Drexel University 2010 2011 Rock SatC Preliminary Design

Drexel University 2010 -2011 Rock. Sat-C Preliminary Design Review Joe Mozloom Eric Marz Linda Mc. Laughlin Swati Maini Swapnil Mengawade Advisor: Jin Kang, Ph. D 1

Mission Overview - Objective � Drexel's Rock. Sat payload will incorporate a platform rotating opposite the spin-stabilization of the Terrier -Orion sounding rocket during ascent, resulting in a rotationally static platform from an outside reference frame. 2

Mission Overview - Purpose � Experimentally determine the feasibility of a despun platform under high acceleration and turbulence, driven by a low power system. � Provide a stable platform with respect to the exterior environment to accommodate experiments requiring constant frame of reference in an ascending object. 3

Mission Overview - Theory �Angular Velocity ω = dθ / dt ω At 5. 6 Hz ω = 35. 18 rad/sec �Radial Acceleration ar at ar = ω 2 r At 35. 18 rad/sec With 0. 0635 meter Radius ar = 78. 62 m/s 2 = 8 g 4

Expected Results WORKBENCH Meet all NASA / WFF requirements � Counter-rotating platform effective from 0. 5 Hz - 10 Hz � Maximum platform spin-rate 10% of current canister spinrate � Data is reliably collected and is usable � FLIGHT Meet all NASA / WFF requirements � Counter-rotating platform engaged when canister is spinning � Platform able to rotate under harsh flight conditions � Data is reliably collected and is usable � 5

Preliminary Design 6

Concept of Operations � There are several flight points which are of interest to our experiment (Seen on next slide) � Rotation measurements of despun platform during following time periods: Terrier Burnout Orion Burnout Remaining Ascent Descent 7

Concept of Operations 8

Subsystem Definitions Despun Platform (DP) Slip Ring Despun Gear Data Systems (DS) Microcontroller Memory Accelerometers Algorithms Motor Systems (MS) DC Micro-motor Pinion Power Systems (PS) Batteries Voltage Regulators G-Switch 9

Despun Platform Subsystem

Despun Platform Definition �System Components Through-Bore Slip Ring Fastener Undefined until Slip Ring is selected q May be unnecessary if mounting holes can be drilled into slip ring q Despun Plate/Cog 2 -axis, High-G Accelerometer 11

DP - Subsystem Description � 4: 1 Gear Ratio between platform and motor pinion Reduces torque needed by motor �Despun gear nominal dimension of 5” (127 mm) �Gear to be CNC cut from ¼” (6. 35 mm) polycarbonate Fabricated In-House 12

DP - Subsystem Requirements # Requirement 1 Platform shall be able to rotate at > 500 RPM 2 System shall be able to pass ≈ 2. 2 m. A from microcontroller to accelerometer 3 System shall be able to pass ≈ 5 V from microcontroller to accelerometer 4 Slip ring shall include > 5 circuits for data and power transmission 5 System shall perform throughout 25 g acceleration 6 System shall allow for center standoff 7 Platform shall be < 7” 13

DP - Slip Ring Trade Study Slip Ring Jinpat LPT 012 Aeroflex CAY-1847 Aeroflex CAY-1666 Max RPM 6 6 10 Max Voltage 10 10 10 Max Amperage 10 10 10 Through Bore 9 8 9 Height 7 7 7 Mass 7 9 8 Cost 10 7 2 Availability 3 9 9 Max Vertical Load 6 8 8 Torque 6 7 7 81 80 Totals 75

DP - Selected Slip Ring �Aeroflex Airflyte CAY 1847 Max RPM: 500 Through-Bore Diameter: 3/8” =9. 525 mm Length: 1. 3” = 33. 03 mm Stator Diameter: 1. 25” = 31. 75 mm # of Circuits: 18 Max Voltage: 210 V Max Current: 2 A/Circuit Cost; $400 15

DP - Risk Matrix CONSEQUENCES PROBABILITY DP. RSK. 3 DP. RSK. 5 DP. RSK. 4 DP. RSK. 1 DP. RSK. 2 � DP. RSK. 1 Sensor will not function � DP. RSK. 2 Teeth on gear will break due to elevated torque levels from acceleration � DP. RSK. 3 Vibrations will cause loss of contact in Slip Ring Terminals � DP. RSK. 4 High Gs will cause slip ring bearings to seize � DP. RSK. 5 High Load causes gear to distort, losing contact with pinion 16

Data Subsystem Power Supply Stationary Accelerometer Microcontroller Despun Accelerometer Slip Ring Digital to Analog Converter Motor 17

DS - Accelerometer vs. Gyroscope Accelerometer Gyroscope Range 10 2 Resolution 5 5 Ease of Calculations 8 10 Maximum Shock 10 8 Cost 10 8 Availability 3 3 Totals 46 36 18

Data Systems Definition �Microcontroller ATMEL 8 -bit AVR Microcontroller Motorola M 68 HC 12 Microcontroller �Accelerometer Analog Devices ADXL 278 MEMS Accelerometer Colibrys MS 8000. D MEMS Accelerometer �External Resistor Ladder for 8 -bit/16 -bit Digital to Analog Conversion 19

