摘要 :
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 establi...
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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 napping 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.
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摘要 :
Design and open-loop hover experiment of a 4-blade Mach-scaled Seoul National University Flap (SNUF) rotor equipped with an active trailing-edge flap is attempted. Its test is performed on the Seoul National University Rotor Test ...
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Design and open-loop hover experiment of a 4-blade Mach-scaled Seoul National University Flap (SNUF) rotor equipped with an active trailing-edge flap is attempted. Its test is performed on the Seoul National University Rotor Test Stand (SNURTS). First, the rotor hub is improved to withstand the centrifugal loads. In it, the original soft in-plane hingeless rotor hub used for blade optimal design is replaced by a rigid hingeless rotor hub. The multi-body dynamic analysis DYMORE and cross-sectional design tool VABS are used to design the new rotor hub adaptor for the flap blade by utilizing time-marching free-wake analysis. Preliminary hover test using two-bladed OLS teetering hub showed excellent repeatability of the SNURTS, but a torque level of 400N-m should be considered. Rotor test stand modal test response and servo kinematics are fully adjusted into the analysis model. Next, a single active flap blade test is performed to assess the flap driving component. The hysteresis of the flap driving mechanism is identified in a static bench test. Bench dynamic tests of the SNUF blade active flap showed that present flap actuation system has 4/rev bandwidth. In the future, flap deflections will be recorded for the 1-5/rev at 1300 RPM, where the tip Mach number is 0.6. The frequency response of the flap mechanism will be identified under hover centrifugal loads while the blades are still in-track.
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In this paper, a selection method of efficient electric propulsion system for small size fixed wing UAV using wind tunnel experimental data base. It will be discussed in three parts: measurements of propeller performance in wind t...
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In this paper, a selection method of efficient electric propulsion system for small size fixed wing UAV using wind tunnel experimental data base. It will be discussed in three parts: measurements of propeller performance in wind tunnel conditions, measurements of electric motor characteristics using dynamometer, and the developments of propulsion performance prediction method using experimental performance data of its components i. e., propeller and motor. Performances of propellers were measured at low speed wind tunnel at Chungnam National University. Test section of wind tunnel has 1.25 by 1.25 meter cross section area and maximum operational speed is 70m/s. 16 RC model propellers which has 9 to 14 inch diameter were tested, at a different operating condition of advance ratio, rotating speed, torque of propeller and speed of wind tunnel were acquired. As a validation of proposed method, predicted matching points were compared with experimental results. And propulsion performance of a 10kg class close-range mini-UAV was compared for the different propeller. At a cruise condition of that UAV, an optimum propeller can be selected by the developed analysis procedure, and the enhancement of endurance can be expected from propeller change.
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摘要 :
In this paper, a selection method of efficient electric propulsion system for small size fixed wing UAV using wind tunnel experimental data base. It will be discussed in three parts: measurements of propeller performance in wind t...
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In this paper, a selection method of efficient electric propulsion system for small size fixed wing UAV using wind tunnel experimental data base. It will be discussed in three parts: measurements of propeller performance in wind tunnel conditions, measurements of electric motor characteristics using dynamometer, and the developments of propulsion performance prediction method using experimental performance data of its components i.e., propeller and motor. Performances of propellers were measured at low speed wind tunnel at Chungnam National University. Test section of wind tunnel has 1.25 by 1.25 meter cross section area and maximum operational speed is 70m/s. 16 RC model propellers which has 9 to 14 inch diameter were tested, at a different operating condition of advance ratio, rotating speed, torque of propeller and speed of wind tunnel were acquired. As a validation of proposed method, predicted matching points were compared with experimental results. And propulsion performance of a 10kg class close-range mini-UAV was compared for the different propeller. At a cruise condition of that UAV, an optimum propeller can be selected by the developed analysis procedure, and the enhancement of endurance can be expected from propeller change.
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