Among the many justifications for using robotics, the most important is to shield people from working in dangerous environments and from handling hazardous materials. From dealing with chemicals that are explosive to handling radioactive substances, robots are routinely used to perform tasks that would kill or maim people.
Robots are ideal for use in hazardous environments by removing people from direct exposure to unfriendly conditions such as materials that are radioactive or highly explosive,’‘ says Isabelle Roberts, Vice President for Business Development at BRIC Engineered Systems, Oshawa, Ontario, Canada.
Haz Mat Robots
By design, munitions are explosive items that are dangerous to humans and consist of hazardous chemicals. When munitions are to be dismantled due to treaty obligations or obsolescence, robotics are the preferred means to take them apart into their constituent pieces. This task is a specialty of PAR Systems, Inc., Shoreview, Minnesota, a robot manufacturer and system integrator. Thomas Frantz, Environmental Products Group Program Manager at PAR speaks of how robotics are used for munition disassembly. ‘‘PAR is focused on handling munitions, such as leftover World War II nerve gas ordnance. The chemicals are decomposing and the materials are corroding,’‘ Frantz says. ‘‘Robots pick up the munitions and place them in various process stations.’‘ Due to the fact that these old munitions are corroding, they are even more dangerous than is typical.
Shielding people from hazardous chemicals and processes was also on the mind of Bruce Toyama, General Industry and Life Science Sales Manager at Applied Robotics, Inc., Glenville, New York. ‘‘One of the justifications for using robotics in handing chemicals and hazardous materials is reducing worker exposure. Companies want to reduce potential liability for workers’ compensation or other costs associated with worker exposure,’‘ says Toyama. ‘‘Liability is a big operating expense for chemical producers and chemical users. Limiting workers’ exposure is a very real and practical driver.’‘ Reducing liability by removing people from hazardous chemicals is a concept that companies can easily quantify to justify investing in robotics.
BRIC’s Isabelle Roberts compares work cells that handle hazardous materials with more mainstream industrial work cells. ‘‘In typical industrial applications, such as automotive, robots are used to do repetitive tasks to increase production. In these cases, robots deal with high volume and a low mix of products,’‘ Roberts says. ‘‘Unlike typical industrial applications, it is the people factor, not production levels, that drives the need for robots in hazardous material handling applications
Likewise, Dr. William D. Drotning, Project Leader of the Intelligent Systems and Robotics Center at Sandia National Laboratories, Albuquerque, New Mexico, says that robots go where people ought not to. ‘‘Robots are used for handling hazardous materials, to get people out of dangerous situations. These robots are in work cells that are remote or closed off from human access when handling radioactive or hazardous materials,’‘ Drotning says. ‘‘SCARA robots are used for handling biological hazards like viruses or other pathogens.’‘
Robots are also used in handling non-hazardous materials that could produce potentially explosive dust. This application is explained by Richard Motley, Manager of Material Handling at FANUC Robotics America, Inc., Rochester Hills, Michigan.
‘‘Robots operate in explosive dust environments such as bag palletizing of grain products,’‘ Motley says. He adds that the assembly of automotive airbags is hazardous due to the fact that inflator propellants are volatile and explosive. Robots are the perfect means to handle these hazardous chemicals.
Randy Schuetz, Motoman’s Technology Leader – Paint, Dispensing, SCARA & Life Science, offers another perspective. ‘‘Robots are not bothered by fumes that might be irritating or toxic to human workers, particularly under close or prolonged exposure. Examples include fumes created during two-part epoxy application or ultrasonic welding of some kinds of plastic parts. Explosion-proof robots are specially designed to work in hazardous areas where fumes and vapors could easily ignite if exposed to heat or sparks. For example, one Motoman customer uses a six-axis painting robot (rated for Factory Mutual Class 1 Division 1 hazardous environments) with a 10 kg (22.1-lb) payload for material handling of automotive steering wheel components in an area where flammable/explosive vapors are present,’‘ Schuetz said.
There is a role for robots to inspect structures or buildings that contain hazardous or radioactive materials. This task is performed by equipment provided by Engineering Services, Inc. (ESI) Toronto, Ontario, Canada. ESI’s President and Chief Executive Officer Dr. Andrew Goldenberg speaks of the role of inspection robots in nuclear facilities.
