1. Frostburg State University Brett Dugan, Adam Rexroad, Kaetie Combs, Michael Stevenson, Daniel Gares, Mayowa Ogundipe, Tyler Lemmert, Jared Hughes, Sean Hughes, Andrew Huntley, Subhasis Ghosh, Derek Val-Addo, 11/27/2011 1

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3.  Mission Statement: Zero Tilt’s goal is to provide, for the first time, a stable environment throughout the flight of a Sounding Rocket via two concurrent objectives: ◦ Tilt correction system ◦ Despun platform system 3

4.  We plan to: ◦ Counteract the platform spin ◦ Orient the platform parallel to the earth’s surface at all times ◦ Confirm the altitude reading using an accelerometer on our platform  We expect to prove that it is possible to correct spin, tilt, and determine the altitude based upon a level reference.  This could benefit any scientific experiment that requires stabilization in order to collect data. 4

5.  The underlying theory and concepts: ◦ negative feedback control systems ◦ concepts of torque and centripetal force ◦ Micro electromechanical systems (MEMS) ◦ Real-Time Systems Theory (for multi- tasking) 5

6.  Mission Objectives: ◦ Counter the spin of the rocket during flight. ◦ Keep a level surface to earth using our conceptual design. ◦ Prove successful by using the stored gyroscope output and the feedback from various motors.  Minimum success criteria ◦ Our main goals as the Zero Tilt team is to receive results indicating that we achieved zero tilt for the flight of a sounding rocket. 6

7. 7 Project Manager Kaetie Combs Mentors Adam Rexroad Brett Dugan Faculty Advisor Dr. Mohammed Eltayeb Despun Platform Daniel Gares Tyler Lemmert Kaetie Combs Zero Tilt Platform Michael Stevenson Daniel Gares Andrew Huntley Sensors Kaetie Combs Tyler Lemmert Andrew Huntley Michael Stevenson Data System Jared Hughes Sean Hughes Mayowa Ogundipe Derek Val-Addo

8. 8 Despun Platform Zero Tilt Platform Data SystemsSensors Design: Daniel Gares Kaetie Combs Tyler Lemmert Gears: Tyler Lemmert Design: Daniel Gares Mike Stevenson Andrew Huntley Everybody will be involved with programming. Processors: Jared Hughes Sean Hughes Motors: Mayowa Ogundipe Val-Addo Subhasis Ghosh Accelerometers: Kaetie Combs Tyler Lemmert Gyroscope: Mike Stevenson Andrew Huntley

9. Zero Tilt Con-Ops t ≈ 1.3 min Altitude: 75 km t ≈ 15 min Splash Down t ≈ 1.7 min Altitude: 95 km -All systems on -Initialize de-spun system -Initialize zero tilt system based on low-G acceler – ometer value. -Despun system prepares for initial spin up. t = 0 min t ≈ 4.0 min Altitude: 95 km Apogee t ≈ 2.8 min Altitude: ≈115 km t ≈ 4.5 min Altitude: 75 km t ≈ 5.5 min Chute Deploys -use the position of the zero tilt plate as initial value for the gyroscope sensor. -switch to gyro input for zero tilt system.

10.  What we expect: ◦ Using feedback analyze whether we were successful in despinning the platform. More than a one percent error in this section would provide too much error in the tilt system. Therefore we expect this system to perform near perfection. ◦ Determine whether we were successful in keeping our platform level. (within a plus or minus 5 degree envelope) 10

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12.  The scope of the project has changed slightly. ◦ We no longer require a viewport for camera due to size constraints. ◦ There was a minor change made to the design which will be discussed in the Mechanical Design elements section. ◦ Due to processor obligations we will not be verifying the altitude with the Low-G accelerometer. ◦ Our method for obtaining power has changed since the 9 volt batteries we were considering do not supply the continuous current necessary. Instead we will use a combination of AA batteries and 9 volts to supply various systems with the correct power. 12

13.  If we run out of time or money, or main goal would become to concentrate on the despun system.  If the tilt system does not have the time to complete the tilt correction, we may have to institute a different system. Such as running two processors and two gyros, one for each motor.  If the intuition that the priority of motors in the tilt system is wrong, then we need to consider major program changes. 13

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16. Mechanical Design Elements – Gear Elements 16

