Method and apparatus for laser beam control of backhoe digging depth

• US 4,231,700 A
• Filed: 04/09/1979
• Issued: 11/04/1980
• Est. Priority Date: 04/09/1979
• Status: Expired due to Term

• Current Assignee: Spectra Precision Inc. (Trimble Inc.)
• Original Assignee: Spectra-Physics Incorporated (MKS Instruments Incorporated)
• Inventors: Studebaker, Robert H.
• Primary Examiner(s): Knowles, Allen N.
• Application Number:
  US06/028,178
• Time in Patent Office: 575 Days
• Field of Search: 414/694, 414/698, 414/700, 414/786, 212/39 MS, 37/DIG. 1, 37/DIG. 19, 172/4, 172/4.5
• US Class Current: 414/700
• CPC Class Codes: E02F 3/30 with a dipper-arm pivoted on a cantilever beam , i.e. boom
• CPC Class Codes: E02F 3/32 working downwardly and towards the machine, e.g. with backhoes
• CPC Class Codes: E02F 3/435 for dipper-arms, backhoes or the like
• CPC Class Codes: E02F 9/26 Indicating devices E02F5/145 takes precedence

Abstract

This invention provides a method and apparatus for controlling the digging depth of the bucket of a backhoe or an excavator so as to move the digging edge of the backhoe bucket in a plane parallel to an overhead reference plane defined by a rotating laser beam. The detecting means for the laser beam is mounted on a medial portion of the downreach boom and the control of the position of the bucket is accomplished by moving the outreach boom of the backhoe relative to the supporting platform so as to maintain the detecting means on the downreach boom in a fixed relationship with respect to the reference plane defined by the rotating laser beam.

Claims

1. In a backhoe having a platform movable about a vertical axis, an outreach boom pivotally mounted on the platform for movement about a horizontal axis, a downreach boom having one end horizontally pivotally mounted to the free end of the outreach boom, a digging bucket pivotally mounted to the other end of the downreach boom, and separate power means for controlling the vertical pivotal movements respectively of the outreach boom relative to the platform, of the downreach relative to the outreach boom, and of the bucket relative to the downreach boom, the improvements comprising:

1. means for establishing an above ground reference plane of laser energy;

2. photocell means mounted on said downreach boom and constructed and arranged to intercept said plane of laser energy throughout the digging stroke of the backhoe;

3. means responsive to the signals generated by said photocell means for varying the vertical pivotal angle of said outreach boom relative to said platform to maintain said photocell means on said downreach boom at a predetermined position relative to said reference plane throughout the digging stroke of the backhoe, and

4. means for maintaining the bucket in a fixed position throughout the digging stroke of said backhoe, whereby the digging edge of said bucket moves in a plane parallel to said overhead reference plane of laser energy.

2. The improvements defined in claim 1 wherein said photocell means is mounted on the outer side of the downreach boom and has sufficient vertical extent to be contacted by said reference plane of laser energy throughout the normal digging stroke of the downreach boom.

3. The method of controlling the operation of a backhoe having an outreach boom pivotally mounted on a platform for movement in a vertical plane, a downreach boom pivotally mounted to the free end of the outreach boom for movement in a vertical plane, a digging bucket pivotally mounted to the other end of the downreach boom for movement in a vertical plane, and separate power means for respectively effecting said pivotal movements, comprising the steps of:

1. creating an above ground reference plane of laser energy;

2. detecting said plane of laser energy throughout the digging stroke of the backhoe by a detecting unit mounted on said downreach boom;

3. manually controlling the power means to pivot the downreach boom relative to the outreach boom through a digging stroke;

4. controlling the angle of said outreach boom relative to said platform to maintain the detecting unit on said downreach boom at a fixed position relative to said overhead reference plane throughout the digging stroke of the backhoe, and

5. maintaining the digging bucket in a fixed angular relationship to the downreach boom throughout the digging stroke of the backhoe, whereby the digging edge of the bucket moves in a plane parallel to the overhead reference plane of laser energy.

4. The method defined in claim 3 wherein step 4 is performed automatically.