The advantage is that, without a fence, workers are able to bring a part one at a time over to the robot and, in essence, hand it off. Without stopping the robot, when the worker enters the zone, a safety zone is created that instructs the robot to continue to work in a restricted area but not move into that zone. The worker can put down a part, pick up another part, and then walk away. And as soon as the person leaves the area, that zone is automatically enabled, so the robot can pick up the part and continue with the manufacturing process. The result is that this safety technology is helping the workers become much more tightly integrated with the robots.
Different robot manufacturers have developed their own safety technology including products such as ABB's SafeMove and Kuka Robotics' Safe Operation software. This technology allows applications to define programmable safety zones that the robot will be programmed not to enter, but applications also need to have a reliable safety system to enable and disable those zones. Possible solutions include a safety mat, area scanner, or light curtain. Many users are implementing a door switch, which is used to unlock a door, and serves as a key, which the workers take into the area. Once the person has completed their tasks, they come out, shut the door, and place the key to enable the safety zone.
With smaller robots, the system is simpler because there isn't a need for the individual safety systems. Applications might use a switch to protect a specific area for workers, and the system might use a light curtain to tell the robot when the worker is out of the area.
For automatic dispensing or clip insertion, for example, it is easier when the robot is working along with factory personnel to use a safety mat, so the robot can work close by but not move too close to workers. When the person steps off the safety mat, the robot knows the worker is gone and can immediately begin working on the same part the worker finished in that area.
The goal is for the robot never to stop. Before, the entire cell would be powered down before the fence would be opened. Workers would move into the area and do whatever tasks needed to be put in place, go out and shut the door, walk to the panel, and restart the system. Because it took so much time for all of those steps, the efficiency of the robot went down. Now, everything is instantaneous.
For pick-and-place systems such as placing products into a shipping carton, for example, new robotic systems using the programmable safety zones enables tighter integration of robotic operations into the production line.
Without the use of programmable safety zone technology, users are less likely to integrate robots directly with other production systems because of the safety guidelines. The problem is that when a door is opened to a robotic system down the line, there has been a requirement in the past to shut down the whole line. This technology, and new software, is allowing zones to be set up which prevent the robot from moving into the area where the worker opened up a door.
With a pick-and-place line, previously systems typically used hard automation because the line could continue to operate as workers moved into other areas of the machine. Now, standard, off-the-shelf robots can be integrated into the line and configured so that if there is a need to service one piece of the machine, all of the robots on the line continue to work but they intelligently know not to move into specific safety zones.