Weather Balloon Altitude Control System. Tim Basta, Trevor Clark, Scott Miller Date: 9/15/2014

Transcription

1 Dcument: Functinal Analysis Prject: Weather Balln Altitude Cntrl System Submitted t: Hngwei Ga Submitted by: Tim Basta, Trevr Clark, Sctt Miller Date: 9/15/2014 Intrductin The fllwing functinal specificatin verviews the high level requirements f the valve cntrl system. Very few if any technical details will be prvided hwever the verall functin f the system will be detailed. The functinal specificatin starts with a black bx mdel which describes what each individual subsystem des alng with a high- level lk at hw the systems are cnnected tgether. The next sectin is functinal specificatins. The functinal specificatins prvides a granular lk at what each subsystem must d t accmplish the verall gal f the prject. Each high level functin is brken dwn int smaller sub functins as needed. Finally the design metrics fr the prject will be presented. The design metrics are the verall design gals that the end prduct will be weighed against t determine if the prject was successful r nt. Black Bx Mdel This prject cnsists f fur main subsystems, the preexisting lng range cmmunicatin system, an Iridium satellite mdem, a cntrller in the main paylad t interface t the Iridium satellite mdem, a cntrller up n the valve with a GPS unit, and the a valve t vent helium. Currently the MSGC BOREALIS prgram is using an Iridium satellite mdem t cmmunicate with the balln paylad ther ballning grups cmmnly use amateur radi DTMF. This prject will entail designing a main paylad cntrller that can interface t an existing cmmunicatins system be that a satellite r amateur radi DTMF. This cntrller will then via a wireless cnnectin cmmunicate with a cntrller up n a valve clser t the balln. This valve cntrller will then directly cntrl a valve that is inserted int the neck f a balln which will pen and clse enabling r restricting the flw f helium ut f the balln t achieve neutral buyance. The valve cntrller will als have the functinality t perate autnmusly, venting helium t achieve neutral buyance at a preprgrammed attitude. It will d this be implementing an algrithm t interpret GPS data and determine when and fr hw lng the valve shuld be pened t achieve the user selected altitude.

2 Valve Cntrl System Autnmus Mde Balln GPS Valve Cntrller Open Or Clse Cmmand Valve Wireless Cmmunicatin Enable Or Restrict Flw Of Helium Telemetry T And Frm The Valve Wireless Cmmunicatin Main Paylad Cntrller Telemetry T And Frm The Grund Statin Preexisting Cmmunicatins Systems Iridium Satellite Mdem Iridium Satellite Netwrk Grund Statin Iridium Grund Statin

