5/24/2002 CDIO3 Class Project 68
Subsystem
RequirementsDetermine separation distance
Goal: sense to one-tenth the control tolerance
Determine relative attitude (direction) ofvehicle to an angular tolerance dependenton angular controllability
Goal: sense to one-tenth the control tolerance
Full field of view : 360 degrees in twodimensionsSensing presence of other vehicles to adistance compatible with test facilities
IntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 69
Trades
Sonic and IR based systemSimilar to SPHERES metrologyExpected improvement inperformance due to 2D operationNew technology should eliminatesome accuracy of the errorsencountered by SPHERESLow refresh rate will require theuse of gyros and accelerometers
IntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 70
Design
A
C
B
αB
βA
sAB
t1
t3
t2
IntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 71
Design
1 ultrasonic omni-directionaltransmitter (Mimio)3 ultrasonic omni-directionalreceivers (cones)3 IR receivers & 2 transmitters1 rate gyro1 2-axis accelerometer
IntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 72
DesignIntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 73
Design
System relies only on distancereadingsUses data from all three sensorsCalculates relative attitude anddistance directly to center ofvehicle
IntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 74
Design
(x + x1)2 + (y + y1)
2 = d12
(x + x2)2 + (y + y2)
2 = d22
(x + x3)2 + (y + y3)
2 = d32
Y
X
d1
•Origin at center of vehicle• xi and yi are position of thesensors
IntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 75
DesignIntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 76
Issues
Omni-directional sonic sensorsHand made cones added to currentsensors
Effect of magnetic forcesRange and accuracyRefresh rate
Sound signal leaving the testing area
Rate gyros and accelerometers
IntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 77
Budget Estimates
1.090.202500Total (per vehicle)
3.270.607500Total (system)
0.180.051200Accelerometers
0.360.061200Gyros
0.250.0430IR (2+3)
0.30.0570Sonic (1+3)
Power(W)
Mass(kg)
Cost($)
PartIntroductionSubsystems•Actuation•Formation Control
•Control•Metrology
•Requirements•Trades•Design•Issues•BudgetEstimates
•Electronics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 78
Communications
Jennifer Underwood
Comm. Board
Comm. Antenna
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 79
Communications
“The technology employed intransmitting messages”
Architecture
HardwareSoftware
Interfacing
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 80
Subsystem
RequirementsSend information and instructions automaticallyfrom vehicle to vehicle
Control and metrology purposes
Send information and instructions on commandfrom ground to vehicle
Begin preprogrammed testsEmergency intervention procedures
Send flight health data to “ground” operatorHave no protruding antennae that might interferewith dynamics
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 81
Trades
HardwareProcessor board (chosen byavionics TT8)Transceiver
Architecture
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 82
Transceiver Metrics
EM rejection (frequency)
Bandwidth/data rateWeight
Ease of interfaceSize
CostPower consumption
Range
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 83
Transceiver Trades
Radio Frequency (RF) vs.. WirelessLAN
Avg cost of LAN > avg cost of RFLAN requires a base station ($$)Size and weight of LAN > RFLAN bandwidth, range > RFPower drain of LAN < RFBoth have capacity to reject EM (highfrequencies) and are easily interfaced
Choice: RF
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 84
RF Trades
DR1012 avail from SPHERESfor prototyping
Company inEurope
Availability
115.2 kbps115.2-882 kbpsData rate
Short-range wireless91m indoorsRange
Relatively EasyRelatively EasyEase of Interface
$35~$245Cost
Hardly any, < AC5124C-100.02 kgWeight
Development kit ready,familiar to staff, students
OEM kit, notfamiliar
Complexity
916.5 MHz2.402 –2.478GHzFrequency
0.04 W0.35 WPower
1”x1.5”2.65˝x1.65˝x0.20˝Size
RF Monolithics (DR3000-1)AC5124C-10IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades
•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 85
Transceiver Selection
Preliminary final product:DR 3000-1
Sufficient EM rejectionFamiliarityPower drain
Prototyping product:DR1012
AvailabilityFamiliarity
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 86
Architecture Trades
SequentialPass token to determine who talks and towhomHub makes calculation
SimultaneousPass token to determine who talks to everyoneAll vehicles make calculations
HybridCombination of Sequential and Simultaneous
Reliability deciding factor