17. 17  Main Gear  75 teeth  12 Diametral Pitch  6.25 inch Pitch Diameter  Pitch Diameter based off design constraints

18. Mechanical Design Elements – Main Gear Calculations 18 NomenclatureFormulaCalculationMeasurement Number of teeth (N)N=P*DN=12*6.2575 teeth Diametral Pitch (P)P=N/DP=75/6.2512 Outside Diameter (Do)Do=(N+2)/PDo=(75+2)/126.4166 inches Circular Pitch (p)p=(Pi*D)/Np=(Pi*6.25)/750.2618 inches Addendum (a)a=1.000/pa=1.000/120.0833 inches Dedendum (b)b=1.250/Pb=1.250/120.1042 inches Working Depth (hk)hk=2.000/Phk=2.000/120.1666 inches Root Diameter (Dr)Dr=(N-2.5)/PDr=(75-2.5)/126.0417 inches 20 degree pressure angle Gear Ratio (GR)GR=Nmain/Ndrive GR=75teeth/15teet h5:1

19. Mechanical Design Elements – Drive Gear 19 Drive Gear 15 teeth 12 Diametral Pitch 1.25 inch Pitch Diameter Pitch Diameter based off strict design thresholds

20. Mechanical Design Elements – Drive Gear Calculations 20 NomenclatureFormulaCalculationMeasurement Number of teeth (N)N=P*DN=12*1.2515 teeth Diametral Pitch (P)P=N/DP=15/1.2512 Outside Diameter (Do)Do=(N+2)/PDo=(15+2)/121.4166 inches Circular Pitch (p)p=(Pi*D)/Np=(Pi*1.25)/150.2618 inches Addendum (a)a=1.000/pa=1.000/120.0833 inches Dedendum (b)b=1.250/Pb=1.250/120.1042 inches Working Depth (hk)hk=2.000/Phk=2.000/120.1666 inches Root Diameter (Dr)Dr=(N-2.5)/PDr=(15-2.5)/121.0417 inches 20 degree pressure angle Gear Ratio (GR)GR=Nmain/NdriveGR=75teeth/15teeth5:1

21.  After cutting the gears, we will utilize one of the electric motors in the campus machine shop to test the durability and precision of the  With the electric motors we can test the durability of the gears by meshing them at high speeds as well as applying a load to the gears. With such testing we can find weak points as well as any points where destructive friction is present.  By testing the gears at max conditions, we will be assured that the gears will survive the ascent and splash-down. 21

22. Upper Center Shaft Tilt Servo Lower Center Shaft Slip Ring Top Plate Spin Bearing Tilt Bearing Tilt Platform Drive Motor Housing Drive Motor Spin Servo Gimbal

23. Main Gear Bearing Slip Ring Leads Bottom Plate Main Gear Drive Gear Support Posts Shield

31.  Since the PDR there has been one crucial design change. The way the design was laid out, there was no way to get power to the spin servo located on the gear. This is shown by the blue arrows in the diagram. When the power source reached the bearing, an additional slip ring would be needed to cross the bearing. To fix this we switched the raised the drive gear and put the servo on top of the gimbal. The servo now can get power through the slip ring shown by the red arrows. The only down side to this, is the weight of the servo will have to be countered to prevent wobble in the system.

32.  The support poles that we are using to hold up the weight of the capsule above us has been changed to a different material.  The old material was 7075 Aluminum. The new material is Carbon Fiber.  The reason we have made this decision is to reduce the weight of the capsule. 32

33. PartMaterialDiamensionscost per unitquantitytotalDistributorPart # support polesCarbon FiberDi=0.414, Do=0.500, h=4838.611 McMaster2153T41 top plate7075 Aluminum12 X 12 X.12542.171 McMaster8885K15 base plate7075 AluminumD=10, 170.051 SpeedymetalsN/A main gear7075 AluminumD=7, 138.341 SpeedymetalsN/A gimbal7075 Aluminum3 X 4 X 797.581 SpeedymetalsN/A drive gear7075 AluminumD-3 X 17.821 SpeedymetalsN/A center shaftABSD=2.5 X 1238.851 McMaster8587K31 platformfiberglass6 X 3 X 157.911 McMaster3345K26 servo gear7075 AluminumMade from base plate shaft excess0N/A Main Gear BearingSteelDi=2, Do=2.5, T=.25195.261 McMaster6656K11 Spin BearingSteelDi=2, Do=2.5, T=.25195.261 McMaster6656K11 Tilt BearingSteelDi=1/4, Do=5/8, T=.19617.461 McMaster3826T17 Slip RingN/A 54.451 Mercotac230 Shield6061 AluminumDi=6.5, Do=6, h=412.721 SpeedymetalsN/A Order Total866.48

