by James L. Nash
There's no such thing as a virtual package - someone's got to deliver it," says Dan McMackin, a spokesperson and former safety supervisor for Atlanta-based United Parcel Service (UPS).
Even in the 21st century, hundreds of thousands of U.S. workers in many industry sectors are injured each year because of overexertion in such old-fashioned activities as lifting, pulling, pushing or carrying objects.
These basic human actions in a variety of material handling operations are the leading causes of back and shoulder injuries that continue to plague many employers and workers, according to ergonomics consultant and former OSHA official Gary Orr.
But there is good news: Recent statistics suggest incidence rates are declining for these types of injuries (see Figure 1 and Figure 2). In addition, new computer-driven machines hold the promise of resolving a number of material handling issues.
What Is an IAD?
Intelligent assist device (IAD) is the name given to a new technology that is attracting the attention of automobile manufacturers and other companies that want to reduce injuries and improve productivity in their assembly and material handling operations.
The American National Standards Institute (ANSI) has established a committee, T-15, that published a draft safety standard for the new devices, according to Jeff Fryman, the T-15 secretary. He is director of standards development for the Robotic Industries Association, a trade association that includes IAD manufacturers (see "ANSI: New Technology Spawns Unusual Process" on page 38).
The committee defines an IAD as "a single- or multiple-axis device that employs a hybrid, programmable, computer-human control system to provide human strength amplification, guiding surfaces or both."
The devices can be programmed to sense the weight of the load that needs to be lifted, so the operator needs only to apply a nominal push - usually just 5 pounds of pressure - up, down or sideways. The more sophisticated IADs also can sense where the object is in space so it can be placed precisely and automatically wherever it needs to go on a moving conveyor.
The technology is intended for material handling and assembly operations that require a human presence, but where reducing the weight and inertia of the object can increase safety and productivity. The devices fit between manual and completely automated operations, offering the advantages of reduced cost and greater flexibility than total automation.
"Intelligent assist devices are going to revolutionize lift assists," predicted Paul Adams, manager of safety engineering and ergonomics at EnSafe Inc., a consulting company with headquarters in Memphis, Tenn. "As the cost of IADs comes down, they will replace traditional lift assists, and that will happen soon."
Consultant Thomas Sawyer, a certified industrial ergonomist at ACE USE Risk Control Services in Doylestown, Pa., agreed. Sawyer believes IADs are one of the most promising innovations he has seen for reducing musculoskeletal disorders in material handling and assembly operations.
According to Adams, the principal advantages of IADs are:
- Productivity. The new devices are much faster than traditional overhead lift assists, as IADs allow the worker to handle objects more quickly with less force and a shorter learning curve, improving productivity.
- Worker acceptance. Because they are easier and faster to use, IADs may win better worker acceptance than traditional hoists, which often collect dust due to worker complaints that they are too slow.
- Safety. Ergonomic injury hazards can be reduced by cutting the force required to move objects.
- Quality. IADs can improve quality because they allow workers to move objects more accurately.
The primary drawback of the new technology, according to Adams and others, is its price. IADs cost approximately $5,000 per axis. The most common type of IAD functions on the "z" axis, or up and down, but manufacturers also sell devices that move objects laterally, on the "x" and "y" axes. Another barrier to IAD acceptance is that they are more demanding to maintain and program than traditional lifting technology.
McMackin of UPS pointed to a third disadvantage: "IADs cannot handle the many different sizes and weights of packages we put in our trucks." UPS emphasizes training and employs other forms of automation where possible (see "UPS: Delivering Safety").
The Problem with Joysticks
The original research money that led to the development of IADs came from Ford Motor Co. and General Motors (GM), according to Nidamaluri Nagesh, advanced manufacturing engineer at GM and co-chair of the ANSI IAD committee. In 1995, the two companies awarded challenge grants to Northwestern University in Chicago and the University of California at Berkeley to develop power assists for moving heavy objects.
