Automatic control of backhoe digging depth

• US 4,129,224 A
• Filed: 09/15/1977
• Issued: 12/12/1978
• Est. Priority Date: 09/15/1977
• Status: Expired due to Term

• Current Assignee: Spectra Physics LaserPlane Inc (Trimble Inc.)
• Original Assignee: Laserplane Corporation
• Inventors: Teach, Ted L.
• Primary Examiner(s): Paperner, L. J.
• Application Number:
  US05/833,432
• Time in Patent Office: 453 Days
• Field of Search: 214/1 CM, 214/138 R, 214/152, 214/761, 214/762, 214/763, 214/DIG. 2, 37/DIG. 1, 172/2, 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

In a backhoe of the type having an outreach boom horizontally pivotally mounted relative to a vehicle and an hydraulic cylinder therebetween, a downreach boom horizontally pivotally mounted on the free end of the outreach boom and an hydraulic cylinder therebetween, and a digging bucket horizontally pivotally mounted on the free end of the downreach boom and an hydraulic cylinder therebetween, apparatus is provided for respectively generating signals proportional to the angle between the outreach boom and the horizontal, the angle between the outreach boom and the downreach boom, the angle between the downreach boom and a line drawn to the digging teeth of the bucket, and an angle equal to the desired slope of the bottom of the excavation relative to the true horizontal. Such signals are combined according to a trigonometric equation to provide a continuous signal and/or visual indication to indicate the absolute elevation of the digging teeth of the backhoe bucket and the same signals are also utilized to control the hydraulic cylinders and the relationships between the aforementioned angles so that the digging teeth of the bucket move parallel to the desired slope of the bottom of the excavation throughout the digging stroke.

Claims

1. The method of operating a backhoe to move the digging edge of the bucket thereof along a path parallel to the desired slope of the bottom of the excavation and with the digging angle of the bucket being substantially constant with respect to said desired slope, said backhoe having an outreach boom vertically pivotal about a horizontal axis defining an Angle A with respect to the horizontal, a downreach boom pivotally secured to the free end of the outreach boom to define an Angle B therebetween, and a digging bucket pivotally secured to the other end of the downreach boom to define Angle C between the digging edge of the bucket and its pivotal axis on the downreach boom, there being three power-actuating means respectively operating on said outreach boom, said downreach boom, and said digging bucket to vary said Angles A, B and C, comprising the steps of:

(1) manually controlling the power-actuating means determining Angle B to move said bucket through a digging stroke;

(2) generating a first electrical signal continuously proportional to Angle B;

(3) controlling one of the two remaining power-actuating means as a trigonometric function of Angle B, the length of the outreach boom, and the length of the downreach boom, thereby determining either Angle A or Angle C;

(4) generating a second electrical signal continuously proportional to the Angle determined by step (3); and

(5) controlling the remaining power-actuating means as a linear function of the sum of the electrical signals generated in steps (2) and (4).

2. The method defined in claim 1 wherein the trigonometric relationship between Angle A and Angle B is defined by the equation ##EQU2## where R1 equals the length of the digging boom,

R2 equals the length of the downreach boom,

S is the angle between the desired slope of the excavation and the horizontal, and

3. The method of claim 1 plus the step of concurrently indicating the depth of the digging edge of the bucket throughout said digging stroke.

4. The method of operating a backhoe to move the digging edge of the bucket thereof along a path parallel to the desired slope of the bottom of the excavation and with the digging angle of the bucket being substantially constant with respect to said desired slope, said backhoe having a power-actuated outreach boom vertically pivotal about a horizontal axis and defining an Angle A with respect to the horizontal, a downreach boom pivotally secured to the free end of the outreach boom and power-actuated relative thereto to define an Angle B therebetween, and a digging bucket pivotally secured to the other end of the downreach boom and power-actuated relative to define an Angle C between the digging edge of the bucket and the axis of the downreach boom, comprising the steps of:

(1) generating a first electrical signal continuously proportional to Angle B;

(2) controlling the power actuation of the outreach boom, hence Angle A, as a trigonometric function of Angle B, the length of the outreach boom, and the length of the downreach boom;

(3) generating a second electrical signal continuously proportional to the Angle A;

(4) controlling the power-actuation of the digging bucket relative to the downreach boom, hence Angle C, as a linear function of the sum of Angles A and B; and

(5) manually controlling the power-actuation of the downreach boom through a digging stroke, thereby varying Angle B.

5. Apparatus for controlling a backhoe to move the digging edge of the bucket thereof along a path parallel to the desired slope of the bottom of the excavation and with the digging angle of the bucket being substantially constant with respect to said desired slope, said backhoe having an outreach boom vertically pivotal about a horizontal axis defining an Angle A with respect to the horizontal, a downreach boom pivotally secured to the free end of the outreach boom to define an Angle B therebetween, and a digging bucket pivotally secured to the other end of the downreach boom to define an Angle C between the digging edge of the bucket and its pivotal axis on the downreach boom, comprising, in combination:

(1) three power-actuating means respectively operating on said outreach boom, said downreach boom, and said digging bucket to vary said Angles A, B and C;

(2) means for continuously generating electrical signals respectively proportional to said Angles A, B and C;

(3) computer means for generating a signal according to the following equation;

##EQU3## where R1 equals the length of the digging boom,

R2 equals the length of the downreach boom,

S is the angle between the desired slope of the excavation and the horizontal, and

space="preserve" listing-type="equation">K = R2 sin (A.sub.o + S + B.sub.o) - R1 sin (A.sub.o + S)

where

A_o and B_o are the measured values of Angle A and B at the beginning of the digging stroke;

(4) circuit means for applying the signal generated by said computer means to the power-actuating means controlling the outreach boom; and

(5) means for controlling the power-actuating means for said digging bucket as a linear function of the sum of said signals proportional to said Angles A and B, thereby determining Angle C.

6. The apparatus of claim 5 plus means responsive to a trigonometric function of angles A, B and C and the distances R1, R2 and R3 for indicating the depth of the digging edge of said bucket, where R3 is the distance from the digging edge to the pivot axis of said bucket.