The evolution of the crash test dummy dates back at least to 1949, when the U.S. Air Force used "Sierra Sam," a dummy developed by Sierra Engineering, to test ejection seats. In the 1970s, General Motors came out with the "Hybrid" dummy, which made several improvements on Sierra Sam. The Hybrid I came first in 1971, followed by Hybrid II in 1972; finally, the ATD still used today, the Hybrid III, appeared in 1976.
Hybrid III ATDs have skeletons of aluminum and steel, including six steel ribs with polymer-based material to imitate a real human chest, encased by vinyl imitation skin. Realistic joints as well as a neck, spine and pelvis made of rubber- or foam-encased metal constructions give a dummy lifelike posture and flexibility -- both of which play a large part in collision injuries.
Beyond its humanlike construction, Hybrid III dummies have extra features that range from simple to sophisticated. Merely smearing the dummies with grease paint allows researchers to see exactly where the dummy hits the car in the crash. Also, sensors inside the dummies measure forces of impact at different points.
The standard Hybrid III represents the 50th percentile male -- the average driver at 5-feet, 10-inches tall and weighing 168 pounds. Federal regulations stipulate the specifications for this ATD as well as the "family" of Hybrid III dummies. Among other things, having dummies of different sizes helps researchers determine the effectiveness of standard seat belts on various body types. In addition to the different Hybrid III dummies, there are also different types of ATDs for different crash tests. Hybrid III dummies are used primarily for frontal impact test crashes. But others include the side impact dummy (SID) and the biofidelic rear impact dummy (BioRID).
The next generation of ATDs is THOR, which has made many improvements on Hybrid III. In particular, THOR can more accurately predict facial injuries because the head is equipped with unidirectional load cells [source: Schmitt]. Other improvements include a new neck and flexible spine design and an advanced rib cage with elliptical ribs.
In recreating a controlled crash, researchers also film it with as many as 20 specialized cameras, which can film at high speeds (about 1,000 frames per second) at different angles [source: Weber]. This way they can watch the crash in clear slow motion to observe every detail.