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'Safe' & Cooperative Robots


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Historically, there has been a separation between worker and robot in industrial settings. This is predicated on safety regulations. And with some good reason. If you check the OSHA STD 01-12-002, for example, you’ll read of industrial accidents including a worker being whacked by a robot (“robot’s arm functioned erratically”) during programming and a worker being pinned to a pole by a robot. Of course, one could undoubtedly find similarly problematic situations with stamping presses, machining centers, and other industrial equipment.

KUKA Safe Robot

One of the things that has occurred of late is that there is improvement in control technology, improvements that do have the potential to make working with robots significantly safer. When asked about new trends in robotic technology, Kevin Kozuszek, KUKA Robotics’ director of marketing cites two things, one of which is a change in the “robot-human interface—safe operating techniques.” In the parlance of the company they’re calling the technical development “KUKA Safe Robot,” which includes among its constituent components “KUKA Safe Operation” and “KUKA Safe Handling.” The former is said to eliminate the need for mechanical axis range monitoring systems, as it monitors the velocity and acceleration of the robot axis and enables a “safe operational stop” of the robot. The “KUKA Safe Handling” is said to allow the worker to work more closely with the robot.

Before proceeding, note well that Kozuszek says that “Safe Robots are being installed in Europe and South America.” Don’t think that if you have a KUKA robot on the floor of your U.S. facility you can simply figure that it is safe, so . . .

Safe Robot Technology

The “Safe Robot” technology uses the robot controller for safety-relevant control tasks rather than an external PLC. What this does is allow the wiring of safety devices—light curtains, scanners, mats, etc.—directly into the robot controller which is said to have the effect of allowing quicker response in the event that a safeguard has been tripped. KUKA claims that this is faster than a centralized safety system. Because of the speed, the robot’s movement can be braked more quickly than would otherwise be the case. So, if the braking can be made faster then, apparently, the safeguards can be positioned more closely to the robot than would otherwise be the case, which then means that the human worker can work more closely with the robot than would otherwise be possible. (There is a dual-channel monitoring system with built-in redundancy and cyclical testing of the brakes—which tests each axis to assure that all are functioning correctly at all times—and robot mastering—to make sure that the motion of the robot in space is correlated with reference positions so that it is known where the robot’s six axes are in space—are deployed to assure that the system is functioning correctly.)

Working Alongside Robots

So why would anyone want a person closer to a robot than has historically been the case? Kozuszek suggests that what this does is allow the superior sensing abilities of a human to come into play. He provides several examples. One is buffing or grinding of a surface. If a person is able to observe the operation, he can provide the feedback necessary to control the robot (e.g., see if the job is done or if additional processing is required). Another is assembly operations, where, for example, the strength of the robot, combined with the sight of a person (which takes less time to train than, say, a machine vision system) could allow the robotic performance of tasks that have been heretofore been considered to be too complex for automation.

Cooperative Robotic Technology

Working Together. The other trend that he sees? “Cooperative robotic technology. Multiple robots working on the same product.” In other words, it could be that one robot picks up a part or an assembly and surrounding robots then perform tasks on the part. One of the benefits of using this approach, Kozuszek says, is that there can actually be fewer robots deployed than would be the case in, say, an assembly line setup. That also leads to a reduction in floor space requirements. This approach is being used in some DaimlerChrysler’s Mercedes production operations in Germany, where it is said to reduce production space requirements by up to 20% and manufacturing system investment by 5%. In the DaimlerChrysler deployment, as many as 15 KUKA robots are used in what are called “RoboTeams” for machining or assembly operations. Each of the robots has its own controller and then is connected to the others via Ethernet. One of the robots is the lead and the others follow; this helps facilitate the programming effort.