatus;
• second reference signal means for generating a second reference signal when said second energy beam is aligned with a second reference line;
• an energy beam receiver operable for detecting said first and second energy beams and for detecting the height at which said first energy beam strikes said energy beam receiver, wherein said energy beam receiver is coupled to a grading implement of an earth-moving vehicle for movement therewith;
• a reference signal receiver operable for receiving said first and second reference signals;
• and
• processing means coupled to said energy beam receiver and said reference signal receiver and responsive to the timing of the detection of said energy beams relative to the receipt of the respective reference signals for determining the position of the earth-moving vehicle relative to said energy beam transmitters, and responsive to the height at which said first energy beam strikes said energy beam receiver for determining the elevation of the grading implement, wherein said processing means includes data base means for defining the desired elevation of the grading implement as a function of the position of the earth-moving vehicle, and includes computational means for determining the elevation error of the grading implement according to the difference between the measured and desired elevations thereof.

A control system for an earth-moving vehicle for use in grading a plot of land to a desired contour, wherein said earth-moving vehicle includes a grading implement that defines the graded surface, said control system comprising:

• first and second reference stations spaced apart at known positions and each including an energy beam transmitter operable for projecting an energy beam that sweeps at a constant angular velocity in a plane across the area to be graded and that periodically strikes the other reference station and a receiver, including an energy beam detector operable for detecting the energy beam from the other reference station, and including a reference signal transmitter responsive to the detection of the other energy beam by said energy beam detector and operable for periodically broadcasting a reference signal, wherein one of said energy beams is denoted a datum energy beam that defines a datum plane for elevation measurements;
• a receiver mounted on an earth-moving vehicle, said receiver including an energy beam receiver operable for detecting when and the height at which said datum energy beam strikes said receiver, wherein said energy beam receiver is coupled to a grading implement for movement therewith, and including a reference signal receiver operable for receiving said reference signals broadcast from said reference stations;
• position measuring means operatively coupled to said receiver and coupled to the earth-moving vehicle for movement therewith and responsive to the timing of the detection of the energy beams by said energy beam receiver relative to the receipt of the respective reference signals by said reference signal receiver for determining the position of the grading implement relative to said reference stations, and responsive to the height at which said datum energy beam strikes said receiver for determining the elevation of the grading implement relative to said datum plane;
• data base means for defining the desired contour of the plot of land in terms of desired elevations of the grading implement relative to said datum plane as a function of the positions of the grading implement relative to said reference stations;
• processing means responsive to the measured position and elevation of the grading implement and responsive to the desired elevation of the grading implement for determining an elevation error of the grading implement according to the difference between the measured and desired elevations of the grading implement;
• and
• automatic control means responsive to the elevation error for automatically adjusting the elevation of the grading implement to reduce the elevation error.

A method comprising the steps of:

• projecting first and second energy beams from two transmitters that are spaced apart, wherein each of said energy beams periodically sweeps in a plane across an area within which position sensing is to occur;
• generating a first reference signal when said first energy beam is aligned with a first reference line;
• generating a second reference signal when said second energy beam is aligned with a second reference line;
• detecting said first and second energy beams with an energy beam receiver that is placed at a location at which the position is to determined;
• receiving said first and second reference signals by a reference signal receiver;
• and
• determining the position of said energy beam receiver relative to said reference lines and said transmitters according to the timing of detection of said energy beams by said energy beam receiver relative to the reception of said reference signals by said reference signal receiver.

A position sensing method comprising the steps of:

• projecting a first laser beam in a first plane at a constant angular velocity and projecting a second laser beam in a second plane substantially parallel to said first plane at a constant angular velocity, wherein said first and second laser beams are transmitted from respective first and second laser beam transmitters that are positioned apart by a known distance, wherein the line between said laser beam transmitters defines a reference line, and wherein said first and second laser beams periodically sweep across an area with which position sensing is to occur and also periodically strike the other laser beam transmitter;
• broadcasting a first reference signal each time said first laser beam strikes a detector mounted on said second laser beam transmitter;
• broadcasting a second reference signal each time said second laser beam strikes a detector mounted on said first laser beam transmitter;
• detecting said first and second laser beams with a laser beam receiver and receiving said first and second reference signals with a reference signal receiver, wherein said receivers are placed at a location at which the position is to be determined;
• and
• determining the position of said laser beam receiver relative to said laser beam transmitters in the plane of the laser beams as the intersection of first and second lines extending in said plane from respective first and second laser beam transmitters and forming respective first and second angles with respect to said reference line, wherein said first angle is determined according to the ratio of the time interval between the detection of said first laser beam and the receipt of said first reference signal to the time interval defined by the period of rotation of said first laser beam, and wherein said second angle is determined according to the ratio of the time interval between the detection of said second laser beam and the receipt of said second reference signal to the time interval defined by the period of rotation of said second laser beam.

