Drive-by-wire, or X-by-wire technology in the automotive industry replaces the traditional mechanical control systems with electronic control systems using electromechanical actuators and human-machine interfaces such as pedal and steering feel emulators. Hence, the traditional components such as the steering column, intermediate shafts, pumps, hoses, belts, coolers and vacuum servos and master cylinders are eliminated from the vehicle. Examples are electronic throttle control (Throttle-by-wire), steer-by-wire, and brake-by-wire.

Drive by wire systems are designed to always fail safe meaning that the engine will always return to idle or near idle if a fault develops. Drive by wire systems allows for a faster throttle response, better control over throttle application when combined with traction control and ABS and eliminates the need for a separate cruise control module. The system basically consists of the accelerator pedal with the built in potentiometer (variation of voltage output with pedal position), this is known as the APP (Accelerator Pedal Position), the TACS (Throttle actuator Controller) module and then the Servomotor and throttle sensor on the throttle body.

Advantages of Drive-By-Wire Systems

  • 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.
  • 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 Active Steering System, or semi-automatic parallel parking which is available in some vehicles.

Disadvantages of Drive-By-Wire Systems

  • The cost of Drive-by-wire 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 in mechanical throttle vehicle.
  • Vehicle 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.