| 摘要 |
A safety interlock system for a robotic apparatus includes a light curtain in combination with ultrasonic sensors to perform a staged interlock to reduce unnecessary alarms or shutdowns. A robotic apparatus, such as a linear travel-type robot system, is protected by a fixed light curtain for detecting intrusion of a foreign object into a work space of the robotic apparatus. Ultrasonic transducers provide signals indicating a distance to an object interrupting the light beams forming the light curtain. An X-axis position of the robotic apparatus is compared with an object distance to determine whether to slow or stop robotic motion. Four stages of response to light beam interruption are provided. If there is no input from the ultrasonic transducer, an interruption of a light beam causes an immediate and complete halting of robotic movement to provide fail-safe operation. If the ultrasonic transducer indicates that the robotic apparatus and object are separated by a safe nominal operating distance, e.g., greater than six feet, an audible alarm is activated but robot maneuvering is not inhibited. If separation is within a warning range of, for example, three to six feet, robot movement speed is reduced and the alarm is activated. Finally, if separation is determined to be less than the minimum value of the warning range, i.e., less than three feet, the robot is fully stopped and the alarm is activated.
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