A surveying method comprising the steps of:

• projecting first and second energy beams from two transmitters that are spaced apart, wherein each of said energy beams periodically sweeps in a plane across the area to be surveyed, and wherein said first laser beam defines a datum plane;
• generating a first reference signal when said first energy beam is aligned with a first reference line;
• generating a second reference signal when said second energy beam is aligned with a second reference line;
• detecting said first and second energy beams with an energy beam receiver that is positioned at a location to be surveyed;
• determining the elevation of the location to be surveyed according to the height at which said energy beam receiver detects said first laser beam;
• receiving said first and second reference signals by a reference signal receiver;
• and
• determining the position of said energy beam receiver at the location to be surveyed relative to said reference lines and said transmitters according to the timing of detection of said energy beams by said energy beam receiver relative to the reception of said reference signals by said reference signal receiver, and recording the position and elevation of the location surveyed according to the measured position and elevation of said energy beam receiver.

A method for positioning markers at one or more locations to be marked, said method comprising the steps of:

• projecting first and second energy beams from two respective transmitters that are spaced apart at known positions, wherein each of said energy beams periodically sweeps in a plane across the area to be marked;
• defining the positions relative to said transmitters of the locations to be marked;
• generating a first reference signal when said first energy beam is aligned with a first reference line;
• generating a second reference signal when said second energy beam is aligned with a second reference line;
• positioning an energy beam receiver near a location to be marked;
• detecting said first and second energy beams with said energy beam receiver and receiving said first and second reference signals with a reference signal receiver;
• determining the position of said energy beam receiver relative to said transmitters according to the timing of detection of said energy beams by said energy beam receiver relative to the reception of said reference signals by said reference signal receiver;
• indicating a positional error of said energy beam receiver relative to the location to be marked;
• repositioning said energy beam receiver until said positional error is substantially equal to zero;
• and
• marking the position of said energy beam receiver when said positional error is substantially equal to zero.

A method for sensing the position and elevation of a grading implement of an earth-moving vehicle and for determining an elevation error of the grading implement relative to a desired elevation, wherein the desired elevation of the grading implement at a particular position is the elevation that would allow the grading implement to produce a desired graded surface at that position, and wherein the elevation error is the difference between the actual and desired elevations of the grading implement, said method comprising the steps of:

• defining the desired elevations of the grading implement as a function of the position of the grading implement throughout an area to be graded;
• projecting a first energy beam that sweeps in a datum plane across the area to be graded;
• generating a first reference signal when said first energy beam is aligned with a first reference line;
• projecting a second energy beam that sweeps in a plane across the area to be graded, wherein said first and second energy beams are transmitted from transmitters that are positioned apart;
• generating a second reference signal when said second energy beam is aligned with a second reference line;
• detecting said first and second energy beams by an energy beam receiver that is coupled to a grading implement of an earth-moving vehicle for movement therewith;
• receiving said first and second reference signals by a reference signal receiver that is coupled to the earth-moving vehicle for movement therewith;
• determining the position of the grading implement relative to said transmitters according to the timing of the detection of said energy beams relative to the reception of said reference signals;
• measuring the elevation of the grading implement according to the height at which said first energy beam strikes said energy beam receiver;
• and
• determining the elevation error of the grading implement according to the difference between the measured elevation and the desired elevation thereof.

A method for sensing the position and elevation of a grading implement of an earth-moving vehicle and for determining an elevation error of the grading implement relative to a desired elevation, wherein the desired elevation of the grading implement at a particular position is the elevation that would allow the grading implement to produce a desired graded surface at that position, and wherein the elevation error is the difference between the actual and desired elevations of the grading implement, said method comprising the steps of:

• selecting a plurality of elevation-defining line segments along which the desired contour of the land has a constant slope, wherein each line segment has end points at which the position and desired elevation is known;
• projecting a first energy beam that sweeps in a datum plane across the area to be graded, wherein all elevations are defined relative to said datum plane;
• generating a first reference signal when said first energy beam is aligned with a first reference line;
• projecting a second energy beam that sweeps in a plane across the area to be graded, wherein said first and second energy beams are transmitted from transmitters that are positioned apart at known positions relative to said elevation-defining line segments;
• generating a second reference signal when said second energy beam is aligned with a second reference line;
• detecting said first and second energy beams by an energy beam receiver that is coupled to a grading implement of an earth-moving vehicle for movement therewith;
• receiving said first and second reference signals by a reference signal receiver that is coupled to the earth-moving vehicle for movement therewith;
• determining the position of the grading implement relative to said transmitters according to the timing of the detection of said energy beams relative to the reception of said reference signals;
• measuring the elevation of the grading implement according to the height at which said first energy beam strikes said energy beam receiver;
• determining the desired elevation of the grading implement according to the steps of finding two elevation-defining line segments near to and surrounding the position of the grading implement, finding the elevations of two points on the line segments, wherein said two points define a line through the position of the grading implement and wherein the elevation of a point located on a line segment is found by interpolating between the elevations of the two end points of that line segment, and interpolating between the elevations of said two points to determine the desired elevation of the position of the grading implement;
• and
• determining an elevation error of the grading implement according to the difference between the measured elevation and the desired elevation thereof.