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 87
Architecture Trades
SequentialVehicle 2 talks
to Hub
Token passedto Vehicle 1
Vehicle 1 talksto Hub
Hub
Vehicle 1
Command
Updates
GroundStation
1st Comm Channel
Has Token
Updates
2nd Comm Channel
Vehicle 2
Hub makes control calculationsand sends commands to Vehicle 1and Vehicle 2
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 88
Architecture Trades
SimultaneousVehicle 2 talks to
Hub and Vehicle 1
Token passed toVehicle 1
Vehicle 1 talks toHub and Vehicle 2
Hub
Vehicle 1
Command
Updates
GroundStation
1st Comm Channel
Has Token
Updates
2nd Comm Channel
Vehicle 2
Updates
Token passed to Hub
Hub talks to Vehicle 1 and Vehicle 2
Each vehicle makes control calculations
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 89
Architecture Trades
HybridVehicle 2 talks to
Hub and Vehicle 1
Token passed toVehicle 1
Vehicle 1 talks toHub and Vehicle 2
Hub
Vehicle 1
Command
Updates
GroundStation
1st Comm Channel
Has Token
Updates
2nd Comm Channel
Vehicle 2
Updates
Token passed to Hub, who talks toVehicle 1 and Vehicle 2
All vehicles make control calculations but onlyHub determines commanded control vectorsends commands to Vehicle 1 and Vehicle 2,ground listens in
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 90
Architecture Trades
SequentialRequires excess code, bandwidth (BW)Reliable from control point of view
SimultaneousEasy to implementNot reliable from control point of view
HybridReliable and versatile from control and commpoint of viewIncreased bit rate required, excess code, BW
Design Choice: Hybrid
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 91
Design
Hub
Vehicle1
GroundStation
Command
Data Flow
Command/Request/Update
Update
Update
Command/Request/Update
Vehicle2
Updates
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 92
Design
Design ConsiderationsComm channel usage
Transmission ratesData framing
Error detection/correctionChannel coding
Automatic Repeat Request (ARQ)protocols
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 93
Data Framing
Data framing is essentialWho to send info toWho sent info (Hub, Vehicle 1, Vehicle 2)Type of dataSize of data packetError checking
Ease of transmitting chunks (1 byte)
Type CheckData 1…Data nSizeFrom/To
Header Data Check
8bit 8bit 8bit 8bit ? ?
Start
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 94
Channel Usage
Cluster Comm Channel6 variables in state vector (Control)4 variables to actuators (EM, RWA)About 800 bits/cycle for controlAbout 500 bits/cycle for health updates
Ground Link Comm ChannelUndefined requirementsOn the order of 400 bits per completecycle
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 95
Transmission Rates
How frequently to measuresystems/states?
Control runs at 50 HzHealth max set at 10 Hz
Therefore, we can estimate thetransmission rate required:
800 bits/cycle * 50 cycles/sec +500 bits/cycle * 10 cycles/sec = 45kbps
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 96
Current Capabilities
TT8 to TT8 communicationCurrently connected through UARTchannel
Two byte transmissionSend and receive between twoTT8’s, one direction onlyHigh-Byte, Low-Byte
[1 1 1 1 1 1 1 1] [1 1 1 1 1 1 1 1] = 1111111111111111High Byte | Low Byte
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 97
Issues
Processor/transceiver shieldingReliability
EM resistanceError probability
Communication channel load
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 98
Budgets Estimates
0.080.24$275Total (ground station)
0.080.24$275Total (per vehicle)
0.320.96$1100Total (system)
--$70Replacements/repairs
-0.1$100Miscellaneous parts
0.040.02$35each
Transceiver
Power(W)
Mass(kg)
Cost($)
PartIntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Requirements•Trades•Design•Issues•BudgetEstimates
•Avionics•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 99
Avionics
Avionics Board
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 100
Subsystem
RequirementsManage timing and resources forall subsystemsRun control loop in real-time
Inputs, calculations, outputs
Administer preprogrammed testsBe easily programmableStay within system budgets
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 101
Trades - Metrics
Processing speedInterfaces (I/O)Data storage (RAM/ROM)Constraint considerations
Cost
Size and massEase of use
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 102
Trades -
Metrics DetailsProcessor speedI/O capabilities
Digital vs.. analogSubsystem input and output needsnot necessarily the same
RAM and ROM capacityFlash memory
Power consumptionCost
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 103
Trades - Interfaces
The avionics team must interface with all subsystems.
