David Loupin's Capstone Blog and WPRs
- WPR JUN 04, 2009
- WPR May 29, 2009
- WPR MAY 21, 2009
- WPR MAY 14, 2009
- WPR MAY 07, 2009
- WPR APR 30, 2009
- WPR APR 23,2009
- WPR APR 16, 2009
- WPR APR 09, 2009
- WPR APR 02, 2009
- WPR MAR 25, 2009
- WPR MAR 19, 2009
- WPR MAR 12, 2009
- WPR MAR 05, 2009
- WPR FEB 26,2009
- WPR FEB 18,2009
- WPR FEB 12, 2009
- WPR FEB 5, 2009
- WPR Jan 29, 2009
- WPR JAN 22, 2009
- WPR January 15, 2009
last week: poster presentation
this week: looked over 2006 capstone documentation to begin final report. spent most of week studying for final on 06/04/2009
next week: documentation and presentation
last week: andrew altered design to use external charger
this week: read through scotts notes on switches. talked with andrew on tuesday about size of components and how they would be mounted. this is due to the use of the external charger, it would be possible to have an external circuit. however it will be on the aps board, and size is limited.
next week: finish circuit design, work on documentation and prep for presentation
last week finished poster
this week: worked on layout, had issue with adding new part to the layout from previous design, they were locked and only modifications i could make was deleting wires to these parts. made a copy of schematic and tried building board from scratch, am curious how we will fit everything on to one board. we were originally going to meet with andrew to work on layout during the tuesday PSAS meeting, but that had to be canceled due to work on the rocket for the May 31 launch. layout meeting to occur on friday.
next week presentation, layout
last week: worked on presentation
this week: finished up standardization of part naming, given number of parts used my range will be 2100-2199 tried out board layout
next week: board layout
last week: design review
this week: revamped charger design to previous project design. added front end part from scotts schematic met with team to discuss poster, mapped out desgin, and assigned tasks. mine involve info on my parts, and acquiring display table, and table cloth.
next week: finish poster design
last week: finished schematic for design review
this week: made minor changes to thermistor selection and the related parts.
contacted prof. Faust about clarifying due date for poster, issue was taken care of.
attended design review: found multiple issue in current design, will meet andrew before meeting to work on those changes.
next week: in eagle, team should be putting design to a board.
last week: presented schematic to team, andrew made comments on it. main issues were ltc4007 part was large red block, and part were to close together and need to be organized based on use.
This week: made changes to schematic, added p-channel part of own design, libraries already had correct n-channel mosfet. finished calculations on thermistor parts. have quick eagle question related to displaying pins/names, should be able to fix quickly.
next week: combine parts
Last week: finished LTC 4007 chip
This week worked on schematic, have all but thermistor related parts selected, as of time writing this document. asked question about it, relating to varying resistances, counting thermistor, all that remains is the thermistor itself, a capacitor, and a resistor. if helpful response by time i get back from work tonight, will have diagram complete, in terms of values. have some parts in diagram not sure of in terms of difference in sizes. will wait till confirmation of correct parts selected, before building said parts, they are the mosfets, but should be a 24-48 hr process to create them. current parts list will be uploaded.
next week: make adjustments as needed to diagrams and parts list
Last week: worked on LTC4007 chip schematic in eagle, had mostly completed
This week: finished LTC4007 chip, need to confirm with Tim. met with Ken and Scott to discuss links between each section, and general project progress read engineering text books to refresh memory on mosfet in order to aid in part select looked at ltc4007 datasheet to see what parts can be selected
next week: meet with scott and ken again to continue dialog on section links finish part selctions on resistors, fets, and other parts related to the ltc4007 work on documentation
I was out of town for last meeting, so i continued work on design of Eagle library item for the LTC4007. I had thought i was further along with my design, but realized so issues dimensions and offsets. they have since been rectified. met with TIM on tuesday to get some assistance with EAGLE, as well as design in general. my main questions related to the solder pads, and labeling of pin, in that whether they should be labeled as pin number of function in the package level. pin were labeled by pin number. function label occurs at symbol level.
we also discussed documentation. i have some notes related to my calculations and part selection, but nothing in the format the is needed i. e. for battery B2000, with a description following. this is the same format that was used during the 2006 capstone project.
discussed again the Rsense and Rprog resistors. found a reasonable resistor for r sense .001 ohms. with the R prog could not find one that was exact, and this brought up the question of whether to select a higher or lower resistance. this in turn led to trying to figure out what we need in terms of transistors, and what is actually needed. this was not resolved by the time the meeting ended.
