The practical possibility of a guaranteed return of budget unmanned aerial vehicles (UAV) to area of the starting point in event of loss radio communication with a video camera or control panel is considered. In this regard, an experimental model of a flying wing with wingspan of 1000 mm and a flight weight of up to 500 g was built, on which a flight controller SPRacingF3 based on the STM32F303 microcontroller with a GPS receiver and a directional video camera was installed to provide FTP flights. Based on INAV firmware, main attention was paid to setting flight modes NAV RTH, NAV FAILSAFE to ensure a guaranteed return. The practical possibility of using GPS Rescue mode for Betaflight firmware to return quadrocopter to a point close in take-off coordinates was also considered. In this regard, an experimental prototype was built with a 250mm frame, but with which OMNIBUSF4V3 flight controller was installed based on STM32F405 microcontroller with a GPS receiver and a heading video camera for FTP flights. During flight tests, it was shown that GPS Rescue mode allows you to return UAV to the launch zone, subject to the settings presented in the work on the assembled quadcopter. When performing GPS Rescue mode, an important condition is the stable connection of GPS receiver with the number of satellites not less than those installed when setting up the firmware. It is established that for the return of UAV of the considered types it is not necessary to use a barometer and magnetometer, functions of which can be performed by GPS receiver.

The design of a copter has been carried out, that can be used to set up air interference, reducing the probability of impact of the enemy air defense systems, reconnaissance operations, and the transfer of military cargo. The developed hexacopter is capable of carrying a useful load of 2.5-3.0 kg, at a speed of up to 45 km/h, based on a Pixhawk family flight controller using the Arducopter firmware. Stability of the flight of a quad-copter on a frame of 850 mm during a gusty wind of 7-8 m/s in navigation modes for firmware Arducopter ver.4.0.7 has been experimentally tested. The use of software dy-namic notch filters to reduce the impact of vibrations from running motors on the readings of the accelerometer and gyroscope is considered.

In the work on the basis of Arduino Mega and the W5100 controller, a web server is built for graphical display of remote client data obtained from temperature, pressure, humidity sensors. The server program is written in the Arduino IDE development environment. The Ethernet library for the W5100 has been updated, which for Arduino IDE ver. 1.0.3, 1.0.5-r2 caused the server to hang. The possibility of using the Dygraphs library for graphical visualization of data obtained with sensors is shown. Written scripts for drawing graphics for the projected web server. The data transfer rate from the Arduino web server for various network controllers ENC28J60, W5100, W5500 for the Arduino IDE programming environment and UIPEthernet, Ethernet, Ethernet2 libraries was analyzed. It is shown that with the lowest speed the data is transmitted by the web server with the ENC28J60 controller - 3.3Kb/s, with the largest controller W5500 - 23.4Kbytes/s. It is noted that these servers do not support multithreaded work. Therefore, they can not be used to create miniature universal web servers for processing multiple requests simultaneously. The server considered in the work can serve only one request from one remote client. The speed parameters of data transfer for the server on the ATmega328p microcontroller (Arduino UNO) with the network controller ENC28J60 are analyzed. The server program is implemented in C language in the AVR Studio programming environment. A high data transfer rate of 140Kb/s and a possibility of multithreading are noted. It is established that with simultaneous transmission of three files to different clients, the total transmission speed reaches 120-130Kb/s, and for each client 40-50Kb/s. It is shown that the use of such a server to solve the problem of graphical representation of data from sensors is difficult due to the complexity of transferring software to other microcontrollers and the limited library for working with a microSD card. The operation of the server developed here for three years has shown high reliability of its operation. The paper discusses the creation of a web server on the Arduino, which is a modernized HTTP basic authentication. The upgrade consists in the fact that for authorization a password is used from the list of passwords that is selected by the user on the basis of the key sent by the server. With each new login to the server, the previous password becomes invalid. Presents a practical example of a web server on Arduino Mega, Ethernet controllers: enc28j60 and w5500.

The paper considers the practical possibility of tuning the PID controller parameters for the cleanflight firmware family of unmanned aerial vehicles (UAVs) of a rotor type and with a fixed wing during flight. It is shown that this requires the use of radio control equipment with a minimum number of channels equal to eight. An unmanned aerial vehicle (UAV) has been developed based on the OMNIBUSF4V3 flight controller with a built-in gyroscope and accelerometer, BMP280 barometer / altimeter. The scheme of connecting the 3-axis compass HMC5883L via the I2C bus and the GPS receiver u-blox NEO-6M to the controller port UART6 is developed. The firmware used is INAV ver.2.2.1, which supports navigation functions. The designed quadrocopter (UAV) is capable of performing the following flight modes: ANGLE - automatic roll and pitch alignment with horizon angle control, the set value of which cannot be exceeded, thereby achieving stable flight. A gyroscope and an accelerometer are used here to hold the horizon. NAV ALTHOLD - hold height. A barometer is used here, which helps to maintain altitude by air pressure. NAV POSHOLD - a position is being held. Uses GPS. NAV RTH (Return To Home) - return home to the take-off point. NAV WP - flight along a given path, which is approximated by waypoints. In this case, waypoints with such parameters as altitude and its flight speed are superimposed on the selected terrain map in the configurator. For low engine speeds, the possibility of using the AIR MODE mode to increase the efficiency of the PID controller is shown. The possibility of using the program STM32 Flash loader demonstrator as a programmer for flashing the flight controller OMNIBUSF4V3 with any Cleanflight family firmware is shown. It was found that for setting the parameters P, I, D it is possible to use a three-position switch on one of the control channels and a variable resistor on the other channel. If the resistor is calibrated to three positions, three parameters can be adjusted, and five parameters to five positions. The issue of tuning the flight stability of the copter is considered. With a sharp increase in the throttle, a crash of the copter in one of the sides and its fall is possible. It was established that in order to prevent this, it is necessary to use identically selected ESC controllers, motors and the correct setting of PID parameters, in particular according to YAW.

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