Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Operations
Subsystem
Requirements
z
Determine separation distance
z
z
Determine relative attitude (direction) of
vehicle to an angular tolerance dependent
on angular controllability
z
z
z
Goal: sense to one-tenth the control tolerance
Goal: sense to one-tenth the control tolerance
Full field of view : 360 degrees in two
dimensions
Sensing presence of other vehicles to a
distance compatible with test facilities
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
68
Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Sonic and IR based system
Similar to SPHERES metrology
z Expected improvement in
performance due to 2D operation
z New technology should eliminate
some accuracy of the errors
encountered by SPHERES
z Low refresh rate will require the
use of gyros and accelerometers
z
CDIO3 Class Project
69
Design
Introduction
Subsystems
t3
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
t1
t2 B
βA
sAB
C
αB
Operations
Implementation
Conclusion
5/24/2002
A
CDIO3 Class Project
70
Design
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
1 ultrasonic omni-directional
transmitter (Mimio)
3 ultrasonic omni-directional
receivers (cones)
3 IR receivers & 2 transmitters
1 rate gyro
1 2-axis accelerometer
CDIO3 Class Project
71
Design
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
72
Design
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
System relies only on distance
readings
Uses data from all three sensors
Calculates relative attitude and
distance directly to center of
vehicle
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
73
Design
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Y
•Origin at center of vehicle
• xi and yi are position of the
sensors
d1
(x + x1 ) 2 + (y + y1 ) 2 = d12
(x + x 2 ) 2 + (y + y 2 ) 2 = d2
X
2
(x + x 3 ) 2 + (y + y 3 ) 2 = d3 2
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
74
Design
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
75
Issues
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Operations
Omni-directional sonic sensors
z Hand made cones added to current
sensors
Effect of magnetic forces
Range and accuracy
Refresh rate
z Sound signal leaving the testing area
z
Rate gyros and accelerometers
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
76
Budget Estimates
Introduction
Subsystems
•Actuation
•Formation Control
•Control
•Metrology
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Electronics
•Structure/Power
Part
Sonic (1+3)
Cost
Mass
($)
(kg)
70
0.05
Power
(W)
0.3
IR (2+3)
30
0.04
0.25
Gyros
1200
0.06
0.36
Accelerometers
1200
0.05
0.18
Total (per vehicle)
2500
0.20
1.09
Total (system)
7500
0.60
3.27
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
77
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Communications
Jennifer Underwood
Comm. Antenna
Comm. Board
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
78
Communications
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
“The technology employed in
transmitting messages”
Architecture
z Hardware
z Software
z Interfacing
z
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
79
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Subsystem
Requirements
Send information and instructions automatically
from vehicle to vehicle
z
Control and metrology purposes
Send information and instructions on command
from ground to vehicle
z
z
Begin preprogrammed tests
Emergency intervention procedures
Send flight health data to “ground” operator
Have no protruding antennae that might interfere
with dynamics
CDIO3 Class Project
80
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Trades
Hardware
Processor board (chosen by
avionics Æ TT8)
z Transceiver
z
Architecture
CDIO3 Class Project
81
Transceiver Metrics
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
EM rejection (frequency)
Bandwidth/data rate
Weight
Ease of interface
Size
Cost
Power consumption
Range
CDIO3 Class Project
82
Transceiver Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Radio Frequency (RF) vs.. Wireless
