Work machines that have boom assemblies serve a variety of functions, such as digging ditches, grading surfaces, and laying pipe. In order to carry out these functions, it is advantageous for the boom assembly to extend and retracted in such a manner that the work implement is kept on a linear path during the function. An operator controls the movement of the boom assembly by moving control levers or joysticks. Hydraulic actuators, connected to the boom assembly, receive the operator commands and move the boom assembly accordingly.
When grading a surface, the operator extends the boom assembly out and places the tip of the work implement into the material at an appropriate depth and angle. In order to create the linear surface, the operator must raise the boom and draw the stick in at a coordinated rate, such that the work implement follows a linear path. This takes high operator skill to coordinate the movement of the boom and stick and remove the appropriate amount of material.
Some manufacturers have tried to anticipate such a scenario and have means to coordinate the movement of the boom assembly. One known control device is found in U.S. Pat. No. 4,332,517, issued to Michiaki Igarashi et al. on Jun. 1, 1982. Igarashi discloses a control device whereupon one cylinder is manually controlled and the operation of the remaining cylinders are calculated using angle detectors provided on the boom, bucket, and arm cylinders.
The present invention is directed to overcoming one or more of the problems set forth above.