In this world there are standards for everything -- including the durability, safety and ergonomic support of car seats. Even rear seats. And where there is a standard, there are companies to certify that products meet those standards. One such company is Tachi-S Engineering USA, a wholly owned subsidiary of Tachi-S Co. Ltd., a major supplier to automakers around the world.

As in any other business where strict standards apply, certifying car seats has become exacting. So much so that Tachi-S recently bought a portable coordinate measuring machine (CMM) to make sure the measurements were correct, to simplify verifying them and, in general, to speed up the whole process.

Tachi-S Engineering recently re-established its lab and testing facilities in its new design and engineering center in the Detroit suburb of Farmington Hills, Michigan. Although only four men work in the seating laboratory, they certify all Tachi-S’s prototypes through production seats.

U.S. automakers have a high degree of confidence in their seating suppliers and the industry relies on self-certification. The seating manufacturers test their products and certify their results to the car companies and, when asked, verify their tests.

The portable CMM has greatly speeded up these tests and certifications, opening up new opportunities for Tachi-S in this highly competitive business. The arm has a 9-foot reach and an accuracy of plus or minus 0.002 inch. The machine weighs a mere 14 pounds.

Seating manufacturers put their products through several tests, each of which presents its own challenges. The most important of these is checking hip points, also known as H-points. “On humans and on seat-testing mannequins, the H-point is the center of the hip joint,” explained Gunn Hurite, manager of test sales for Tachi-S. From H-points, designers of car interiors calibrate just about everything in the way the cockpit envelops the driver. This runs the gamut from the height, angle and positioning of the seat itself to the locations of the steering wheel, floor-mounted shifters, the driver’s instrument panel controls, anchoring of the shoulder and lap safety belts, and even the placement of the accelerator and brake pedals. In small cars this also means assuring sufficient space for foot and ankle movement plus clearance for the knees.

The portable CMM is also used in anchor-pull tests to measure various deflection points of the seat and its anchorages. To make sure front and rear seats will stay put in a crash -- and fulfill their assigned energy management role -- they are stressed as in a 30 mph collision. “We use the arm to measure the deflection points and anchorages in 3D space before and after each test,” said Tom Kralik, lab manager for Tachi-S. “With the old methods, it was very difficult to measure the deflection point movement precisely or easily. With the arm it’s a breeze.” Old methods, he noted, required preselecting points and using scales to measure metal stretch around deflection point. “It was a very tedious, time-consuming job,” Kralik added.

Another portable CMM role, Hurite noted, is to measure final contours of the seat and then overlay data on original drawings. Measuring a soft surface such as that of a seat is a challenging task for any touch-probe machine, regardless of whether it’s portable or bolted down. Working with the arm and a machine-vision company, Tachi-S is exploring replacing the arm's touch-probe with a laser. A current hurdle to overcome is the low reflectivity of most seating materials: this presents a challenge to machine-vision systems. Lasers of various bandwidths are being tested by a representative on the Tachi-S account, Paul Marinos of MariForm Ltd., also in Farmington Hills.

Previously, using a conventional CMM, two front bucket seats and the rear bench seat for a given car took eight to ten hours. “With the portable CMM we are four to five times faster,” Hurite said.

Tachi-S first got into this type of certification work with the Hummer, the civilian version of the Army and Marine Corps HumVee light truck. “It was big and roomy so getting into the right places to make the measurements wasn’t too bad,” Hurite said. “We used traditional magnetic blocks, scales, height gages and squares.”

In mid-1997 Ford asked us if we could do H-pointing on some of their smaller cars -- quite a different matter considering the size of the Hummer. Seeing an opportunity to get into a new and growing part of the testing business, Tachi-S said yes. The automaker provided very little guidance, Hurite recalls. “They didn’t tell us what to buy or how to go about it. Looking back now, we’re not sure they knew. They just told us what they had to have in the way of results.”