Nagesh said the impetus for the research stemmed from the auto industry's dissatisfaction with pneumatic assist tools and electric hoists. "Many times, we waste time and money because these devices are not user-friendly," he commented.
The traditional devices are often so rigid that they constrain operators, slowing them down. "Second, it's hard to control air," Nagesh said. "You get very jerky behavior even with electronic air devices."
To illustrate a third problem with pneumatic devices, Nagesh reached for an automobile analogy. "It's like bad power steering: If it's too powerful, you have no 'force feedback.' This happens with button-press air devices."
Other experts confirmed the importance of force feedback. "There's a massive movement toward replacing hydraulic or mechanical controls with an electronic control," observed Steve Casey, president of Ergonomic Systems Design, a consulting firm in Santa Barbara, Calif. "From an ergonomic point of view, it has a major impact on what we do."
Instead of dozens of moving parts, workers now have a single joystick with a few wires. The joystick could be on a forklift or any number of warehouse machines. The challenge is "how to build in the feedback that is found in a mechanical control," said Casey, who added that doing this is now a big part of his job.
IADs solve the force feedback problem because they are generally programmed to provide approximately 5 pounds of resistance.
Another reason GM became interested in a new approach to material handling tools is the company is using more pre-assembled modules in its manufacturing processes. As a result, some of the parts can be large and weigh 100 pounds or more.
GM has completed test runs of the devices and plans to begin installing IADs this month. "In the test runs we did, IADs were very well-received by workers," Nagesh said.
Thomas Zens, manager of packaging, engineering and design at Miller Brewing Co. in Milwaukee, said his company has been considering IADs. "The devices can offset the inertia required to start and stop the load, and that means less fatigue in operators, more productivity and improved cycle time."
Miller Brewing confronts a number of material handling issues, such as palletizing full and half kegs of beer and feeding packing materials that weigh up to 40 pounds into machines that turn them into boxes.
Zens confirmed that worker resistance to traditional lifting or manipulating devices is one big problem with them and one reason the company is pursuing IADs. "We've found that if the worker can do the job quicker and faster without the manipulator, generally speaking they won't use it," he said.
Zens is not yet convinced that IADs can overcome this hurdle. "The thought, which is not yet proven for us, is that workers will use IADs," he said. "We're looking at doing some testing along those lines."
Training and Other Approaches
Important as innovative tools like IADs are, they are only the final step used by companies with sophisticated programs for addressing material handling issues.
"We have a clear mandate to achieve a 50 percent reduction in ergonomic stressors in the beginning of any new car program," Nagesh said. As a result, GM starts farther upstream by incorporating ergonomic safety concerns into the design of its components. Second, the assembly process is set up to minimize musculoskeletal disorders as well as other safety or health concerns. The use of tools represents a third set of controls.
GM has the market clout to pressure its suppliers to comply with its safety concerns and the resources to spend on designing safety into its components. In addition, market forces periodically require automobile manufacturers to produce completely new cars, so compared to other employers, it may be easier for auto companies to take a fresh look at their components and processes.
A final line of defense used by companies with material handling issues to prevent ergonomic injuries is training. Training is generally centered on convincing workers to use existing tools and lifting devices while avoiding unsafe postures and work practices. "We have a very aggressive training program," Zens said. "The problem is getting workers to relate to it. It really comes down to whether the individual worker realizes, 'This has a benefit for me.'''
Zens likened the issue to the use of seat belts. "Ten or 15 years ago, people didn't perceive the value of using seat belts." Originally, seat belts weren't available in many cars. Over time, auto companies were compelled to provide them, although people didn't always use them. Now, many states have laws requiring motorists to wear seat belts.
"That's where ergonomics is going, in my opinion," said Zens, although he was not speaking about a governmental regulation. "Right now, ergonomics is still too new a concept, but we require hard hats and safety glasses in many plants. Once we get agreement with workers and the unions, our company may make the use of ergonomic controls mandatory too."
