Process for automatically controlling actuators of excavator

A process for automatically controlling an apparatus for operating an excavator, said apparatus including a pair of hydraulic pumps driven by an engine, a plurality of actuators actuated operably connected to said hydraulic pumps, directional control valves operably connected to the actuators, and control levers and control pedals for generating electric control signals to control the actuators, the process comprising the steps of:

• determining handling values of the control levers and control pedals for controlling said actuators upon reception of electric control signals outputted from said control levers and control pedals;
• calculating desired actuation speeds of said actuators in accordance with the determined handling values of said control levers and control pedals;
• calculating actual actuation speeds of said actuators as sensed by displacement sensors on said actuators;
• comparing the desired actuation speeds of said actuators with the actuation speeds of said actuators and determining whether said actuators are overloaded;
• determining whether at least two actuators are being driven at the same time and whether at least two actuators are being driven by both of said hydraulic pumps, and further determining whether a control process for removing an overload condition on said actuators was performed in a previous operation of the excavator, still further determining whether controlled actuation speeds stored in the apparatus are equal to the actual actuation speeds of said actuators;
• outputting electric signals representing the controlled actuation speeds of said actuators when it is determined that the actual actuation speeds of said actuators are equal to the controlled actuation speeds of said actuators, but calculating a quantity of hydraulic fluid under pressure to be supplied to said actuators in accordance with a given load on said actuators when it is determined that the actual actuation speeds of the actuators are not equal to the controlled actuation speeds of the actuators;
• and
• outputting control signals to the directional control valves for controlling said directional control valves according to the quantity of hydraulic fluid to be supplied to said actuators.