UHMC students win 2020 AAS International CanSat Competition
KAHULUI — The Agdeppa family, residents of Lahaina and throughout Maui, are proud of Arthur Agdeppa, a student at University of Hawaii Maui College (UHMC), for his role as leader of Team Onipa’a in the college’s Engineering Technology Program.
UHMC sent two teams to the American Astronautical Society (AAS) 2020 International CanSat Competition. Team Onipa’a placed first and UHMC Team Paka’a placed 23rd.
Thirty-three teams from more than a dozen countries around the world entered the final phase of competition that required teams to design, build and launch a container holding a science payload.
AAS organized and hosted the annual ten-month-long event to inspire future engineers seeking creative solutions. The UHMC teams were sponsored by the NASA Hawaii Space Grant Consortium.
The 2020 competition challenge was to design a glider capable of unpowered flight and autonomous navigation after being launched to altitude by a rocket stage. Teams followed the design phases and structure of a standard NASA project with a Preliminary Design Review (PDR), Critical Design Review (CDR), Launch Operations, and Post Flight Review.
Only the top teams from around the world were selected to continue after the PDR evaluation. A majority of those chosen were from countries other than the U.S., such as Turkey, South Korea and India.
“The CanSat competition is designed to reflect, on a small scale, a typical NASA aerospace program,” said faculty advisor Dr. Jung Park, associate professor, UHMC Engineering Technology Program, and associate director, NASA Hawaii Space Grant Consortium.
“The challenge included all aspects of a space program from the preliminary design review to the post mission review, which incorporates the telemetry requirements, communications, autonomous operations and sensor data collection, while withstanding the extreme forces of a rocket launch. The CanSat project this year had to be judged only by PDR and CDR. The rocket launch at Virginia Tech was canceled because of the COVID-19 pandemic.”
“Our team developed designs, prototype, test concepts and generated a PDR slide package using the provided template,” said Onipa’a Team Leader Agdeppa.
“The electronics and ground control station software were designed, fabricated and confirmed operational in a test environment per CanSat specifications. The team designed and 3D-printed the mechanical parts, and the closed-loop control system Arduino code was written and simulated in Matlab. The results showed that the critical payload systems are designed to operate in the conditions outlined in the CanSat Competition Mission Guide.”
As the teams finalized their design and started ordering components, manufacturing parts, testing subsystems and developing the flight unit, they generated a CDR slide package using the provided template. They submitted CDR slides only in PDF format at the designated due date, and had a half hour to discuss a subset of the CDR slides via teleconference.
“In real missions, direct communications between a ground station and satellite may be limited to small-duration ‘passes’ during which data stored on-board the spacecraft is transmitted in bursts to the ground,” said Agdeppa. “It is often possible to utilize data relay satellites, such as the Tracking and Data Relay Satellite System, which provides a beyond-line-of-sight data relay between the spacecraft and ground tracking stations.”
Agdeppa reflected, “We were fortunate that our team finished our preliminary design and prototype building before our school shifted to virtual. Our team bonded and got to know each other well by then. The glider control system and all sensor data telemetry had already been fully operational. During the online-only, my team members and I were fine-tuning our assigned subsystems and finishing critical design write-ups. We often collaborated via Discord about the project, and we did our weekly progress report through Zoom with our advisor. Dr. Park. With our laptop connected via home internet or the UHMC outdoor Wi-Fi, we shared our ideas as if we were in the same room.”
Just as with a real satellite mission, the design team had to organize the work into tasks and sub-tasks, and then give close attention to every aspect of the system’s design and operation:
The payload designed by Team Onipa’a was split into subsystems to simplify the complex and challenging project. The subsystems defined were the sensor subsystem, descent control subsystem (DCS), mechanical subsystem, flight software (FSW), electrical power subsystem (EPS) and ground control station (GCS).
The sensor subsystem included all of the components required to operate the payload and gather specific data of interest outlined in the mission guide. To operate the glider, the flight software had information about its orientation and coordinate position. To comply with the mission guide requirements, the glider also collected and transmitted other environmental data, including the cleanliness of air particulates, true airspeed, temperature, humidity and power source health.
Descent Control Subsystem
The DCS included all of the mechanisms the glider used to control descent throughout the different phases. During the first phase of flight, the glider navigated in a 250-meter radius circle for one minute by using elevons attached to servo motors actively controlled by a closed-loop proportional-integral-derivative (PID) controller. The elevons were 3D-printed using PETG filament, a plastic used commonly in the production of water bottles. After the first phase of flight was completed, a parachute was deployed, and the active flight control surfaces were disabled.
The mechanical subsystem included all of the mechanisms and components on which the glider relies for structural integrity, orientation control and deployment. The two primary components of this system are the payload and the container in which it launches. The container is a simple 120-millimeter diameter cylinder with a height of 300mm.
To achieve maximum wing surface area while also being able to fit in the canister, the aircraft wing is foldable. A spring-loaded piston pushes the payload out of the container when it reaches an altitude of 450 meters. The payload unfolds its wings upon deployment using high-temperature silicone rubber.
The FSW included all of the algorithms loaded onto two payload microcontrollers. The first of two microcontrollers was solely dedicated to communicating with all of the sensor subsystem components. Orientation and navigation data were passed off to a second microcontroller dedicated to the control system. Calculations to actively maintain glider orientation and update setpoints for navigation about the 250-meter circle were done in these algorithms. A real-time clock and the EEPROM of the ATMega328P microcontroller board were used to recover from catastrophic in-flight failure by storing and extracting critical variables.
Electrical Power Subsystem
The EPS included all the components that power the electronics, including the battery, fault monitoring system and the power distribution system. The EPS featured power and reset switches, lighting and sound indicators for real-time visual and audio cues, and constant payload protection devices. A five-volt voltage regulator down-converted the 8V power supply used to power most sensors onboard the payload. The primary power source was utilized for high-amperage applications such as nichrome wire deployment via an IRF520 MOSFET switch and Arduino voltage regulator.
Ground Control Station
The GCS included a laptop computer operating a Graphical User Interface (GUI). The GUI was developed to display the flight data and allow the operator to monitor the stages of payload operation from start to finish, ensuring the performance of the flight systems throughout the launch. It collected data from the Xbee via a serial port and updated the GUI, which was created in Matlab.
The project’s results were prototypes for the EPS, FSW, GCS and sensor subsystem. CAD visualizations showed mechanical conformity between all designed subsystems.
A board of AAS engineers judged the results. Results for PDR, CDR and a cumulative competition score were released on June 16, 2020.
UHMC Teams Onipa’a and Paka’a ranked first and 23rd, respectively. The CanSat 2020 results are posted at http://cansatcompetition.com/winners.html.
Agdeppa concluded, “Each member of my team offered a diverse set of expertise, views and knowledge, which was optimal to integrate various subsystems of our science payload and container. They took responsibility and pride in their weekly assigned tasks, and they welcomed the CanSat competition opportunity. It pushed us to be creative in our design, be resilient in our failures, and to be team players. One of our project’s external objectives was to promote STEM (science, technology, engineering, mathematics) in our community and gain the confidence of young aspiring engineers. We hope that our winning the competition accomplished just that. The CanSat project was also an excellent way for us to showcase all that we have learned at UHMC.”