PhD Thesis Develops Fault Estimation and Tolerant Control Strategies for Nonlinear Systems

The Department of Electrical Engineering has awarded a PhD degree to Ru’a Hamid Ahmed for her thesis titled Observer-Based Fault Estimation and Fault-Tolerant Control Approaches to Sustainable Operation of Nonlinear Systems. The research focuses on developing advanced strategies to estimate and manage faults in nonlinear systems, ensuring their sustainable and efficient operation.

Innovative Fault Estimation Strategies

Ru’a’s thesis introduces two cutting-edge fault estimation strategies for linear systems:

1. Adaptive Unknown Input Observer (UIO):
   This approach estimates sensor faults while isolating the effects of frictional forces, ensuring precise fault detection in dynamic systems.
2. Sliding Mode Unknown Input Observer (SMUIO):
   This strategy estimates system states, actuator faults, and implicitly sensor faults without increasing the observer’s complexity, offering a robust and efficient solution.

Fault-Tolerant Control for Nonlinear Systems

The research also developed a Takagi-Sugeno Multiple-Model Sliding Mode Observer (TSMMSMUIO). This innovative observer is integral to a fault-tolerant control (FTC) framework for nonlinear systems affected by time-varying actuator and sensor faults. Key highlights include:

• A novel estimation/separation technique eliminates bidirectional interaction (BDI) between estimated sensor and actuator faults.
• Achieving robust fault reconstruction, independent of the faults’ temporal behavior, by decoupling observer dynamics from sensor fault effects.
• Utilizing the difference between measured signals and observer state signals to implicitly estimate sensor faults, while the observer directly estimates actuator faults.

Committee Evaluation

The thesis defense was conducted under a distinguished panel chaired by Dr. Ahmed Taha Abd Al-Sada. Committee members included Dr. Abdul Rahim Diyab Hamoud, Dr. Sefana Mazhar Raafat, Dr. Farzad Rafiq Yassin Taha, Dr. Iman Saleh Karim, and Dr. Montadhar Sami Shakir, who also supervised the research.

The committee praised the thesis for its advanced methodologies and practical applications in fault-tolerant systems, making a significant contribution to the field of sustainable nonlinear system operations.