Manufacturing AUTOMATION

Ryerson prof sees the value of visibility in workplace safety

February 6, 2009
By Manufacturing AUTOMATION

When it comes to ergonomics in the workplace, visibility is largely ignored – quite the oversight since vision plays a major role in nearly all of our daily tasks. That’s why one Ryerson University researcher developed a model to assess visual perceptibility in a workspace, which could potentially decrease injury and increase productivity.

Dr. Farrokh Sharifi, of Ryerson’s Department of Mechanical and Industrial Engineering, explains that humans gather approximately 90 percent of environmental information through their eyes, meaning that even when a task is conducted with one’s hands, the eyes still maintain control. Given this reliance on sight, the professor asserts that more attention needs to be paid to vision when evaluating the ergonomics of a workspace.

Current assessment techniques fail to examine visual perceptibility from a three-dimensional perspective and also ignore the differences between perceiving moving and static objects within the _workspace. The professor, who specializes in image-based controls, which traditionally applies the mechanics of human biological systems to machines, has now developed a model to evaluate the ergonomics of visual perceptibility in the workplace by applying the mechanics of machines to biological systems.

Using cameras and LED diodes as markers on human subjects, Dr. Sharifi and his former graduate student at Ryerson (and now collaborator), Behdad Masih-Tehrani, doctoral candidate at Pennsylvania State University, took kinematic measures to predict the movement of the eyes in relation to the movements of the arm, neck and shoulder, of each subject. With data extracted from examining the functionality, focus, field of view, acuity (similar to the resolution of a computer screen) and motion resolvability, they developed the first simulation system to evaluate workspace design with an emphasis on vision, both identifying problems and suggesting solutions.


Adaptable to any kind of workspace, including manufacturing, this new model will eventually be translated into software for widespread use.

“We need to draw attention to vision problems at work, which have not been the primary focus of workplace ergonomics to this point,” said Dr. Sharifi. “Just because people are able to see something in their workspace, doesn’t mean they can see it well or without strain. Oftentimes, people will change position in order to see things better, adopting a different posture than usual, and not necessarily the best posture, which can lead to injury. This model we’ve developed takes all of that movement into account while proposing the best positions for parts and components in order for workers to easily see and handle them so they can complete tasks with greater comfort.”

The next phase of Dr. Sharifi’s work will include refining the model through an extensive two-year experimentation period as well as developing a system to assess visual disabilities in the workplace and their effect on task completion. This research is being funded through a grant from The Workplace Safety and Insurance Board (WSIB).

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