In 1987, Ronald Reagan challenged Mikhail Gorbachev to “tear down this wall.” The Berlin Wall had been constructed in 1961 to prevent massive emigration from East Germany, and it eventually came down in 1990. Those of us who watched those events unfolding remember the rejoicing, if not always the struggles Germany faced with reunification. The robotics industry is going through a similar moment with the introduction of collaborative robots.
Companies are searching for technological freedom from traditional safeguards, but parts of the industry may be reluctant to give up standards that have taken many years to develop, often in reaction to fatal accidents on factory floors.
The goal is to safely bring down barriers between workers and robots for greater efficiency and productivity. One of the first things to consider is the design. Robots intended to work alongside humans have unique features, such as manipulators with seven degrees of freedom, low-inertia servo motors, and elastic actuators. Such devices are designated as collaborative robots or cobots. They may also be referred to as power- and force-limited robots.
Regardless of what a robot is called, verify that it was designed to be used in collaborative operation, i.e., without a safety cage. After checking the functionality of the cobot, evaluate the system’s entire process.
A collaborative robot on its own may be considered “inherently safe by design.” But even an “inherently safe by design” vehicle has the potential to be deadly when it is misused in situations such as drunk or reckless driving.
While unloading parts from a mold-injection machine may be a suitable job for a cobot, does its design allow a worker access to a hazard? If so, hard guarding may not be necessary, but the robot may require some other safeguards.
If an automated process involves sharp parts or a device capable of causing injury, such as a hot glue gun, perhaps the use of a co-working robot should be reconsidered if those hazards cannot be contained.
A collaborative robot’s location could present a hazard if pinch points exist between columns, walls, or other machines that could lead to crushing.
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Altering the way a controller door opens could help avoid entrapment by changing how the door is hinged or changing it from a rigid to a collapsible type.
If a co-robot will be transported among different workstations, unique hazards could exit at each location. At the same time, some of those risks can be reduced with thoughtful design application for how surrounding machines will be accessed or even how operators will approach workspaces.
Don’t forget to secure endpoints
Users of industrial automation should consider new ideas for tooling and fixtures to reduce the risk of injury. Most collaborative robot designs have rounded edges, reduced openings, enclosed cabling, and wider surface areas. These concepts are also applicable to tooling and fixture designs, since the operators will now be exposed to these devices more frequently.
Simple things like putting a protective cover over sharp edges when it is difficult to design it out could effectively reduce the exposure risk. Increasing surface areas where the operator has a greater chance of exposure can spread out the energy if contact occurs. The location of fixtures and tooling could be angled or located so the hazardous sections are away from the operator.
There are many examples of cobots reducing their speed when an operator approaches or enters the collaborative or shared workspace. This involves controlling power and limiting collaborative robot operations.
One thing to evaluate is where the operator would get hit by the robot if contact is made. Look beyond just normal operation, and predict operator motion if something out of the ordinary occurs. For instance, will a person need to bend down if he or she drops a part, or are noises in the surroundings that could cause an operator to suddenly react?
And what happens if the operator had a long day and loses focus on the task? If a worker can be hit in the head or neck, how can the layout or height be changed to reduce the risk for of contact with such critical areas?
In speed and separating or monitored stop applications, the robot ceases motion when the operator is in close proximity to the robot or enters the workspace. Consider how the collaborative robot detects where operators are located. In many cases, this still requires a calculation of safe distances. The system may require presence sensors and devices such as safety mats.
ISO spec marks turning point
The International Organization for Standardization released ISO/TS 15066 in early 2016 with additional guidelines. This technical specification was developed by industry experts and users after many intense discussions.
The difficulty with something new is predicting all of the scenarios where the technology will be used and how operators will respond.
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For instance, back in the days of the first Model T cars, motorists would come to intersections and not know what to do, leading to collisions. New guidelines were then developed.
As you embrace the changes around cobots, we can help you understand and track them. Also, it’s important to share your experiences and ideas, as they may help improve worker safety.
Wouldn’t it be great if in 25 years we could look back and remember the introduction of collaborative robots as a joyful event?
To learn more about collaborative robots, download our series of whitepapers on “Getting to Know Collaborative Robots” here.