‘‘Robots handle nuclear material or perform operations in proximity to the nuclear material where everything is radioactive. Robots are also checking the structural integrity of the reactor or the building where the radioactive material is stored,’‘ Goldenberg says. ‘‘Periodic checks need to be done to ensure there are not faults in the structure.’‘
Goldenberg says other uses of robots include collecting samples for analysis of soils contaminated by hazardous chemicals or are radioactive.
Built to Last...Or Not
Because of the harsh environments that chemical handling robots operate in, there are special requirements that these work cells need to meet in order to function. Isabelle Roberts of BRIC explains the special needs of hazardous material handling work cells.
‘‘For highly critical tasks, a lot of redundancy is designed into the overall system. If something fails, other systems will compensate. This redundancy is more so than in other robotic applications,’‘ Roberts says. ‘‘A lot testing is required of the equipment to ensure it meets tighter specifications.’‘
Maintaining work cells that handle chemicals is crucial for integrators and operators. Cleaning the robot and its peripheral equipment after exposure to harsh chemicals or radioactivity is often difficult. Andrew Goldenberg of ESI says there are a several strategies users can follow to keep up production in harsh environments.
‘‘For lightly radioactive materials, operators can wash down equipment by use of special chemicals. Another option is that there will not be maintenance performed on the equipment,’‘ Goldenberg says. ‘‘In some cases, there is no way back if the robot is too highly contaminated so users dispose of the robot as it wears or becomes too contaminated.’‘
PAR’s Tom Frantz says system design is vital in order to meet the requirements demanded by the robot’s operating environment. ‘‘It is important to design the equipment for the environment, especially if it has any special requirements such as in nuclear applications where the equipment must be radiation tolerant,’‘ Frantz says. ‘‘If the environment is controlled with an inert gas, the equipment must be designed to work in that environment.’‘
Frantz went on to say, ‘‘The equipment needs to be decontaminated before people can perform maintenance on it. The equipment has to be designed for ease of maintenance.’‘
Frantz adds that there are two ways of maintaining robotic systems subjected to harsh chemicals: Remote maintenance and contact maintenance. ‘‘If the environment is such that end users cannot guarantee that the equipment can be decontaminated to a safe level, the equipment must be designed for remote maintenance,’‘ says Frantz. ‘‘This is done by remote control, through shielded windows where operators can see, or by using cameras to view what is taking place through monitors.’‘
Contact maintenance has a person actually working on the equipment, because it can be decontaminated to the point where it is safe. Contact maintenance has people shielded by bulky protective suits and gloves, which is the primary reason that the robot has to be designed for ease of maintenance.
Bruce Toyama of Applied Robotics also believes that design is important in facilitating maintenance of work cells that handle hazardous chemicals and materials. ‘‘Material in construction (of the cell) is important when it comes to maintenance. When constructing a hazardous material handling work cell, it is important to use materials that are less susceptible to corrosion,’‘ Toyama says. ‘‘Maintenance is a consideration on how integrators choose to set up the system. Disposable equipment is very expensive.’‘
Toyama goes further by saying that there is a need to sterilize equipment when handling biological pathogens, so the work cell’s constituent materials need to withstand the sterilizing process.
In order to decrease the amount of maintenance on hazardous material handling robots, it is wise to protect the robot from harsh elements that can infiltrate the equipment. Preventing the need for maintenance is addressed by William Drotning of Sandia. Drotning says that the means to make work cells explosion-proof are also ways of lowering the need for maintenance.
‘‘Often, the interior of the robot is pressurized with an inert gas like nitrogen so materials go out rather than having hazardous or flammable materials get inside. Reliability has to be built into the robot and the robot needs to have the ability to have its arm replaced,’‘ says Drotning. ‘‘Integrators have to plan for the fact that people might not get access to the robot if it breaks or it picks up so much dust and grit that its mechanical structures start failing. End-users have to plan for the robot being expendable or replaceable remotely.’‘
As the number of chemicals used in industry continues to increase along with the potential health and environmental risks associated with them, the demand for robots to handle these chemicals will increase. To successfully robotically handle these chemicals, improved and new technologies will need to be introduced to handle hazardous materials safely. This technology will include improved vision and other sensory equipment. Tom Frantz of PAR Systems, Inc. gives his take on what the future holds for chemical and hazardous material robotics.
‘‘I see more sensory perception added to robots, whether it is vision or tactile feedback. This will allow the robot to be more autonomous,’‘ Frantz says. ‘‘There will be more sensory perception as well as tactile feedback, to enable the robot to handle more delicate objects for pick and place applications.’‘
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