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 System-Level Design PhasePhase Summary:
- During this phase, the team developed a high-level plan for how engineering specifications would be met through various electrical and mechanical systems
- The required functions of the HABIP were clearly laid out and systems were considered as potential options to satisfy these functions
- Preliminary concept selection was performed
- The majority of resources were used for benchmarking and developing systems used in last year's project
- A plan of action was set for the next phase
PurposeDefine the total list of functions and subfunctions, based on the Customer and Engineering Requirements, that must be delivered by the final design. This establishes the need for specific concepts necessary to deliver the overall objectives of the project
MethodTo create this document, the engineering specifications and customer requirements were reviewed to understand the most basic needs of the HABIP. Some systems achieve the goals of many requirements, while other functions are singular. In this way, each system concept that is generated throughout this phase is done so with the purpose of satisfying at least one of the lower-level functions set forth in this document. click here.
PurposeAvoid redundant work by identifying already available solutions and concept options. Most benchmark products were found by previous HABIP teams, here complied for analysis.
Reaction Wheel Motor
PurposeTo generate new concept options or combinations that can potentially exceed the benchmark concepts
Morphological ChartCategorical list of multiple concept options to satisfy each necessary function. Brainstorming leads to some concepts that are more feasible than others, though this tool can be used to create a conglomerate system that serves all necessary customer requirements. click here.
Feasibility: Prototyping, Analysis, Simulation
- Confirm that the selected concepts can deliver functionality.
- Understand what is physically available as a jumping-off point for testing and prototyping.
- Support the evaluation of concepts with quantitative information.
BackgroundDr. Patru has requested that the design stay generally the same as previous models apart from modifications to the following systems:
- Frame & foam insulation
- Digital radio system replacing:
- Analog cameras
- On Screen Display board
- ATV transmitter
- ATV Battery
- 70cm Antenna
- Balloon plug
- 2m antenna
- Reaction wheel motor, controller & battery (under investigation)
The customer will be consulted with regard to any ideas about how to (re)design a system, part, or software. Otherwise, the previous design will be iterated in pursuit of satisfaction of all requirements.
MethodMost of the action in this phase was centered around using the efforts from last year to understand what steps can be taken moving forward. The physical and digital systems were reviewed and restored to analyze what worked and what failed, as well as what systems could be treated as a direct continuation of previous work (as opposed to starting with a blank slate). The research that was conducted last year was also reviewed, as this information remains the guiding force in what is feasible in a final product.
Simulation/Understanding of Previous Systems
Reaction Wheel Testing
- The reaction wheel from the 2016-17 team was tested and found to be functional
- This system failed to operate in flight during the last launch, so ensuring functionality on the ground is the first step in ensuring future functionality
- Early action is being taken to ensure proper integration with the IMU and microcontroller during our build phase
- The customer has requested investigation into a smaller and lighter reaction wheel or a flywheel system
- Feasibility analysis will begin shortly
- If a smaller reaction wheel motor is not feasible, the current setup is operable and may be used (per the customer)
- The ground recovery support systems were enabled to ensure that the HABIP can be found after landing
- This system worked well in previous launches and will remain mostly the same in the future
- Frame was designed based on the successes and failures of the previous design
- A circular top-down cross section was chosen, as electronics can be packaged in a way that distributes the weight most effectively and more efficiently integrates with the reaction wheel
- Frame was designed as a mounting plate with integrated heat sink, so that electronic and the reaction wheel bolt to both sides of it
- The foam forms a protective shell around the frame and electronics
- Lighter material was used upon customer’s request
- Customer approved all of these design changes early on
- Meets FAA Specifications for impact force, etc.
Thermal Management Prospects
- Frame-mounted electronics means that thermal dissipation is vastly improved
- Frame will serve to conduct heat away from hot electronics and deliver heat to cold electronics, reducing the risk of electronics failure due to extreme temperatures within the HAB
- Previous HAB launch experienced similarly high altitudes without any electronics failing due to temperature extremes
- Previous HAB experienced high temperatures within the HAB at altitude, not low temperatures as was expected
- New design will use much less power for radio transmission, so heat buildup should be less of a concern (reaction wheel is an investigation point)
- Detailed thermal analysis will be performed starting in the next couple of weeks to confirm validity of assumptions
ResearchThe vast majority of this research was modified from information found on previous projects. Data and Telemetry Transmission
- For data and telemetry, we will be using the 2m frequency band, a common Amateur radio band, which uses a frequency of (144-148 MHz). Previous teams used a 2m Yagi antenna (brand: C3i, model: FO12-144). It had a gain of 12.6 dBi.
