Congratulations to Purdue University Northwest for being selected for Honorable Mention for Best Design, GSBC 2019. Text excerpt from their submission is below:
The purpose of this weather balloon flight is to measure and estimate total solar irradiance at different altitudes during the flight. A Pyranometer sensor system (Kipp-Zonen SMP10) is utilized to measure the solar irradiation; a Gyroscope and Magnetometer sensor is implemented to monitor the orientation of the Pyranometer; And a custom-made Data Acquisition (DAQ) and Filtering system is built to record and filter the solar radiation data from the Pyranometer and orientation data from the Gyroscope and Magnetometer sensor. All the above components are anchored on an aluminum frame that can withstand impact of landing and can be easily manufactured and light weighted. Meanwhile, a comparative solar irradiance measurement was conducted on the ground with a second Pyranometer mounted on the top of a vehicle that is roughly traveling at the same path as the first Pyranometer in the air.
Due to an electronic wire issue, the solar irradiance collection in the air was not able to cover the entire flight. However, the collected available data is sufficient to prove and support the finding that the solar radiation can be significantly increased at high altitude.
The renewable energy market share has grown rapidly in the recent decades and is expected to grow continually in the future as the fossil fuel resources decline. Current renewable energy collection effectiveness is determined by factors such as: locations, weather, land cost and so forth. Solar energy collection with solar panels, for example, is producing electric energy inconsistently and is adversely affected by the cloud casting and air pollutants. The conventional way of harvesting solar energy on the ground has being proved inefficient.
In the space, before the sun light enters the atmosphere, the strength of solar radiation is only affected by the distance away from the Sun. However, inside the atmosphere, the solar radiation will be scattered by small particles (such as water droplets, dust particles and clusters) and blocked by cloud castings, forming attenuated diffused radiation. Only a small portion of the original solar radiation can be unaffected and form Beam, or Direct radiation. Solar panels are only effective to certain high frequency radiation and will be affected by the atmosphere during the operation.
By reducing particles/diffusion, and less scatterings and blockages of sun light, solar panels can yield higher electric energy production. Complementing this, the recent idea of harvesting solar energy at high altitude creates a new opportunity and solution of harvesting the solar energy at greatly improved efficiency and consistency. To estimate and understand the potential of harvesting solar energy at high altitudes, our weather balloon flight facilitates and utilizes a pyranometer sensor to accurately map the solar irradiance at different altitudes.
MATERIALS AND METHODS
To take the measurement of solar radiation at different altitudes, listed components are utilized and manufactured. All these parts were utilized in the flight conducted on 04/22/2019.
Arduino Mega 2560, used for data acquisition, filtering, and calibration of input data.
High-Altitude Science Eagle Flight Computer used for tracking GPS coordinates in flight.
Two Temperature/Pressure Sensors used to record temperature and pressure.
1.5 Meter Spherical Parachute
Adafruits’ LSM9DS1 9-DOF Gyroscope+Magnetometer used to track orientation of the craft via Euler Angles, and a MicroSD Breakout Board to catalog data onto a MicroSD card.
Spot Trace GPS used to track the craft during and after flight.
GoPro Hero 4 Session used to record footage of the flight, but also doubles as a shadow-tracker for the Pyranometer sensor to correlate with data for dips in data.
Finally, the critical piece on board the flight is the Kipp-Zonen SMP10 Radiometer, a very costly ($2000+) sensors that can allow for ISO 9001-standard collection of data at upper atmosphere where pressures would cause most pyranometers to fail.
Aluminum pieces, for making the main frame.
The total weight of the payload is 6.8 lbs. Working directly with the Flight Safety Director’s Office for Indianapolis Intl Airport, the craft was given an ok for flight on April 22nd, 2019.
DESIGN: ALUMINUM SQUARE-FRAME
In designing the aluminum frame for holding all the components required for the flight, several key factors were considered for a successful flight.
Craft landing impact
Space to wire and feed connections between several components
A stable frame for Pyranometer operation
Weight limitation (to be less than or close to 6 lbs.)
Regarding the first consideration, several simulations were conducted in Finite-Element software (ANSYS Mechanical and Solidworks FEA Simulation). A FEA model is presented, showing the equal g-force of a 30 mph (several hundreds of psi across the entire frame) implied onto the frame from impact. Simulations confirmed that the frame could withstand 30 mph impacts while it also showed resilience to items also placed under loading on the frame. Note that where higher numbers are noted, are where the frame experiences the highest stress points under collision.
Regarding to the last two considerations, a square frame was used: researching into other HAB Flights, it was noted that frames and crafts that used a square design for a frame maintained better balance in the air versus delta frames. By having a wide frame, space for wiring and stability could also be reached. As well, should the frame tilt in flight, it should be able to have the Pyranometer be unobstructed by shadows casted by the aluminum frame/components. By also having aluminum, weight was cut tremendously to 6 lbs. but maintained a rigid structure.
In choosing and designing the electronics, following factors were considered.
Calibration of the gyroscope/magnetometer needed to be done automatically before flight.
Data logging at high frequencies while maintaining real-time data reading.
Filtering and processing incoming data while writing it to an SD card.
An Arduino Mega 2560, an Adafruit LSM9DS1 9-DOF Sensor and MicroSD Breakout Board were utilized in recording gyroscopic/magnetometer data. The microcontroller was chosen because it was easy to code for data filtering, and it processed data through Madgwick/Bandpass Filters quickly with good results.
In software coding, a Madgwick Filter was utilized for its high accuracy in tracking orientation in flight. Because of how critical orientation can be in total radiation estimation, having filters and sensors that can read accurately were crucial for data analysis. The additional benefit of the Madgwick Filter allowed the orientation to be processed in any angle, allowing for better orientation tracking.
For the Adafruit hardware, an Adafruit LSM9DS1 9-DOF Sensor was chosen for recording flight due to its high accuracy in cold environments. It was also much easier to code and filter data versus other AHRS or gyroscope/GPS systems. It also had higher precision in readings, increasing accuracy in data analysis. For easy access and coding, an Adafruit MicroSD Breakout Board was used to write the data.
The overall flight test took roughly 2 hours and 6 mins. A video with important moments of flight can be found in the link: https://youtu.be/-sXZ6Lc2WmM. Figure 4 presents two snapshots from the GoPro during the flight near Michigan Lake and right before the burst at 104,000 feet.
The raw measured solar irradiance data is summarized in below. The Pyranometer data measured in the air is compared with the one measured on the ground by taking the ratio between the two: Gair/Gground and plotted against the altitude upto 4500 meters (Electronics Wire issue stopped the recording of the Pyranometer data over 4500 meters). Clearly, with the altitude increased to 4500 meters above the ground, the radiation increases to about 1.3 times of the corresponding value of radiation on the ground, proving that the solar radiation can be significantly increased at higher altitude.