Method and apparatus for laser beam control of backhoe digging depth

Claim 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.

Claim 4

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.

Claim 5

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.