DS - Software Schematic 20

DS - MEM Accelerometers �ADXL 103/ADXL 203 Size: 5 mm x 2 mm Resolution: 1 mg at 60 Hz Bandwidth: 0. 5 Hz – 2. 5 k. Hz Sensitivity: 960 -1040 m. V/g Supply Voltage: 3. 0 -6. 0 V Supply Current: 1. 1 m. A 3500 g Shock survival 21

Accelerometers Trade Study Specification Size System Requirements ADXL 203 ADXL 278 5 mm x 2 mm 5 mm × 2 mm, Resolution > 2 mg 60 Hz Bandwidth 0. 5 Hz – 2. 5 k. Hz Sensitivity Minimum 1 mg at 60 Hz 0. 5 Hz – 2. 5 k. Hz 960 -1040 m. V/g 2 mg 60 Hz 0. 5 -400 Hz 25. 65 -28. 35 m. V/g Supply Voltage 3 V 3. 0 -6. 0 V 4. 75 -5. 25 v Supply Current 1. 1 -3. 0 m. A 1. 1 m. A 2. 9 m. A Full scale range x-y ± 50 g ± 1. 7 g ± 35 g/± 35 g, ± 50 g/ ± 50 g, or ± 70 g/± 35 g 22

DS - Accelerometers Testing �ADXL 203 tested and specified at Vs = 5. 0 V �Radiometric output Vs = 3. 0 V output sensitivity ≈ 560 m. V/g �Noise density decreases as the supply voltage increases. Vs = 3. 0 V, Noise Density = 190 μg/√Hz �When ratiometricity of sensitivity is factored in with supply voltage, self test response is roughly proportional to the cube of power supply voltage. Vs = 3. 0 V, Self Response ≈ 150 m. V 23

DS - Analog to Digital Conversion � Requirement for our electronic system: to convert signals from digital to analog forms � Analog to digital convertor (DAC)needed 24

DS - Risk Matrix PROBABILITY CONSEQUENCES DS. RSK. 1 DS. RSK. 2 DS. RSK. 5 DS. RSK. 3 DS. RSK. 4 � DS. RSK. 1 Microcontroller Power Failure � DS. RSK. 2 Motor Communication Failure � DS. RSK. 3 Stationary Accelerometer Communication Failure � DS. RSK. 4 Despun Accelerometer Communication Failure � DS. RSK. 5 Microcontroller can’t survive launch conditions 25

Motor Subsystem

Motor Systems Definition �Required RPM: 600 (without gearing) 2400 RPM with 1: 4 gear ratio �Amperage: < 300 m. A �Torque: 80 m. Nm (without gearing) 20 m. Nm with 1: 4 gear ratio �Max Length: 3” = 7. 62 cm �Max Diameter: 2”= 5. 08 cm �Max Mass: 250 g �Pinion to be CNC cut from ½” (12. 7 mm) polycarbonate Fabricated In-House

MS - Motor Trade Study System Re-16 Specification Requirements Maxxon 3257 G MICROMO 3242 SCDC DC –Servo Motor RPM 2400 RPM 7130 RPM 5700 RPM 5300 RPM Voltage 12 Volts Amperage < 300 m. A 6. 05 m. A 258 m. A 199 m. A Torque > 20 m. Nm 5. 47 m. Nm 70 m. Nm 50 m. Nm Length <762 mm 61 mm 790 mm 720 mm Mass <250 grams 38 grams 242 grams 189 grams Cost <300$ Brushed/Brus hless $283. 00 Brushed Brushless

MS - Brushed vs. Brushless Specification Brushed Brushless Efficiency Medium High Speed/Torque Moderately flat (difficulty in switching speeds at very high rpm) Enables operation at all speeds Electrical Noise High Low Communication Mechanical Electronic Maintenance High Low Life Shorter Longer Motor Size Larger due to commutator and heat removal Smaller Speed Ranges Commutator limits speed Can rotate at high speeds Drive Complexity Simple and inexpensive Complex and expensive

MS - Selected Motor � 3242 SCDC DC Servomotor from Faulhaber. �Selection Criteria This brushless motor fit all of our design criteria- electronic communication, high speed, data transfer and reception and small size. �Gearing Requirement Can be provided with the motor (3242 SCDC 012) 32 A-available on request from the supplier. 30

MS - Risk Matrix PROBABILITY CONSEQUENCES MS. RSK. 1 � MS. RSK. 1 Required Torque exceeds stall torque � MS. RSK. 2 Motor-Battery MS. RSK. 4 Communication Failure MS. RSK. 5 MS. RSK. 3 MS. RSK. 2 � MS. RSK. 3 Motor gear head and platform may lose contact under 25 G � MS. RSK. 4 Battery unable to sustain variable rpm requirements � MS. RSK. 5 Motor may not respond to the micro-controller signals correctly. 31

