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2 Journal of KONES

2 2017

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Propeller optimization for small unmanned aerial vehicles

Kusznir T., Smoczek J.

Journal of KONES

2017

Vol. 24, No. 2

125--132

Small-unmanned aerial vehicle propellers usually have a low figure of merit due to operating in the low Reynold’s number region due to their size and velocity. The airflow on the airfoil becomes increasingly laminar in this region thus increasing the profile drag and consequently reducing the figure of merit of the rotor. In the article, the airfoil geometries are parameterized using the Class/Shape function transformation. Particle swarm optimization is used to design an airfoil, operating in a Reynolds number of 100,000, which has a high lift to drag ratio. To avoid exceeding geometric constraints of the airfoil, a deterministic box constraint is added to the algorithm. The optimized airfoil is then used for a preliminary design of a rotor; given some design, constraints on the tip chord the rotor radius and the blade root chord, with parameters that achieve the highest theoretical figure of merit. The rotor parameters are obtained using a combination of momentum theory and blade element theory. The figure of merit of an optimal propeller with the same geometric parameters is then compared using the optimized airfoil and the Clark Y airfoil. The optimization is done in MATLAB while the aerodynamic coefficients are obtained from XFOIL. The results of the numerical simulation are presented in the article.

Fuzzy-Lyapunov based controller for a quadrocopter

Kusznir T., Smoczek J.

Journal of KONES

2017

Vol. 24, No. 4

125--132

Quadrocopters are nonlinear and inherently unstable systems. To be able to account for the nonlinearities during more aggressive manoeuvres nonlinear control methods need to be utilized to obtain the desired position while at the same time guaranteeing stability. In the article, the quadrocopter dynamics is modelled using the Newton-Euler method. The propeller aerodynamics is modelled using a combination of momentum theory and blade element theory. There are two different control objectives; the 1st objective requires the quadrocopter to reach a desired attitude set point using, while the 2nd objective requires the quadrocopter to track an attitude trajectory. In both cases, Lyapunov stability criterion, in conjunction with LaSalle’s invariance principle, is used to guarantee the system becomes asymptotically stable. In the case of reaching the desired attitude set point, a direct Lyapunov control method is implemented with the control constants determined empirically. For the trajectory tracking, limited knowledge is assumed on the system dynamics and the Mamdani fuzzy controller is used with a rule base that satisfy the Lyapunov stability criterion. The fuzzy membership functions developed empirically and a centre of gravity defuzzification method is used. All simulations are done in MATLAB/Simulink. The results of the numerical simulation are presented in the article.