Patent ID: 7930970

Claim:
A control unit for a work machine comprising: in a work machine where at least a part of a work arm to be operated by a fluid pressure actuator is provided so as to be replaceable, a pilot-operated control valve that controls the fluid pressure actuator; a proportional solenoid valve that pilot-controls the pilot-operated control valve by a pilot control pressure according to an electrical signal corresponding to a manual operation amount; a measuring device that measures a weight of at least a part of the work arm, comprising: a pressure sensor measuring a holding pressure of the fluid pressure actuator of the work arm; and a controller converting characteristics between the manual operation amount and the pilot control pressure of the proportional solenoid valve to characteristics according to the weight of the work arm measured by the measuring device, the controller comprising: an automatic stop function to stop the work arm in a fixed holding pressure measurement posture; and a weight calculation function to estimate the weight of the work arm from the holding pressure measured by the pressure sensor in the fixed holding pressure measurement posture.