System for determining the position of a tool mounted on pivotable arm using a light source and reflectors

An apparatus for determining a position of a bucket mounted on an earthmoving machine relative to a grade elevation, said earthmoving machine including a platform, an arm with a plurality of pivot points, a rear end pivotally attached to said platform at one of said pivot points and a leading end pivotally attached to said bucket at another of said pivot points, and at least one actuating mechanism for pivotally moving said arm and for pivotally moving said bucket, said apparatus comprising:

• a plurality of reflectors mounted on and in a known relationship to said machine, each of said plurality of reflectors being operatively adapted for reflecting light back toward a light source, and said plurality of reflectors including at least one reflector mounted on said earthmoving machine for indicating movement of said arm and another reflector mounted on said earthmoving machine for indicating movement of said bucket;
• a laser transceiver mounted on said earthmoving machine in a known relationship to at least one of said plurality of reflectors and said pivot points and operatively adapted for
• transmitting a beam of laser light to illuminate each of said plurality of reflectors and thereby generate reflected laser light from each of said plurality of reflectors,
• detecting said reflected laser light and the angular orientation of said reflected laser light with respect to an index position,
• generating at least one output signal in response to detecting said reflected laser light and the angular orientation of said reflected laser light with respect to said index position;
• and
• a computer for computing the position of said bucket relative to the grade elevation from a plurality of said output signal.

An apparatus for determining a position of a bucket mounted on an earthmoving machine relative to a grade elevation, said earthmoving machine including a platform, an arm having a first arm segment, a second arm segment and a plurality of pivot points, said first arm segment having a rear end pivotally attached to said platform at a first pivot point and a leading end, said second arm segment having a rear end pivotally attached to the leading end of said first arm segment at a second pivot point and a leading end pivotally attached to said bucket at a third pivot point, and said earthmoving machine including at least one actuating mechanism for pivoting said first arm segment about said first pivot point, at least one actuating mechanism for pivoting said second arm segment about said second pivot point, and at least one actuating mechanism for pivoting said bucket about said third pivot point, said apparatus comprising:

• a plurality of retroreflectors, including at least one first retroreflector mounted on said platform for indicating movement of said first arm segment, a second retroreflector mounted so as to rotate with said second arm segment, and a third retroreflector mounted to move as said bucket rotates, each of said retroreflectors being mounted on said machine in a known relationship to at least one of said plurality of pivot points and being operatively adapted for reflecting light back toward a light source;
• a laser transceiver mounted on said first arm segment in a known relationship to each of said retroreflectors and pivot points, said laser transceiver including a transmitter for transmitting a rotating beam of laser light to illuminate each of said retroreflectors and thereby generate reflected laser light from each of said retroreflectors during each rotation of said beam of laser light, and a detector for detecting said reflected laser light and the angular orientation of said reflected laser light with respect to an index position, and said laser transceiver being operatively adapted for generating at least one output signal in response to detecting said reflected laser light and the corresponding angular orientation;
• a reference measuring system for measuring the elevation of a point on said earthmoving machine relative to the grade elevation;
• and
• a computer operatively adapted for determining the position of said bucket relative to the grade elevation from a plurality of said output signal and an elevation measurement from said reference measuring system of the point on said earthmoving machine.

A method of determining a position of a tool mounted on a machine having a base, an arm with a plurality of pivot points, a rear end pivotally attached to the base at one pivot point and a leading end pivotally attached to the tool at another pivot point, and at least one actuating mechanism for pivotally moving the arm and for pivotally moving the tool, said method comprising the steps of:

• transmitting a beam of light at a plurality of light reflectors mounted on the machine in a known relationship to one another;
• illuminating each of the reflectors with the beam of light;
• generating reflected light when each of the reflectors is illuminated with the beam of light;
• detecting the reflected light and the angular orientation of the reflected light from each of the reflectors;
• generating at least one output signal in response to detecting the reflected light and the corresponding angular orientation from each of the reflectors:
• and
• determining the position of the tool using a plurality of the output signals generated.