Control device for an earthwork machine

A control device for an earthwork machine having a boom pivotally secured at a first end thereof to one point of a machine body, an arm pivotally secured at one end thereof to the other end of the boom, and a bucket rotatably secured at the upper end thereof to the other end of the arm, a boom cylinder for varying an angle .alpha. between the vertical axis from the first end of the boom and the boom, an arm cylinder for varying an angle .beta. between the boom and the arm, a bucket cylinder for varying an angle .gamma. between the arm and the bucket, first setting means for providing a set value corresponding to the desired motion of a predetermined one of the boom, arm and bucket, second setting means for providing a set value corresponding to the desired pivotal or rotatable position of another one of the boom, arm and bucket, third setting means for providing a set value corresponding to the desired pivotal or rotatable position of the other thereof, and controllers for respectively controlling the movements of the boom, arm and bucket in accordance with the set values of said first, second and third setting means, comprising:

• angle detectors for detecting the pivoted or rotated angles of the boom, arm and bucket, respectively,
• an arithmetic unit for producing control data necessary to move the sharp edge of the bucket along a straight path of a predetermined gradient on the basis of the detected angles of the boom, arm and bucket when said first setting means is manually operated, and
• switch means located between said second and third setting means and the corresponding controllers for selectively applying to the respective controllers either the control data indicating calculated movement amount of the boom, arm and bucket or signals from the second and third setting means.

A control device for use in earthworking equipment of the type having a body, a boom which is pivotally secured to the body, an arm which is pivotally secured to the boom, a bucket pivotally secured to the arm, boom means for pivoting the boom with respect to the body, arm means for pivoting the arm with respect to the boom and bucket means for pivoting the bucket with respect to the arm, said control device comprising:

• first control means for manually controlling one of the boom means, arm means and bucket means;
• detection means for detecting the pivotal positions of the boom, arm and bucket;
• arithmetic circuitry for determining, in response to the detected pivotal positions, the amount of movements of the two of the boom means, arm means and bucket means other than the manually controlled one necessary to move the edge of the bucket along a straight path;
• and
• second control means for automatically controlling the two of the boom means, arm means and bucket means other than the manually controlled one in accordance with the output of the arithmetic circuitry.