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35.  Please show finalized block diagrams, state how many PCBs/breadboards you will use and what each one will do, sensors they will have  Show the schematics for each PCB/bb ◦ I know they will be large and difficult to see in detail but I’m looking to see that they have been completed  Any changes to this system since PDR? ◦ How does this affect your mission requirements? ◦ What has been finalized that wasn’t at PDR?  Will you activate with command line or gswitch/LEDEX? ◦ If command line, state how early you want to activate and show the schematic you have derived to comply with the User’s Guide reqs 35

36. 36 Schematics Despun and Zero tilt on following slides

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40. 40 Accelerometer 1 Accelerometer 2 Microcontroller Power Supply Digital to Analog Converter Slip Ring Gyroscope Microcontroller Motor Servo φ Servo θ

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44.  Timer – From system start: counts down from start to calculated stop time, ending all programs, powering down systems at end.  Low-g accelerometer – Used at system start, before lift off, to orient tilt system with respect to gravity. Provides Initialization point.  High-g accelerometers – Major despun input, measures rocket rotational acceleration to be opposed equal and opposite to by platform.  Motor0 – Despun motor that rotates platform to cancel out rocket’s rotation. 44

45.  Gyroscope – Major tilt input, measures tilt platform orientation with respect to x and y axis.  Motor 1 – Tilt motor (servo) rotates tilt platform from x axis measurements to keep tilt platform level relative to initialization point.  Motor 2 – Tilt motor (servo) rotates tilt platform from y axis measurements to keep tilt platform level relative to initialization point. 45

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47. 47 Altitude plot of past Rockon flight, analyzed on the following slide. Latitude vs Longitude plot of past Rockon flight, anlayzed on the following slide. Chute Deploys

48.  What this data tells us about flight: ◦ Due to the Latitude vs Longitude plot we can conclude that the motor controlling the spin in the tilt system is of a low priority. This is because the maximum angle the rocket can change in the plane of concern is 45 degrees. ◦ The altitude plot demonstrates that the majority of the change in the tilt will occur at the apex. It must be able to rotate 180 degrees. This means that the tilt motor will have priority over the spin motor due to the greater degree in change over a shorter time period. ◦ As will be explained in the software section we believe our processer will be able to perform both the tilt and spin tasks without falling behind due to the small variations in spin coupled with the priority placed on tilt. 48

49.  The programming of our processor has made considerable strides with a demonstration of the PVM capabilities of the motor.  The Motor was controlled using the program provided on the following slides.  We now are assured we can control the servo motors (motors 1 and 2) and are working toward accomplishing similar goals with the despun motor (motor 0), and the sensors. 49

50. * Created: 11/13/2011 11:32:10 PM * Author: Mayowa & Derek */ //#define F_CPU 1000000 // If processor speed (or clock) changes, redefine #include "inc.h“ #include //#include // include interrupt from compiler #include // Include Delay Functions from compiler 50

51. int stop=67,forward=14,backward=128; // values at points corresponding to move motor 2 void M1_move(unsigned int pwm) // function call to move motor 2 { OCR0 = pwm; // output compare register for timer 0 } void motors_init() // initialization for timers { TCCR0 = 0x7A; // configure for fast inverted PWM output on motor control pins: 51

52. OCR0 = 67; // initialize all PWMs to 0% duty cycle; point where motor brakes DDRB |= (1 << PORTB3); // set PWM pins as digital outputs } void move_90ryt() // Test for 90 degree turn under no load { OCR0 = forward; // motor 2 moves clockwise _delay_ms(262); // continue moving 262 ms OCR0 = stop; button_check: // Debounce implementation 52

53. if ((bit_is_set(PIND,PD3))) { return;} Else {goto button_check; } int main( ) // main program starts { 53

