Robot controller with abnormality monitoring function

Abstract

A robot controller having a function of monitoring abnormality of a robot operation to prevent an accident by stopping supply of energy or operational substance to an operational tool when the operational tool is abnormally stopped. Motion command pulses for a robot motion are obtained by computing operations when a motion statement of the operation program is read out and stored in a shared memory. Motors for driving respective robot axes are driven based on the motion command pulses. When an I/O output command is issued on a signal line to actuate an arc welder, the operation control software demands to set a predetermined waiting time period to a timer. The managing software demands to start a countdown of the timer and informs the operation control software of an elapse of the set waiting time period. The operation control software determines that an abnormality has occurred if all of the present motion command pulses stored in the shared memory are zero, and turns off the signal line to forcedly terminates the actuation of the operational tool. In the midst of the operation, if the operational tool remains unmoved over a predetermined time period, it is also determined that an abnormality has occurred and the operation is forcedly terminated.