To inhibit occurrence of unnecessary emergency stop, and to improve safety by more reliably determining whether a real moving trace of a robot teaching reference point is located in an operation enabling region.
An instructed coordinate on a real space of the robot teaching reference point is calculated from a command value regarding a motion displacement quantity of a motor for driving respective shafts of a robot. The command coordinate is determined as to whether it is located within the operation enabling region. An actual coordinate of the teaching reference point in the real space is computed from actual values of the respective shafts. Whether a relation between the actual value and the command value is appropriate is determined from a distance measured from the current actual coordinate to a command obtained by coupling a predetermined number of past command coordinates from the current time in a time series order. Either when the command coordinate is determined to be out of the operation enabling region, or when the relation between the actual value and the command values is determined to be inappropriate, an emergency stop signal for bringing the robot into a safe condition is outputted.
KOMURO KATSUHIRO
FUJIMURA SUKEYUKI
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