54. motors_init(); // initialize pwm while (1)// infinite loop { if (bit_is_clear(PIND,PD0))// check for input on switch 0 { M1_move(stop); // call for brake } if(bit_is_clear(PIND,PD1))// check for input on switch 1 { M1_move(forward);// call to move clockwise } 54

55. if (bit_is_clear(PIND,PD2))// check for input on switch 2 { M1_move(backward);// call to move counterclockwise } if (bit_is_clear(PIND,PD3))// check for input on switch 3 { move_90ryt();// call for 90 degree turn } 55

56.  Constructions of the size of various mechanical components. ◦ Acryllic board made to model the zero-tilt platform.  Clearance considerations  Length by width comparisons to components  Motor placement ◦ Metal half-capsule made for a visual idea of size constraints  Used to decide upon things to be included and those to be thrown out.  Instrumental in the decision to abandon camera option.  Motor/Processor prototype to test controllability. ◦ Necessary to prove to ourselves that we could manipulate the servo motors effectively. 56

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58. 58 Weight Budget Assembly5.5lbs. Container3lbs. Fixed components1lbs. Total9.5lbs. Total allowed10lbs Under/Over0.5lbs

59. 59 Sub- System Voltage (V) Current (A) Time (h) Amp- Hours Motor 0242.590.250.6475 Plate 15.250.00350.250.000875 Plate 260.31730.250.079325 0.7277 Total A*h 0.2723 Under Over (A)

60. 60 DescriptionLoadSourceAA Quantity1 32 Voltage (V)24Voltage1.5 Current (mA)2590Continuous Current (mA)2000 Power (mW)62160Current Capacity (mA)3000 Time (H)0.25Time (H)0.25 Energy (mW-H)15540Current Capacity (mA)6000 Continuous Current Capacity (mA)4000 Energy Capacity (mW-H)96000 Needed:Available:

61. 61 Load Description Low G Acceler- ometerGyroscopeProcessor Motor 1 Motor 2 High G Acceler- ometerProcessorTotal Energy Quantity1111121 Voltage (V)5.253356 3 Current (mA)1.16.11.11891202.91.1 Power (mW)5.77518.33.394572015.2253.3 Time (H)0.25 Energy (mW-H)1.443754.5750.825236.31807.61250.825431.53125

62. 62 Source9V Quantity3 Voltage (V)9 Continuous Current(mA)150 Current Capacity(mAh)1200 Time (H)0.25 Total Current Capacity (mA)3600 Total Continuous Current Capacity (mA)450 Energy Capacity (mW-H)32400

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64.  The following part will need to be machined: upper center shaft, lower center shaft, top plate, bottom plate, gimbal, tilt platform, drive motor housing, main gear, drive gear, support posts, and shield. These parts will be machined in house.  The bearings will be ordered from Mcmaster- Carr. The slip ring will be ordered from Mercotac.

65.  Despun System  Tilt System  Integration of both 65

66.  Needs To be manufactured ◦ PCB ◦ Soldered our self  AVR, speed controller, resister, capacitors, voltage regulators, diodes, header, and transistors ◦ Place on the PCB by the company  Flash, accelerometers, gyro  Realistically we envision at least 3 revisions of our designed layout but hope to have our finalized piece up to specifications for the company by the time listed in the schedule section.

67.  The first block of code is the code read and process data from the two high-G accelerometers.  The second block of code controls the despun motor and therefore depends upon the first block of code.

68.  The first block of code in this system assumes that the despun system worked properly. The low-G accelerometer code is used to initialize the system. The gyroscope code is used to maintain orientation during flight.  The second block of code depends on the readings from the gyroscope and the accelerometer. The motor code translates sensor data into the amount the motor needs to turn to maintain zero tilt.

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70.  Sensor output evaluation ◦ Understanding the sensor output ◦ Test of real-time transfer of the data ◦ Self test of each sensor  prove accuracy  Assure workability ◦ Survivability test  The system passes if we maintain a steady data transfer

71.  Despun test ◦ Use the machine shop lathe to spin at variable speeds.  Measures rotational force  Assures platform compensates for spin  This test will be successful if Motor 0 keeps up with the spin.

72.  Tilt test ◦ Test the system using a variety of orientations, the motors will compensate our influence.  The system passes testing if Motors 1 and 2 correct tilt properly, maintaining a maximum error of plus or minus 5 degrees. ◦ This will be the final test assuming all other systems perform perfectly!