LAN
z
z
z
z
z
z
Avg cost of LAN > avg cost of RF
LAN requires a base station ($$)
Size and weight of LAN > RF
LAN bandwidth, range > RF
Power drain of LAN < RF
Both have capacity to reject EM (high
frequencies) and are easily interfaced
Choice: RF
CDIO3 Class Project
83
RF Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
AC5124C-10
RF Monolithics (DR3000-1)
Size
2.65˝x1.65˝x0.20˝
1”x1.5”
Power
0.35 W
0.04 W
Frequency
2.402 –2.478GHz
916.5 MHz
Weight
0.02 kg
Hardly any, < AC5124C-10
Data rate
115.2-882 kbps
115.2 kbps
Range
91m indoors
Short-range wireless
Ease of Interface
Relatively Easy
Relatively Easy
Cost
~$245
$35
Availability
Company in
Europe
DR1012 avail from SPHERES
for prototyping
Complexity
OEM kit, not
familiar
Development kit ready,
familiar to staff, students
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
84
Transceiver Selection
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Preliminary final product:
z
DR 3000-1
Sufficient EM rejection
z Familiarity
z Power drain
z
Prototyping product:
z
DR1012
Availability
z Familiarity
z
CDIO3 Class Project
85
Architecture Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Sequential
z
z
Pass token to determine who talks and to
whom
Hub makes calculation
Simultaneous
z
z
Pass token to determine who talks to everyone
All vehicles make calculations
Hybrid
z
Combination of Sequential and Simultaneous
Reliability deciding factor
CDIO3 Class Project
86
Architecture Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Vehicle 1
Sequential
zVehicle
1st Comm Channel
Command
2 talks
to Hub
Ground
Station
zToken
passed
to Vehicle 1
zVehicle
Hub
Updates
1 talks
to Hub
zHub
makes control calculations
and sends commands to Vehicle 1
and Vehicle 2
CDIO3 Class Project
Updates
Vehicle 2
Has Token
2nd Comm Channel
87
Architecture Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Vehicle 1
Simultaneous
2 talks to
Hub and Vehicle 1
1st Comm Channel
Command
zVehicle
Updates
Ground
Station
zToken
passed to
Vehicle 1
Hub
Updates
zVehicle
1 talks to
Hub and Vehicle 2
Updates
Vehicle 2
Has Token
2nd Comm Channel
zToken
zHub
passed to Hub
talks to Vehicle 1 and Vehicle 2
zEach
vehicle makes control calculations
CDIO3 Class Project
88
Architecture Trades
Introduction
Subsystems
Hybrid
Vehicle 1
1st Comm Channel
•Actuation
zVehicle 2 talks to
•Formation Control Hub and Vehicle 1
Command
•Electronics
Ground
•Comm
zToken passed to
Station
•Requirements
Vehicle 1
Updates
•Trades
•Design
zVehicle 1 talks to
•Issues
Hub and Vehicle 2
•Budget
Estimates
zToken passed to Hub, who talks to
•Avionics
Vehicle 1 and Vehicle 2
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Updates
Hub
Updates
Vehicle 2
Has Token
2nd Comm Channel
zAll
vehicles make control calculations but only
Hub determines commanded control vector Æ
sends commands to Vehicle 1 and Vehicle 2,
ground listens in
CDIO3 Class Project
89
Architecture Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Sequential
z
z
Requires excess code, bandwidth (BW)
Reliable from control point of view
Simultaneous
z
z
Easy to implement
Not reliable from control point of view
Hybrid
z
z
Reliable and versatile from control and comm
point of view
Increased bit rate required, excess code, BW
Design Choice: Hybrid
CDIO3 Class Project
90
Design
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Command/Request/
Update
Update
Command
Ground
Station
Vehicle
1
Updates
Hub
Update
Data Flow
Command/Request/
Update
CDIO3 Class Project
Vehicle
2
91
Design
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Design Considerations
Comm channel usage
z Transmission rates
z Data framing
z Error detection/correction
z Channel coding
z Automatic Repeat Request (ARQ)
protocols
z
CDIO3 Class Project
92
Data Framing
Introduction
Subsystems
•Actuation
•Formation Control Start
•Electronics
8bit
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Header
Data
From/To Type Size Data 1…Data n
8bit
8bit
8bit
Check
Check
?
?
