Automatic excavation control system and method

A control system for automatically controlling a work implement of an excavating machine through a machine work cycle, the work implement includes a boom, stick and bucket, each being controllably actuated by at least one respective hydraulic cylinder, the hydraulic cylinders containing pressurized hydraulic fluid, the control system comprising:

• position sensing means for producing respective position signals in response to the respective position of the boom, stick and bucket;
• means for receiving the position signals, comparing at least one of the boom, stick and bucket position signals to a predetermined one of a plurality of position setpoints;
• pressure sensing means for producing respective pressure signals in response to the associated hydraulic pressures associated with the boom, stick, and bucket hydraulic cylinders;
• means for receiving the pressure signals, comparing at least one of the boom, stick and bucket pressures to a predetermined one of a plurality of pressure setpoints;
• means for producing a material condition setting, the material condition setting being representative of a predetermined condition of the excavating soil;
• means for producing a command signal in response to the pressure and position comparisons, the command signal having a magnitude responsive to the material condition setting;
• and
• actuating means for receiving the command signal and controllably actuating predetermined ones of the hydraulic cylinders to perform the work cycle.