Incremental Control System Design and Flight Tests of a Micro-Coaxial Rotor UAV

This paper proposes a control algorithm for controlling the position and attitude of a coaxial rotor drone without knowing the model dynamics. To overcome the major drawback of model-dependent approaches, an optimal model-free fuzzy controller (OMFFC) based on the estimation of the unknown dynamic function of the system is proposed. A time-delay estimation (TDE) technique is effectively exploited to approximate the unknown dynamic function of the system. The estimation error is then offset using a robust adaptive fuzzy logic compensator. Based on Lyapunov stability arguments, the global asymptotic stability of the coaxial rotor drone system is proven. Moreover, a flower pollination-based algorithm is also proposed to generate the optimal parameters to address the trade-off between optimal tracking performance and the design conditions related to the closed-loop stability requirements. The numerical simulations illustrate how the proposed methodology leads to the best performance, as well as less computational complexity compared to the standard proportional–integral–derivative and time-delay estimation-based controllers in the presence of external disturbances. 

Trajectory tracking control of a coaxial rotor drone: Time-delay estimation-based optimal model-free fuzzy logic approach.

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Incremental control system design and flight tests of a micro-coaxial rotor UAV

This paper investigates the attitude control problem for underactuated body-flap hypersonic vehicles (BFHSVs) with mixed disturbances. First, the control-oriented model for BFHSV is introduced. Then, an improved finite-time super twisting disturbance observer (STDO) is designed. Finite-time convergence of estimate error and smoother inputs are achieved. Meanwhile, a parametric command method is introduced to calculate the differential of inputs which can enhance the dynamic response of the closed-loop system. Subsequently, the virtual control signal is derived by a second-order filter to avoid the differential explosion problem. The overall stability of the closed-loop system is demonstrated by applying the Lyapunov stability theory. Finally, the performance of the proposed control scheme is evaluated through extensive and comparative numerical simulations under multiple disturbances.

/pdf/finite-time-super-twisting-disturbance-observer-based-1840ldwi.pdf

Finite-Time Super Twisting Disturbance Observer-Based Backstepping Control for Body-Flap Hypersonic Vehicle

This paper describes a sliding mode control (SMC)-based disturbance observer-based controller (DOBC) to improve coaxial helicopter UAVs' robust attitude control performance. A coaxial rotor aerodynamics test environment is established to select motors and propellers suitable for the propulsion system of a coaxial helicopter UAV. The motor rotation speed required for the operation of the UAV is identified, and the rotor diameter and motor are selected. Then, the aerodynamic data of the rotor are analyzed to calculate the aerodynamic coefficient. In this paper, a coaxial helicopter UAV is developed based on the rotor experiment. The developed UAV has a seesaw, feathering, and flapping hinge mounted on the blade hub like a typical helicopter. The numerical dynamics modeling consisted of the forces and moments of the propulsion and the body of the UAV using the aerodynamic coefficients for the rotor from aerodynamic experiments. The aerodynamic interference of the upper and lower rotors of the coaxial rotor acts as a disturbance to the UAV. In addition, this disturbance increases the model uncertainty and degrades the attitude-tracking performance of the controller. For robust attitude control against disturbance, in this paper, SMC-based DOBCs are designed and implemented. SMC is designed with angle, angular velocity, and altitude controllers in a cascade structure. DOBC is connected to the angular velocity loop to eliminate disturbances that are difficult to model and cannot be estimated by SMC. In the numerical simulation, disturbances are applied to the roll, pitch, and yaw axes, and model uncertainty is considered. The attitude-tracking performance of SMC-based DOBC is superior to that of SMC, and disturbance estimation and compensation effects are improved. The controller is implemented in the flight control computer (FCC) to check the controller's performance. A tether test environment and a hovering and attitude command tracking test of a coaxial helicopter UAV is conducted. 

Ke-wei Li

Papers

Research on a combinatorial control method for coaxial rotor aircraft based on sliding mode