RAppelling Cave Exploration Rover
Advisor:
James Nabity
Customer:
Barbara Streiffert
Manufacturing Status Review
PROJECT STATEMENT
• This project encompasses designing, building and verifying a
rappelling child rover (CR) that can deploy from the legacy TREADS
Mother Rover (MR). The mission is to:
• Rappel a 90 surface down 5m into cave/pipe
• Explore up to 5m out from the rappel touchdown point
•
•
Surface has scattered rocks 3cm diameter
A Ground Station(GS) operator will control CR motion and imaging
• Know its distance travelled and depth within 10cm
• Return to and re-dock with the MR
• This CR will add the capability to rappel and explore vertical shafts,
caves and pipes to the JPL legacy rover projects
Overview
Schedule
Manufacturing
Budget
2
CONOPS
GROUND STATION (GS)
COMMANDS
DATA
TETHER
0) Arrival
- Child Rover
(CR) on MR
5
TREADS
Mother
Rover (MR)
1) Deployment (5 min)
- CR undocks
- CR enters cave/pipe
CR movement controlled
by GS operator input
2) Rappelling (15 min)
- CR rappels 5m
- Transitions from
vertical  horizontal
After command from GS, rappel
is autonomous with feedback
loop from CR range-finder
1
NOTE: The return and comm
dropout retraction will only
continue to approximately the
location of the start of Phase 2,
based on the range-finder and
stepper motor steps, respectively
GS operator has direct line-ofsight view for navigation
3) Exploration (120 min)
- CR traverses 5m
- CR takes/stores
image of POI
Images from CR imaging
system used for navigation
4) Return (15 min)
- CR is retracted by
MR winch system
NOTE: If comm is dropped during
exploration, the CR will be retracted by
the MR winch system, after the GS
operator says ‘OK’, until comm is
restored or operator commands a stop
4
2
5) Re-docking (5 min)
- CR re-enters MR bay
3
10cm diameter
POI
Anticipate transmitting ~100
images in the 3hr mission
RACER Mission Timeline:
5
15
Margin
RACER Mission Duration: 160 min
Margin: 20 min
15
120
Overview
Schedule
TOTAL: 180 min
Manufacturing
Budget
5
20
3
FUNCTIONAL BLOCK DIAGRAM
An Arduino Mega serves to replace
the non-functional MR C&DH
A Raspberry Pi SBC
performs C&DH for the CR
Another Arduino Mega
interfaces with peripherals
except for imaging
MR
CR
Controller
Overview
Schedule
Manufacturing
Budget
4
POST-WINTER BREAK UPDATES
• Major areas of concern at CDR:
•
•
Software schedule slips
•
•
Utilizing Git repositories to program in parallel
Completed Software Phase 1 ~5 days ahead of schedule
Communications not propagating in mission environment
•
Performed signal strength test with new hardware (2 mW radios w/ 10dBi antennas)
• Took JPL & PAB feedback into account
CONCRETE
WALLS
Max required
range @ 5m
5m
Path CR XBee
is moved
MR
XBee
25m
Outside
CR
XBee
5m
Point where packets
were first dropped
Overview
Only started to lose packets
at a separation well above
what is required in mission
Hallway
Point where Comm.
was lost
Schedule
Theoretical
minimum
sensitivity
Manufacturing
Budget
5
WORK PLAN PRE-WINTER BREAK
CDR
Week 1
Week 5
Week 10
Week 15
Legend
= Manufacturing
= Integration
= Testing
= Software
= Uncertainty
= Class Milestone
= Internal Milestone
Overview
Schedule
Manufacturing
Budget
6
WORK PLAN POST-WINTER BREAK
CDR
Week 1
Week 10
Week 5
Week 15
Extended manufacturing and basic
integration periods and added specific tasks
Basic/Full Integration are now partially in parallel
