Cadalyst - May 2008 - (Page 43)

plmstrategies station (figure 2). “So I can now see, for instance, whether Jack’s hand is colliding with the fender in the back when he’s reaching for a door,” explained Stephens. Easier simulation produces a cascading effect on the product development cycle. “Because we can do our verification early, without waiting for Figure 2. The ability to see the virtual model in context — right alongside the vehicle and a physical prototype, we’re now two the workstation — allows ergonomists to redesign the product or the task, if necessary, to years ahead of where we used to be,” minimize on-the-job injuries. Stephens said. In the past, by the time the prototype was ready for safety and ergonomic evaluation, the design was frozen. That left Stephens and her team with limited options if they discovered a nagging issue. “Mostly, we had to decide what we could live with and what we couldn’t,” Stephens said. Now, with the ability to run tests roughly 24 months in advance, she can make suggestions to the design engineers on how to reshape the vehicle (for example, move the protruding fender approximately 5 centimeters) for worker safety and assembly-line efficiency. Occupational Hazard Under the U.S. Government’s Occupational Safety and Health Administration (OSHA), employers such as Ford are required to provide “safe and healthful working conditions for working men and women” (OSH Act of 1970, www.osha.gov). An employer may be cited for ergonomic violation if, for example, the task an employee is required to perform exposes him or her to spinal compression forces beyond the acceptable tolerance (based on data compiled by the National Institute for Occupational Safety and Health, NIOSH, www.cdc.gov/niosh). “3,400 N [newton] is NIOSH’s recommended limit,” said Stephens. “So JACK software can actually calculate the compression force based on the digital model’s posture and compare the results with NIOSH standards.” In other words, if Ford is ever asked to prove that its manufacturing practices are OSHA compliant, Jack and Jill can testify on behalf of the automaker. Figure 3. This view of a worker’s posture speaks volumes about the practicality of a task. human models, Stephens and her team try to answer basic questions about the assembly process: u Can an operator put his or her hand around a component? u Can an operator reach the component? u Is an operator strong enough to install the component? In an initial test, Ford ergonomists simply insert a static human model into the digital environment. If the result shows that the operator is in collision with nearby structures, the team moves ahead with a more comprehensive analysis. Using the same type of motion-capture technology used by video game developers, Ford ergonomists place a real human operator in a virtual space representing the production environment. JACK on Film Perhaps the best value that JACK offers is its visual appeal. The simulation created with the software can be output as screen captures and movie clips in AVI format. Stephens might have trouble swaying a budget-conscious executive by citing the spinal compression force to which the assembly worker would be subjected. “But when I play back the AVI file to the management team, the engineers, and the project managers,” said Stephens, “they suddenly see the awkward posture of the digital model (figure 3), and they say, ‘Oh yeah, we so need to change that.’” Jack and Jill hide somewhere in the hard drive, awaiting their next assignment. Cadalyst contributing editor Kenneth Wong explores the innovative use of technology and its implications. E-mail him at Kenneth.Wong at cadalyst.com. 43 See Them in Context To do the same type of design and process verifications in the past, Ford ergonomists had to wait until the physical prototype was available and then use a real human operator to study his or her posture and the risk of injury. “Computer programs to calculate the impact of human motion have existed for nearly 20 years now,” said Stephens. “Not long ago, we could take a photograph of an assembly worker, digitize his or her joints, then use something like a free-body diagram to figure out the forces applied on the joints. But now, the technology has progressed so much that we can actually place the digital human model in the virtual environment — and do all this in real time.” This allows ergonomists to observe the digital model in context, right alongside the virtual vehicle and workMay 2008 cadalyst www.cadalyst.com http://www.osha.gov http://www.cdc.gov/niosh http://www.cadalyst.com

Table of Contents Feed for the Digital Edition of Cadalyst - May 2008

Cadalyst - May 2008 Contents Editor's Window Cad Central A Solid Job in AutoCAD Today’s Power — Quad-Core Workstations Performance — Tomorrow’s Possibilities Reverse Engineering an Antique Italian Treasure Trends in Reverse Engineering NextEngine 3D Scanner — Reverse-Engineering Tool Setting CAD Standards Fight for Your Hardware Rights The Jack and Jill of Ergonomics Technology for Civil Infrastructure Cad Cartoon Issue Indexes Shortcuts and Solutions

Cadalyst - May 2008

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