Assembly-line work is not easy. Producing a vehicle every 60 seconds requires a lot of stretching, reaching, lifting, pulling and pushing. By bringing motion tracking and simulation to a new peak in immersive engineering, Ford Motor Co. is making huge gains through ergonomic analyses in dramatically reducing assembly injuries. As an added benefit, quality has improved.
Since the automaker integrated ergonomic analyses into the manufacturing process, its premiums for workers' compensation insurance have fallen dramatically. The biggest portion of the drop was in repetitive-stress injuries, which ergonomic analyses play such a big role in preventing. Ford medical records show dramatic reductions in injuries related to spinal compression, back and upper body strains and shoulder/rotator cuff injuries. Behind these statistics are huge reductions in physical pain and suffering, work time lost to injuries and lost wages.
In addition, new vehicle quality has soared five times more than the industry average — an unprecedented 11 percent measured 3 months after sale. The North American industry average was just 2 percent. (Data comes from a Global Quality Research System survey of new-vehicle buyers by the RDA Group, Bloomfield Hills, Mich.)
The injury and quality statistics are inversely linked; as injuries declined, quality has risen. Allison Stephens, Ford technical specialist in assembly ergonomics for Ford's Advanced Engineering & Technology department and a certified professional ergonomist (CPE), explained, “The benefits of fewer injuries and higher vehicle quality come to us together and they result directly from joining sophisticated ergonomic analysis to Ford's Virtual Build program.” Stephens and her team of 10 ergonomists and their Dearborn Ergonomics Lab are part of Ford Vehicle Operations Manufacturing Engineering.
Virtual Build is digital manufacturing — putting new vehicles together in the computer — applied to Design for Assembly (DFA).
All automakers use virtual simulations but none have carried it is far as Ford or reaped greater benefits. Even Toyota, often considered the industry leader in quality and productivity, is asking for a closer look. “We're talking with them on how to improve the digital human model,” Stephens said, “but not how the model is used.”
“Before Motion Analysis Corp.'s MAC and Jack (Digital Human Model), we never had the capability to look at ergonomics issues this early in development,” Stephens added. “We work 2 to 3 years ahead of product launch.” Virtual Build starts as soon as the engineering data is available for fenders, quarter panels, hoods and doors that are used in the analysis.
At the heart of the lab is the integration of digital cameras, and motion-tracking software from Motion Analysis Corp. of Santa Rosa, Calif. The MAC system at Ford consists of 15 digital cameras (10 Hawk and four Eagles). Any two of them capture movement and change in orientation in the Dearborn Ergonomics Lab's 3D space. MAC's Eva Real-Time (EVaRT) software reconciles overlapping views.
To create the virtual assembly line, Ford ergonomists use MAC, integrated with:
Jack human simulation tools from the Tecnomatix suite of Siemens PLM Software.
Siemens' TeamCenter for product lifecycle management (PLM) where all Ford vehicle designs are managed.
Through TeamCenter, with Ford's 3D design engineering data for each component as it would be located and oriented on the vehicle.
The human simulations of worker movements on the assembly line are created with MAC motion tracking. Tasks are performed, or mimed, by an assembly-line engineer immersed in a virtual environment created from engineering data, the use of MAC cameras, Siemens's Jack and a head-mounted display. The result is a lifelike digital representation of workers/avatars performing assembly tasks on digital models of future vehicles.
Stephens pointed out that motion tracking provides quick, realistic capture of movement. “Predicting human movement is very difficult,” she noted. “Simulations of complicated movements are typically based on manual posturing techniques that can be variable and unreliable for complex tasks. That's where we use MAC motion tracking.”
Jack and his female counterpart, Jill, provide biomechanically accurate digital humans that track the movement of a subject with MAC. These represent actual complex movements that would be expected on the assembly line because the subject is immersed in a virtual assembly plant. The captured postures can then be analyzed in terms reach, visibility and potential for injury and fatigue.
MAC even captures head movements. They can be used to generate eye views in Jack — an invaluable feature in analyzing operations that must be done “blind,” or by feel, where the worker's view of the task is blocked.
Motion tracking plus engineering data — component, workstation and the vehicle at any stage of assembly — add up to immersive engineering. Immersive engineering is the best technique yet for communicating with large amounts of complex data, and ensuring it will be comprehended.
“With MAC, we can immerse the operator in a virtual environment and this immersion is the key to understanding and analyzing real-life assembly processes,” Stephens said.
Components, worker movements and tessellated engineering data are displayed for the wearer but the props and the walls of the lab disappear.
Combining motion tracking, Jack and engineering data also offers much speedier visualizations than can be done with computer animations or physical mockups. In addition, the motion of parts and tools such as nut-runners or welding guns, not just humans, in 3D space can be captured.
Since the late 1980s, virtually all automakers have done some ergonomics investigations before product launches. But traditionally “we had to wait until we had a prototype vehicle,” Stephens said. “By then, with just a few weeks until launch, there was time only to analyze the most critical issues,” and very little time for re-engineering.
Ford began using Jack in 2000, “but early use was limited to what could be simulated manually,” she explained. “Motion tracking adds so much more realism when all the engineering data is lifelike.” Ford has used MAC since early in 2004. Integration between Jack and MAC is straightforward and accommodates both real-time and offline streaming of motion data. Moreover, Siemens and MAC have a solid working relationship. Jack business managers recommended MAC to Ford.
