1. Frostburg State University Adam Rexroad, Brett Dugan, Mayowa Ogundipe, Kaetie Combs, Michael Stevenson, Daniel Gares, Tyler Lemmert, Subhasis Ghosh, Jared Hughes, Sean Hughes, Andrew Huntley, Derek Val-Addo October 26, 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)  Electromagnetic field theory  Real-Time Systems Theory (for multi-tasking) 5

6. Drexel University’s 2011 project incorporating a despun platform. The Results have not been published but the CDR offered evidence of successful trial runs at large stress. We plan to elaborate on Drexel’s design. Modifying and improving the despun platform design in our project. 6

7.  Mission Objectives:  Counter the spin of the rocket during flight.  Keep a level surface to earth using our conceptual design.  Prove successful by comparing the acceleration data from our zero tilt platform with that from the plate.  Minimum success criteria  Our main goals as the Zero Tilt team is to receive results indicating that we achieved zero tilt and confirming the altitude. 7 crestock.com

8.  What we expect:  Determine whether we were successful in keeping our platform level based on data analysis. (within a 10°tolerance)  Find altitude within a reasonable tolerance again based on the data we collect. 8

9.  Radial Acceleration The max rate of spin of the rocket is 5.6Hz 5.6Hz(2π)= 35.18 rad/sec a rad =146 m/s²=16g

10.  Roll, α o X = 0 o Y = cos(α) o Z = sin(α)  Pitch, β o X = cos(β) o Y = 0 o Z = sin(β)  Yaw, γ o X = cos(γ) o Y = sin(γ) o Z = 0

11.  Converting to Spherical Coordinates

12.  Counter the rotation ◦ Speeds up 8Hz ◦ Stay within +- 5% the actual speed  Zero tilt ◦ Keep the plate level ◦ Stay with in +- 10% of level  General Goals ◦ Meet all NASA requirements ◦ Fast respond time ◦ Reliable data collection ◦ Reliable circuitry

13. Zero Tilt ConOps t ≈ 1.3 min Altitude: 75 km t ≈ 15 min Splash Down t ≈ 1.7 min Altitude: 95 km -G switch triggered -All systems on -Initialize despin system -Initialize zero tilt system based on magnetometer. 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.

14. Despun Platform Zero-TiltDataMotorsPower GearsGimbalMicro- controller DC motorsBatteries MaterialsGearsMemoryServo- Motors Voltage Regulators Slip RingGyroscopeAccel- erometers Motor Speed Controller Arming AlgorithmsDAC

16.  The platform will be able to keep the platform parallel to the Earth independently of the rockets orientation.  All electrical components must be wired to a battery source without twisting the wires.  The assembly must be contained within the size requirements.

17. 1.Motors 1.Drive motor 2.Tilt motor 3.Spin motor 2.Gears 1.Drive Gear 2.Main Gear 3.Gimbal 4.Platform 5.Slip ring 6.Center shaft 7.Bearings 1.Spin bearing 2.Tilt bearing

18. Main gear Drive motor Spin motor Tilt motor Drive gear Gimbal Platform Slip ring Center shaft Spin bearing Tilt bearing

19. http://www.daerospace.com/MechanicalSystems/GearsDesc.php Gear 1 is the drive motor. It will be 1” in diameter. Gear two is the main gear and will be 6.5” in diameter. This will make the gear ration 6.5:1. Both gear will be made of 7075 Aluminum machined in-house.

21.  The Gimbal will support the platform and spin with the assembly. This component will be made out of 7075 Aluminum.

22.  The platform will be made of polycarbonate and will hold the microprocessor. The microprocessor and components to control the tilt and The tilt motor will also be embedded in the platform.  The platform will have a hollow shaft which runs through it, this will allow the wires to be run of the board and onto the gimbal. The tilt motor will act as a bearing at one end, while the hollow shaft will be encased in a bearing on the other end as it enters into the gimbal.

23. ELECTRICAL  1. Contacts: Gold on gold  2. Bearings: Precision ball bearings  3 Dielectric Material: High grade epoxy  4. Torque:.20 in.-oz. maximum (12 rings)  5. Speed: 1000 rpm maximum, intermittent  6. Life: 30 x 106 revs min. @ 100 rpm  7. Rotation: Bi-directional  8. Frame: Stainless steel MECHANIAL  1. No. of Rings: 12 maximum  2. Current: 1 amp maximum  3. Voltage: up to 150 volts  4. Dielectric Strength: 500 vrms, all combinations  5. Contact Resistance Variation: Less than 10 milliohms  6. Leadwire: #30 awg, teflon insulated

24.  The center shaft will encase the slip ring. This will not only take the force off of the slip ring, but also act as a gear for the spin motor. Teeth will be machines to the outside of the shaft to allow the gear on the spin servo to adjust the yaw of the gimbal.

