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Working hand-in-gripper

By Amanda Silliker
| www.cos-mag.com

Last July, a robot killed a contract worker in a Volkswagen plant in Germany. The 22-year-old was in the process of setting up the robot when it grabbed and crushed him against a metal plate. A spokesperson for the car manufacturer said human error was to blame, rather than a problem with the robot itself.

The incident made headlines worldwide and started a Twitter frenzy. It even prompted the Robotic Industries Association in Ann Arbor, Mich., to release a statement on robot safety, noting safety standards to keep workers safe and the requirement for manufacturers to incorporate a number of safety features in each robot.

“Robots seem to get a really bad rap when they’re probably some of the most reliable, proven technology out there,” says Ken McLaughlin, general manager of JMP Automation in London, Ont.

Fatalities involving industrial robots have occurred at an average rate of one per year over the past 15 years, according to the Occupational Safety and Health Administration in the United States.

As pointed out in a blog by Robotiq, an industrial robotic gripper manufacturer based in Saint-Nicolas, Que., you are more likely to be killed by a shark (five deaths yearly on a global scale) than a robot.

Still, employers in the automotive industry need to be aware of the risks robots pose and know how to keep workers safe, especially with more and more robots working side-by-side their human counterparts.

Robots are used in a variety of applications in the automotive industry, the most common being welding. The fastest growing applications for robot orders in North America in 2014 were arc welding (up 58 per cent) and spot welding (up 57 per cent), according to the Robotic Industries Association. Welding is used in car manufacturing for the assembly of a vehicle’s body, motor and gearbox.

“It’s fractions of a second that it’s making contact with the metal being welded. You might have one robot doing 20 to 30 welds on each application as it goes by,” says Jim Van Kessel, vice-chair of CSA Z434-14 Industrial robots and robot systems committee and owner of JVK Industrial Automation in Kitchener, Ont.

Robotic vision systems are common in car manufacturing to conduct quality checks. Robots are also used for painting and coating, installing windshields and stamping and cutting out parts from sheet metal.

At the Honda car manufacturing plant in Alliston, Ont., — which makes the Civic and CR-V — robots are used for a wide range of applications, including spot and mig welding, painting, applying sealer and material handling, says Dave Smith, equipment and construction safety specialist at Honda of Canada Manufacturing and chair of the ISO/TC299 – Robots and robotic devices committee.

A robot is the most dangerous when it is first introduced on the shop floor because safety fences haven’t been put in place yet, says Van Kessel.

“The robot gets put on the floor, the first thing (the workers) want to do is get power to it, get it moving, so they can start the whole process up. They want it wide open so everybody can get involved and that’s when high risks start to develop,” he says. “There are too many people involved and the safeguards aren’t in place yet.”

Once the robot is erected, contact, struck by or caught between are the risk factors in a robotic cell, says Van Kessel. Typically, maintenance workers are the ones who are going to be injured.

“They need power to do things, to troubleshoot what’s going wrong,” he says. “And it could be cleanup staff that are going into the robot and not following proper lockout and control and energy control; they are getting struck by the robot.”

Sometimes other workers need to enter the cell for teaching, programming or program verification, so they put the robot in manual reduced speed mode. Engineers at Honda use a teaching pendant to manually program the robots, which has a three-position enabling switch. In the case of an emergency, if the worker grips the teaching pendant fully or releases it, the robot stops.

Another safety measure Honda employs is a key system. If a worker has to go into a cell and a full energy lockout is not suitable, he needs to take a key with him. If there are not enough keys — which ensure the drive power to the robot can’t go back on — then other people can’t go in, says Smith.

“We back that up with administrative controls, so we are very tight. If you go into a cell and you don’t take your key, there are consequences for that,” he says.

All of its robotic cells meet the CSA Z434 standard and they are barricaded with safety fencing that is six feet high.

“At operator loading stations, we have light curtains, laser scanners and safety mats to ensure people can’t get into the cell without triggering it to stop,” says Smith.

As per the CSA standard, every robot is required to have a protective stop function and an emergency stop function. 

At Honda, a robot operator will spend several weeks at the robot manufacturer’s site to learn how to operate the robot, the controllers and teaching pendants.

“They’re learning how to program the robots, how to recover the robot if there’s any kind of abnormality and basically they go through the paces and they have mock production applications that they have them teach the robot,” says Smith.