Legend
= Manufacturing
= Integration
= Testing
New critical path follows
manufacturing and integration
instead of software and testing
= Software
= Uncertainty
= Class Milestone
= Internal Milestone
More time is now given for SFR prep which is now in parallel to final testing
Overview
Schedule
Manufacturing
Budget
7
MANUFACTURING AND INTEGRATION SCHEDULE
Week 1
1/30/2015
Week 5
Now have specific manufacturing
tasks with their scheduling based
on priority
Legend
= Manufacturing
= Integration
= Class Milestone
The higher-priority items
must be completed before
some basic integration
Power distribution PCB had to
be extended by 2 weeks due to
delays in ordering and shipping
Overview
Schedule
Manufacturing
Budget
8
DESIGN OVERVIEW: FULL SYSTEM
MR Comm System
2 x 2mW 2.4GHz XBee Radios
Serves as relay between GS&CR
GS Comm System
2mW 2.4GHz XBee Radio
Transmits commands from user
Fixed Rappelling
Attachment Point
Zinc-plated steel U-bolt
Rappelling Tether
7x19 Braided Steel
Only provides physical connection
CR Comm System
2mW 2.4GHz XBee Radio
5dBi dipole antenna
CR Wheels
18cm diam., Nitrile rubber treads
Front pair powered for driving/turning
Back pair free for odometry
Overview
Imaging System
720p Raspberry Pi Cam
Pan/tilt servos and LED light panel
Driving Motors
0.53Nm Faulhaber DC Motors
134:1 internal gear-box
CR Mass: 6.1 kg
Schedule
Manufacturing
Budget
9
DESIGN OVERVIEW: RAPPELLING SYSTEM
• Rappelling System
Spool Drum
L=12cm, D=7.6cm
•
L
Winch Motor
23.5 Nm Stepper Motor
D
•
Connection
to existing
MR 80/20
Structure
Connection
to existing
MR 80/20
Structure
MR Addition Mass: 6.67 kg
Overview
Schedule
is attached at back
end of TREADS CR
bay
Rappelling tether is
11x19 braided steel
cable
Manufacturing
•
Budget
Threaded through
the spool drum from
the inside and held
to the spool drum
using cold weld
steel reinforced
epoxy
Copper oval sleeve
on inside of spool
10
DESIGN OVERVIEW: CPE’s
Tether
Back and Forward Motion
Scattered Rocks
Rappelling
Driving
PROJECT
ELEMENT
Subsystem
Breakdown
Rappelling
Winch and Drivetrain
Driving
Software/Electrical
Software/Electrical
On
Schedule?
Rationale
The CR shall have the capability to rappel up to 5 m into
a cave/pipe
✔
Chassis, Wheels, and Motors
The CR shall have the ability to explore 5m out from the
dropdown point on floor of cave/pipe
✔
Microcontrollers, Range Finder,
Encoders, Xbees, Imaging, PCB
and Batteries
The software will integrate functionality and provide for:
•
Position tracking
•
Communication
•
Power analysis
✔
Overview
Schedule
Manufacturing
Budget
11
RAPPELING SYSTEM: CURRENT STATUS
• Drive System: COMPLETE
• Structure: COMPLETE
• Spool: IN PROGRESS
•
A
Mounted Bearings
NOT SHOWN
COTS Stepper
Motor
Drive Shaft
Shaft Coupler
B
A
A
D
D
C
C
A
Al Machined Mount
Plates
D
D
A
Threaded ¼-28
B
Threaded 5/16 -18
C
Unthreaded 5/16 -18
D
Threaded 8-32
Overview
80/20 Al Machined
Structure
Schedule
Manufacturing
Budget
12
RAPPELLING SYSTEM: SPOOL PROGRESS
• Machined Components
•
•
Spool End Caps: COMPLETE
Spool Drum: IN PROGRESS
• Purchased Components
•
•
Flanged Shaft Collars
8-32 9/16” connector screw
End
Cap
8-32
Screws
Shaft
Collar
Spool
Drum
End Cap
Holes: Size 8 , 0.164 in
Diameter: 7 in
Overview
Schedule
Manufacturing
Budget
13
MR ADDITIONS MECHANICAL TREE
Battery
Panel
Legend
Support
Structure
Make

