Design and Implementation of a Compact Rotational Speed and Air Flow Sensor for Unmanned Aerial Vehicles

Unmanned aerial vehicles (UAV) have gained massive interest due to their wide range of applications. In this work, we focus on the design of compact rotation speed sensors (RSS) and air flow sensors (AFS) that can be integrated into nature-inspired monocopters UAVs which generate lift by spinning at high frequencies. Combining barometric sensors and sensing elements embedded into soft elastomers, compact, accurate, reliable, and low power sensors that can measure rotation and air flow speed can be fabricated. Through numerical analysis and design, it is possible to customize the sensor to measure rotation speed or air flow at specific operating ranges. The AFS was experimentally capable of measuring airflow speeds up to 60 m/s, a range in which anemometers commonly saturate at. Consequently, the developed RSS can measure frequencies up to 10 Hz accurately, whereas inertia measurement units (IMUs) saturate at 5.5 Hz. Finally, the RSS sensors were mounted on a monocopter prototype, to evaluate and assess the sensors under actual flying conditions, where the UAV's movements were tracked by an onboard flight controller's (Pixracer) in-built IMU as well as a high accuracy external optical motion capture system (OptiTrack). The RSS proved to be a reliable alternative to IMUs for navigation control of Monocopters.