3 Functinal Specificatins The purpse f the valve system is t allw users f latex high altitude ballns t fly them at neutral buyancy. This will be accmplished by venting a certain amunt f helium ut f the balln during flight t affect the amunt f lift prduced by the displaced air. This will allw users t extend the duratin f their flights, and allw them a degree f cntrl in flight duratin and altitude. The electrnics package will cnsist f tw functinal subsystems: a cntrl subsystem and a valve subsystem. The cntrl subsystem will reside within the main paylad cntainer that the end user supplies. The cntrl subsystem is respnsible fr interfacing with the end user's tracking and cmmand system (Iridium satellite mdem, amateur radi, etc. ) The interface prtcl will need t be well dcumented fr easy integratin with the end user's existing paylad. The interface will allw fr remte cntrl f the valve and its varius functins. The cntrl subsystem must wirelessly cmmunicate with the valve subsystem. The cntrl subsystem must have an endurance f 6 hurs. The valve subsystem interfaces directly with the valve mechanics and is respnsible fr actuating the valve as required. A wireless cnnectin must be established between the cntrl subsystem and the valve subsystem if required. The valve subsystem must als have a autnmus mde which wrks independently f the cntrl subsystem if activated. The autnmus mde will use internal lgic and varius sensrs t determine when t actuate the valve mechanics. In either mde the valve subsystem must be able t wirelessly send status updates and sensr readings t the cntrl subsystem. Specific design requirements fr this prject are as fllws: The valve system will be required t have a sufficiently high flw rate t allw the user t bring the balln t flat (Neutral buyancy) within 15 minutes f being pen. Due t the ascent rate f the average high altitude balln flight, the time windw fr venting is limited t a maximum f 15 minutes. If the vent time takes lnger, the balln may burst at high altitude due t excessive vlume. The valve system will be required t achieve flat at a pre- specified altitude t within a 10% degree f accuracy. This design requirement is aimed at making this prduct marketable t institutins that cllect meterlgical sunding data that will require altitude cntrl that is acceptably accurate. The valve system will be required t perate inside the temperature range f - 60 C t 40 C. This is the average perating temperature range frm grund level t 100,000 ft. The valve system will be designed fr use with 300 gram Kaymnt brand ballns. Future designs may include a design that is cmpatible acrss ther brands r sizes f ballns, but this prject will be designed fr a balln cmmnly used fr meterlgical data cllectin. The ttal weight f the valve system cannt exceed 8 z. The 300 gram ballns cmmnly lift a 2 lb. paylad, and the additin f a valve system weighing mre than 8 z. becmes unreasnable cmpared t the average paylad weight. Cmmunicatin specificatin fr interfacing the valve system with the end user's paylad The valve system is nt required t cntrl r track the end user's paylad, hwever a data link prtcl is prvided t interface with the user's system if desired. The prtcl specifies the methd f cmmunicatin the valve system expects frm the external cntrl system such as baud rate, serial prtcl, timing, etc.

4 Battery endurance f 6 hurs The cmplete valve system must perate fr a minimum f 6 hurs, hwever n particular pwer usage specificatin is required as lng as the ther functinal specificatins are still met (temperature range and weight wuld likely be mst affected). The valve system design must determine hw best t achieve this gal thrugh efficiency f peratin, battery capacity, DC/DC cnverter requirements, sleep states f the micrprcessr, etc. The 6 hur requirement is based n the intended use f the end prduct. Cst per unit less than $100 fr 100 units. Due t the average cst f weather sunding packages, it wuld be unreasnable t expect a custmer t pay mre than $100 fr the neutral buyancy upgrade. The valve system will be required t prvide flight terminatin fr the balln by venting a significant vlume f Helium t cause the balln t descend back t grund level. The valve will be required t have an in- line fill system that will allw the user t attach the balln t the valve prir t fill, then inflate the balln with Helium thrugh the valve. This system will als require a fill statin that will interface with the Helium tank regulatr. This prject will be required t be accmplished within 3 test flights and 1 demnstratin flight due t budget and time requirements. Design Metrics The design metrics fr the prject are the mst imprtant prject gals that must be met fr the prject t be a success. These specificatins are the mst imprtant high level gals as they are the specificatins given t the prject grup by the end user. If these design metrics are nt met the end user will nt nly be displeased, they may prceed with anther cmpany's prduct. The design metrics fr the prject are specified as fllws: The valve mechanics must be simple t cnnect the latex weather balln t and als hld nt the balln s it des nt discnnect in flight. The valve mechanics must allw fr inline fill f the latex weather balln. Inline fill allws the end user t attach their latex weather ballns t the valve mechanics and then cnnect their helium supply t the valve. The valve system must nt be cumbersme t cnnect r interface with. A flat altitude between 30,000-60,000 feet within a 10% tlerance must be achievable with the system. This altitude range encmpasses the altitude regins in which the end user wuld typically utilize such a system, and an acceptable tlerance level at thse altitudes. The valve must weigh n mre than 1/2 pund. If the valve system is heavier than that specified the end user will lse valuable paylad weight fr their experiments. The entire system must cst n mre than $100 per unit in 100 unit quantities.

5 T be cmpetitive r desirable with the intended market the entire valve system must nt cst mre than the cst f a typical weather balln ($100). Up t three test flights and ne final flight may be used t test the prject design.