Low Altitude Balloon Experiment in Technology (LABET)

Group Members Mike Svendsen – Computer EngineerSteve Towey – Computer EngineerBrian Walker – ArchitectRichard George – Industrial Technology

Client – ISU Space Systems and Control Lab (SSCL)

Advisor – Matt Nelson

OverviewClient Statement of NeedProject Requirements and DeliverablesProject PlanSubsystem Designs & ImplementationsTestingLessons Learned

Client Statement of NeedThe SSCL desires a blimp platform for

research and outreach events.  The need is to have an outdoor blimp

platform capable of carrying a small payload and able to navigate in calm to light winds.

Requirements

Non-FunctionalDurable and reusable designControlled via computer interfacePositional data displayed on computer

Operating EnvironmentOutdoorsWinds up to 10mphHumidity up to 90%

Functional RequirementsVertical lift - 500 feetWireless control - 1500 feetCarry 7 ounce payloadFly time of 20+ minutesSensor to determine position

Project DeliverablesComplete balloon system meeting

requirementsOperating manualsDetailed design documentation

Project PlanWork Breakdown

Mike and Steve responsible for electronic components

Brian and Richard for non electronic components

Task Breakdown

Gantt Chart

Communication / CollaborationWeekly meetings with team and advisor

(client)At least a weekly meeting with just

electronics teamFrequent meetings in lab for implementationUsed Dropbox to facilitate SVN like roleUsed GoogleDocs to facilitate sharing of

information

Costs

System Overview

Balloon DesignHybrid Latex Blimp System

Balloon ImplementationInitial implementation

Struggled to achieve liftWeight calculation

inaccuraciesPropellers not performing

as specified

RedesignRemove stiffenersRemove latex balloonsIncrease to 2 mil plastic

Frame DesignCross Foam Core Load Frame

Rigid material yet light, inexpensiveBass wood for motor mountsPropeller shroudsSystem box

Frame ImplementationDifficulties attaching balloon

around electronics boxShortened weight distributors

Propellers not exact specified length, did not fit in vertical shroudSlightly trim propeller tips

Propulsion DesignWeight constraintBattery life requirement10 mph wind requirement

Thrust CalculationsBattery Life Calculations

Propulsion ImplementationMount motorsAttach propellers securelyAttach easy to use bullet

connectorsAttach Deans plugsConnect motors to

Electronic Speed Controllers

Circuit DesignCompile list of sensors

Select specific sensorConsider cost,

voltage, accuracySelect processor

capable of handling inputs

Circuit ImplementationPackage typesESCs raising voltage

Solution – DiodeVoltage drop during

XBee TransmissionClean signal off of

regulator pinBreadboard potential

issue

Onboard Control Logic Design

Onboard Control ImplementationImplemented each sensor separately

XbeeADC (gyro)I2C (compass, pressure)GPSTimers (ESCs)

Simple, flexible message formatDealing with limited program space

Base Station DesignC++ on Linux

Base Station Implementation

Writing KML FilesImplementing OpenGL GUISerial communicationThread interaction

Testing Approach

Important TestsIndividual module testsSystem liftBase station and onboard system interactionAssembly testsBattery LifeCommunication RangeIndoor test flights (Uncooperative weather

recently)

Tests not carried outOutdoor tests – Fight winds

Lessons LearnedSkills

Basics of constructing practical circuitsBasics of PIC Programming

Be flexible - hold up in one area, work on another

Test changes one at a time to isolate unknowns

Budget enough time for documentationInterdisciplinary team

Questions?