초록

A control system for a liftcrane that utilizes a closed loop hydraulic system that utilizes feed back and feed forward control architecture to provide responsiveness normally associated with systems that do not require feedback.

대표청구항 ▼

[ What is claimed is:] [1.]1. A control system for a liftcrane, the control system comprising:a hoist actuator powered by a hydraulic pump, said hoist actuator connected to said pump by a closed hydraulic loop;a brake mechanism having an engaged state and a disengaged state;hoist system sensors oper

[ What is claimed is:] [1.]1. A control system for a liftcrane, the control system comprising:a hoist actuator powered by a hydraulic pump, said hoist actuator connected to said pump by a closed hydraulic loop;a brake mechanism having an engaged state and a disengaged state;hoist system sensors operable to detect pressure in said closed loop and speed of said hoist actuator and said pump, and output signals indicative thereof;an operator control sensor operable to output signals representative of an operator command; anda programmable controller coupled to said brake mechanism, said hoist system sensors, said pump and said operator control sensor, said programmable controller adapted to run a routine operable to output signals to said pump and said brake mechanism for the operation thereof based upon the signals output by said hoist system sensors and said operator control sensor, wherein said routine includes a pressure mode operable to output a first pump control current signal i.sub.p to said pump when said brake mechanism is in its engaged state, the operator control sensor indicates that motion of the hoist is desired, and the detected system pressure is less than a load induced pressure, wherein said pump control current signal i.sub.p is determined by adding a threshold value I.sub.o to an error signal indicative of the difference between the detected system pressure and the load induced pressure.