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Drive By Wire - Automatic Skeleton Watches - Skeleton Dial Watches
Advantages
AdvantagesSafety can be improved by providing computer controlled intervention of vehicle controls with systems such as Electronic Stability Control (ESC), adaptive cruise control and Lane Assist Systems.
Ergonomics can be improved by the amount of force and range of movement required by the driver and by greater flexibility in the location of controls. This flexibility also significantly expands the number of options for the vehicle's design.
Parking can be made easier with reduced lock-to-lock steering wheel travel as with BMW's Active Steering System, or semi-automatic parallel parking which is available in some Toyota Prius in Japan, Lexus LS460 models worldwide and newer European Volkswagen models. Although neither of these are strictly Steer-by-Wire (SbW) because they retain mechanical linkages, they show the capabilities that are possible.
Disadvantages
The cost of DbW systems is often greater than conventional systems. The extra costs stem from greater complexity, development costs and the redundant elements needed to make the system safe. Failures in the control system could theoretically cause a runaway vehicle (although this is no different from the throttle return spring snapping on a traditional mechanical throttle vehicle). The vehicle could still be stopped by turning the ignition off if this occurred. Another disadvantage is that manufacturers often reduce throttle sensitivity in the low-mid throttle range to make the car easier or safer to control - or to protect the drivetrain (gearbox, clutch, etc) from driver abuse. The feeling to the driver is that the throttle feels less responsive. There are aftermarket electronic kits to increase throttle sensitivity, to re-gain a more direct-feeling relationship between pedal position and throttle valve opening.
Steer by Wire
This is currently used in electric forklifts and stockpickers and some tractors. Its implementation in road vehicles is limited by concerns over reliability although it has been demonstrated in several concept vehicles such as ThyssenKrupp Presta Steering's Mercedes-Benz Unimog, General Motors' Hy-wire and Sequel and the Mazda Ryuga. A rear wheel SbW system by Delphi called Quadrasteer is used on some pickup trucks but has had limited commercial success.
Competitors in the DARPA Grand Challenge, an automated driving competition, relied on 100% DbW systems, in some cases including a SbW system provided by the manufacturer .
This is not to be confused with Electric Power Steering.
Passenger car state-of-the-art
Electronic fuel injection metering in diesel and gasoline engines is now widely used. Electronic throttle control is also in widespread use for gasoline engine control. Purely electronic brake and steering systems have yet to find widespread application in passenger cars. This is primarily because of the significant safety implications of steering or braking systems without a redundant mechanical backup in case of failure of the DbW system. Although it is technically feasible to address these concerns with multiple redundant electronic systems (as in fly-by-wire systems used by many airliners and military aircraft), the additional cost and service requirements have made these systems commercially uncompetitive to date. Hybrid electric vehicles employ limited electronically controlled regenerative braking, but the standard hydraulic braking system is retained. The growth in sales of hybrid and electric vehicles is likely to become an enabling factor for drive-by-wire systems in the future because of the availability of high power electrical supplies required for the new electrical actuators.
In early 2010, several Toyota models which employ drive-by-wire throttle control were the subject of a recall due to out-of-control acceleration. At the time, Toyota said they have not found any evidence that the DbW systems were the culprit. All the toyotas in the recent recalls have DbW . Many articles and accident reports Toyotas crashing at speeds over 100 mph. In one theory, the DbW is in control of the car and the driver is unable to stop the acceleration or use the brakes. In older cars the acclerator is wired to the gas pedal and then to the engine and the only way to go 100 mph would be for the driver to mistake the gas pedal for the brake. In some NTSHA reports released in the L A Times the dead drivers feet were found only on the brakes.
The future
Some fanciful theories and applications abound as to what the ultimate implications of DbW technology might be. It has been suggested that DbW might allow a car to become completely separate from its controls, meaning that a car of the future might theoretically be controlled by any number of different control systems: push buttons, joysticks, steering wheels, or even voice commands whatever device that designers could come up with. This would have many advantages, such as:
increased flexibility for handicapped or disabled drivers
less weight in the car
more space in the car
See also
Brake-by-wire
Electronic throttle control
Fly-by-wire
External links
Missing data compensation for safety-critical components in a drive-by wire system
Fusion of redundant information in brake-by-wire systems, using a fuzzy Voter
Position sensing in by-wire brake callipers using resolvers
Categories: Automotive engineering | Mechanical engineering | Technology by type | Vehicle braking technologies
by: gaga