INPUTSMetrology:
3 Ultrasonic sensors (digital)1 IR timing (digital)1 rate-gyro (analog)Possibly 2 accelerometers (analog)
CommunicationInter-vehicle data and instructions (digital)
Health Indicators (digital)
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 104
Trades - Interfaces
The avionics team must interface with all subsystems.
OUTPUTSCommunication
Requests and commands (digital)
Actuators3 for Y-pole magnet (analog)1 for RW (analog)
Metrology1 for ultrasonic transmitter (digital)1 for IR timing transmitter (digital, split)
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 105
Trades: Computer
Comparison
Low
Low
~8kB
~16 kB
4D, 1A in1D, 4A out
50 Hz
Needs
N/AN/A1.8 WattsPower
HighCustom(~$500)Cost
512 kB640 kB256kBROM
16 MB16 MB256kBRAM
N/AD parallel64 I/O
25D I/O8A, 14 time
I/O
167 MHz 1GFLOPS
50MFLOPS
16 MHz
4 MIPSSpeed
6701C40TT8FeatureIntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 106
Trades: other
considerationsOther Computer ConsiderationsSize/weight satisfactory for structure?Available/Replaceable?Easy to use?Expandable?
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 107
Design: Hardware
Computer
A/D
D/A
RWA
Metrology
Control
EMPower
Structure
SW
SW
Physical
V in
Comm./OpsIntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 108
Design: Software
Language: CCoding environment
Creating: Metroworks CodeWarriorLoading to vehicle: Motocross
ProceduresControl loop
Metrology updatesMatrix calculationsActuation commands
Test programsHealth, test data reports
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 109
Issues
Software is the high-risk item for theavionics subsystem.Preliminary Test Prototyping Designto find complications early.
Develop a clock-interruptBlink an LEDSignal Reproduction via PWM
Preliminary Prototype to becompleted by end of semester.
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 110
Budget Estimates
Mass0.028 kg per tattletale
May need two0.028 per subsystem circuit board
PowerHighest power draw: two main computersPower required: 3.6 Watts
CostPer-vehicle needs, system-wide extras$500 total allocated for TT8 repairs$6500 for circuit boards (power, comm.,controls, metrology)
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 111
Budget Estimates
(cont.)
?0.1131060Total(vehicle)
7000
6500
500
Cost ($US)
?0.339Total(system)
?0.113Boards
3.60.057TT8 (x2)
Power (W)Mass (kg)Part
IntroductionSubsystems•Actuation•Formation Control•Electronics
•Comm•Avionics
•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure/Power
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 112
Power
Amy Schonsheck
Power
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 113
Requirements
No external umbilicalsOn-board power supply
Provide sustainable power for30 minutesUse a renewable orrechargeable energy source
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 114
Power Trades
Solar power vs.. batteriesPower requirements toodemanding for solar powerRechargeable batteries the bestoption
Choice of battery chemistry
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 115
Battery Selection
For expected voltage and currentrequirements, viable options include:
Lithium Ion (Li-ion)Nickel Cadmium (NiCd)
Nickel Metal Hydride (NiMH)
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 116
Battery Selection
Li-ion:High energy densityLow discharge rate (2 Amps max.)
NiCd:Adequate discharge rateLow efficiency at high current draws
NiMH: Final choiceHigh energy densityFast discharge rateEfficient even at high current draw
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 117
Power Design
Subsystem power estimates:
60-7012 (min.)EM: Electromagnet
1328?RWA: Reaction Wheel
~ 90 W (max)TOTAL:
0.19-12Comm/Ops: (shares Tattletale)
0.0663Metrology: Transmitters/Receivers
0.3612-18Metrology: Gyros
0.188-30Metrology: Accelerometers
2 (each)9-12 (each)Avionics: Tattletale (x 2?)