Data framing is essential
z
z
z
z
z
Who to send info to
Who sent info (Hub, Vehicle 1, Vehicle 2)
Type of data
Size of data packet
Error checking
Ease of transmitting chunks (1 byte)
CDIO3 Class Project
93
Channel Usage
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Cluster Comm Channel
z
z
z
z
6 variables in state vector (Control)
4 variables to actuators (EM, RWA)
About 800 bits/cycle for control
About 500 bits/cycle for health updates
Ground Link Comm Channel
z
z
Undefined requirements
On the order of 400 bits per complete
cycle
CDIO3 Class Project
94
Transmission Rates
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
How frequently to measure
systems/states?
z
z
Control runs at 50 Hz
Health max set at 10 Hz
Therefore, we can estimate the
transmission rate required:
z
800 bits/cycle * 50 cycles/sec +
500 bits/cycle * 10 cycles/sec = 45kbps
CDIO3 Class Project
95
Current Capabilities
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
TT8 to TT8 communication
z
Currently connected through UART
channel
Two byte transmission
Send and receive between two
TT8’s, one direction only
z High-Byte, Low-Byte
z
z
[1 1 1 1 1 1 1 1] [1 1 1 1 1 1 1 1] = 1111111111111111
High Byte
| Low Byte
CDIO3 Class Project
96
Issues
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Processor/transceiver shielding
Reliability
EM resistance
z Error probability
z
Communication channel load
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
97
Budgets Estimates
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Avionics
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Part
Cost
($)
Mass
(kg)
Power
(W)
Transceiver
$35
each
0.02
0.04
Miscellaneous parts
$100
0.1
-
Replacements/repairs
$70
-
-
Total (per vehicle)
$275
0.24
0.08
Total (ground station)
$275
0.24
0.08
Total (system)
$1100
0.96
0.32
CDIO3 Class Project
98
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Avionics
Avionics Board
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
99
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Subsystem
Requirements
Manage timing and resources for
all subsystems
Run control loop in real-time
z
Inputs, calculations, outputs
Administer preprogrammed tests
Be easily programmable
Stay within system budgets
CDIO3 Class Project
100
Trades - Metrics
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Processing speed
Interfaces (I/O)
Data storage (RAM/ROM)
Constraint considerations
Cost
z Size and mass
z Ease of use
z
CDIO3 Class Project
101
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Trades Metrics Details
Processor speed
I/O capabilities
Digital vs.. analog
z Subsystem input and output needs
not necessarily the same
z
RAM and ROM capacity
z
Flash memory
Power consumption
Cost
CDIO3 Class Project
102
Trades - Interfaces
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
The avionics team must interface with all subsystems.
INPUTS
Metrology:
z
z
z
z
3 Ultrasonic sensors (digital)
1 IR timing (digital)
1 rate-gyro (analog)
Possibly 2 accelerometers (analog)
Communication
z
Inter-vehicle data and instructions (digital)
Health Indicators (digital)
CDIO3 Class Project
103
Trades - Interfaces
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
The avionics team must interface with all subsystems.
OUTPUTS
Communication
z
Requests and commands (digital)
Actuators
z
z
3 for Y-pole magnet (analog)
1 for RW (analog)
Metrology
z
z
1 for ultrasonic transmitter (digital)
1 for IR timing transmitter (digital, split)
CDIO3 Class Project
104
Trades: Computer
Comparison
Introduction
Subsystems
Needs
TT8
C40
6701
50 Hz
16 MHz
4 MIPS
50
MFLOPS
167 MHz 1
GFLOPS
4D, 1A in
1D, 4A out
25D I/O
8A, 14 time
D parallel
64 I/O
N/A
RAM
~16 kB
256kB
16 MB
16 MB
ROM
~8kB
256kB
640 kB
512 kB
Operations
Power
Low
1.8 Watts
N/A
N/A
Implementation
Conclusion
Cost
Low
(~$500)
Custom
High
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
5/24/2002
Feature
Speed
I/O
CDIO3 Class Project
105
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Trades: other
considerations
Other Computer Considerations
Size/weight satisfactory for structure?
Available/Replaceable?
Easy to use?
Expandable?