73.  Complete system maximum stress test ◦ Method to be decided ◦ We were thinking about dropping the unit from a height and rebound the fall with bungee cords ◦ This test will simulate the initial shock from the launch  The unit passes the stress test if all systems and subsystems survive

74.  Vibration and rotation test  Utilizes a shaker table and lathe ◦ De-spun platform test ◦ Spin of gimbal test  Also we must insure the following: ◦ Remain under mass constraints of 10lbs ◦ Remain under volume constraints of a 9.3in Diameter and 4.75in height. ◦ Keep center of gravity within the 1 x 1 x 1in envelope  We’ll know the system passed if there is minimal wobble and the system doesn’t break apart during rotation

75. Mechanical Design Elements – Gear Testing 75  After cutting the gears, we will utilize one of the electric motors in the campus machine shop to test the durability and precision of the gears.  With the electric motors we can test the durability of the gears by meshing them at high speeds as well as applying a load to the gears. With such testing we can find weak points as well as any points where destructive friction is present.  By testing the gears at max conditions, we will be assured that the gears will survive the ascent and splash-down.

76.  Evaluation Boards ◦ Test Gyroscope output, real time sample rate, accuracy, and power. ◦ Test the motor response, speed, and power consumption. ◦ Processor performance including speed, storage of data, and power. ◦ Test all Accelerometer output, and confirm power consumption.  If we can adequately supply power to our components, communicate between all of our devices, and accomplish the goals of our subsystems then we would call this a success. 76

77.  After the evaluations have been completed as of the systems need to be integrated to make sure that they can be successfully supplied with power.  Finally, the electrical components need to be finalized in preparation for fabrication (PCB construction), this is when severe revisions will be performed. 77

78.  Software determines how well our devices can communicate as well as the optimum speed. Therefore it is instrumental in our electrical system.  In order to test the accelerometers on the base plate we will need to read data, process the data into motor ready commands, and relay it to our despun motor: motor 0.  In order to test the gyroscope we will need code to read from the gyroscope, process this data, and relay it to the necessary motors: motor 1 and 2. 78

79.  In order to test that we are storing data correctly, sections of code will need to be dedicated to transferring readings to the flash memory.  In order to test that we can initialize the zero tilt system correctly we must have code to use the Low-G accelerometer for initialization, then switch to Gyroscope control.  Finally, in order to assure zero tilt, our code must be able to prioritize tasks, such as what was discussed in the analysis section. 79

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81. 81 Consequence RSK.1- Despun System Fails RSK.2- Power Failure RSK.5- Communication Failure RSK.4- Tilt System Fails RSK.3- Zero-tilt Fails to Initialize RSK.3- Mechanical Flaw Possibility What have we done to mitigate them? With a better understanding of the function-ability of our subsystems we were able to walk-down several of our risk factors. The most important was the Despun system (RSK.1). With a feedback system we are more confident that we can control the motors speed effectively.

82. 82 Consequence RSK.1- Despun System Fails RSK.2- Communication Faliure RSK.3- Mechanical Flaw Possibility Do we have plans to walk these down? Yes, we hope that we are able through testing to iron out any mechanical flaws or imperfections of material. In addition we hope to vigorously test the electrical components so that the risk of a communication failure becomes even less likely. Are there any risks you just have to accept? The risk we must accept is that our despun system fails. Hopefully with enough tests we can alleviate the possibility further.

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84.  Mass – we verified that we are within the 10lb maximum in mass budget.  CG within 1”x1”x1” envelope? How have you checked this ◦ With the addition of batteries to our mechanical drawings we were able to verify that we could remain within a 0.5”x0.5”x0.5” envelope.  Batteries: We will be using a combination of 9V batteries and Lithium AA’s.  RESTATE: We plan to activate prior to launch and have changed our time after reviewing the allowable constraints. With a maximum of 10mins we would like to use a 9 minute initialization time. 84

85. 85  We are sharing with Harding University  According to their PDR, their mission is to design, build, test and fly a spectrometer that will measure transmission spectra of gases in Earth’s atmosphere at lower altitudes and the Sun’s irradiance at higher altitudes.  Plan for collaboration: ◦ We intend to communicate with them via E-Mail. We have not communicated with Harding University as of yet because we only need to verify their mass in order for our stress testing. Thus, this communication is not of high priority at the moment. Also, looking at their PDR they said they sent us Design models but we have received nothing of the sort.  Structural interface – Our systems will be separated by a plate, however their capsule will screw into ours. grandpmr.com