In Progress
✔
Completed

Future
80/20 Aluminum


On Order
✔
Completed

Future
Purchase
•
Non Motor
Plate
#R-NMP
Spool Drum
#R-SD
Spool
End-caps
#R-EC
Motor/ Gearbox
Shaft Collar
Motor Mount
Winch
System
Ref Doc
•
#R-MP
Mounting Plates
MR
Additions
Procure
Motor Plate
Drive Shaft

Spacer for Bearings
#R-SB
Pillow Bearing
Total man-hours spent:
•
Coupler
~15-20
Total man-hours remaining:
•
Wire
~5
Overview
Schedule
Percent
Complete
Manufacturing
Item-wise
Completion
Man-hour-wise
Completion
80%
75-80%
Budget
14
DESIGN OVERVIEW: CR MECHANICAL SYSTEM
Current focus is Front
and Rear Drive Train
Assemblies
Other sub-assemblies are
on schedule for completion
in the next 2 weeks
Overview
Schedule
Manufacturing
Budget
15
FRONT DRIVE TRAIN ASSEMBLY
4-4 Metric
Set Screws
Need to purchase 4-4 Metric Set Screws
Encoder
Planetary Gear
Motor
Wheel
Flanged
Shaft Collar
Drive Shaft
L-Bracket
3-8 Metric
Machine Screws
Need machine L-Bracket
All other parts
procured/finished
Overview
Schedule
Manufacturing
Budget
16
FRONT DRIVING ASSEMBLY
8-32 Screws
All material has
been received
Aluminum L-Channel
L-Channel must be machined
Drive train not assembled
.19” thk Al stock
LiPo Battery
Pillow Bearings
Front Drive Train
Overview
Schedule
Manufacturing
Budget
17
REAR DRIVING ASSEMBLY
Everything but 8-32
screws acquired
18-8 Machine Screws
Need to machine L-Channel, Drive
Shafts, and Mounting Plates
L-Channel
Wheel
8-32 Machine Screws
Drive Shaft
Optical Encoder
Flanged Shaft Collar
Overview
Mounting Plate
Pillow Bearings
Schedule
Manufacturing
Budget
18
CR MECHANICAL TREE
Legend
Wheels
Make

✔

Power Drivetrain
In Progress
Front Cross
Member
Completed

#D-FCM

Procure
Motor/Gearbox
Motor Attachment


Drive Shaft

On Order
✔
Completed


Spacer/Pillow Bearing
Al L-Chanel
Future

Drive Shaft
Passive Drivetrain
Rear Cross
Member
CR
Future
Purchase


#D-RCM
#D-PDT
Spacer/Pillow Bearing
Al L-Chanel




Encoder Attachment
Rappelling Attachment
Point
Ref Doc
•
Wheels


•
Total man-hours
spent:
•
~45
Total man-hours
remaining:
•
~40
6x4 Extended Chanel
Item-wise
Completion
Percent
Complete
Man-hour-wise
Completion
20%
Camera
Central Chassis
53%