25.  There are two bearings included in this design. The first is the bearing located in the gimbal which allows the platform to rotate. This will be a very small grade 5 or 7 ball bearing.  The second bearing supports the gimbal. It is a grade 5 ball bearing.

26.  There were four materials considered for this project. ◦ Aluminum  Pros - light weight  Cons – low shear strength ◦ Steel  Pros – easy to machine  Cons – high density

27. ◦ Titanium  Pros – very strong  Cons – high density, expensive ◦ Polycarbonate  Pros – Very high tensile strength  Cons – not rigid After considering all of the materials chosen, Aluminum and polycarbonate were chosen as our materials. The poly carbonate was chosen for the platform material because of its light weight and strength. Aircraft grade aluminum was chosen for the gears and gimbal because it has a high strength and light weight. 27

28.  In the conceptual design, thrust bearing were going to be used to keep the rotating parts stable. Due to the compact size of the rotating parts, using a ball bearing should be sufficient in stabilizing these parts. By not using the thrust bearing the friction will be kept to a minimum.

30.  DP.RSK.1 ◦ Gear teeth shear off  DP.RSK.2 ◦ Main gear flexes until it no longer makes contact with drive gear  DP.RSK.3 ◦ Wires snag or twist and break  DP.RSK.4 ◦ Assembly becomes off balance and wobles  DP.RSK.5 ◦ Two points of rotation bind PROBABILITY CONSEQUENCES DP.RSK.3DP.RSK.4 DP.RSK.1 DP.RSK.2DP.RSK.5

32.  System Components:  Gimbal, “Goal Post” structure now moved to underneath the despun platform.  Servo Motors  One will make adjustments in spin so that the long side of the plate is parallel with the direction of the rocket.  One will correct the tilt relative to the earth’s surface.  Microprocessor and Gyroscope  Gyro will send data for tilt correction (spin and tilt) to the microprocessor.  Microprocessor will forward the data it receives to the two servo motors.

33.  Servos  Servo 1 attached directly to shaft to resolve spin.  Servo 2 attached to side of gimbal to resolve tilt.  Zero Tilt Gear  Weight should not be a concern on the tilt platform. Therefore the torque produced in a one to one gear ratio between motor and tilt gear should be sufficient.  Fabrication  Currently have a prototype of the zero tilt platfrom made from polycarbonate.  Hoping to use the same material for tilt gear. (all manufactured in-house)

34. Number of Requirement Description of requirement 1Initially we hope to be able to rotate the platform 360°. This is to ensure it remains stable through the entire flight. 2Microprocessor should be able to pass minimum voltage requirement of 2.4V to gyroscope. 3 4Gimbal, Platform, and components shall survive the intital shock and 25g in flight acceleration. 5The platform will be balanced to conform to center of gravity constraints, 6The platform will be within specified design constraints. Preliminarily < 2 inches in height and 4 inches in diameter, 7Servo motors are adequately powered and provided with correction data in appropriate time frame.

35. CharacteristicL3G4200D (digital)LPR403AL (analog) Voltage Requirement97 Current Requirement97 Process speed810 Angular Rate Noise Density 79 Self-Test Capable710 Survivability( shock, g’s) 10 Availability88 Size108 Cost810 Total (out of 100)8584

36.  Three selectable full scales (250/500/2000dps)  I2C/SPI digital output interface  16 bit-rate value data output  8-bit temperature data output  Two digital output lines (interrupt and data ready)  Integrated low- and high-pass filters with user selectable bandwidth  Ultra-stable over temperature and time  Wide supply voltage: 2.4 V to 3.6 V  Low voltage-compatible IOs (1.8 V)

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38.  ZT.RSK.1 ◦ All of the risks associated with the despun platform  ZT.RSK.2 ◦ Servo motors will not be able to keep up initially.  ZT.RSK.3 ◦ Vibrations will destroy gimbal arms or ZT platform  ZT.RSK.4 ◦ High Gs will cause disrupted platform adjustment  ZT.RSK.5 ◦ Stress on joining areas resulting in breaking.

