Project Overview

Executive Summary

Oregon State's 2019-2020 AIAA Micro Air Vehicle (MAV) team was tasked with designing a small coaxial helicopter worthy enough to compete in the annual Vertical Flight Society MAV Student Competition. The Electrical Engineering subteam was responsible for designing and implementing a robust flight control system for the MAV. Their goal was to create a system capable of achieving hover stability while carrying dense payloads, and processing data from onboard sensors to transmit to the pilot. To meet this goal, the team developed three custom PCBs, custom flight control firmware, and selected all the peripherals to meet competition specifications.

The phase of development was researching and understanding the MAV design of years past. The VFS MAV competition sees many quadcopter designs due to their mechanical simplicity - with a quadcopter design, four motors are connected four fixed-pitch props. However, our team was inspired by the implementation of last year's design, we decided to favor the coaxial helicopter due to its superior stability, efficiency, and unique construction to the competition. With a coaxial design, there are only two sets of rotors on the helicopter and they are stacked on top of each other.

Once the overall direction of the helicopter was decided, the team moved on to the design phase of their development plan. The electrical subteam started with the plans from last year's team and made considerable improvements and changes to them. Among some of the most signifigant changes were:

• Infrared Time-of-Flight sensors were used in favor of ultrasonic sensors due to their smaller footprint, electrical efficiency, and simplicity to implement.
• A Teensy 4.0 microcontroller was used in favor of the AVR ATMega328P due to a greater power-to-package ratio to handle data processing of the MAV sensors, and rudimentary integration with the overall system.
• Self stabilization algorithms were designed using PID controllers in the flight control firmware
• Optical encoders were mounted onto the motors to provide RPM feedback to the self stabilization algorithm.
• New, larger motors were selected to matched the increased weight limit of the new competition rules.
• Among several more...

The team spent several months implementing the designs they had created and began work on integrating them together. There were several changes and revisions made to the design. Once the essential blocks were working, the team began integrating and testing all of the components from their design. Multiple test flights of the MAV were performed before work had to stop in March because of COVID-19. At that point, the MAV could take off, but it was very difficult to fly. The self stabilization algorithm was not tuned and the team could only get the MAV to take off with the algorithm disabled. Future plans were made to tune the PID controller on the MAV, but those plans were not realized.

The final result of this project was signifigant progress in the development of OSU AIAA's MAV team. Hopefully the work done by the team this year will carry on as future teams pick up the project and aim to compete in the Micro Air Vehicle Student Competition!