1993-09-01

Computer-Assisted Control of Excavator-Based Machines 932486

Recent computer-based improvements in excavator-type machines have addressed fuel economy and power delivery to the implement for various types of tasks. Although some developments have been made in task-specific bucket control, the basic pattern of hand control motions for operating these machines has remained little changed over many years. This paper reports on a hand control interface, its computer-based hydraulic control system and the results of human factors studies carried out on a Cat 215B-based log loader.
By means of a set of real-time excavator simulator studies, a new approach to directing the control of the implement motion has been developed. A testbed machine was made available by Caterpillar and the control system was implemented on an excavator, a log loader and at present is also being implemented on a feller-buncher. A commercial version of the concept has also been successfully implemented on grapple yarders.
A single hand controller has been developed to allow the operator to match the hand controller's translational direction of motion in X, Y and Z, to the visually-determined desired direction of motion of the implement.
A machine control system was designed to ensure that the implement follows the commanded direction of motion specified by the hand controller within the capabilities of the hydraulic system. Two different control systems have been investigated - with and without pressure sensing.
Results of the human factors testing on novices and experienced operators is reported. The results compare machine operation using standard machine hand controls and coordinated controls.

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