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

41. 41 Tilt Sensor Gyro vs. Accel GyroscopeAccelerometer Cost 10 Availability 10 Noise 82 Range 10 Accuracy 108 Power Supply 88 Average: 9.38 The cost and availability are both 10 because they are both less then $15. The Gyroscope filterers out Angular Rate Noise The Gyroscope has faster and easier calculations

42. 42 Spin Sensor Gyro vs. Accel GyroscopeAccelerometer Cost 10 Availability 10 Range 010 Accuracy 88 Power Supply 108 Average: 7.68 The cost and availability are both 10 because they are both less then $15. The max rate of spin of the rocket is 5.6 HZ. This means the accelerometer need to read up 16 G The ADXL278 has a range of ±37g. The gyroscope will need to be able to read up to 2016 dps

43. 43 Accelerometers: ADXL203 vs. ADXL278 Accelerometer ADXL203ADXL278 Cost 10 Availability 10 Range 10 Accuracy 102 Power Supply 108 Average: 108 The cost and availability are both 10 because they are both less then $15. The range is ok for the ADXL203 and the ADXL278. The ADXL has a range of ±1.7g which gives it more accurate low g readings. The ADXL278 has a range of ±37g which collects more accurate high g readings. The power supply for the ADXL203 is between 3 and 6 volts which gives a wider range of voltage than the ADXL278 which has a voltage range of 3.5 to 6. The ADXL203 is a better fit for initializing zero-tilt.

44. 44 Accelerometers: ADXL203 vs. ADXL278 Accelerometer ADXL203ADXL278 Cost 10 Availability 10 Range 010 Accuracy N/A8 Power Supply 108 Average: 7.59.2 The cost and availability are both 10 because they are both less then $15. The range is better for the ADXL278 since it can collect high g readings. Although the ADXL203 has a better accuracy, it will not be taking readings in a high g range so accuracy it N/A. The ADXL278 is not as accurate but it will meet our requirements. The power supply for the ADXL203 is between 3 and 6 volts which gives a wider range of voltage than the ADXL278 which has a voltage range of 3.5 to 6. The ADXL278 is a better fit for determining angular velocity.

45. 45 ADXL278 ADXL203

46.  Our electronic system requires a conversion from Digital to Analog signals for our motors.  A Digital to Analog convertor (DAC) is needed 46

47.  ATMEGA32-16PU-ND: we chose this chip due to its operating temperature and its compatibility with our devices and program language.  This chip is also familiar to our team, the previous model was used in our mentors Rockon project and have been extensively researched.  Having been used in the Rockon project we know that the stresses the chip undergoes will not produce an undesirable outcome. 47

48. 48  DS.RSK.1 ◦ Microcontroller Power Fails  DS.RSK.2 ◦ Motor Communication Fails  DS.RSK.3 ◦ Stationary Accelerometer Communication Fails  DS.RSK.4 ◦ Motor fails in measuring own speed.  DS.RSK.5 ◦ Microcontroller can’t survive launch conditions.  DS.RSK.6 ◦ Communication between despun and zero tilt systems fail. PROBABILITY CONSEQUENCES DS.RSK.1 DS.RSK.2 DS.RSK.5 DS.RSK.3 DS.RSK.4 DS.RSK.6

50. The motor subsystem is divided in to two sub systems:  Motor for de-spinning the platform  Motors for adjusting the tilt of the platform and turning the gimbal

51. Requirement for motor 0 (despun motor)  The rocket is estimated to spin at 5.6 Hz (336 rpm)  Requirements:  Current <.4A  Voltage < 30V  Torque < 5.0152mNm  Max. Height < 2.75in

52. SpecificationSystem Requirement s 2232…BX4 S3268...BX4 SC 3268...BX4 SCDC RPM12,100 rpm5,500 rpm4,500 rpm Voltage< 30V24V Amperage<.4A.088A.215A.210A Torque< 5.0152 mNm 29.4mNm137mNm Height< 2.75in1.95in3.36in Costn/a $383.90n/a Brushed/ Brushless

53.  3268...BX4 SC Brushless DC-Motor from Faulhaber.  Criteria Selection:  possible PWM controllability.  Ease of use.  Technology  4 pole brushless motor  Has an integrated speed controller.  Pre-configured to a continuous current.  integrated feedback system.