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
106
Design: Hardware
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Comm./Ops
SW
RWA
Power
D/A
EM
V in
Computer
Physical
A/D
Structure
SW
Metrology
Control
CDIO3 Class Project
107
Design: Software
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Language: C
Coding environment
z
z
Procedures
z
5/24/2002
Control loop
z
z
z
Operations
Implementation
Conclusion
Creating: Metroworks CodeWarrior
Loading to vehicle: Motocross
z
z
Metrology updates
Matrix calculations
Actuation commands
Test programs
Health, test data reports
CDIO3 Class Project
108
Issues
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Software is the high-risk item for the
avionics subsystem.
Preliminary Test Prototyping Design
to find complications early.
z
z
z
Develop a clock-interrupt
Blink an LED
Signal Reproduction via PWM
Preliminary Prototype to be
completed by end of semester.
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
109
Budget Estimates
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Implementation
Conclusion
5/24/2002
Mass
z
0.028 kg per tattletale
z
z
May need two
0.028 per subsystem circuit board
Power
z
z
Highest power draw: two main computers
Power required: 3.6 Watts
Cost
z
z
z
Per-vehicle needs, system-wide extras
$500 total allocated for TT8 repairs
$6500 for circuit boards (power, comm.,
controls, metrology)
CDIO3 Class Project
110
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Comm
•Avionics
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure/Power
Operations
Budget Estimates
(cont.)
Part
Cost ($US) Mass (kg) Power (W)
TT8 (x2) 500
0.057
3.6
6500
0.113
?
Total
1060
(vehicle)
0.113
?
Total
7000
(system)
0.339
?
Boards
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
111
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Power
Amy Schonsheck
Power
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
112
Requirements
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
No external umbilicals
z
On-board power supply
Provide sustainable power for
30 minutes
Use a renewable or
rechargeable energy source
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
113
Power Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Solar power vs.. batteries
Power requirements too
demanding for solar power
z Rechargeable batteries the best
option
z
Choice of battery chemistry
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
114
Battery Selection
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
For expected voltage and current
requirements, viable options include:
Lithium Ion (Li-ion)
z Nickel Cadmium (NiCd)
z Nickel Metal Hydride (NiMH)
z
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
115
Battery Selection
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Li-ion:
z
z
NiCd:
z
z
Adequate discharge rate
Low efficiency at high current draws
NiMH: Æ Final choice
z
Operations
z
Implementation
Conclusion
z
5/24/2002
High energy density
Low discharge rate (2 Amps max.)
High energy density
Fast discharge rate
Efficient even at high current draw
CDIO3 Class Project
116
Power Design
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Operations
Subsystem power estimates:
Subsystem
Power (W)
Avionics: Tattletale (x 2?)
9-12 (each)
2 (each)
Metrology: Accelerometers
8-30
0.18
Metrology: Gyros
12-18
0.36
Metrology: Transmitters/Receivers
3
0.066
Comm/Ops: (shares Tattletale)
9-12
0.1
RWA: Reaction Wheel
28?
13
EM: Electromagnet
12 (min.)
60-70
Implementation
Conclusion
5/24/2002
Voltage (V)
TOTAL: ~ 90 W (max)
CDIO3 Class Project
117
Power Design
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Operations
Total current draw: 7 Amps (current design)
Operation time: 30 minutes (min.)
Total energy: 3.5 Ah
Candidate battery: Panasonic HHR200SCP
z
z
z
z
Voltage - 1.2 V
Capacity - 1.9 Ah
Weight – 42 g
Dimensions: 23 mm diameter, 34 mm height
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
118
Power Design
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Operations
Implementation
Conclusion
5/24/2002
Candidate battery architecture:
z
1 “Pack” = 15 batteries x 1.2 V (wired
in series)
18 V
z 1.9 Ah
z
z
2 Packs wired in parallel
18 V
z 3.8 Ah
z Sufficient voltage, current for the system
z
CDIO3 Class Project
119
Power Design
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Operations
Implementation
Conclusion
5/24/2002
Voltage Regulators used to
step down voltages
z 9-12 V : Tattletale processors
z 5 V : Transmitters/Receivers
z Gyros, accelerometers may have built-in
voltage regulators
Switchmode amplifier used
to control current through
electromagnet
z Commercially available
CDIO3 Class Project
120
Power Flowchart
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
Gyro,
•Design
•Issues
Accel.
