Subsystem Build & Test
Table of Contents
Project RecapThe High Altitude Balloon Instrumentation Platform (HABIP) is a multi-functional system that allows users to collect and analyze data from near-space experiments. The device records internal data, and also telemeters data that has been gathered from an array of sensors to a ground communications center. The goal of this project is to create the aforementioned array in a configuration that is lightweight, cheap to manufacture, and highly reliable. The final product will undergo a mission lasting for several hours in harsh conditions, and will parachute back to Earth from an altitude of over 100,000 feet to be recovered and analyzed. This project seeks to improve upon the progress of two former MSD groups: P17104 and P17105, and is intended to be a design which can be further improved in the future.
Team Vision for Subsystem Level Build & Test Phase
During this phase, the team worked to test the individual subsystems and ensure that they are ready to be integrated into the final system. Many steps were also taken to ensure a high probability of success in a single launch attempt.
Test Results Summary
The APRS was tested for 4 hours. Though the physical location was not varied for this test, the changes in pressure, relative humidity, and temperature were logged for over 200 samples. The data was decoded in Excel. To view the full document, click here.
The reaction wheel was tested to ensure proper response to motion detected by the IMU gyro. The input and response are shown, with minimal delay between detection of angular velocity and correction by the reaction wheel. Proportional amplitude of response will be assigned once final weight is established.
The Raspberry Pi Zeros being used for Data Acquisitions were tested to ensure that all sensors were operational and that data could be written. Some calibration still may be necessary, but reasonable readings of the above metrics were taken while performing simple tests to vary measurement environment.
Thermal Model (Demo)
The thermal modeling technique is described below:
- Run SS worst case hot (max radiation, insulation and heat generation)
- Run SS worst case cold (min radiation, insulation and heat generation)
- Run SS best guess
- Compare sensor data to SS best guess and make necessary adjustments to sim
- Calculate convection coefficients for:
- Natural convection inside the HAB
- Forced convection outside the HAB
- Run SS best guess at 10,000 ft increments including convection
- Create and run transient sim (best guess, worst case high and low)
- Run transient sim with previous teams conditions and compare results
- IMU Data Read via SPI Bus
- IMU Select to choose between IMU0 and IMU1
- IMU Calibration Initiated by User (Stores both IMU0 and IMU1)
- Reaction Wheel Algorithm integrated and prelim tested
- New Method of SD Card Writing while motor is on, to make algorithm more efficient
- Temperature and Pressure Reads via I2C
- ADC reads for Battery Voltages (9 Total Cells)
- If Battery falls below certain level it will be switched to alternate
- Multiple SD Files added (a new file every 5 minutes)
- Self Test Results displayed on Red LED. LED is blinked for a "soft" failure (a failure that we are able to run with) and LED is held on for a "hard" failure (a failure that will make us unable to operate)
- Current Sensor Read via I2C
- The main board is shown
- Currently this is in hand, and is being investigated for errors
- Population will be complete by early next week.
- Switch to ethernet networking has been successful so far
- Throughout this phase, DTV has remained the biggest
- Currently able to send video data from cameras to compression Pi
- Troubleshooting issues with BladeRF transmission
- Rooftop antenna has been installed
- Currently tracking two week arrival of pre-amp (international purchase caused delay)
- Foam frame has been assembled
- GRSS and cameras have been mounted
- Outside thermal layer will be added closer to launch date
As of now we have spent $1308.04, with $191.96 remaining in our budget.
Risk and Problem Tracking
|Pre-amp does not arrive in time||Find new supplier before final week of March|
|Errors in PCBs are not solvable||Spend remaining budget on final iteration PCBs|
|Remaining funds are inadequate||Limit future purchases to exclusively “must-haves”|
|Problem||Adaptation to Resolve|
|Switch to ethernet networking for DTV has set this subsystem back||Diverting ME resources to contribute heavily to getting back on track|
|Minor errors exist in PCB||Manual board modifications to resolve|
|Lacking complete understanding of ground station software||Continued communication with previous users|
|Significant time overruns in scheduled tasks||Assigning shorter timelines and building in buffers, reassigning resources as strengths become apparent|