Electronics Board

Schedule
Manufacturing

Servo Assembly
Acrylic Panel
#D-CH
Overview
Acrylic Panel (F)
L-Channels


#D-EB
Budget
19
SOFTWARE: OVERVIEW
CR ARDUINO MEGA
(C++)
GS (MATLAB GUI)
•
•
•
•
Send Commands
Receive
Acknowledgments
Display Images
Record Mission
Status
CR RASPBERRY PI
(Python)
•
MR ARDUINO MEGA
(C++)
•
•
Relay Commands,
Acknowledgments,
and Images
Stepper Motor Control
for Rappelling
•
•
Relay Commands and
Acknowledgments
Capture, Save,
Compress, and
Transmit Images
LED control
•
•
•
•
Measure Depth and
DistanceTraveled
Driving
Turning
Pan/Tilt Camera via
Servos
Commands
Acknowledgments
& Data
Images
Overview
Schedule
Manufacturing
Budget
20
SOFTWARE: GS GUI
DISPLAY IMAGES
•
•
•
PORT DETECTION
•
Displayed to user as
they arrive
Image transmitted
wirelessly
John from ~5m
• DR.IMAGE
COMMAND PANE
•
STATUS PANE
•
•
Implemented with
simulated statuses
TIME STAMP
•
Automatically
detects serial port
User options are
limited
Deploy command
removed post CDR
MISSION LOG
•
Image transmitted in
29 seconds
Overview
Schedule
Manufacturing
Budget
Dynamic log to
display mission
events
21
SOFTWARE: EXAMPLE COMMAND, RAPPEL
MR ARDUINO
Rappel Command
Ex: $R0+500\n
GS
parseCommand()
‘R0’ = Rappel
Serial.read()
‘$’ = Command
Acknowledgment
Ex: $R0P\n
CR RASPBERRY PI
processRappelCommand()
‘+500’ = 500cm down
$R0\n
Serial.read() -> ‘$’
Get depth from CR Arduino
CR Depth
Ex: $R0500\n
Depth = 500cm
$R0\n
CR ARDUINO
Compute CR depth
Serial.read() -> ‘$’
parseCommand() -> ‘R0’
readRange()
processRappelCommand()
Overview
Schedule
processRappelCommand()
parseCommand() -> ‘R0’
Get depth from CR
Send acknowledgement
Compute error
Set stepper
motor speed
error
<1m?
Yes
No
error
=0?
No
Apply
proportional
gain to
motor speed
Constant
motor speed
Yes
Manufacturing
Budget
22
SOFTWARE: PROGRAMMING STATUS
MR ARDUINO
GS
MATLAB GUI
95%
mrmain.h
parseCommand()
processStatusRequest()
setup()
CR RASPBERRY PI
Pi Libraries
30%
loop()
Process Commands
90%
Capture Images
Compress Images
LIBRARIES/CLASS FILES
Serial.h
commDropoutProtocol()
processDriveCommand()
processReturnCommand()
StepperMotor.h
mrconstants.h
processRappelCommand()
OVERALL ≈ 𝟓𝟎%
Remaining Man-hours: ~75
processImageCommand()
Save & Transmit Images
CR ARDUINO
CRArduinoMain.h
LIBRARIES/CLASS FILES
parseCommand()
crconstants.h
processStatusRequest()
Serial.h
setup()
commDropoutProtocol()
Encoder.h
30%
processDriveCommand()
StepperMotor.h
processReturnCommand()
DCMotor.h
Incomplete
processRappelCommand()
Servo.h
Provided
processImageCommand()
RangeFinder.h
commDropoutProtocol()
LEGEND
Completed
In Progress
loop()
Overview
Schedule
Manufacturing
Budget
23
SOFTWARE: FUTURE WORK
processStatusRequest() & commDropoutProtocol()
•
Increasing Functionality
•
Every 10s the GS sends a status request to the system. The CR and MR must return
battery and position status.
Implement communications dropout protocol.
processReturnCommand()
•
Estimated
Completion
Date:
Mar. 15
Mar. 8
Switch to reading front encoders and simply reel in tether
processDriveCommand()
•
•
•
Combine DC motor control with encoder readings via control algorithm
The MR must let out the appropriate amount of tether before the CR can drive
Also includes performing turning maneuvers as commanded
Feb. 22
processRappelCommand()
•
•
Combine stepper motor control on MR Arduino with range finding from CR Arduino
Implement proportional control when error < 1 meter
Feb. 9
Software completion deadline: Mar. 21
Overview
Schedule
Manufacturing
Budget
24
ELECTRICAL SYSTEM: OVERVIEW
High Priority Design Decisions
• Meets design requirements
• Voltage levels
• Current supply
• Ease of manufacturing
• Minimize fine-pitch SMD components
• Maximize through-hole
Medium Priority Design Decisions
• Cost
• Keep entire PCB cost under $100