Sidebar: UPS: Delivering Safety
UPS has had plenty of experience with material handling issues. Last year, UPS delivered 3.4 billion packages and documents. That works out to 13.6 million parcels every day, posing some intense safety challenges to the company's 370,000 employees.
The company believes that training is the key element in keeping people safe, but a UPS spokesperson conceded that making training effective has not always been easy. "We've learned a lot over the past 20 years," said Dan McMackin, a spokesperson and former safety supervisor and truck driver for the company. "We used to have safety committees that were management-driven - and not that effective," he said. "It was management telling people to be safe in big, bold letters."
In 1995, UPS established its Comprehensive Health and Safety Process committees (CHSP), made up primarily of hourly employees, with one management co-chair on every committee. There are now more than 2,400 CHSP committees that conduct safety audits and incident investigations, recommend work process changes, conduct safety compliance training, perform safety analyses and develop action plans to prevent injuries.
"Their job is to find out why injuries are occurring and then solve the problem," McMackin said. "They come to management and make their case, and we listen."
To ensure consistency, UPS uses a train-the-trainer approach that begins with frontline managers and supervisors who teach hourly employees the specifics of each course.
A few facts suggest the level of management support and the effectiveness of safety training at UPS:
- UPS employees receive nearly 1.3 million hours of safety training annually, including HABITS (health, body mechanics, inspect, tools, and equipment and safety compliance).
- The company spends $38 million per year on safety training.
- Lost workday injury and illness frequency declined 45 percent between December 1996 and June 2001. The vast majority of injuries at UPS are bumps, bruises, strains and sprains, according to McMackin.
UPS does not rely solely on training to improve safety. Packages still must be delivered by a person, but the company has applied technology in its large trailer trucks and hub facilities that reduce human effort and fatigue. For example, powered conveyor belts extending the length of most trailers have adjustable heights to enable the transfer of packages laterally. This reduces walking and carrying, while keeping the packages in the "power zone" between the shoulders and knuckles.
Power lifts are reducing the need to lift packages weighing more than 70 pounds, while slides and chutes move packages without handling.
At hub facilities where packages are sorted and routed, automated sorting equipment eliminates manual handling by reading labels and directing packages to the appropriate conveyor belt.
Sidebar: ANSI: New Technology Spawns Unusual Process
"I think IADs are an exciting new technology," said Jeff Fryman, secretary of ANSI committee T-15, which is preparing a safety standard for the new devices. "The biggest payoff will be in the prevention of ergonomic injuries."
Appropriately enough, ANSI has adopted an unusual approach in developing a standard for the innovative devices. This safety standard is being developed concurrently with the refinement of the technology. A draft standard was issued earlier this year, and after March 14, 2003, when the trial period ends, comments will be reviewed and the final standard released.
"Normally, the standard comes out after the technology, when the horse is out of the barn door," Fryman said.
Why is the process different for IADs? "I think it has to do with the principal companies, Ford and GM, their corporate safety philosophies and the heavy influence of the United Auto Workers," Fryman said. Just as the Food and Drug Administration tests drugs before releasing them to the marketplace, Fryman thinks that unions will try to require that new technologies have safety standards before being widely adopted by industry.
IADs have three modes of operation. The operator can move the object with:
- Hands on the IAD controls;
- Hands on the payload; or
- Hands off the controls, which means the device returns to its home station automatically.
The third mode is not being used because of safety issues, but the ANSI committee is anticipating it in the standard.
Primary safety concerns posed by IADs are safeguarding workers from moving machinery, according to Fryman. The faster the device moves and the greater the force it exerts, the greater the potential hazard.
For auto companies, Fryman explained, the real beauty of IADs is that they know where they are in space.
"In the auto industry, 18 percent of the cars they produce must go back for paint touchup because the surface gets nicked during assembly," he said. "These devices can funnel a part right into place without touching the paint job, cutting down on the cars that need to be repainted. That pays for these devices real quick."