Robotics

Scope

Hazards are present in every work environment. Being unaware of them when dealing with robotics can be fatal. Although there are currently no specific standards for robotics, OSHA’s General Duty Clause requires you to furnish a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees.

Regulatory citations

• 29 USC 654 — Duties of employers and employees (including Pub. L. 91–596 “OSH Act of 1970” 5(a)(1), the “General Duty Clause”)

Key definitions

• Continuous path: A robot whose path is controlled by storing a large number or close succession of spatial points in memory during a teaching sequence is a continuous path-controlled robot.
• Control errors: Intrinsic faults within the control system of the robot, errors in software, electromagnetic interference, and radio frequency interference are control errors. In addition, these errors can occur due to faults in the hydraulic, pneumatic, or electrical sub controls associated with the robot or robot system.
• Controlled path: A path or mode of movement that ensures that the end of the robot’s arm will follow a predictable (controlled) path and orientation as the robot travels from point to point.
• Crushing and trapping accidents: An instance where a worker’s limb or other body part are trapped between a robot’s arm and other peripheral equipment, or the individual may be physically driven into and crushed by other peripheral equipment.
• Impact or collision accidents: Component malfunctions or unpredicted program changes related to the robot’s arm or peripheral equipment may result in contact accidents.
• Nonservo robots: Robots that do not have the feedback capability, and their axes are controlled through a system of mechanical stops and limit switches.
• Point-to-point: A path designed for a robot to move from one discrete point to another within the robot’s working envelope.
• Servo robots: Equipment that can be controlled through the use of sensors that continually monitor the robot’s axis and associated components for position and velocity.
• Unauthorized access: Entry into a robot’s safeguarded area without being familiar with the safeguards in place or the robots activation status.
• Mechanical failures: Operating programs that may not account for cumulative mechanical part failure, and faulty or unexpected operation may occur.
• Environmental sources: Electromagnetic or radio-frequency interference (transient signals) should be considered to exert an undesirable influence on robotic operation and increase the potential for injury to any person working in the area. Solutions to environmental hazards should be documented prior to equipment start-up.
• Power systems: Pneumatic, hydraulic, or electrical power sources that have malfunctioning control or transmission elements in the robot power system which can disrupt electrical signals to the control and/or power-supply lines.
• Improper installation: The improper construction of the robot’s design, requirements, and layout of equipment, utilities, and facilities of a robot or robot system.

Summary of requirements

• Assure that no one is allowed to enter the operational area of a robot without first putting the robot on “hold,” in a “power down” condition, or at a reduced operating speed mode.
• Ensure that operators are not in reach of the robot while it is operating.
• Ensure that workers are constantly alert while operating any piece of equipment.
• Include physical barriers that incorporate gates equipped with electrical interlocks so that operation of the robot stops when the gate is opened.
• Include, as a backup to electrical interlocks, motion sensors, light curtains, or floor sensors that stop the robot whenever a worker crosses the barrier.
• Provide adequate illumination in the control and operational areas of the robotic system so that written instructions, as well as buttons, levers, etc., are clearly visible.
• Provide barriers, as may be appropriate, between robotic equipment and any freestanding objects such as posts limiting robot arm movement so that workers cannot get between any part of the robot and the “pinch points.”
• Train workers to be familiar with all working aspects of the robot, including full range of motion, known hazards, how the robot is programmed, emergency stop buttons, and safety barriers, before operating or performing maintenance work at robotic work stations.
• Identify on floors or working surfaces, clearly visible marks that indicate the zones of movement of the robot.
• Instruct employees not to become complacent if they work with the same robots on a day to day basis.