• Robustness
• Output transients will not cause change in output
voltage
• Protection circuitry
Low Priority Design Decisions
• Size/footprint
• Thermal
Overview
Schedule
12v
regulation
Back36v
EMF
regulation
Protection
Appropriate
90%
power
through-hole
connectors
components
Manufacturing
Budget
5v
regulation
Low count of
fine pitch
components
25
ELECTRICAL SYSTEM: STATUS
Power Distribution PCB
• Designed, ordered, in assembly
Power Distribution
Percent of Work
Battery
Percent of Work
• Assembly done by RACER
PCB
• Completed by 2/2
Designed
Purchased
65
40
Level 1 Testing
• No load voltage level tests with 14.8v
Purchased
Delivered
5
10
input
Item-wise
Man-hour-wise
• Target completion: 2/3 – Original
Completion
Completion
Delivered
Discharge Profile
0
50
due date was 1/26, schedule allows
Percent
testing until 2/8
55-60%
60-70%
Complete
Assembled
10
Level 2 Testing
• Dynamic load testing, thermal
Level 1 Testing
5 be over-estimate
testing, subsystem-level integration
May
based
• Target completion: 2/18, schedule
on if 3rd revision is required
Level 2 Testing
15
allows testing until 3/21
Battery
• Purchased and delivered
Finished: 75%
Finished: 70%
• Discharge profile is needed for
capacity estimation
Overview
Schedule
Manufacturing
Budget
26
ELECTRICAL SYSTEM: FUTURE WORK
•
Manufacturing
•
Board Revision
•
Level 1 testing
•
•
•
•
•
•
•
•
•
10 capacitors, 3 inductors, 1
transistor, and power connectors
still to be added
Add headers for the battery
voltage measurement
Increase trace widths throughout
board
Fuse is missing
Any additional changes based on
level 1 testing
Test to ensure correct voltage
levels are produced (2/8)
Input sensitivity testing (2/8)
Second battery discharge test
Future testing
•
•
Dynamic load testing (2/18)
Subsystem integration and
testing (2/18)
Missing
connector for
battery
measurement
Vias not large
enough for
component leads
Incorrect
component footprint
- Lead pitch is too
fine
Missing
fuse
Traces are too thin
27
BUDGET UPDATE
Testing
0%
• Have budget left for
duplicates of any
critical component
• All procurements
for 1 rev. of project
have been purchased
Spending
Category
Miscellaneous &
Shipping
8%
Imaging
3%
Power
8%
Software
3%
Remaining
Budget
42%
• Expect to spend
only $1000 more on
parts, printing, etc.
Rappelling
15%
Communication
5%
Overview
Schedule
Driving
16%
Manufacturing
Money Spent ($)
Testing
17.91
Miscellaneous &
Shipping
431.1
Imaging
124.27
Power
391.24
Software
149.7
Rappelling
740.56
Driving
781.71
Communication
251.18
Money Spent
2905.67
Remaining
Budget
2094.33
Budget
28
LEVELS OF SUCCESS
•
•
Currently confident in achieving Level 2
success
Testing of Comm. dropout protocol will
determine if Level 3 success can be met
Level 1
Level 2
Level 3
Level Criteria
Status
Level Criteria
Status
The CR shall be able to
undock/re-dock to the TREADS
CR bay
Needs to be
Tested
The CR shall be able to traverse up
to 5m from the rappel touchdown
point, controlled via the GS
Needs to be
Tested
The CR shall be able to
rappel/ascend a 90 degree incline
to a max depth of 5m
Needs to be
Tested
The CR Shall be able to
transition from traversing a
vertical to horizontal surface and
vice versa
The CR shall able to resolve a
10cm diameter object from a
distance of 5m using the imaging
system
Needs to be
Tested
The CR shall be able to take and
transmit/store at least 5 images
Demonstrated
The imaging system shall have
azimuthal and elevation angular
coverage of 180 and 90 degrees
Needs to
be Tested
The CR shall know its horizontal
distance travelled accurate to +/- 10
cm
Needs to
be Tested
In Progress
The CR shall be able to return to the
MR at the conclusion of a mission
Needs to
be Tested
Demonstrated
The CR shall handle communication
dropouts with the MR/GS
