As robots become more common in a growing number of industries, ensuring that they operate safely is becoming a greater concern. Standards bodies have responded by updating two leading safety standards and harmonizing them so global compliance is more straightforward.
The Robotic Industries Association estimates that some 230,000 robots are now at use in United States factories. That number is increasing at a record pace, with a total of 10,854 robots valued at $679.3 million sold by North American robotics companies
in the first six months of 2013, according to RIA.
Two revised standards form the basis for certifying the safety of robots in production facilities. ANSI/RIA R15.06-2012, developed by the American National Standards Institute and the Robotic Industries Association, has been updated for the first time since 1999.
This standard has also been harmonized with the International ISO 10218:2011 standard for robot manufacturers and integrators, which was also recentlyupdated. The ANSI/RIA 15.06 document addresses a range of safety concerns, beginning with definitions that are unambiguous.
“Control responsibility is a concept that’s difficult to quantify,” says Roberta Nelson Shea, chair of the ANSI RIA R15.06-2012 committee. “It’s now clearly defined, with four levels of reliability.”
Clarifications are not the only reason that the standard will be easier to implement. ANSI/RIA 15.06 and ISO 10218 have commonalities, not differences. That will help drive down compliance costs and make it easier for global companies to produce equipment that can be sold anywhere.
Shea notes that ISO 10218 has two sections: Part 1 for equipment manufacturers and Part 2 for integrators and installers. However, she cautions that it’s the end user who’s responsible for any accidents that occur.
“The user is ultimately responsible for the safety of industrial robot systems, including integration and installation,” she said in a Siemens-sponsored webinar.
That’s because any changes done by the operating company must meet safety requirements. For example, an existing cell that’s moved can remain compliant with the 1999 version of ANSI/RIA R15.06. But if any aspect of the layout or controls are changed, it’s considered a new system that must comply with ANSI/RIA R15.06-2012.
Over the past few years, risk assessment has been one of the big trends in safety. Not surprisingly, it’s a central factor for both documents. They leverage another standard, EN ISO 13849, which provides guidance for determining the level of risk for different subsystems on the robot. Product developers, integrators, installers and users must run through a list of risks and come up with solutions.
“A lot of the decisions on which way you should go with safety functionality are based on risk assessment,” says Scott Krumwiede, Business Development and Safety Manager for RWD Technologies, a Division of General Physics. “With risk assessment, you can set the robot’s performance level to the hazards and the safety circuitry.
Both ANSI RIA R15.06-2012 and ISO 10218 also address installations that have multiple robots. Robot cells have safety issues that go beyond the norm of injuring people. Operators must ensure that robots don’t collide with each other. The documents provide techniques for protecting people and equipment during programming and normal operations.
The standards set risk and safety levels, such as performance level (PL) and safety integrity level (SIL) concepts found in ISO 13849 and IEC 62061, respectively. Companies need to pick one of these levels and use it throughout their certification and validation process, Krumwiede noted.
When robots are operating, stopping them when problems arise is one of the important issues for safety. ISO 10218 addresses a number of emergency stop conditions and protective stop controls.
Emergency stop controls must be placed on every control station in an area where operators have unobstructed access. Protective stops can be handled by either manual or automatic means. Another important parameter is to make sure that the robot stops in a safe position.
“Energy isolation is required, you have to be able to shut off everything — electrical, hydraulic or pneumatic,” Krumwiede says. “You also want to stop in a safe mode, you don’t want a robot that’s carrying a heavy load to drop its payload when the power is stopped.”
The ISO standard also sets parameters for programming robots. Users can be in the work space during programming, when movement is restricted to 250 mm per second. When the operator is standing next to the device during programming, the robot may run only if the operator continually takes action, such as holding down a control button.
Shea notes that all ANSI and ISO standards are voluntary. But European machine directives specify the standards, so they’re effectively required by law for any product sold there. In the U.S., OSHA personnel are trained using ANSI and ISO standards, making the standards the basis of U.S. safety regulations.
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