Anthropomorphic metrics” isn't a term you encounter in trucking every day, if at all, but in many ways it's the bread and butter of H. Lenora Hardee's job as chief engineer of human factors engineering for International Truck & Engine Corp.
To Hardee, who has a Ph.D. in industrial engineering, those metrics represent the many different shapes of the human body — especially those of truck drivers who sit at the wheel for hours at time, day after day. And her analysis of those metrics is correct, the result could be a cab that easier to use and more comfortable for the vast majority of drivers-whether large or small, young or old, male or female — long before International has to spend a dime in pre-production costs.
“A comfortable cab environment is one thing that can help keep drivers happy. But the real objective is to create an environment that better matches the capacity and limitations of the driver, making it easier to reach and operate the controls, for instance,” she says. That also applies to labels, visual displays and gauges, which are designed so that drivers can quickly read and understand them.
One Hardee's biggest challenges today is helping engineers develop a vehicle that can satisfy the increasingly diverse physical size of the driver population. “Various elements are taken into consideration, including height, weight and gender,” Hardee says. “Seat travel, placement controls and comfortable access to the sleeper all need to be studied from the various perspectives to arrive at trade-offs that best meet customer needs.”
That's where anthropomorphic metrics come in. It involves taking hundreds upon hundreds of human body measurements, from simple body height, width and weight statistics to individual arm lengths, and feeding the data into computer software that will create a series of “virtual” truck drivers engineers can use in the vehicle design stage.
“Since I joined International in 1998, we've measured over 1,200 drivers, from over-the-road truckers to school bus operators, collecting 36 to 44 different metrics from each one,” says Hardee. “We've compiled all of that metric data so we can come up with cab designs that satisfy the ergonomic needs of the majority of the driver population.”
The research also includes hours of video of drivers on the road, contributing to a more accurate picture of how they operate their vehicles.
“The key to gathering this ergonomic data is to end up building a cab that better matches the capabilities and limitations of the majority of drivers, so there's no awkward sitting positions, no straining to reach controls, and a dashboard that is easy to understand without too much thought,” Hardee explains. “It really boils down to reducing the workload of the driver in the cab — physically and mentally — which also helps reduce fatigue.”
Hardee spends a lot of time in truck cabs herself, paying particular attention to the safety aspect of ergonomics. “You have to look at cab entry/exit; that's a major problem in terms of slip and fall accidents,” she says. “It's not just about adding more steps or grab handles; it's where you locate them so they are intuitive to locate and you don't forget where they are.”
While the primary goal of ergonomics research is to improve driver comfort and safety, there's also a benefit to manufacturers in terms of design costs. The ergonomics data is fed into “human digital software” that enables cab engineers to develop more accurate internal standards on the front end of truck development work before they waste any money cutting steel for design mockups.
“The ideal is to create this virtual person that [engineers] can plan sleeper cabinetry, control knobs, and leg room around. A digital person far more accurately represents the real truck driver population,” Hardee notes. “A good ergonomic design doesn't just happen; it requires a systematic approach based on accurate digital modeling.”