Feedback control systems

In the last decade there has been an increasing effort to apply X-by-Wire technology in modern vehicles. The adoption of this technology enables the replacement of mechanical linkages associated with vehicle controls such as throttle, steering, braking, shifting and clutch, by network enabled sub-systems comprising devices such as sensors and actuators.

Some of the perceived benefits of adopting X-by-Wire technology include the reduction of the weight of the vehicles, an increased operational accuracy and an extension of the time between service visits.

In this project existing X-by-Wire implementations are evaluated and a process to enable the development of feedback control algorithms that can optimise future X-by-Wire implementations is investigated.

Project aims

The main aim of this project is to develop a framework to enable the rapid development of feedback control algorithms to suit vehicles that have its capabilities reliant on X-by-Wire technology. Consisting of a set of guidelines and a generic model featuring a modular layout representing the common elements of a feedback control system, this framework can help developers to have a broader visualisation of the system under development while also influencing design decisions towards achieving a modular solution with minimal internal inter-dependencies between the algorithms running on the different modules of the system. Also, by making provision for dedicated safety and security modules on its core model this framework can create awareness for the need to consider safety and security aspects at an early stage of development.

Project findings and impact

Results indicate that the first development iterations using the suggested framework, incur an additional development time which is reduced significantly as the user becomes more familiar with the development approach and learns to re-apply lessons learned from previous development iterations and re-use previously developed algorithms.

A Feedback Control System (FCS) was developed through the use of the suggested framework. The FCS developed in the simulation environment was tested for generic functionalities and then implemented on a hardware platform featuring X-by-Wire capabilities. The specifics of the FCS relating to real-world scenarios were identified during the implementation and the short comings were addressed by modifying the FCS. The modular and structured design the FCS as an outcome of following the framework facilitated the fine tuning of the developed feedback control algorithm resulting into an efficient design process.

As a consequence of the modular architecture, the development process aids in certifying systems in a modular fashion. Safety and security was also considered during the development of the framework since, these aspects have much relevance in the network world and ignorance towards these aspects could affect the safety of the passenger as a result of malicious attacks.