Team Vision for System-Level Design Phase
After finishing the Problem Definition phase, our team wants to have a detailed system level diagram at the end of this phase. In addition, resources such as power, data, and weight are to be taken account of as well. Due to the complexity of the system, a large number of parts are to be benchmarked and considered when selecting concepts. Feasibility analysis was done for several aspects of the system. At the end of this phase, Detailed Design will begin with a good idea of the subsystems and parts that will be used.
We were able to create a system architecture that will satisfy all the customer and engineering requirements developed in the previous phase.
Functional DecompositionWe started this phase by breaking down the need functionality of the high altitude balloon into smaller parts. We identified six major subsystems, each having a few levels of sub functions. The six sub functions are Attitude Control, Solar Power, Support/Protect BioX Cell, Communication, Software, and a Plant Growth Experiment.
System Architecture Selection Process
The System Architecture Selection Process page goes through the selection of the system starting with benchmarking and ending with a Pugh Analysis.
BioCell Selection Process
The functional decomposition of the BioCell is shown below.
The BioCell Selection process page goes through the selection of the system starting with benchmarking and ending with a Pugh Analysis.
Communication System Selection Process
The functional decomposition of the communication is shown below.
The Communication System Selection process page goes through the selection of the system starting with benchmarking and ending with a Pugh Analysis.
Power Selection Process
The functional decomposition of the Power System is shown below.
The Power Selection process page goes through the selection of the system starting with benchmarking and ending with a Pugh Analysis.
Structure Selection Process
The functional decomposition of the structure is shown below.
The Structure Selection process page goes through the selection of the system starting with benchmarking and ending with a Pugh Analysis.
Environment StudyThe SF1 will make it into the stratosphere, at 120,000ft (36.5km, 23mi) up into the air. In this layer there is most of the ozone layer. The area between 11km and 20km is the limit to where clouds exist and is where the jet stream exists. It is in this area that the balloon may travel at its maximum speed.
Air PressureThe air pressure at this altitude will be ~5mb, or 0.005 atmospheres.
TemperatureUpon accent, the temperature around the balloon will drop to -60°C(-80°F) at 20km, then rise to ~ -30°C(-22°F) at its maximum altitude. The temperature in the Troposphere drops with increasing height at an average rate of 6.5°C/km because the atmosphere is mainly heated from below by the underlying ground surface. In the stratosphere, the temperature increases because ozone gas molecules, present in this layer, absorb ultraviolet sunlight creating heat energy.
Information on atmosphere found at: http://www.atmo.arizona.edu/students/courselinks/fall12/atmo336/lectures/sec1/structure.html
System Architecture: Designs and Flowcharts
System ArchitectureIn order to better show the interactions between different subcomponents, a block diagram of the systems was created and can be seen below.
The diagram shows how the power comes from a central system and is distributed to all of the subsystems. It also shows the flow of data through the system going to and from the communication system. This diagram is very high-level and a more detailed block diagram is shown below.
This diagram shows the communication protocols that are expected to be used between each of the subsystems as well as an expected power draws. For many of the subsystems it also shows the microcontroller that we plan on using.
BioCell Block Diagram
A block diagram of the Biocell is shown below.
Communication SystemThe portion of the communication system that will transmit and receive on the 2m wavelength is shown below.
The portion of the communication system that will transmit digital video is shown below.
Solar Power System
Risk AssessmentThe risks identified in the Problem Definition phase were updated. The risks that are directly applicable to systems design are shown below.
A link to the full document can be found here:
Design Review Materials
A link to the Pre-Read is here: Systems Level Design Documents/System_Design_Presentation.pptx
A link to the notes taken from the presentation is here: Systems Level Design Documents/System_Design_Presentation_notes.docx
Plans for next phase
A Gantt chart describing the schedule for the next phase of MSDI is included here: Systems Level Design Documents/SF1_Schedule.pdf
Three-week plans for individual team members: