Concept of the magnetic launcher for medium class unmanned aerial vehicles designed on the basis of numerical calculations

In the paper we present development work on an electromagnetic launcher (EML) for micro aerial vehicles (MAVs). The requirements of controlled take-off were shortly described and main advantages and disadvantages of the commonly used rubber and pneumatic launchers were enumerated. Concept, design and construction of the magnetic coil launcher were presented. The driving coils geometry determination with using the method, which was based on finite element method (FEM) and mechanical power analyses, was proposed. Finally, construction and assembling process of the device were described. In addition, the results of preliminary laboratory tests, control issues and controller target platform were mentioned.

Assisting in the starting procedure of Unmanned Aerial Vehicles (UAVs) is one of many very important areas of modern aviation research. Supported start-up saves fuel or electrical energy, increases operator safety and level of autonomy, extends the application area, and, in some applications, even enables the operator to shape the motion characteristics of the initial phase of a UAV’s flight. Currently used solutions, depending on an aircraft’s class, are based on the utilization of rubber, pneumatic or electromagnetic launchers. All of these launchers are used for the medium class of UAVs and all of them use the potential energy previously stored in stretched rubber, compressed air or electrical voltage. In this paper, authors propose the novel concept of a launcher powered through kinetic energy stored in a rotary wheel driven by an electric motor. Using the transmission systems of the drive and the controlled clutch and an electromagnetic brake, it is possible to precisely control the speed and acceleration of the launched object. Within the paper, the authors present and discuss the applied equations of dynamics, the results of a simulation that was carried out using the MATLAB/Simulink software and a conceptual CAD model of preliminary engineering solutions for the kinetic UAV launcher. The work is summarized in the conclusions section, which details the practical implementation of the device.

This paper describes the process of a coil launcher parameters selection. Objective function Θ was defined and crucial variables were sought. The electro-mechanical system consisting of a copper coil and a ferromagnetic core was designed. Displacement of the core was computed. The magnetic force and coil inductance were calculated in many core position in relation to solenoid. Simulations were done by means of Finite Elements Method (FEM). The model parameters were being changed and the best system geometry was sought. In order to achieve better legibility, the research results were shown in the graphs. Selection process turned out to be very complex. In order to determine the best device parameters, the currents thermal effects should be taken into consideration. As the final conclusion some constructional conceptions of the magnetic launcher were proposed. The research will be continued to improve the coil launcher optimization process. The aim of future investigations is to achieve greater magnetic force and lower inductance of the electro-mechanical system.

In this paper we describe numerical model and designed construction of the EML consisting of 10 coils with a moving ferromagnetic core inside. Friction coefficients were introduced into the system equations and next we proposed an algorithm which enabled us to fit the numerical model to the constructed device. In the paper we present comparison of the signals from computer simulations and measurements which were taken during laboratory and field trials.

The paper presents a model of the 10-coil launcher, which can be used as a catapult of micro aerial vehicles (MAVs). The main advantage of such a device is the possibility of controlling its acceleration. We have also shortly described main disadvantages of pneumatic and rubber launchers and compared them to our solution which involved magnetic phenomena. The history and the classification of magnetic launchers were also mentioned. The investigated magnetic system was described in details. The system voltage equations and energetic conversions which take place during the launch were presented. With the use of finite element method we calculated the lumped parameters of the system (self-and mutual inductances). Nonlinear model was implemented in the MATLAB packet. Launch operation was divided into an acceleration and a braking phase. Thus, nine coils operated as accelerators and the last one was employed as a magnetic brake. The system was controlled by means of PID regulators which were tuned manually. Current values in the modelled coils were also limited by bang-bang controllers. In the last part of the paper we presented results of simulations and discussion about possible improvements of the model in the future.