Needs to
be Tested
FURTHER WORK NEEDED
ACHIEVABLE
Overview
Schedule
Status
The CR shall know its depth within
the cave/pipe accurate to +/- 10 cm
Demonstrated
The CR shall provide adequate
scene lighting
Level Criteria
Manufacturing
Budget
29
DESIGN OVERVIEW: CR MECHANICAL SYSTEM
Overview
Schedule
Manufacturing
Budget
30
QUESTIONS?
31
SUMMARY
Project Element Subsystem
Breakdown
Rappelling
Driving
Software/Electrical
•
•
Rationale
Status
Spooling, MR
attachments, and
Drivetrain
The CR shall have the
capability to rappel up to 5
meters into a cave/pipe
In Progress, estimated date of
completion:
Chassis, Wheels, and
Motors
The CR shall have the ability
to explore 5m out from the
dropdown point on floor of
cave/pipe, while going over
the scattered rock terrain
In Progress…
Microcontrollers, Range
Finder, Encoders, Xbees,
Imaging, PCB and
Batteries
GS, MR and CR shall be
controlled with software. The
software will integrate
functionality and provide for:
•
Position tracking
•
Communication
•
Power analysis
Stage 2 in Progress
All critical project elements are being worked on to meet their design driving requirements
Steps forward:
• Putting a lot of time into manufacturing these next couple weeks
• Continue with software integration of the electronics
32
DESIGN OVERVIEW: MANUFACTURING TREE
Main Subsystem
Legend
Subsystem
Components
Rappelling
Ref Doc
Driving
Communication
RACER
Structure
#R-ST
Spool
#R-SPL
Drive Train
#R-DT
Chassis
#D-CH
Wheel
#D-WH
Motors
#D-MTR
Xbees
Sonar Range Finder
Software/
Electronics
Encoders
Micro Controllers
CR, MR and GS
Code
Raspberry Pi
Imaging
LED Panel
PCB
#P-SCH
Power
Batteries
Overview
Schedule
Manufacturing
Budget
33
ALUMINUM MOTOR MOUNT PLATE #R-MP
34
ALUMINUM NON-MOTOR MOUNT PLATE #R-NMP
35
SPOOL DRUM #R-SD
36
SPOOL DRUM END CAPS #R-EC
37
PILLOW BEARING MOUNTS #R-SB
38
LED PANEL ELECTRICAL SCHEMATIC
39
CR IMAGING DEMONSTRATION
OVERVIEW:
• 10cm Point of Interest (John’s hand)
captured at a distance of 5m
• Command sent from GS to Raspberry Pi to
take picture
• Picture was sent back to GS for viewing
POI
TAKE AWAYS:
• GS can send picture taking
commands to Raspberry Pi
• Image can be sent back to GS
• 10cm object can be resolved at 5m
• Total time required: ~30s per image
FUTURE WORK:
• Use dark room and LED light panel as the
light source
40
MECHANICAL SYSTEM: Turning Feasibility
𝑀 = 2 𝐹𝑤 ∗ 𝐷1 − 2(𝐷2 ∗ 𝐹𝐹𝑦 ) > 0
𝐹𝐹𝑦 =
𝑀𝑐
∗ 𝜇𝑁 co s( 𝜃)
4
𝑙𝑤 = 34.5cm
𝐷1 = 20.3cm
𝐷2 = 34.5cm
𝑚𝐶𝑅 = 9.8kg
μN = 1.22
𝜃 = 36˚
The force from each wheel will needs to be greater than 4.2N
which equals 0.37Nm of torque needed from the drive train.
This is below the 71.2 N-m available from the drive train.
41
SOFTWARE: COMMAND STRUCTURE
Command
Start Identifier
Data
End Acknowledgment
Rappel
$
R0
[+/-] = Direction of rappelling
[###] = 3 char distance in cm
\n
$R0 1)
[P/F] = Pass/Fail
\n
Drive/Turn
$
D
[F/B/L/R] = [Forward/Back/Left/Right]
[###]
- if [F/B] then 3 char distance in cm
- if [L/R] then 3 char angle in degrees
\n
$D2)
[P/F] = Pass/Fail
\n
Capture Image
$
I
[+/-] = Sign of pan angle
[##] = 2 char pan angle in degrees
[##] = 2 char tilt angle in degrees
\n
$I
[IMAGE] = String
[EOF] = ENDOFFILE
\n
Return
$
RU
N/A
\n
$RU
[P/F] = Pass/Fail
\n
1) & 2) Will
Overview
return position & battery status in the future
Schedule
Manufacturing
Budget
42
Communication Command Structure
Command
Type
ID Character
Data
(Char Count)
Data Type
Drive
D
[1Char][4Char]
[F-Forward|B-Back|R-Right|L-Left][B/F-cm|R/L-Deg]
Imaging
I
[3Char][2Char]
[±[Pan Deg:0-90]][Tilt Deg:0-90]
Rappelling
R
[1Char][4Char]
[D-Rappel Auto|U-Retract Auto|0-Manual][M-±cm]
Abort
A
None
None
Status ID
Character
From
Data (Char Count)
Data Type
S
GS
[1Char]
[R-Request]
S
MR
[1Char][1Char][6Char]
[M-MR][B-Battery][Batt:mV]
S
CR
