Rotation Speed and Air Flow Sensors
Supervisor: Associate Professor Shaohui Foong (AIR Lab), carried at SUTD in 2018 - 2020
Whisker-like Sensors with Soft Resistive Follicles
Supervisor: Assistant Professor Pablo Valdivia y Alvarado (BRD Lab), carried at SUTD in 2017
Summary
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 60m/s, a range in which anemometers commonly saturate at. Consequently, the developed RSS can measure frequencies up to 10Hz 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.
Publications
Federico Fries, Shane Kyi Hla Win, Emmanuel Tang, Jun En Low, Luke Thura Soe Win, Pablo Valdivia y Alvarado and Shaohui Foong, Design and Implementation of a Compact Rotational Speed and Air Flow Sensor for Unmanned Aerial Vehicles, IEEE Sensors Journal, July 2019.
DOI: 10.1109/JSEN.2019.2931002
This paper was featured by Science on the August 2019 issue: https://doi.org/10.1038/s41928-019-0298-y
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Federico Fries, Shane Kyi Hla Win, Danial Sufiyan bin Shaiful, Luke Thura Soe Win, Pablo Valdivia y Alvarado and Shaohui Foong, Control of a Transformable Hovering Rotorcraft (THOR) with Compact Rotation and Air Speed Sensors, IEEE Robotics and Automation Letters (RA - Letters) (work in progress).
Concept
Video
Soft Sensors
Summary
The perception of changes in the environment is essential for any robot to successfully navigate through its surroundings. Ongoing research on soft sensors is primarily directed to measuring strains. However, less work aims to provide position and navigation feedback. In this study, we present the design and fabrication of soft resistive sensors embedded into whisker follicles and the simple synthesis of a conductive composite by mixing 99% silver powder and a soft elastomer. Whisker follicles can be tuned to detect a specific frequency. These kind sensors are a simple, robust and straightforward method to detect changes in the environment. The performance is compared to bend sensors commercially available. Finally, a frequency detection experiment is presented to show the capabilities of the sensor.
(For more information on the conductive composite refer to the Composite Materials section)
Publication
Federico Fries, and Pablo Valdivia y Alvarado, Whisker-like Sensors with Soft Resistive Follicles, IEEE International Conference on Robotics and Biomimetics 2017 (ROBIO), Macau, China, pp 2038-2043.
Gallery
Video
Initially soft sensors found application in the field of soft robotics. Nonetheless, their durability, versatility, and multifunctionality allow them to be integrated in other types of devices such as underwater robots, UAVs and healthcare applications. I focus on the simple manufacture of such sensors, and their implementation in various fields.