Driving simulators have evolved from flight simulators for aviation training. The simplest driving simulators resemble video games. However, an advanced driving simulator actually uses a real car, like a Ford Taurus or Chevy Malibu. The car might look and feel fully functional, but under the hood, you'll find that the engine has been replaced by a computer.
Dr. Azim Eskandarian, who works with a driving simulator at George Washington University, described how the system works. A driver who sits in the cab of a car can see a virtual world projected on a screen. The driver steers, accelerates and brakes like normal. But these actions get translated into the computer, which translates them into the virtual world. Dr. Eskandarian explains that when the driver presses on the gas, the amount of force on the pedal is electronically fed into a data acquisitions system.
Researchers have created physics-based models that allow the computer to translate the pedal force into the right amount of acceleration in the virtual world. These models have mapped out how much pedal pressure results in how much acceleration. Each component of the engine process has a corresponding dynamic model, which is a physics-based equation that describes the relation between the input and the output. This computational process that translates vehicle control into virtual reality is called total vehicle dynamics [source: Eskandarian].
The researchers also create a virtual world to drive in. They project this world, complete with marked roads, stop signs, stop lights, pedestrians, cyclists and more, on a screen in front of the driver. Many simulators can also adjust weather, time of day and traffic.
However, even this can seem unrealistic if it doesn't "feel" like driving. In other words, it can feel like you're floating or driving on a sheet of glass rather than a real road [source: Ahmad]. The National Advanced Driving Simulator (NADS) at University of Iowa tries to fix this problem as one of the most immersive driving simulators. Omar Ahmad, the Assistant Director of NADS, explains that the car is housed in a dome hexipod with four vibration actuators and six hydraulic legs. This amounts to a 360-degree world with various degrees of vibration for imitating smooth, bumpy and gravel roads. The dome and hexipod move laterally and longitudinally on a 64 foot by 64 foot electric rail system. It even allows for 13 degrees of tilt for realistic stops, starts and turns. Ahmad explains that test subjects walk through a covered canopy to enter the dome, where they get into a typical car, which helps them suspend disbelief.