Fighting Musculoskeletal Disorders by Building a Better Mouse
Nearly two million Americans develop work-related musculoskeletal injuries
each year, according to the Occupational Safety and Health Administration
(OSHA), which held public hearings on proposed ergonomics standards in
the workplace last week in Chicago. The agency said the new, sweeping
rules should help reduce the injuries. An HSPH researcher adds that an
emerging field called "haptic technology" could help in that
reduction, and he puts his money where his mouse is.
Jack Dennerlein, assistant professor of ergonomics and safety in the Department of Environmental Health, directs the Harvard Occupational Biomechanics Laboratory. He studies the way people interact with their work environments. Last year, he evaluated a new kind of mouse that was developed by California-based Immersion Corporation and marketed last fall.
The mouse employs haptic technology, or virtual touch. A growing rage in computer circles, haptic technology builds the illusion of tactile dimension into virtual worlds. In a flight simulator, it rocks the real hand of a pilot during feigned turbulence. On a standard computer desktop, it lends the feeling of mass and texture to icons made of nothing more than pixels.
The haptic mouse is motorized, which creates sensations such as resistance and vibration clearly felt by the user. The concept is called forced feedback. When the pointer of the mouse sweeps across a computer screen, software recognizes the motion and affects the mouse's response. Icons feel different than the desktop pattern and can be made to feel distinguishable from each other. More than that, the pointer reacts like it is being pulled towards icons. The point-and-click interface shifts into a pulled-and-click interface.
The mouse offers "an artificial mode of what the icons would feel like if you could actually pick them up," said Dennerlein. More importantly, the haptic mouse saves time. Dennerlein found that users of the haptic mouse performed point-and-click tasks 25 percent faster than standard-mouse users.
The technology decreases the need for precision, but can it also decrease risk of work-related musculoskeletal injuries? Dennerlein thinks so, if employed correctly.
Musculoskeletal disorders include conditions such as carpal tunnel syndrome, lower back pain, tendinitis, and some head and neck injuries. These types of injuries often result from repetition and force and were formerly called repetitive stress disorders. Each year, more than one-half million American workers take time off from work because of these disorders, according to OSHA.
"Haptic technology could help prevent musculoskeletal disorders or perhaps rehabilitate them because it could be used to teach good habits," said Dennerlein. The haptic mouse, for example, controls the range of motion of the hand and wrist and for some tasks decreases the physical stress on the body.
Haptic technology has been around for more than 10 years, but Dennerlein was among the first to investigate the link between it and ergonomics. Researchers, with the goal of building a better mouse, have focused on changing how one holds the mouse but had not examined incorporating forced-feedback models into the workplace.
"People have been suffering from musculoskeletal disorders for years," said Dennerlein, "but now it is a hot topic because the computer has brought manual labor into the office environment. What is known is that the more time you spend in front of a computer, the more likely you are to develop one of these disorders. The specific causes remain unknown."
Dennerlein is investigating the possible risk factors for computer-related musculoskeletal disorders. He is developing a monitoring system to be used in the field, as opposed to the lab, to characterize the physical exposures that may lead to injuries such as carpal tunnel syndrome. He also is investigating why more women than men suffer from chronic musculoskeletal disorders of the upper body.
In the meantime, haptic technology is being applied to an astonishing variety of fields. Joysticks and controllers in some video game systems use the technology to create the feel of rapid gunfire. And advocates for the blind hope that the haptic-computer interface will help blind people navigate desktops more easily because they will be able to distinguish icons by the resistance of the mouse combined with acoustic cues.