Followup training is put in place at Honda whenever there is a change in the robot’s technology or design.

Certain robots require more education and training for workers than others. For example, one of Honda’s newest robots, which has a 900 kilogram capacity, lifts up the welded body of a CR-V and transfers it to another line. If a worker has to enter the cell to teach the robot, it could be dangerous.

“Just because of the sheer size of them and the potential hazard, we definitely go over that with our teachers because we have to identify safe areas in the cell for them to teach in the event something happens, where the body fell or anything else, so they’re always out of the line of fire,” says Smith.

The CSA standard comes with an annex that includes a laundry list of all training required when there are robots in the workplace. Some examples include:

general workplace safety procedures

capabilities of safeguarding devices

response to abnormal/unexpected events

hazards encountered during teaching

hazards related to each task

emergency procedures

hazards involved in maintenance procedures on live robots.

Collaborative robots 

Sometimes workers need to interact with the robots to get the job done.

There are four types of collaborative robots:

 

Safety-rated monitored stop: This robot is powered up but stops when a human is in the collaborative work space. The robot can resume automatic operation when the human leaves.

“Sometimes you will have a situation where the robot does 90 per cent of the work on its own behind fencing… and then it comes over to an area and presents whatever it’s got in its gripper to an operator and it stops and is held — kind of like when you tell a German Sheppard don’t move for this dog biscuit — it’s held but in a safe way that’s approved by applicable standards,” says McLaughlin.

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Speed and separation monitoring: This robot needs to be programmed to maintain a determined speed and separation distance from the operator. For example, as the worker comes closer to the robot, it slows down and as the worker moves away, it speeds up again. 

Hand guiding: This occurs when the operator is using a device to physically move the robot for the collaborative portion of the task. For example, a hand-guiding collaborative operation can be used for installing automotive seats with a high-payload robot.

Power and force limiting robots: This type of robot has limits on the amount of power and force being exerted and can work alongside an operator.

Power and force limiting is the type of collaborative robot that is growing in popularity and is similar to the mental image most people have of a robot — small, lightweight and more human-like. The new ISO/TS 15066 Robots and robotic devices – Collaborative robots document is due out any day now and is expected to outline weight, force and other specifications for these types of robots.

They are mainly used for “pick and place” applications, so bringing parts from one area to another or feeding a machine, says Jean-Philippe Jobin, chief technical officer at Robotiq.

“It is possible to have workers working alongside the robots. Either the robot and the human are working on the same task or they are each doing their own task, but they are alongside without any fences,” he says.

At the BMW manufacturing plant in Spartanburg, S.C., employees work side-by-side lightweight robots that apply sealant to car doors. When the robots were first introduced, the workers “breathed a sigh of relief,” says BMW.

“To install the door sealing cover, the associate placed the cover to the door and then used a tool to apply force in order to create a tight seal. Needless to say, this put strain on the wrist and hand of the associates. So, when the innovative robot took on the task, workers were happy to leave it to the machine,” the company says on its website.

BMW is looking at introducing collaborative robots for installing windscreens, lifting heavy body parts and applying adhesives.

There are many safety concerns with these types of robots, however, such as contact between the robot and humans, says Jobin.

“Depending on the shape of the robot, if it has sharp edges, for certain force, the injury would be higher,” he says. “From the manufacturer-of-robot side, it’s important for them to develop and put on the market robots that have round edges, instead of sharp edges, to minimize injuries.”

Some of these robots have padding in key areas and reduced pinch-points. Other are equipped with skin-sensing technology that detects a collision and limits the contact force to the human. If contact is detected, the robot’s movements are stopped and its cushioning elements absorb shocks and collisions to prevent a “hard” impact to the worker.

Entrapment is also a big concern. For example, the robot could trap the worker between itself and a wall. Fortunately, most of the collaborative robots are lightweight enough that they can easily be pushed away, says Jobin.

The parts the robot handles can be dangerous as well.

“If you are manipulating soft objects, there’s probably no injury that can happen there, but lets say you are manipulating plates, the risk will be completely different,” says Jobin.

It’s important for workers to feel comfortable working day in and day out next to these types of collaborative robots. Comprehensive training is one way to achieve this.

