Meeting the challenge of drive-by-wire electronics

For 100 years, the majority of systems concerned with the direct control of the vehicle by the driver have been under direct actuation by mechanical, hydraulic or pneumatic means. If such a system fails and the driver is unable to continue to control the vehicle, the consequences could affect the safety of the vehicle or other road users. Safety has always been a high priority for vehicle designers and engineers. Mechanical components are designed and tested to ensure they have the correct characteristics and to meet the international safety standards. Most of the time, more critical systems are often designed with a degree of redundancy. An example is the fitment of dual-circuit braking systems to vehicles. If one circuit fails, the other affords the driver a degree of control authority over braking.

There is considerable interest in increasing functionality and safety of modern transport by developing drive-by-wire systems where electronic controls are used to supplement the driver controls. In a full-authority drive-by-wire system, the driver controls are simply inputs to a computerized system rather than directly commanding the vehicle functions.

Drive-by-wire engine control

The development of engine controls shows how electronics have been gradually introduced to the point where the majority of vehicles sold in the European market now have full-authority drive-by-wire engine control. Early engines were controlled by the driver regulating induced air with the accelerator pedal (Figure 1).

Figure 1: Original engine control concept (simplified)