An ultrasonic MEMS-based airspeed sensor for lightweight drones

Sammanfattning

This thesis is conducted together with the Swedish Sea Rescue Society (SSRS),where an ultrasonic airspeed sensor for lightweight fixed-wing drones is developed.The project acts as an alternative to the currently used sensor on the drone, whichis based on a Pitot-static system. The ultrasonic technique has shown significantpotential for airspeed measurement. This work further explores the technique withthe aim of developing a compact sensor design better suited for small aerial vehicles.To achieve this, ultrasonic Micro Electro Mechanical Systems (MEMS) are utilized.The developed prototype consists of three main parts. First, two transceiver moduleswhich are facing each other at a 45◦ angle relative to the airflow, enabling collectionof upwind and downwind data. Second, a microcontroller software that controlsthe transceivers and produces airspeed estimations. Third, a control circuit whichenables communication between microcontroller software and transceiver modules.The core of the airspeed estimation is based on the difference between upwind anddownwind data, along with different signal processing techniques.The results demonstrate that the prototype offers advantages in terms of size, weightand power consumption, with the potential to match conventional Pitot-static systems.Furthermore, the developed prototype is able to accurately record airspeed inone direction. It also demonstrates the limitations of this kind of hardware, as wellas the ultrasonic airspeed measurement technique in general.