Importance

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Abstract

An apparatus for testing an industrial machine safety system that allows the machine to begin operation only when a plurality of safety push buttons have all been depressed, and that stops the machine's operation when any safety push button is released. The apparatus includes an artificial hand that can depress and, upon command, release one of the safety push buttons, and has a release detector for detecting the release of the artificial hand. The release detector operates optically. A lamp directs a light beam along a path that is blocked by a plunger when releasing the safety push button and not blocked when depressing the safety push button. A photodetector detects interruption of this light beam. Thus release of the safety push button is detected upon detection of interruption of the light beam. The machine begins to stop upon release of the safety push button. A motion detector detects the stoppage of the machine. A timer produces either an indication of the time between release of the artificial hand and the stoppage of the machine or a minimum safe distance between the machine and each safety push button as determined by a predetermined maximum hand velocity constant and the time between release of the artificial hand and the stoppage of the machine.

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First Claim