X-By-Wire Technology in Motor Vehicles
In the last few years, x-by wire in motor vehicles has been slowly working its way into production vehicles. X-by-Wire is a term derived from the aviation industry where it is known as fly-by-wire.
The term "By-Wire" is the general term that means effectively replacing a pure mechanical system of motion or control with a sensor, and an actuator, with a computer between them. In aviation industry, for a performance fighter aircraft to achieve high aerodynamic surface control response, the design of the aircraft is made to be inherently unstable in flight. Without a computer on board to ultimately manipulate the flight surfaces, the aircraft would be uncontrollable. The computer allows the aircraft to convert instability into responsiveness. So even when the pilot holds the stick straight and level, the computer and control surfaces are constantly working to keep the plane straight and level.
In the automotive industry, X-by-wire technology is traditionally referred to primarily three categories: Throttle-by-wire, Brake-by-wire, and Steer-by-wire. These are listed in order of their perceived complexity and risk, from lowest to highest.
INTELLITURN is a system that replaces the traditionally exclusive mechanical control system of turn signal shut off with sensor based, computer controlled lamp drivers. This system, however, replaces a method that has many delicate moving parts with a method that has no moving parts. INTELLITURN is the world's first and only Turn-Signal-By-Wire.
Of the three traditional X-by-wire devices, throttle-by-wire is in current production on many engines with almost every new engine in development using a motor to actuate the throttle butterfly valve, a gas pedal position sensor, and a computer in between the two. This application is advantageous in that many functions are covered with this arrangement, besides eliminating the traditional cable. Cruise control is incorporated and controlled in the same computer, traction control as well as cold/hot engine idle speed control is incorporated, emissions are improved by overriding a driver's "bad emission practices" at the gas pedal.
Brake-by-wire is the next riskiest x-by-wire method. This can consist of a pure electrical actuation at all four corners or a combination of hydraulic and electric, as in front wheel hydraulic, rear wheel electric. What this can do is eliminate hydraulic lines to the rear of the vehicle. Anti lock brakes are modulated easier to the electric brakes. Even load biased brake balance can be achieved for high and low loads and optimized braking balance under all conditions. One manufacturer is even touching the electric brakes momentarily every 15 seconds whenever the windshield wipers are on in order to keep the brakes dry (presuming that if the wipers are on, the brakes are most likely wet).
Steer by wire is considered the most risky. Most people might not like the idea of a car that the steering is not a mechanically connected tires-to-steering wheel system. Steer by wire does has some benefits, such as the ability to change steering ratios throughout the turn or by selecting a sport or normal mode. It is likely that steer-by-wire is many years away.
Which brings us to Turn-Signal-By-Wire and INTELLITURN. On the sliding scale meter of risk, cost and difficulty to implement, the pointer points to low risk, low cost and low difficulty. The simple idea is that a computer can compute copious and pertinent information from two existing vehicle sensors, and vastly improve a system that all drivers would admit is currently far from perfect. Unfortunately, turn signal control has remained unimproved with the same outdated mechanical method for more than sixty years. Sure, we have improved tactile feel of the switches, added a lane change mode to the switch some thirty years ago, and more recently even added turn signal flashers on various locations of the outside mirrors. All of these are features are great, but none of these improvements could be classified as revolutionary.
Imagine a turn signal system that does not shut off if the driver moves the steering wheel left to right while sitting at a traffic light. Imagine a turn signal that shuts off within seconds if the driver does not realize that it is on on the highway. Imagine a turn signal that is smart enough to stay on if you put on your right turn signal and move into a right turn lane ahead of the actual right turn. Imagine a turn signal that is smart enough to shut off part way through a cloverleaf entrance to a highway. Imagine a turn signal with no moving parts. Imagine a turn signal that could be made totally silent where there is no need for the tick-tock noise because this system takes care of itself and does not need the attention of the driver to tend to its frequently flawed operation. Imagine a turn signal switch movement that is so smooth with just the right amount of movement travel that spells pure luxury. Imagine a turn signal that resets to off when the ignition is shut off. Imagine a turn signal that has not only the stalk lever on the traditional left-side-of-steering-wheel position, but has redundant, full function, automatic turn signal controls on the steering wheel as well. This is what you get when the turn signal finally meets the computer.
This "imagined" system is actually "for real". INTELLITURN is an x-by-wire system that is easy for all to accept and in fact customers may even seek out in their next vehicle purchase. A company who would implement this by-wire system is likely to open the acceptance for more complex by-wire systems to the consumer. The company that implements this would also enjoy a substantial per vehicle cost savings to boot.
The bottom line is that the low risk, low cost, high visibility and high performance of INTELLITURN will advance the cause of X-By-Wire technology for the entire motor vehicle industry throughout the world.
©2008 RLP Engineering