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87. 87 Tentative Schedule Finalize Design Beginning of November: Start ordering parts Now until end of semester: Start testing electric components, test gyroscope output, test accelerometer outputs, test servo response, make sure we are able to supply necessary power, and complete despun subsystem. Next semester End of February: Zero Tilt platform completed For the rest of the semester we will continue testing and correcting problems to prepare for the launch in June.

88. Schedule - Schedule for the Rest of this Semester (Fall 2011) December 12/1Critical Design Teleconference 12/1-12/12Continue Testing Electrical Components, Accelerometer and Gyroscope Output, and Motor Response Acquire All Necessary Components for Project. Begin Machining of Mechanical Components so They are Prepared for the Spring Semester 12/12Last Day of the Semester

89. Schedule (continued) - Schedule for Start of Next Semester (Spring 2012) January 1/25First Day of the Semester 1/25-1/30Prepare Progress Report 1 Fabricate and Begin Testing on De-spun System Begin Testing Tilt System Send Flash, Accelerometers and Gyroscopes to Company of Choice to be Placed on PCB Complete Sensor Output Evaluation 1/30-2/13Test Individual Subsystems and Prepare Reports Finish Testing De-spun System Finish Testing Tilt System Conduct Stress, Force, and Gear Tests Ensure that Electrical Systems are Functioning Properly Verify that Code Performs as Expected Walk-Down Risk Factors 1/30Progress Report 1 Due February 2/3First Payment Due 2/13Individual Subsystem Testing Reports Due 2/14Individual Subsystem Testing Reports Teleconference 2/14-3/12Prepare Progress Report 2

90. Schedule (continued) - Schedule for Middle of Next Semester (Spring 2012) March 3/12Progress Report 2 Due 3/12-4/2Work on Payload Subsystem Integration and Prepare Testing Reports April 4/2Payload Subsystem Integration and Testing Report Due 4/3Payload Subsystem Integration and Testing Report Teleconference 4/6Final Payment Due 4/15RockSat Payload Canisters Sent to Customers 4/15-4/16Work on Placing Entire System in Canister for Testing 4/15-4/23Simulate Mission and Prepare Test Report 4/23First Full Mission Simulation Test Report Presentation Due 4/24First Full Mission Simulation Test Report Presentation Teleconference 4/24-5/28Continue Simulations and Testing and Prepare for Launch Readiness Review

91. Schedule (continued) - Schedule for End of Next Semester (Spring 2012) May 5/7Weekly Teleconference 1 5/14Weekly Teleconference 2 5/21Weekly Teleconference 3 5/28Launch Readiness Review Presentations 5/29Launch Readiness Review Teleconference June 6/4Weekly Teleconference 4 6/11Weekly Teleconference 5 6/14Visual Inspections at Refuge Inn 6/15-6/18Integration/Vibration at Wallops 6/20Presentation's to Next Year's Rock Sat 6/21Launch Day

92. Budget StatusItemQuantityUnit priceTotal price ReceivedProcessors2$5.20$10.40 ReceivedEvaluation Board (Processors)1$82.16 ReceivedGyroscope10$0.00 ReceivedEvaluation Board (Gyroscope)1$27.00 Need to BuyMotor Controller1$5.00 Need to BuyMotor 01$365.00 Need to BuyMotor 11$8.92 Already HaveMotor 21$0.00 OrderedAccelerometer ADXL2032$27.95$55.90 OrderedAccelerometer ADXL2782$33.83$67.66 Need to BuyMaterialsSee Next Slide $866.48 Total$1488.52 Total with Margin$1637.37

93.  Issues we still have include: ◦ A viable test for the initial stress (takeoff). ◦ Real-time functionality of the tilt system. ◦ A steeper price for the raw materials then previously anticipated.  The plan of action (before break): ◦ To acquire the remaining components. ◦ Finish tests concerning the motors. ◦ Begin testing of sensors using evaluation boards. ◦ Evaluate price inflations. ◦ Continue to walk-down our risk factors. 93