Transcript PDR_Drexel2011x - University of Colorado Boulder

Joe Mozloom
Eric Marz
Linda McLaughlin
Swati Maini
Swapnil Mengawade
Advisor: Jin Kang, PhD
1

Drexel's RockSat payload will incorporate a platform
rotating opposite the spin-stabilization of the TerrierOrion sounding rocket during ascent, resulting in a
rotationally static platform from an outside
reference frame.
2

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

Angular Velocity
 ω = dθ / dt
ω
 At 5.6 Hz
ω = 35.18 rad/sec
ar

Radial Acceleration
 ar = ω2 r
at
 At 35.18 rad/sec
 With 0.0635 meter Radius
ar = 78.62 m/s2 = 8 g
4
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
6
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
8
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

System Components
 Through-Bore Slip Ring
 Slip Ring Fastener
 Undefined until Slip Ring is selected
 May be unnecessary if mounting holes can be drilled into
slip ring
 Despun Plate/Cog
 2-axis, High-G Accelerometer
11

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
Requirement
1
Platform shall be able to rotate at > 500 RPM
2
System shall be able to pass ≈ 2.2 mA 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 25g acceleration
6
System shall allow for center standoff
7
Platform shall be < 7”
13
Slip Ring
Jinpat
LPT012
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

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: 2A/Circuit
Cost; $400
15

 Sensor will not function
PROBABILITY
CONSEQUENCES

DP.RSK.3
DP.RSK.5
DP.RSK.4
DP.RSK.1
DP.RSK.2
DP.RSK.1
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
Power Supply
Stationary
Accelerometer
Microcontroller
Despun
Accelerometer
Slip Ring
Digital to Analog
Converter
Motor
17
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

Microcontroller
 ATMEL 8-bit AVR Microcontroller
 Motorola M68HC12 Microcontroller

Accelerometer
 Analog Devices ADXL278 MEMS Accelerometer
 Colibrys MS8000.D MEMS Accelerometer

External Resistor Ladder for 8-bit/16-bit
Digital to Analog Conversion
19
20

ADXL103/ADXL203
 Size: 5mm x 5mm x 2mm
 Resolution: 1mg at 60Hz
 Bandwidth: 0.5 Hz – 2.5 kHz
 Sensitivity: 960-1040 mV/g
 Supply Voltage: 3.0-6.0 V
 Supply Current: 1.1 mA
 3500g Shock survival
21
Specification
Size
System
Requirements
ADXL278
5mm x 5mm x 2mm 5mm x 5mm x 2mm 5 mm × 5 mm × 2
mm,
Resolution
> 2 mg 60 Hz
Bandwidth
0.5 Hz – 2.5 kHz
Sensitivity
Minimum
Supply Voltage
3V
Supply Current
1.1-3.0mA
Full scale range x-y
ADXL203
± 50g
1mg at 60Hz
0.5 Hz – 2.5 kHz
960-1040 mV/g
3.0-6.0 V
2 mg 60 Hz
0.5-400Hz
25.65-28.35mV/g
4.75-5.25v
1.1 mA
2.9mA
±1.7g
±35 g/±35 g, ±50
g/ ±50 g, or ±70
g/±35 g
22


ADXL203 tested and specified at Vs = 5.0 V
Radiometric output
 Vs = 3.0 V output sensitivity ≈ 560 mV/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 mV
23
 Requirement for our
electronic system: to
convert signals from
digital to analog forms
 Analog to digital
convertor (DAC)needed
24

PROBABILITY
 Microcontroller Power Failure

CONSEQUENCES
DS.RSK.1
DS.RSK.2
DS.RSK.1
DS.RSK.5
DS.RSK.2
 Motor Communication Failure

DS.RSK.3
 Stationary Accelerometer
DS.RSK.3
Communication Failure

DS.RSK.4
 Despun Accelerometer
DS.RSK.4
Communication Failure

DS.RSK.5
 Microcontroller can’t survive
launch conditions
25

Required RPM: 600 (without gearing)
 2400 RPM with 1:4 gear ratio


Amperage: < 300 mA
Torque: 80 mNm (without gearing)
 20 mNm with 1:4 gear ratio




Max Length: 3” = 7.62 cm
Max Diameter: 2”= 5.08 cm
Max Mass: 250g
Pinion to be CNC cut from ½” (12.7 mm)
polycarbonate
 Fabricated In-House
Specificatio
n
System
Re-16
Requirements Maxxon
3257 G
MICROMO
3242 SCDC
DC –Servo
Motor
RPM
2400 RPM
7130 RPM
5700 RPM
5300 RPM
Voltage
12 Volts
12 Volts
12 Volts
12 Volts
Amperage
< 300 mA
6.05 mA
258 mA
199 mA
Torque
> 20 mNm
5.47 mNm
70 mNm
50 mNm
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
Brushed
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


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)
 32A-available on request from the supplier.
30

 Required Torque exceeds
PROBABILITY
stall torque

CONSEQUENCES
MS.RSK.1
MS.RSK.1
MS.RSK.4
MS.RSK.2
 Motor-Battery
Communication Failure
MS.RSK.5
MS.RSK.3
MS.RSK.2

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.
31
32





Rechargeable Battery
9 V NiMH Powerizer Batteries
Amperage : 170mA
Amount needed : 4
Weight:125g

Voltage Regulator
 ±3.3 V Linear regulator for flash memory and
accelerometers
 ± 5.0 V Linear regulator for microcontroller

Parallel and Series connection to achieve
requirements of motor and electronic devices
33
34
Specification
System
Requirements
Energizer
175 mAh 9V
NiMH
NiMH
Powerizer
Batteries
Nickel-metal
Hydride
Effective
Voltage
16V
9V
9V
12V
Number
-
4
4
2
Type
Amperage
Rechargeable Rechargeable Rechargeable
300mA
Non rechargeable
175 mA per
170 mA per
2450 mA
Mass (total)
32g
125g
255g
Cost
$32.0
$27.0
$ 71.90
35
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






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
Sharing ½ can with Temple University
Temple University will be measuring gamma and xrays, up to 100keV, 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
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


The center of gravity for our Design will be
confined within a 1inch 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

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
Item
Dual Axis
High-G Accelerometer
Microcontroller
Slip Ring
Part Number
Manufacturer
AT26DF161A
Analog Devices
ATMega32-16PU
Atmel
CAY-1666
Vendor
Quantity
Price (each)
Total
Analog Devices
2
12
24
Digi-key
1
9
9
Aeroflex
1
400
400
Pressure Sensor
ASDX015A24R
Atmel
Digi-Key
1
25
25
DC Micro-motor
3242-SCDC
MICROMO
Faulhber
1
283
283
12”x24”x.25”
PC Sheet
85805K43
-
McMaster-Carr
1
20
20
12”x12” x 0.50”
PC Sheet
8574K32
-
McMaster-Carr
1
28
28
Flash Memory
AT26DF161A
Atmel
Digi-Key
1
4
4
9 V NiMH
Powerizer
Powerizer
Digi-Key
4
7
28
-
-
Drexel
Provided
-
-
0
Total
800
Battery
Voltage Regulator/Misc
Electronics
42
43
Advisor: Dr. Jin Kang, PhD.
Team Leader : Joe Mozloom
MEM Department, Drexel University
Senior, Drexel University
Subsystem Head: Despun Platform
Team Members
Name
Eric Marz
Linda McLaughlin
Swati Maini
Swapnil Mengawade
Year and
Major
Senior, Electrical
and Computer
Engineering
Senior, Electrical
and Computer
Engineering
Senior, Mechanical
Engineering and
Mechanics
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




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