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Similar to the fly-by-wire systems used in many aircraft, drive-by-wire technology uncouples the mechanical automobile controls and replaces them with electronic controls. For example, the steering wheel may no longer be connected to the pinion through a steering shaft in a rack and pinion steering system. The steering wheel would be connected to an electrical device that measures the rotation of the wheel and sends that data to an on-board computer. The computer may then control hydraulics connected to a pinion gear driving the rack. Since the steering wheel no longer has to be directly connected to the steering mechanism, manufacturers have far more flexibility in where they place the driver controls. This also works similarly for braking and throttle controls.

Most, if not all, the major automobile manufacturers are investigating drive-by-wire technology. BMW, for example, has allowed journalists to test drive some of their prototype vehicles. General Motors recently announced their prototype fuel-cell chassis, nicknamed "The Skateboard", which is a full drive-by-wire vehicle. Mercedes has a modified SL 500 for the test track. It is equipped with dual joystick controls - one for steering and one for acceleration and braking.

A few example advantages of drive-by-wire systems:

  • Flexibility in interior design and control placement
  • New control designs like including braking and throttle on controls on the steering wheel or even replacing the steering wheel with a joystick, aircraft style controls, etc.
  • Enhanced braking as the vehicle can monitor and modulate brake pressure at each wheel. This is already being done somewhat in anti-lock braking systems.
  • Better variable steering. Variable steering is normally done through varied tooth pitches on the rack, however this is not truly speed sensitive. 2.5 turn lock-to-lock steering may finally disappear.
  • Safety enhancements. The steering wheel is actually quite dangerous for drivers as it often gets pushed back into their chest in head-on collisions. Replacing the steering wheel and column with a joystick, for example, may help reduce injuries.
  • Designs which allow better reaction times from drivers. Mercedes has been researching joystick controls and has found that reaction times are significantly better for joystick acceleration and braking. It takes less time to pull back on a joystick to brake than to take your foot off the gas and apply pressure to the brake pedal.

Unfortunately, electrical failure or computer crashes may render a drive-by-wire vehicle inoperable. It will be a while before we see complete drive-by-wire vehicles on the road, as currently drive-by-wire vehicles are not even allowed off the test track. However, it's only a matter of time before our traditional notions of automobile controls are replaced by something that may be completely different.

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