Science Spin March 2008 : Sponsored Content - NUI Maynooth

Designing safer cars

With a funding from the Purdue University at West Lafayette, located in Indiana, USA, he commenced the MSc programme in the School of Aeronautics & Astronautics with a focus on dynamics and control. He initially conducted research in the area of orbital mechanics, which aims to model motion of objects in the planetary system. But towards the end of his masters programme, he developed a bigger interest for the general area of control theory. Control engineering, as a discipline, is about mathematical modelling of dynamical systems, and it utilizes control theory to design controllers that will cause systems to behave in a desired and stable fashion. Also, many engineering (mechanical, chemical, aerospace, etc.) and non-engineering (e.g., finance, sociology, biology) disciplines overlap with control engineering, as the results of control theory can be applied to any dynamical system, where a mathematical model can be derived to describe the dynamics.

One of Selim's lecturers at Purdue University, Prof Martin Corless, recommended him to apply for a PhD at the Hamilton Institute, which is an applied mathematics research center located in NUI Maynooth. Having been impressed by the institute's multidisciplinary research environment, and with generous support from Science Foundation Ireland, Selim commenced his PhD studies under the guidance of Prof Robert Shorten in 2003. During the first year of his PhD, Selim worked as a visiting researcher at Daimler Chrysler Research AG in Esslingen, Germany, where he had first hand experience with the state of art research in automotive dynamics control. Motivated by this, he was involved in the development of novel estimation and control algorithms for automotive vehicles since his return to the Hamilton Institute in October 2004.

For Selim, automotive vehicles are particularly interesting among other engineering systems due a number of reasons. First of all, vehicle dynamics control is very challenging due to cost constraints, which forces researchers to think of new and radical ways of utilizing existing sensors and actuators. While designing controllers for other engineering systems, there are fewer constraints with regards to the availability of sensors, actuators and the processing power; so if you need an extra sensor or a faster processor you just include these in the development process of your product and the cost is usually justifiable with your customer.

However, when it comes to cars this is not the case. Improving or adding new safety systems to cars and keeping production cost at low levels often involves conflicting requirements, and this is why control engineers such as Selim spend weeks and months on trying new software algorithms to improve the way we drive. Another reason why Selim finds this area interesting is because there are still many open problems centred on safety, efficiency, and driving dynamics enhancement. Selim also believes that improvements in vehicle safety and fuel efficiency can have significant impact on our society. Considering the fact that the global vehicle fleet is in the range of hundreds of millions makes it easier to understand how environmentally friendly vehicles equipped with a range active/passive safety systems can affect our society.

During his PhD programme Selim worked on several theoretical problems on the stability of switched dynamical systems, which are motivated by and applied to the control of automotive dynamics. Selim believes that viewing a car as a switched dynamical system is rather a radical approach for designing control systems for cars, as the current industry practice for designing active control systems is often based on dynamical models with fixed and known parameters. While they simplify the design and development process, the assumptions of known and fixed parameters are too optimistic, which necessitates studying alternative methods to take this changeability into account for improved robustness and performance. Selim studied many such methods during his PhD for a particular vehicle dynamics problem known as the rollover.

Statistically, vehicle rollover causes the highest number of passenger fatalities among all car accidents and its prevention can save hundreds of thousands of lives worldwide. Although there are a number of active/passive rollover prevention systems in the market, the high cost of such systems prevent them to be adopted in the automotive industry. Selim has found that one of the most important factors for rollover occurrence is the center of gravity (CG) position of the car, which can change depending on the number of passengers as well as the amount of the load on the vehicle. Accordingly, he developed an algorithm that can estimate the changes in the CG position utilizing the existing vehicle sensors such as lateral acceleration, yaw rate, steering angle and spring displacement sensors, which are available as part of other safety control systems.

The estimation of the CG position can then be used to warn the driver about the impending rollover, or alternatively, the estimation can be used in conjunction with the brakes or the steering system to automatically prevent the accident. Selim sees a significant commercial potential for this technology in the near future as the technology requires no additional hardware and it can potentially be implemented in existing electronic control units. For taking his ideas to the market, Selim has been working closely with the NUI-Maynooth technology transfer office, as well as Enterprise Ireland.

Another recent achievement for Selim was the securing of a research grant from Enterprise Ireland for developing a device to recognize the hand gestures of a driver. Selim hopes to develop his idea to enable new and alternative ways to interact with cars. He also thinks that this new technology will help prevent drunk driving, and it may be useful for enabling disabled persons access to cars.

Selim finished his PhD in November 2007; he has been employed as postdoctoral researcher at the Hamilton Institute since then. During and after his PhD he authored many articles which were published in leading academic journals, and were presented in major control conferences, worldwide. Selim is teaching two control related subjects in the NUI Maynooth electronic engineering masters program and he also supervised two master theses. Selim is also helping with a mathematics competition organized by the Hamilton Institute, which is aimed at secondary school students of all ages, who are studying mathematics at any level.