•Budget
Estimates
RW
•Structure
Operations
15 x 1.2 V
15 x 1.2 V
5V
9-12V
Regulator
Trans. /
Receivers
Regulator
Tattletales
Switchmode
Amplifier
EM
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
121
Issues
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Operations
Implementation
Conclusion
5/24/2002
NiMH batteries have strict
charge/discharge limits
Overcharging decreases performance
z Rapid discharge Æ produces heat
z
Safety precautions
Avoid excessive heat
z Avoid contact with water
z
CDIO3 Class Project
122
Issues
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Possible greater power requirements
z
z
Charging takes ~ 1.2 hours
z
Operations
Implementation
Conclusion
5/24/2002
Current design allows 7 amps
EM may require up to 10 amps
z May require more batteries
z Possibly switch to next higher battery
model (much higher mass)
Two or three complete battery sets
needed (per vehicle) Æ higher cost
CDIO3 Class Project
123
Budget Estimates
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Mass:
30 batteries
z 42 g each
z Total battery weight: 1.26 kg
z Additional components: ~ 50 g
(regulators, amplifier)
z
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
124
Budget Estimates
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Requirements
•Trades
•Design
•Issues
•Budget
Estimates
•Structure
Cost:
Switchmode amp: ~$65
z Voltage regulators: ~ $60
z Batteries: $400 - $500
z
Power:
z
Supply 100% of EMFFORCE
power needs
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
125
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Structure
Structure
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
126
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Operations
Implementation
Conclusion
5/24/2002
Structure
Requirements
Vehicle Casing:
z
z
z
Provide physical interfacing capability
Prevent damage in case of collision
Thermal considerations due to magnet
heating
Magnetic Shielding:
z
Protect electronics hardware from
magnetic interference
Air Carriage:
z
Provide adequate cushion height for
vehicle mass
CDIO3 Class Project
127
Geometric Overview
Introduction
Subsystems
Lid
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
Body encasing
•Structure
•Requirements
•Geometrical
Overview
Base
•Trades
•Design
Air Carriage
•Budget
Estimates
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
128
Geometric Overview
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
129
Geometric Overview
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
130
Shielding
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Sample kit includes various materials
of different properties.
Determine functional material at least
mass.
Conduct tests using electronics/
electromagnets, and
test shielding material.
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
131
Air Carriage: Trades
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Fabricate vs.. Off-the-Shelf
z
Cost, Efficiency
Tanks vs.. Compressors
Cost, Power, Mass
z Infinite(?) air supply
z
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
132
Air Carriage: Design
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Operations
Implementation
Conclusion
5/24/2002
Objective: For a given weight
accurately predict and obtain a
maximum air cushion thickness
Design variables
Supply pressure
z Puck radius
z Supply orifice
z
CDIO3 Class Project
133
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Operations
Air Carriage: Model
Assumptions
Linear radial pressure distribution
for single, central orifice
P (rp ) = Ps − ( Ps − Pa )
rp
Rp
Possible compressible effects
near aperture
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
134
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Operations
Implementation
Conclusion
5/24/2002
Air Carriage:
Lubrication Theory
Thin film:
h << Rp
z very low Reynolds Number
z
ρ aU c
ρ a R pU p
∝
Re =
µa
µa
§ h2
¨
¨R 2
© p
·
¸
¸
¹
Similarities to Couette and
Poiseuielle flows: parabolic
velocity distribution
CDIO3 Class Project
135
Air Carriage: Next
Steps…
Introduction
Subsystems
•Actuation
•Formation Control
•Electronics
•Structure/Power
•Power
•Structure
•Requirements
•Geometrical
Overview
•Trades
•Design
•Budget
Estimates
Lubrication flow solver
z
z
z
z
Pressure gradient
Flow Velocity
Load
Cushion thickness
Assess compressible behavior
Assess puck designs
Operations
Implementation
Conclusion
5/24/2002
CDIO3 Class Project
136