Chapter 1: Introduction -- Chapter 2: Disturbance Observer-Based Backstepping Control of Tail-sitter UAVs -- Chapter 3: Energy Efficient Bi-Quadrotor Powered by Li-ion Battery for Payload Delivery -- Chapter 4: Adaptive Backstepping Controller Design Of Quadrotor Biplane For Payload Delivery -- Chapter 5: Biplane Trajectory Tracking Using Hybrid Controller Based On Backstepping And Integral Terminal Sliding Mode Control -- Chapter 6: Observer Based Rotor Failure Compensation For Biplane Quadrotor With Slung Load -- Chapter 7: Dual Observer Based Adaptive Hybrid Controller For Hybrid UAV -- Chapter 8: Biplane Quadrotor With Total Rotor Failure: A Novel Approach.