54.  MS.RSK.1 ◦ Required Torque exceeds stall torque  MS.RSK.2 ◦ Motor-Battery Communication Failure  MS.RSK.3 ◦ Motor gear head and platform may lose contact under 25G  MS.RSK.4 ◦ Battery unable to sustain variable rpm requirements  MS.RSK.5 ◦ Motor may not respond to the micro-controller signals correctly. Consequence MS.RSK.5MS.RSK.3MS.RSK.2 MS.RSK.1MS.RSK.4 Possibility

55. Requirement for motor 1 (tilt motor)  We estimate no more than 20 degrees/sec.  Requirements:  Current <.3A  Voltage = 5-6V  Torque approximately 400mNm  Max. Height < 3in

56. SpecificationSystem Requirements HS-5245MGAM2224- R3 Series 3056 (Stepper Motor) RPM36083.33 rpm5,500 rpm8790 rpm Voltage 5-6V4.8-6.0 Volts1.4V12V Amperage<.3A.18A1 A.168A Torque 400 mNm567mNm22 mNm95mNm Height< 3in1.54in1.98in2.64in Costn/a$70.00n/a ControlPWMSeparate Encoder Separate Motor Controller

57.  HS-5245MG Digital Mini Motor from ServoCity.  Criteria Selection:  High standing torque  PWM controllability  Ease of use.  Technology  Has an integrated speed controller.  360 degree continuous rotation.

58.  MS.RSK.1 ◦ Required Torque exceeds stall torque  MS.RSK.2 ◦ Motor-Battery Communication Failure  MS.RSK.3 ◦ Motor gear head and platform may lose contact under 25G  MS.RSK.4 ◦ Battery unable to sustain variable rpm requirements  MS.RSK.5 ◦ Motor may not respond to the micro-controller signals correctly. Consequence MS.RSK.5MS.RSK.3MS.RSK.2 MS.RSK.1MS.RSK.4 Possibility

59. Requirement for motor 2 (turn motor)  Requirements:  Current <.3A  Voltage = 5-6V  Torque approximately 400mNm  Max. Height < 3in

60. SpecificationSystem Requirement s HSR-1425CRAM2224- R3 Series 3056 (Stepper Motor) RPMN/A52 rpm5,500 rpm 8790 rpm Voltage 5-6V6 Volts1.4V12V Amperage<.3A.12A1 A.168A Torque 400 mNm330mNm22 mNm95mNm Height< 3in1.59in1.98in2.64in Costn/a$0.00n/a ControlPWMSeparate Encoder Separate Motor Controller

61.  HSR-1425CR Robotic servomotor.  Criteria Selection:  High standing torque  PWM controllability  Ease of use.  Technology  Has an integrated speed controller.  360 degree continuous rotation.

62.  MS.RSK.1 ◦ Required Torque exceeds stall torque  MS.RSK.2 ◦ Motor-Battery Communication Failure  MS.RSK.3 ◦ Motor gear head and platform may lose contact under 25G  MS.RSK.4 ◦ Battery unable to sustain variable rpm requirements  MS.RSK.5 ◦ Motor may not respond to the micro-controller signals correctly. Consequence MS.RSK.5MS.RSK.3MS.RSK.2 MS.RSK.1MS.RSK.4 Possibility

64.  9 Volt Lithium

65. 5V 3.3V

66.  Who are you sharing with? ◦ Harting  Plan for collaboration ◦ Communicated through email ◦ We shall share designs and ideas through email  We are still working on the structural interface with them but have decided upon position in the cannister. Harting will be above us below. (plate in between) 66 grandpmr.com

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68. 68 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

69. 69 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

70. 70 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.

71. 71 ItemPart NumberManufacturerVendorQuantityPrice (each) Total Dual Axis High-G Accelerometer AD22284Analog Devices 21224 Dual Axis Low-G Accelerometer AD220372Analog Devices 110 MicroprocessorATMEGA32-16PUAtmelDigikey28.2814.56 Slip RingCAY-1398Aeroflex 1As of yet unknown ~300 GyroscopeL3G4200D ST MicrosystemsArrow31545 DC Despin Motor3268BX4SCFaulHaberMicromo1383.90 Tilt Servo motorHS-5245MGHitecServocity170 Spin ServoHSR-1425CRHitecIn house2 0 Flash MemoryAT26DF161AAtmelDigi-key248 Components still under research Raw materials Total Ceiling1500

72. 72 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

73.  We hope to order 90% of the materials required and begin fabrication of the gears.  We need to solidify our power requirements as well as our electric circuitry.  We must test our materials for weight and decide if our current materials will handle the stresses of rocket flight.  We intend to finalize our budget and remain within our $1500 ceiling.  Determine how fast the rocket changes angle with respect to starting position. 73