At last meeting went over what had done so far in terms of schematics with tim. found that choices for rsense and rprog were correct but they created to much loss for the circuit, and to reevaluate with using R sense as a constant and solving for Rprog. previous calculations had done the opposite. had decided to go that way originally as was not certain as to the extent of use of C/10 comparison.
also at meeting tried to extract old ltc4007 chip from past design schematics, but was unable to, partially due to lack of access to libraries. access may be possible in future, but not in time for project. have begun design of new ltc4007 chip on EAGLE. have basics down, working out pad placement currently. should have all calculations related to chip dimensions, looking like i need to just adjust size of pads. should have something posted to server late friday, maybe early saturday, as i will be out of town till friday afternoon at earliest. will also post current battery and charger schematic.
set up public key with andrew, using cygwin. at the meeting it seemed that was going to be the program of choice for the team, as most had used it during ece371. had to download git and ssh libraries, could of done set up at meeting but download took to long. when i did download at home, still took about an hour, went through GA tech mirror.
FINALS WEEK Did not have much time due to it being finals week. had last final Thursday morning. During study breaks spent some time on schematics, but not enough to finish design on ltc4007 chip.
During last meeting had brief discussion with andrew as he had to present to undergrads as there we no other PSAS members available for the presentation. he suggested have meeting later at 3:30. i had some items to take care of for my search and rescue training the following day, so i asked Andrew the questions i needed to ask at that moment, and then left.
during the week worked on a number of different tasks. worked on battery research for the HAP mostly. checked single cell companies that i had found during my aps battery research, but selection seems to be small based on the capacity of 450 mA. many companies have products at that level, but are usually cylindrical. will present what i have so far at next meeting, and will continue from there.
added all psas libraries for EAGLE, but non contained the necessary ltc4007 part. emailed PSAS avionics, got response from Andrew that he could not find the part either, said he'd talk w/ Tim about location of part, or if their exists script to get part from existing schematic.
have done some fuse research, but having issues as many surface mount models, do not list time to trip. will talk with Tim, incase there is something else listed that means the same thing.
During the last meeting Scott and I Proposed the use of the LTC4007 charger for our design. out of the chargers we had looked at it seemed to fit our needs the best. Andrew then suggested we look a bit more, given it was used in the previous design, and he was hoping for something newer that would fit our needs. given the battery and power switch group of myself, Scott and Ken were to meet with Tim and Andrew on tuesday, we set the goal of a bit more research. with a final decision to be made at our meeting on Tuesday.
also at the capstone team meeting, given how much work is going into the switches and system on the pyro node, i was given the task of finding a battery for the HAP. at the time it was not know the exact value needed, Ken was to provide that data once he had a better idea of power usage.
at the meeting tuesday after a bit of research by everyone there it was decided that the LTC4007 would be the charger we would use. the major issue with the other chargers was either they were multi chemistry, or in the case of the other models by linear, they were simply remodels of the 4007.
next Andrew wanted me to begin putting the charger and its system into a schematic. I started working on it, but due to a midterm today, did not make much progress in the design. have done some calculations, and looked through the libraries i had to see if the LTC4007 existed there. I did not see it, will talk to Tim at capstone team meeting about it.
At the last meeting it was announced that we would be using the 4.25 Ah battery, from batteryspace.com. by choosing this battery, we would be only incurring a cost of roughly $16 for the 8 batteries we will be using. they will be arranged in a 4s2p set up. Andrew said he would work on ordering the batteries.
the next goal is charger selection. requirements changed to (,1C,C/2) in terms of charge rate. the reasoning behind this was that we wanted to find charger that both provided a large enough charge rate, while also possibly gain some bonus abilities related to balancing, and status.
Met with Scott on FEB 24, 2009 to discuss the charger as he is dealing with the power switches and umbilical, and depending on which charger i select will affect some of the components he is dealing with. based on the requirements, and the what is needed related to feedback control, we decided to go with the LTC4007, which is the same charger used in the previous design. the charger has a dc connection detect, and charges at 4 Ah. I had found some chargers that operated at 8 A, but had some sort of AC adapter connection, and detect. if we knew that it would be easy to modify one of these chargers for our needs, we might of selected differently.
this week also worked on fuse research. found one model right away, but Tim wanted to see if a surface mounted model was available. have looked at many models, but most don't fit our needs or documentation is scarce, or in a foreign language.
This week concentrated on charging circuits. I was able to find a few contenders. research on chargers will continue. the next stage will involve meeting with Scott as he is working on the umbilical, in order to figure our which combination will work best for our needs. so far the components that i have found all charge at 8A.
This week attended EAGLE workshop on tuesday, FEB 17, 2009. during this workshop, Tim went over the basics of moving components around, edit schematics, and the program in general. I had to leave a bit early though due to working night shift at UPS. I had already loaded EAGLE on to my laptop, and had been using it when viewing the schematics of the past design projects.
Talked briefly with Tim prior to workshop about battery selection, as he needed to look over a datasheet, before a final decision could be made on which battery will be used. Tim said he would look it over after the workshop.
