Emergency robot shutdown circuit

An emergency robot shutdown circuit for controlling operation of a robot by disconnection of power supplied thereto upon movement of the robot from a normal operating range to a limit position comprising:

• a detecting circuit responsive to movement of the robot into the limit position and disconnecting a first power line in response thereto;
• a first relay, connected to the first power line, which becomes deenergized and disconnects a second power line upon disconnection of the first power line;
• a second relay, connected to the second power line, which becomes deenergized and disconnects a third power line upon disconnection of the second power line;
• a latch connected to the second relay and the second power line which maintains the disconnection of the second power line upon return of the robot to the normal operating range from the limit position and subsequent reconnection of the first power line by the detecting circuit;
• a third relay, connected to the third power line, which becomes deenergized and disconnects the power supplied to the robot upon disconnection of the third power line;
• and
• a cancel switch connected to the third power line which energizes the third relay through reconnection of the third power line in response to switching thereof.

A method for operation of a robot in response to movement of a dog into contact with a limit switch, said method comprising the steps of:

• detecting an overtravel condition of a robot beyond a normal operation range in response to movement of the dog into contact with the limit switch;
• inhibiting connection of a power supply to the robot in response to the detected overtravel condition;
• continuing to inhibit connection of the power supply to the robot when the dog is removed from contact with the switch;
• and
• restoring power from the power supply to the robot in response to an overtravel unlatching signal.