Engineers refine safety standards as collaborative robots enter the warehouse
Now that robots are becoming a common sight in many warehouses, logistics companies face a new challenge—how to design their robots and train their employees to work together in safe, productive teams? That issue was a central topic last week at the RIA’s International Collaborative Robots Workshop, held in Boston May 3 and 4.
The traditional standard for ensuring safe relations in mixed human/robot workplaces has been to encase the robots in cages, isolating them to guarantee they would not crush a human worker’s hand or roll over his foot. A slightly more flexible approach set safety distances, so that robots run slower—or even stop—as humans cross light curtains and cross into pre-determined danger zones.
However, those approaches become unwieldy as robots increasingly move around the warehouse, shuttling merchandise from point to point. So the latest strategies involve power and force limiting, Roberta Nelson Shea, global marketing manager for safety components at Rockwell Automation, said in a session at the conference.
Engineers are drafting design standards through the International Organization for Standardization (ISO) that will govern how quickly robots can move when sensors show they are near various points of the human body. For example, a moving part might slow slightly when it is near a worker’s leg, but move nearly to a stop if it s near a human’s face or neck.
These safety steps can allow warehouses to achieve better productivity by using collaborative robots—known as “Cobots”—to work alongside humans. Depending on their proximity, designers can also adjust the robot’s payload limit, speed, reach, arm stiffness, and force sensors, said Corey Ryan, manager of medical robotics at Kuka Robotics Corp.
For example, one of Kuka’s robots that works on the dishwasher assembly line at a Maytag plant features a safety feature that will automatically stop the robot in the midst of any task when a person touches the robotic arm. When the employee touches the arm again, the robot resumes its work.
Additional ISO standards require robot manufacturers to install redundant software and sensors to ensure they stay within those parameters, Ryan said.
As robots emerge from their cages and begin to collaborate with human colleagues, designers can use a variety of standards to deliver the ideal level of collaboration, said Nicolas de Keijser, of ABB Robotics. This can range from:
- no collaboration (with the robot secured behind a safety fence),
- fenceless operation (allowing robots to move without physical safety structures separating them from workers),
- sporadic interaction (where human occasionally reload a machine, or feed materials in and out of the workflow)
- open co-working (where the robot constantly interacts with human employees).
Whether robots are serving to assemble devices, test products, deliver tools, move pallets, or swap parcels with a conveyor, these mechanical colleagues are here to stay. Collaboration between human employees and their robotic collaborators could be the beginning of a beautiful friendship.