\begin{acknowledgements}
In the name of Allah, the Most Gracious and the Most Merciful.
Alhamdulillah, all praises to Allah for the strengths and His blessing in completing this thesis.\\ 
the proper shape of this thesis. During my PhD studies in UKM, I learnt a lot from him not only about research but also about life. One simply could not wish for better or friendlier supervisor. I would also like to express my deep and sincere gratitude to my co-supervisor Dr. Yuzita Yacob for her endless support, understanding, kindness, and great co-supervision.\\
I would also like to extend my appreciation to my sponsor, the Ministry of Higher Education of Iraq and my employer, Foundation of Technical Education, for the funding given to fulfil my PhD studies.\\
For my colleagues in the Mechatronics and Control Systems Group, past and present, for their useful discussions and also advice, thank you very much.\\
 words could not express how much I appreciate and thank you for the unconditional love, kindness, support, sacrifices and 
understanding during the most difficult times of the completion of this thesis. 
And at the same time to my precious three, Abdullah, Yousif, and Hassan, please forgive me for being unable to be around with all of you as much as I would really love to. Without your sacrifices, this thesis would not have been possible. And to those who have come across my life throughout the duration of my life, thank you for all the wonderful moments.
\end{acknowledgements}