Power Subsystem 32

Power System Definition �Rechargeable Battery � 9 V Ni. MH Powerizer Batteries � Amperage : 170 m. A �Amount needed : 4 �Weight: 125 g �Voltage Regulator ± 3. 3 V Linear regulator flash memory and accelerometers ± 5. 0 V Linear regulator for microcontroller �Parallel and Series connection to achieve requirements of motor and electronic devices 33

PS - Power Flow 34

PS - Battery Trade Study Specification System Energizer 175 Requirements m. Ah 9 V Ni. MH Powerizer Batteries Nickel-metal Hydride Effective Voltage 16 V 9 V 9 V 12 V Number - 4 4 2 Type Amperage Rechargeable Non -rechargeable 300 m. A 175 m. A per 170 m. A per 2450 m. A Mass (total) 32 g 125 g 255 g Cost $32. 0 $27. 0 $ 71. 90 35

Critical Interfaces Interface Description Potential Solution Despun Gear / Motor Pinion Motor will spin Despun Platform via spur gear. Number of teeth to be determined but GR set to 4: 1 Optimal number of teeth to distribute stress for PC but sill give adequate response Despun Platform / Data System Connected via slip ring leads. Slip ring connection may be susceptible to vibrations Vibration test prior to launch. Slip ring connections can be adjusted to compensate for vibrations Despun Platform / Power System Connected via slip ring leads. Slip ring connection may be susceptible to vibrations Vibration test prior to launch. Slip ring connections can be adjusted to compensate for vibrations Motor / Data System Connections between motor and MC may not survive launch conditions Validate connections method is will survive vibrations of launch with vibrations testing Motor / Power System Connections between motor and MC may not survive launch conditions Validate connections method is will survive vibrations of launch with vibrations testing Data System / Power System Connections may not survive launch conditions Validate connections method is will survive vibrations of launch with vibrations testing 36

PS - G-Switch Definition � TBD – Specified by WFF � Activate/deactivate at Wallops command � Light switch form � Current flow can be inhibited by Wallops via Relay � No latch activation � Able to allow Wallops to have full control of activation/deactivation 37

Shared Can Logistics � Sharing ½ can with Temple University � Temple University will be measuring gamma and x- rays, up to 100 ke. V, through the use of a scintillator and photomultiplier-tube. They will use visible solar light as a directional z-axis reference point to characterize the high energy particles as solar or cosmic rays. � No Ports needed for experiment � Drexel and Temple have been communicating regularly thus far � Close geographic proximity allows for the teams to meet face to face and will aid in future collaboration 38

Preliminary Mass Estimates Components Mass Lower Platform Weight 268 grams Upper Disk 105 grams Slip Ring 250 grams Battery 100 grams - 250 grams Motor 189 grams - 242 grams Accelerometers 25 grams Electronic Components 100 grams Total 1037 grams – 1240 grams Design for 2 Kg, Leaving minimum margin of 760 grams 39

Center of Gravity Estimate �The center of gravity for our Design will be confined within a 1 inch cube from the center of the canister. �This will be obtained by placing the large components in such a way that their resulting moment will be within the center of gravity envelope. 40

Prototyping Plans �Gearing Physical prototypes of gears to verify gear ration/ teeth size �Digital to Analog Converter Created with resistor ladder and Op-Amp �Motor control algorithm �Slip Ring fastener Interface stator section of slip ring to fixed platform

Budget Item Dual Axis High-G Accelerometer Microcontroller Slip Ring Part Number Manufacturer AT 26 DF 161 A Analog Devices ATMega 32 -16 PU Atmel CAY-1666 Vendor Quantity Price (each) Total Analog Devices 2 12 24 Digi-key 1 9 9 Aeroflex 1 400 Pressure Sensor ASDX 015 A 24 R Atmel Digi-Key 1 25 25 DC Micro-motor 3242 -SCDC MICROMO Faulhber 1 283 12”x 24”x. 25” PC Sheet 85805 K 43 - Mc. Master-Carr 1 20 20 12”x 12” x 0. 50” PC Sheet 8574 K 32 - Mc. Master-Carr 1 28 28 AT 26 DF 161 A Atmel Digi-Key 1 4 4 9 V Ni. MH Powerizer Digi-Key 4 7 28 - - Drexel Provided - - 0 Total 800 Flash Memory Battery Voltage Regulator/Misc Electronics 42

Timeline 43

Team Overview Advisor: Dr. Jin Kang, Ph. D. Team Leader : Joe Mozloom MEM Department, Drexel University Senior, Drexel University Subsystem Head: Despun Platform Team Members Name Eric Marz Linda Mc. Laughlin Swati Maini Swapnil Mengawade Year and Major Senior, Electrical and Computer Engineering Senior, Mechanical Engineering and Mechanics Subsystem Head Micro-controller, Storage and Gswitch Sensors, DAC and Power Systems Motor System and Organization Modeling, System level requirements and Compliance to User guide 44

Future Work �Finalize design for slip ring holder �Choose number of teeth/ tooth design for gearing system �Determine interfacing between motor and fixed platform �Continue to become comfortable with Solidworks