Have you ever wondered what is ‘Drive-by-wire’ or ‘x-by-wire’?

We come across the terms like drive-by-wire, steer-by-wire, throttle-by-wire, 0r x-by-wire, but how many of you have ever wondered what is this x-by-wire technology? Today, let’s see what it actually is.

Drive by wire, Steer-by-wire, or x-by-wire technology in the automotive industry is the use of electrical or electro-mechanical systems for performing vehicle functions traditionally achieved by mechanical linkages. This technology replaces the traditional mechanical control systems with electronic control systems using electro-mechanical actuators and human-machine interfaces such as pedal and steering feel emulators. Components such as the [steering column], intermediate shafts, pumps, hoses, belts, coolers and vacuum servos(components used in cars to assist drivers by decreasing the braking force required) and master cylinders are eliminated from the vehicle. This is similar to the fly-by-wire systems used widely in the aviation industry.

What are the advantages and disadvantages associated with this technology?

Advantages: 

• Reduces the vehicle’s weight as electromechanical components are much lighter compared to mechanical linkages.

• Vehicle design freedom is increased as the electromechanical components occupy less place compared to the mechanical counterparts. And also, the number of options to place x-by-wire components(though not all) inside the vehicle is more than that of mechanical  components. For example, in a traditional steering mechanism the steering column’s position is fixed and it can be cannot be changed where as in steer-by-wire system the control modules can be placed wherever the design permits. This adds to design freedom
• Safety 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.
• Improved ergonomics due to flexibility of location of controls.

Disadvantages:

• Drive by wire systems can be hacked, and their control faulted or shut off, by either wired or wireless connections.
• Increased complexity.

Uses in automobiles:

Throttle by wire: This system helps accomplish vehicle propulsion by means of an electronic throttle without any cables from the accelerator pedal to the throttle valve of the engine. In electric vehicles, this system controls the electric motors by sensing the accelerator pedal input and sending commands to the power inverter modules.

Brake by wire: A pure brake by wire system eliminates the need for hydraulics completely by using motors to actuate calipers and lock the wheels in comparison to the currently existing technology where the system is designed to provide braking effort by building hydraulic pressure in the brake lines.

Shift by wire: The direction of motion of the vehicle (Forward, Reverse) is set by commanding the actuators inside the transmission through electronic commands based on the current input from the driver (Park, Reverse, Neutral or Drive).

Steer by wire: This kind of system will provide steering control of a car with fewer mechanical components/linkages between the steering wheel and the wheels. The control of the wheels’ direction will be established through electric motor(s) which are actuated by electronic control units monitoring the steering wheel inputs from the driver. Such a system is illegal in most jurisdictions for passenger or commercial vehicles. The first production vehicle to implement this was the Infiniti Q50. This is not to be confused with Electric Power Steering. Electric Power Steering can be considered as a stage of evolution from mechanical steering to steer by wire systems.