Smart ergonomics starts with analyzing medical claims by frequency and severity of injury. Stephens calls this “chasing medicals” and accident investigations and she has been at it for 22 years. That includes 5 years “establishing and empowering” the virtual-build approach to ergonomics in numerous Ford plants, beginning in St. Thomas, Ontario, Canada.
Ford's ergonomic approach is pragmatic and focused on factory-floor challenges of DFA. “To reduce injuries and risk of them, we go after the high hurts,” she explained, “jobs that have a history of injuries.” These include hose installations, electrical connections, interior trim, reaching to the center of the vehicle and into the engine compartment.
Stephens says Ford sees the integration of this lab and motion-tracking with the Virtual Build as doing an excellent job of planning for assembly for ergonomics. “We help set the work content ergonomically to optimize each station to human physical capabilities,” she said. “We understand the maximums and minimums of what people can lift, reach or exert. We find the sweet spot for every task to minimize exertion.”
Reducing exertion reduces fatigue, a root cause of quality problems. Part of the success is a kaizen approach to solving problems by searching out root causes. (Kaizen is Japanese for continuous improvement.)
For about 10 percent of the Ford simulations, motion tracking is indispensable as body postures are too complex to recreate and predict. Examples include climbing inside a vehicle to install an instrument panel, a center console or seats and reaching deep inside the engine compartment.
Stephens and Ergonomic Simulation Specialist Jim Chiang put motion tracking human movement simulation to work. “We work directly with the program engineers,” Stephens said. “They come to the lab, suit up for motion tracking and are immersed into the assembly plant of the future.”
The lab blends the physical and virtual or digital worlds. The MAC cameras are mounted on a truss in the lab. Props provide physical hard points that are referenced in the virtual environment. On the line, workers reach around, over and beneath these components to do their jobs, and often lean on them. In the lab, engineers do the same and those movements are captured.
“The use of props and MAC has cut the time to create simulations by a third,” said Stephens. “All this helps cut the cost of change.”
The realistic human simulations created by MAC and Jack allow ergonomists to analyze assembly jobs not in existence today. Typical analyses include the NIOSH lifting calculation developed by the National Institute for Occupational Safety and Health, the University of Michigan 3D Static Strength Prediction Program for Joint torque evaluations and “HandPak” from Dr. Jim Potvin, McMaster University in Canada, for upper extremity assessments.
APPROACHING ZERO ERGO ISSUES
“Ford has a goal of zero ‘red' or unacceptable ergonomic issues going into production, and these are tracked and measured. Ford has seen dramatic improvements in reducing high-risk jobs entering the assembly facilities,” Stephens said.
“We are seeing huge vehicle quality improvements as a result of using MAC and Jack in a proactive engineering approach of designing the assembly process correctly, right from the start.”
Motion tracking, said Stephens and Chiang, is essential for feasibility studies, developing programs to reduce high-injury-risk situations, specifications for ergonomics in assembly plus requirements for facilities, processes and workstation design and research strategies and targets.
QUALITY STILL IS JOB ONE
Worker safety may have been the main driver for the Ergonomic Lab, but in sales what really matters is quality, and especially “perceived” quality in dealer showrooms and in the first few months of ownership. These dictate what customers tell family and friends, influencing buying decisions for better or worse.
The quality-ergonomics link was shown in the installation of weather stripping — rubber seals inserted around vehicle doors and windows. The Ergonomics Lab identified fatigue and insertion efforts as major reasons for injuries of operators along with misinstalled weather stripping. That led to interior noise at highway speeds, a quality problem categorized as noise/vibration/harshness or NVH. “Those workstations were redesigned and complaints fell dramatically,” said Stephens.
“The impact on cost-savings and quality improvement is significant,” acknowledged Cheryl Bruins-Rozier, Virtual Build manager at an early 2008 media day at the Dearborn lab. “The technology contributed to high quality early builds of the Ford Flex and Lincoln MKS, both launching as 2009 models.”
In each case, “the vehicles reached the prototype build stage with 80 percent fewer manufacturing feasibility issues,” she continued. “Thanks to the virtual tools, parts compatibility on both vehicles was extremely high.” Industry veterans say gains like these save hundreds of thousand of dollars in last-minute launch costs and go a long way to keeping everything on schedule and at or below budget.
“The goal of our virtual manufacturing tools is to drive compatibility between the product design and the assembly plant process,” explained Vehicle Operations Chief Engineer Dan Hettel. “We validate each assembly process virtually to ensure that it can be completed with quality. The quality results of our recent vehicle launches show that the virtual process is working.”
Jack Thornton is principle of MINDFEED Marcomm in Sante Fe, N.M. He can be reached at [email protected] or (505) 690-0828.
Facts about Motion-Tracking in Ergonomics and Quality at Ford
Goes beyond simulation to reduce injury and raise quality.
Is the best way yet found to represent complex tasks.
Overcomes reliability shortcomings of predictive methods.
Allows human interaction with the vehicle in the virtual assembly plant.
Involves assembly-line specialists and design engineers in ergo simulations and analyses.
Uses actual 3D part data from the engineering prototype of each new vehicle, or the Digital Buck.
Uses a virtual vehicle years before a physical prototype or a full vehicle is available.
Gives engineers and analysts tools to mix virtual product data and real parts.
Is far faster than manually creating computer animations or doing full physical mockups.