When the first industrial robots moved onto America's automobile assembly lines in the 1960s, most were rather primitive. Today, innovations have ushered in a new age of robotics. Yet despite breakthrough applications, robots carry risk: Without precautions, it's possible for robots to injure people and damage capital equipment.
To address the issue, the automation industry champions standards through the International Organization for Standardization (ISO) for robots and their systems integration. ISO 102181 - Part 1 (2006) specifies requirements and provides guidance for the assurance of safety in design and construction of the robot itself, though not the entire robot system. Part 2 or ISO 10218-2, which is undergoing development and is expected to be published in 2011, covers the integration and installation of a robot system or cell — for a more comprehensive set of requirements for robot safety.
Smarter robots help protect people
Early industrial robots were large, hydraulically powered machines. They boasted significant strength, but no intelligence beyond their human operators. By the 1980s, robots transitioned to become electrically driven units, with improved accuracy and performance.
Now, recent geometric increases in microprocessing power and strides in automation and controls have made robots indispensible in manufacturing, hospitals, warehouses and laboratories, and even for manipulating toxic substances and working in extreme environments. However, though robots contribute to human safety in such applications, their ranges of motion and power to handle superhuman payloads also pose potential dangers to people, especially during faults and failures.
Those robotic safety issues and others are addressed in the current U.S. robot safety standard, ANSI/RIA R15.06-1999. However, the guidelines were adopted in 1999, and don't cover innovations developed since then — designs that increase safety and worker productivity, and reduce total robot footprint by eliminating traditional technology based on hard mechanical safety stops and external sensors and controls.
The team of global experts drafting the new international standards includes Americans representing the U.S. Robotic Industries Association (RIA). Once the international standards are confirmed, the RIA is expected to update R15.06 to comply with the new ISO criteria.
Standards for latest features
By establishing guidelines to govern the safe use of four new innovations that we'll now describe, the ISO standard will broaden their use around the world.
- Cableless teach pendants
A teach pendant is a handheld robot control that facilitates programming robots for a specific task. Traditionally, a cable connected the robot controller to the pendant; now, new wireless technology eliminates the cable, reducing the risk of tripping or entanglement. Cableless technology permits the teacher to be in close proximity to the robot during the teaching function, and reduces installation costs.
To prevent confusion about which pendant controls a specific robot, the new ISO standard includes requirements for unique identification of cableless devices — so only one cableless pendant can be used per robot to prevent unintended operation of another robot that may result in a hazard to personnel.
- Human-robot collaboration
Traditional safety guards or other barriers cordon robots off from people to prevent injuries from fast-moving robots. Here, if an operator must interface with the robot (to load or unload parts in a machine's workspace, for example) traditional safety controls require help to confirm that the robot is in a safe state or position, which typically means safely limiting its motion, or bringing it to a full stop and removing its energy source.
New software-based safety systems can slow a robot to a safe speed or otherwise direct its motion to a safe position or state, allowing people to share its workspace with far less risk. These collaborative robots or cobots work hand-in-hand and side-by-side with people. For instance, with safe-speed core technology, a robot might lift and position a heavy sheet of metal while skilled human hands weld parts onto the larger piece.
In addition, the development of environmental-awareness sensors allows collaborative robots to “see” human coworkers, which triggers robots to go into safe positions or states, and wait in safe mode until the human moves out of range and an operator resets the motion.
- Robot-to-robot synchronization
The traditional robot configuration is simple: one arm, one controller, and one teach pendant held by a human teacher. In this scenario, robots lack the capability to easily coordinate sophisticated actions with other robots in jobs that require more than one arm.
The result: Even a simple task such as wringing a washcloth becomes complicated. One teacher first must teach his robot to perform an action, such as turning one end of the washcloth one way, and then stop. Next, the other teacher instructs her robot to turn the other washcloth end in the opposite direction, and then stop — and so on.
In contrast, new technology allows one teacher or maintenance person to employ a single controller and teach pendant to coordinate the actions of multiple robots, and significantly increase productivity by reducing commissioning times.
- Vision-based guard systems
New 3D safety-rated vision intrusion systems can keep robots and people separated without the costs and hazards involved of perimeter fencing.
These electronic (and programmable) perimeter-guarding systems include three video cameras mounted overhead in the work cell that detect when someone enters the hazard zone. The system then signals the intruder about the danger (visually or audibly) and robots in the space to slow down or stop. Once the hazard zone is clear, the robots are reset and operations safely resume.
For more information, call Rockwell Automation at (414) 382-2000 or visit rockwellautomation.com.
Integration enables work-zone protection
Increasingly capable and complex robotics require integrated safety data, and advanced automation systems manage and make sense of this data, providing workers with a systemic view of overall operations within the work cell. More specifically, safety-rated PLCs collect data from sensors about the status of a person versus a robot within the space, as well as inputs from e-stops, pendants, position sensors, and interlock switches. The PLC then helps command the robot power circuit, robot servos, and other servos in the cell, plus any motors, hydraulics, or pneumatic devices. Safety components that directly connect robots to a safety bus can provide more granular data reports via human-machine interfaces.
With automated safety diagnostics that already exist, users of robotic systems can easily obtain information about the specific component and circuit of the component causing a problem, rather than having to manually check each part of the safety system. This reduces troubleshooting and mean time to repair.
Ultimately, data provided by advanced automated safety systems contributes to continuous-improvement initiatives by measuring a robot system's faults and failures on a statistical and historical basis. For example, if managers know that a certain safety component historically fails more often than another, then the problem can be corrected to save future maintenance time and money.