“The people need to understand what they can do and what they cannot do and for them to understand it is safe for them to have a robot alongside them, so they don’t have fear,” says Jobin. “It’s not just physical injury but in certain circumstances, if they are afraid of the robot, it’s a health problem.”

Baxter by Rethink Robotics is probably the most famous power and force limiting robot on the market. It is used in the automotive industry in parts manufacturing. It can be adjusted to stand as tall as human colleagues and it weighs about the same. It has a screen with big eyes that allow Baxter to communicate his “emotions,” including concentrating, sleeping and sad. The entire screen lights up orange for the “surprised” expression to indicate Baxter had unexpectedly detected someone in his space. The screen also allows motion, so if Baxter understands a task, he nods his head.

Advantages

No matter the type of robot, they all offer many advantages for employees.

“There are a lot of dangerous, dirty, unpleasant, uncomfortable jobs that people do in a factory and that’s where you don’t want people doing that. If we can get people out of those and put a robot in, you have taken people out of harms’ way,” says McLaughlin.

And getting rid of ergonomically unfriendly tasks is a big advantage from a health and safety perspective.

“Picture a robot as being motors and gears. They are programed to do an instruction over, over and over. It’s an endless procedure of repetition. If you picture a worker doing those tasks, their motors and gears become their joints and their tendons, ligaments, everything takes a beating,” says Van Kessel. “By getting a robot to do it, we should definitely see an improvement from an ergonomic standpoint.” 

When Smith first started at Honda in 1988, they would do spot welding for a lot of the car by hand, so he was happy when robots took that job away.

“After you use a welding gun the entire day, your hands are very sore and my fingers would be almost locked shut,” he says.

Businesses like robots because they can work 24-7 without a break and perform the same mundane tasks over and over again; they are quicker and more efficient than humans; they can withstand exposure to chemicals in the air and physical contact with parts and structures; they are extremely precise and accurate; they have greater physical capacity than humans; and they don’t get fatigued.

The downside of course from a worker’s perspective is the more robots and automation take over, the more low-skilled jobs get eliminated.

Risk assessment

Before implementing any robots in the workplace, a risk assessment needs to be completed. The newest edition of CSA Z434 focuses heavily on this requirement, unlike the previous itineration.

“The risk assessment needs to be done always and it must be done with all stages of the product in mind, from the installation to operation to maintenance and also to remove when its life is done,” says Jobin. “All those aspects need to be taken into account and those are completely different.”

According to the standard, a risk assessment shall be carried out on those hazards identified in the hazard identification. This risk assessment shall give particular consideration to:

the intended operations of the robot

unexpected startup

access by personnel from all directions

reasonably foreseeable misuse of the robot

• the effect of failure in the control system

• the hazards associated with the specific robot application.

The risk assessment may reveal some applications are just not suitable for robots. For example, a power and force limiting robot working with razor blades may not be a good idea, says Van Kessel.

“The robot could be swinging around, I’m distracted by co-workers or by something else that’s going on and I’m not paying attention, the robot comes along with the blade and I lose a finger or get a severe laceration.”

Honda is in the process of conducting risk assessments for introducing power and force limiting robots for lightweight applications that would replace poor ergonomic processes, says Smith. It has an internal robot safety committee and it also engages employees in the process.

“We always get the voice of the floor. We’re going to go out to our associates and we are going to ask them, as we introduce these robots, we’re going to show them what they are and talk to them about applications they think they would be suitable for,” he says.

New technologies and capabilities for industrial robots are emerging all around the world. At the University of British Columbia’s Collaborative Advanced Robotics and Intelligent Systems Laboratory, researchers recently completed the design for a robot that can execute unscripted handovers to humans. Funded in part by GM, one application for the robot is helping a worker build a car door. If the robot brings the worker a part that is damaged or unsuitable, the worker discards it and the robot automatically fetches a replacement part.

And cognitive computing — or artificial intelligence — is coming down the pipeline, which allows a robot to think more like a human and respond to the environment by itself, without pre-programming. Cognitive computing systems can sense, learn, infer and interact.

“Usually the human will teach the machine to do something, but we will need a way for the robot to tell the worker what is good, what is not, what’s the status,” says Jobin. “Will it be lights, more screens, will it be sound or voice or something else, I don’t know, but I think this could help safely introduce more robots.”

Photo: KUKA Robotics Canada

This article originally appeared in the February/March 2016 issue of COS.











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