Design, development and implementation of a UAV flight controller based on a state machine approach using a FPGA embedded system

Abstract

This article presents the development of a fixed-wing UAV flight controller using a complete parallelism embedded system as a FPGA. Many solutions for UAVs flight controllers are based on embedded sequential systems. However, these systems are not perfect. The greater number of processes and tasks being executed simultaneously, the more variables such as precision, speed of response and synchronism may suffer. Our proposed flight controller solves this problem because it is based on a concurrent system and can therefore, execute many processes at the same time. The development of this flight controller represents just one part of the “Drone Bosco” project, where university students from Universidad Don Bosco are constructing the first UAV designed completely in El Salvador. The solution was designed and implemented taking into consideration specific characteristics of other areas of the project such as Radio Control Systems, Power Generation Systems and Aerodynamics. These considerations are outlined in this article. The flight controller is based on a state machine system that migrates from state to state depending on the stimulus received from sensors like accelerometers, tachometers, compass, pitot, GPS, etc. Another feature developed in this project is an emergency system that provides enough intelligence and robustness to secure the integrity of the aircraft in case a problem occurs during missions. Features like high speed of response, adaptable calibration and parallelism are achieved with our solution. Moreover, given that many parameters are generic, it has the flexibility to migrate to other fixed-wing UAVs with different characteristics. A similar approach could be applied in the future for the development of other devices that need navigation controllers with these characteristics, for example rockets or rovers. The results obtained in the simulations and tests of the flight controller system are described in detail in this article.