The objective of this study is to design a Controller that is stable under varying conditions of system parameters from the trim conditions and also robust for parametric variation for an Unmanned Air Vehicle (UAV) System. The PID and Sliding Mode Controller are the control models for the UAV system that are studied, designed and analyzed. The proposed Sliding Mode Controller was applied to a nonlinear second order system (Single Input Single Output (SISO)) and tested for stability and robustness of the system for parametric variation. The control model indicated chattering effect with switching (signum) function. Therefore, in order to negate this chattering effect Saturation and ATAN functions were proposed for the control input. It was observed that the modified system demonstrated robustness in presence of parameter uncertainties such as inertial mass, stiffness, damping, input gain and nonlinear gain. The same model is tested with a PID Controller and observed that the controller is stable but the tracking error is 10 times more than the sliding mode controller, this is due to inability of the linear PID controller to control nonlinear systems. The sliding mode controller was then extended to control a Single Input Two Output system for parametric variation. It was observed that the controller was able to stabilize the system and make the system robust. Then, Sliding Mode Controller based on Switching theory and Lyapunov's theory was designed for Unmanned Air Vehicle System under uncertainty conditions. Stable sliding mode and robust asymptotic stability in uncertain UAV systems were investigated for variation in Velocity and Angle of Attack parameters. Finally, simulation results are presented to show the effectiveness of the design method.

Library of Congress Subject Headings

Sliding mode control; Vehicles, Remotely piloted; Lyapunov stability

Publication Date


Document Type


Student Type


Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)


Agamemnon Crassidis

Advisor/Committee Member

Mark Kempski

Advisor/Committee Member

Alan Nye


Physical copy available from RIT's Wallace Library at TJ220.5 .V36 2003


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