This week my goal was to finish battery research. in the past had concentrated my searches to Battery backs, however Andrew and Tim want individual cells. a battery pack could work, but we would have to harvest the cells. ideally with the cells we would form a cube which would fit within an area comprised of sides of 3.5" . using cells rather than packs seem to make more sense, upon further review, as we would be harvesting the cells anyways from the packs, and even if we do not harvest, there are the connections within the packs that we would not have control over, which could lead to failures. also have found a big difference in costs, as the 5.35 Ah pack costs >$180, while placing the 5 Ah cells in series would cost, just under $100, assuming we wanted a voltage of 14.8 V.
if we do stick with a pack, the 5 Ah would be top choice.
I found 7 cells of varying capacities, and discharges, which could satisfy our needs.
my top choices from are in order: 1-5Ah cell with 2C Discharge - positive: dimension do not exceed 3", not including tabs, negative: discharge rate
2-10Ah cell with 1C discharge - positive: capacity and discharge, negative: length >6"
3-2.5 Ah cell with 2C discharge - positive: Capacity and dimensions, negative: energy density and comparative cost to larger capacity models
At next meeting we will finalize battery choice, which will aid in looking for chargers
questions: discussed sizes and type of switches near end of meeting, curious as to what preference there is to a particular type in terms of the charger?
During the last meeting we adjusted the dimension requirements for the battery. before it was limiting to a 3.5" x3.5" x 3.5" cube. I was able to find some batteries that had fit that criteria, but was limiting us to about 4 Ah, maybe a little more than that. the adjustment to the dimensions was that the length can be up to 10", which helped, as the higher capacity batteries usually had a length of nearly 5". found many batteries that would suit our needs, but a lean to two particular ones. both are made by Polyquest, and the only major difference is the capacity. one is 4.25 Ah, and the other is 5.35 Ah. if we put two of either one in parallel, we can get 8.5 and 10.7 Ah respectively. the only question left is which one, as we were looking for about 8 Ah, but there was no upper limit. not sure which one will be better, as am not sure what parts are available for each respective capacity.
both batteries are listed under the battery design page with the relevant specs for each.
also finished power usage, and got result a bit lower than what one of the doc i researched had listed, but the doc was an older one, and they had said that depending on the power source, it was possible for values to be lower.
my next goal is related to the battery charger. had sent out email to Tim and Andrew, and got back some information related to my query. currently waiting till we meet on friday to figure out what battery we will use, as well as whats going on with the umbilical, as the charger will deal with both.
group met at usual time, in FAB 20-05. during meeting was given dimension for battery packs, after doing some calculation found space to be 3.7". however requirements listed max at 3.5". Tim discussed with Scott and I basics of whats going on in schematics, and cleared up issues. also had brief discussion on presentations, and deliverables.
This week began research on batteries as well as worked on power usage. found a few batteries that seem to fit criteria. biggest challenge was size, as many that fit both 4s criteria, and capacity, yet are too large, usually are 5 in in length. have posted what i have found so far , as well as power usage info on design page. link: http://psas.pdx.edu/capstone2009/design/aps/battery/
Also briefly looked at chargers in general, but was curious as to a type. next meeting is Friday, Jan 30, 2009. at 2 PM.team evaluation form is due at meeting.
questions: how do we combine batteries to get higher Capacity ? chargers-> type, weight, dimensions, none listed in requirements.
During the previous meeting we discussed further details of project as well as some new design idea, including the universal rocket bus, URB, as they had deamed it at that moment. their is still some debate as to what to call the system. the URB will be on the APS and will operate as a hub for the main components of the avionics system. in terms of project assignments, I am now only handling the Battery and Charger. as part of this my homework for the week was to reat the battery pdf that tim had written. overall a lot of it made sense despite the mathmatica script, a program that i was unfamiliar with. my next stage will include working on a power usage list to figure out how much we will need in the design. I have also begun some research on batteries. Andrew wants them to be Li ion, both for power/ weight ratio, as well as shape, as they are rectangular, rather the cylindrical. as part of this am trying to learn a bit on the chemistry of the li ion battery, have not found anything online so far, but will continue.
When does adviser want team evaluations, given the delays due to the weather?
In terms of batteries, are there any manufacturers that the sponsors want me to look at?
given we will be using a new design element, the URB, will the hub it self need power, and if so, how much?
When will the workshops begin?
Are their any textbooks, or websites related to batteries/ chargers that i should look at?
Team had first official meeting of 2009. we met in room FAB 20-05 at 4pm. we discussed whether to change meeting time. next we discussed who is doing what on the project. I am handling power switches and battery system for the system. We discussed a general overview of the requirements which were on the capstone website. A more formal list should be available at our next meeting. It will be at 2 pm in FAB 20-05.
The homework involved reading the material on the Avionics webpage related to the APS and the battery system. The documents included a general view of components, as well as links to the specific components. found it useful the calculations, as it will ease comparing what component i might be looking at and the ones used on LV2. also gives a little better idea of what is important to the design in terms of specifications.
What changes are being made between the previous design and what I will be designing? How much power will be needed? What type of external connects will be needed? in terms of the sleep mode, what is a reasonable time for the sleep mode to kick in?