[1Char][1Char][6Char][1Char][3Char][3Char]
[C-CR][B-Batt:mV][P-Position][Depth:cm][Dist:cm]
Acknowledgements Type
ID Character
Data
(Char Count)
Data Type
Drive
D
[1Char]
[P-Pass|F-Fail]
Imaging
I
[1Char]
[P-Pass|F-Fail]
Rappelling
R
[1Char]
[P-Pass|F-Fail]
43
SOFTWARE: EXAMPLE COMMAND, TURN
MR ARDUINO
Turn Command
Ex: $DL010\n
GS
Serial.read()
‘$’ = Command
processDriveCommand()
‘L’ = Turn Left; ‘010’= 10 deg
Acknowledgment
Ex: $DP\n
CR RASPBERRY PI
$DL010\n
Serial.read() -> ‘$’
parseCommand()
‘D’ = Drive
Let out appropriate length
of tether
Relay
acknowledgment
Relay command to CR
parseCommand() -> ‘D’
processDriveCommand()
Relay command to CR Arduino
$DP\n
processDriveCommand()
$DL010\n
Send
acknowledgment
CR ARDUINO
Drive motors at
constant speed
Serial.read() -> ‘$’
Error
=0?
Calculate error
parseCommand() -> ‘R0’
processDriveCommand()
‘L’ = Turn Left; ‘010’= 10 deg
Overview
Set target distance
using arc-length
equation
Schedule
Get distance
traveled from
encoders
Manufacturing
Set motor
directions
Budget
44
SOFTWARE: EXAMPLE COMMAND, IMAGE
MR ARDUINO
Turn Command
Ex: $I+1025\n
GS
Serial.read()
‘$’ = Command
Image
Ex: $I..EOF\n
GS - MATLAB
Check for EOF delimiter
processImageCommand()
‘+10’ = pan 10deg; ‘25’= tilt 25deg
Relay command to CR
Reconstruct image via Python
$I+1025\n
Stream image to GS
Display image to GUI
processeImageCommand()
CR RASPBERRY PI
CR ARDUINO
Transmit Image
Serial.read() -> ‘$’
Serial.read() -> ‘$’
Compress Image
parseCommand() -> ‘I’
processImageCommand()
parseCommand() -> ‘I’
Save Image
processImageCommand()
‘+10’ = pan 10deg;
‘25’= tilt 25deg
Capture Image
Relay command to CR
processeImageCommand()
Overview
parseCommand()
‘I’ = Image
Schedule
Move Servos
Manufacturing
Budget
45
SOFTWARE: MR IMAGE RELAY
• Objective: Relay image through the MR in real-time
• Solution: Read and transmit image character by character (stream image)
• The Arduino Mega has a clock frequency of 16MHz.
• Fast enough to avoid filling up the serial buffer (Serial3 above, MR-CR link)
• The serial baud rate of the system is 115200 bits/sec
46
SOFTWARE: COMMS DROPOUT TIMELINE
t = 0 when last acknowledgment is sent from CR
47
ELECTRICAL SYSTEM: Battery Discharge
• Discharge the battery
3250 mAh 14.8V Battery Discharge
at 3.08A until voltage
reaches 3.2V/cell
•
3.08A is maximum
expected current draw
on this battery (MR)
Below 3.2V, battery
lifetime deteriorates
• Test shows a capacity
•
of 4567 mAh (1.4x
advertised)
Roughly linear
decrease until battery
voltage reaches 14.5V
17.00
Battery Voltage (V)
•
18.00
16.00
15.00
14.00
13.00
12.00
0
20
40
60
80
100
Time (min)
48
ELECTRICAL SYSTEM: PCB Changes
•
Critical Changes
•
•
•
•
•
Transistor Q1 has incorrect footprint. Leads are too close together
Inductors L1 and L3 have vias that are too small for the component leads
Connector P5 needs to be added to the PCB (for battery voltage measurement)
Fuse F1 needs to be added to PCB (for protection)
All traces need to be widened. Especially on nodes P1,D1,L1, L3, D2, U2SW, L2
•
These are the major current-carrying nodes in the design
•
Non-critical changes
•
Any fundamental changes that testing reveal need to be made
• Increase vias for R3, R14, R16
• Components are tight, but still fit in place
• Change lead spacing for C12, C13, C15, R14
49
ELECTRICAL SYSTEM: Level 1 Testing
• Level testing
•
Ensure that correct voltage levels are produced
•
•
•
12V
36V
5V
•
Check that tolerances are met at steady state
•
Very input voltage from 12.8V – 16.8V
• Input sensitivity testing
•
•
Range of possible input voltages from battery
Check that correct voltages are produced and tolerances are met
Power Source
Maximum Allowed Voltage
Fluctuation
Maximum Simulated Voltage
Fluctuation - Transient
5V
0.25 V
0.15 V
12V
0.5 V
0.27 V
36V
12 V
4V
50