- The antenna used on previous METEOR designs is a dual-band Comet SBB-1, which had a gain of 1.5dB for 2m.
- Based on the transmit and receive antenna gains, the total combined antenna gain for the 2m system is 14.1dB.
- Previous research based on the free space path loss formula (below) indicates that a 9 dB gain adjustment is necessary to account for adjustment from 70cm to 2m antenna. Thus, the total gain used to determine power requirements for data and telemetry transmission is 23.1 dB. Since the required distance of transmission is roughly 26.5 miles, it follows using the graph below that a 2m antenna will require of between 1W and 5W (approximately 2W).
- From the vertical temperature profile, temperature will range from room temperature (about 23 degrees Celsius) to -57 degrees Celsius. In the Troposphere, temperature decrease 6.5 degrees Celsius per km; the jet stream is also at this level of the atmosphere. The Tropopause is the border between the Troposphere and Stratosphere; air temperature is constant in this layer. Temperature increases with height from the base of the Stratosphere until the service ceiling of the HABIP is reached.
- As altitude increases, atmospheric pressure and the concentration of water vapor/particulate all decrease.
- These considerations are important as it will affect the ability to heat and cool the components on the HABIP. Previous projects have had to focus primarily on cooling, because the ATV is a significant source of thermal energy that cannot be dissipated easily at high altitude (where convention is minimal). Since the new design will utilize digital video, the need to cool the system will be less significant, though more research will have to be done to determine if there is a need to heat components in the new configuration.
Environmental Factors (Vertical Temperature Profile, Atmospheric Pressure and Particulate Concentration by Altitude)
- A preliminary estimation of component weights was compiled, with conservative estimates made when exact weights were not known. The target weight is between 6-10 lbs, which this estimate satisfies. Additional steps will be taken to understand if an additional ~2 lbs can be shed from the design, in order to bring the weight below 6 lbs (which reduces the FAA regulatory requirements that would govern a launch). It is notable that none of the components that are being replaced face an increase in weight.
Concept Identification and Selection
- Develop multiple concept options to deliver the required list of functions.
- Ensure that concepts (means) are available to deliver every required function.
- Select the optimal set of concepts that can be integrated to meet the project objectives.
Restate Engineering SpecificationsThe Engineering Specifications defined in the last phase are reiterated below to indicate what the functional goals of concept selection are. click here.
Pugh ChartThe Pugh Chart is used to select a concept based on the scores of various categories. The classification system is kept consistent with the previous iteration of this project, and the final design of the HABIP from 2016-17 is used as the datum for reference. click here.
PurposeDefine system functions, as well as flow of energy, information, and forces, on a high level. Determine how sub-systems are interrelated.
Previous Block Diagram
Flow Diagramsclick here.
Block Diagramclick here.
- Strain on internal power
- Using digital video reduces this strain
- Potentially not enough bandwidth to transmit/receive data
- Poor fabrication of PCBs is possible
- Excessive time needed to write to microSD for data storage
- Off-shelf components may not work as expected at altitudes of >100,000 feet
- Heightened difficulty programming due to change to digital from ATV
- Difficulty analyzing code from past teams
- Difficulty securing funding
- Access to necessary labs may not be available
- Access has been gained, or can be easily obtained
- Meeting times are challenging to coordinate with seven team members
- Extremely limited testing opportunities for many
- Some testing complete, some may still be difficult
- Potential for shock or burn when preparing electrical components
- Launch and recovery may be hazardous in the case of rapid descent
- Some risk that HABIP lands in a dangerous location regardless of controlled velocity on descent
- Failure to recover HABIP may lead to environmental waste
- Loss of payload would be expensive for the customer
- FCC and FAA regulations may be broken unless proper
precautions are taken
- These precautions are being taken
Plans for Next PhaseThe next phase of the project involves the completion of several key tasks:
- Creation of a mockup for simulation purposes
- In-depth feasibility analysis, moving out of the past
research stage and further into the future-state design
- Includes preliminary heat transfer model, detailed power consumption model, layout for weight distribution, and analysis of new data transfer systems
- This is naturally more cross-disciplinary, as these tasks require an understanding of how all sub-systems fit together
- More detailed flowcharts and schematics that better define the relationships between subsystems and the underlying requirements therein
- A BOM that lays out in detail all of the necessary components for the purpose of final selection and budgeting
- Test plans that serve to define the degree to which engineering requirements are met
- Mitigation of risks that have been discovered thus far
Design Review Materials
- Functional Decomposition
- Morphological Chart
- Engineering Specifications
- Pugh Chart
- Flow Diagrams
- Block Diagram