| 摘要 |
PURPOSE:To prevent a runaway of a robot for welding, etc. by detecting a disconnection and defective connection of potentiometer according to the voltage change of the element connected to a potentiometer of a feedback control system. CONSTITUTION:A voltage is applied from a potentiometer 22 to a controller 20 of a servo mechanism 24 of feedback control system of a robot for welding, etc. When a line A 28 or line C 30 of this potentiometer 22 is disconnected, etc. an electric current, dute to the voltage between lines 26, 28, is not flowed to a resistance 70 and the output of an amplifier 72 of a disconnection detecting circuit 34 becomes on a high level and FF76 is set via an OR gate 68. A transistor 76 is then turned on and a closed contact 48 is opened by a relay 80. The disconnection, etc. of a line B 28 of the potentiometer 22 are similarly monitored and detected and at the time of disconnection, etc. the contact 48 is opened and the mechanism 24 is shfut off from the potentiometer 22 and the runaway of a robot for welding, etc. is prevented.
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