Designing a Sliding Mode Controller for Fixed-wing Unmanned Aerial Vehicle for Medical Supply Mission
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Date
2021-11
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Addis Ababa University
Abstract
Over the past many years, the application of unmanned aerial vehicles (UAV) has increased. UAV’s such as this has become an easy solution to tasks that are difficult and dangerous. Because of its highly non-linear and coupled nature, the control problem seems to be a challenge. As a contribution to this area, this thesis presents the modeling and control of a fixed-wing unmanned aerial vehicle for medical supply mission such as delivering blood, medicinal drugs and test kits to remote areas. The overall research work stars with conducting a literature survey to review thoroughly the works that has been done with regard to the subject matter to identify the gaps. Then after a careful mathematical modeling of the system using the Newton-Euler formalism was done. Furthermore, longitudinal and lateral-directional motions are addressed separately to minimize the coupled nature of the dynamics. The model was validated by considering two flight scenarios and in both scenario’s, it meets the expected requirements. After model validation the next task performed was designing the controllers for regulation and reference tracking problems using the classical & super twisting sliding mode controller techniques. The simulation results shows that the classical sliding mode controller produces a faster response time, 1.75 seconds for roll angle, 2 seconds for pitch angle and 7 seconds for yaw angle but it suffers from an associated high frequency chattering problem in the control signal whereas the super twisting sliding mode controller eliminates the high frequency chattering problem in the control signal but takes 9 seconds to stabilize the system. The results show that despite a relatively large response time the elimination of the associated high frequency chattering problem in the control signal makes the super twisting sliding mode controller preferable.
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Keywords
Fixed-wing UAV, Model-based design, Flight dynamics, classical SMC, Super twisting SMC, Longitudinal Motion, Lateral-Directional Motion