Power (W)Voltage (V)Subsystem
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 118
Power Design
Total current draw: 7 Amps (current design)Operation time: 30 minutes (min.)Total energy: 3.5 AhCandidate battery: Panasonic HHR200SCP
Voltage - 1.2 VCapacity - 1.9 AhWeight – 42 gDimensions: 23 mm diameter, 34 mm height
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 119
Power Design
Candidate battery architecture:1 “Pack” = 15 batteries x 1.2 V (wiredin series)
18 V1.9 Ah
2 Packs wired in parallel18 V3.8 AhSufficient voltage, current for the system
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 120
Power Design
Voltage Regulators used tostep down voltages
9-12 V : Tattletale processors5 V : Transmitters/ReceiversGyros, accelerometers may have built-involtage regulators
Switchmode amplifier usedto control current throughelectromagnet
Commercially available
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 121
Power Flowchart
15 x 1.2 V
Gyro,
Accel.
RW
5V
Regulator
Trans. /
Receivers
9-12V
Regulator
Tattletales
SwitchmodeAmplifier
EM
15 x 1.2 V
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 122
Issues
NiMH batteries have strictcharge/discharge limits
Overcharging decreases performance
Rapid discharge produces heat
Safety precautionsAvoid excessive heatAvoid contact with water
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 123
Issues
Possible greater power requirementsCurrent design allows 7 ampsEM may require up to 10 amps
May require more batteriesPossibly switch to next higher batterymodel (much higher mass)
Charging takes ~ 1.2 hoursTwo or three complete battery setsneeded (per vehicle) higher cost
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 124
Budget Estimates
Mass:30 batteries
42 g eachTotal battery weight: 1.26 kg
Additional components: ~ 50 g(regulators, amplifier)
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 125
Budget Estimates
Cost:Switchmode amp: ~$65
Voltage regulators: ~ $60Batteries: $400 - $500
Power:Supply 100% of EMFFORCEpower needs
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Requirements•Trades•Design•Issues•BudgetEstimates
•Structure
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 126
Structure
Structure
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 127
Structure
RequirementsVehicle Casing:
Provide physical interfacing capabilityPrevent damage in case of collisionThermal considerations due to magnetheating
Magnetic Shielding:Protect electronics hardware frommagnetic interference
Air Carriage:Provide adequate cushion height forvehicle mass
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 128
Geometric Overview
Lid
Body encasing
Base
Air Carriage
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 129
Geometric OverviewIntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 130
Geometric OverviewIntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 131
Shielding
Sample kit includes various materialsof different properties.Determine functional material at leastmass.Conduct tests using electronics/electromagnets, andtest shielding material.
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 132
Air Carriage: Trades
Fabricate vs.. Off-the-ShelfCost, Efficiency
Tanks vs.. CompressorsCost, Power, Mass
Infinite(?) air supply
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 133
Air Carriage: Design
Objective: For a given weightaccurately predict and obtain amaximum air cushion thicknessDesign variables
Supply pressure
Puck radiusSupply orifice
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5/24/2002 CDIO3 Class Project 134
Linear radial pressure distributionfor single, central orifice
Possible compressible effectsnear aperture
Air Carriage: Model
Assumptions
p
passp R
rPPPrP )()( −−=
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
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5/24/2002 CDIO3 Class Project 135
Thin film:h << Rp
very low Reynolds Number
Similarities to Couette andPoiseuielle flows: parabolicvelocity distribution
∝= 2
2
Repa
ppa
a
a
R
hURcU
µρ
µρ
Air Carriage:
Lubrication TheoryIntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion
5/24/2002 CDIO3 Class Project 136
Air Carriage: Next
Steps…Lubrication flow solver
Pressure gradientFlow VelocityLoadCushion thickness
Assess compressible behaviorAssess puck designs
IntroductionSubsystems•Actuation•Formation Control•Electronics•Structure/Power
•Power•Structure
•Requirements•GeometricalOverview•Trades•Design•BudgetEstimates
OperationsImplementationConclusion