Design of the Life-ring Drone Delivery
System for Rip Current Rescue
Andrew Hardy, Mohammed Rajeh,
Lahari Venuthurupalli, Gang Xiang
Tether
Hold/Release
System
Life-ring/Ring-buoy
Dji.com, (Schenkel, 2014), Parks.ca.gov, 2015, NOAA
Solution
60 93
Victim
survival
time limit
Lifeguard
Reach
Time
Time (s)
1. Context 2. Stakeholders
3. Problem/Need Statements
4. Requirements
5. Con-Ops
6. Alternatives
7. Method of Analysis
8. Future Work
9. Thanks
Beach Analysis
About 42% of the US adult population
visited the beach every year (EPA, 2015)
About 6,200 beaches in the US (EPA, 2015)
Beaches are owned by municipalities
More than $320 billion annual revenue
from US beaches (ASBPA, 2014 )
Beach management in the US cost less than
4% of 2.65 billion annual park service
budget (ASBPA, 2014 )
• Example: Ocean City beach patrol expenses
2.3 million (Town of Ocean City Adopted
budget, 2015)
3
Beach Rescues
Rip Current, 334184,
81% Surf,
73670, 18% Swiftwater, 2459, 0%
Scuba, 2538, 1%
0
100000
200000
300000
400000
Rescues
Rip Current Primary Cause of Rescue 2003 – 2012
Rip Current Surf Swiftwater Scuba
Rip currents are the primary cause of rescue
• Rip currents account for 81% (334,184) from 2003 to 2012
• Note:
– Some Beach Agencies Only Report Totals For Fatalities and Rescues
– Some Beach Agencies Do Not Report Certain Subcategories
– Some Beach Agencies Do Not Report to USLA
Rip Current,
35935, 82%
Surf, 7288, 17% Swiftwater,
307, 1% Scuba, 272,
0% 0
10000
20000
30000
40000
Rescues
Rip Current Primary Cause of Rescue 2012
Rip Current Surf Swiftwater Scuba
y = 889.41x - 2E+06
0
10,000
20,000
30,000
40,000
50,000
2000 2005 2010 2015
Num
ber
of
People
Year
Rip Current Rescues
y = 1163.4x - 2E+06
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
2000 2005 2010 2015
Num
ber
of
People
Year
Total Rescues
(USLA, 2013)
4
Beach Fatalities
Fatalities From Rip Current Accounted For 79% in 2014
10 Year Average for Annual Rip Current Fatalities is 51
Annual Deaths Due to Rip Currents Exceed 100 • Note:
– Some Beach Agencies Only Report Totals For Fatalities and Rescues
– Some Beach Agencies Do Not Report Certain Subcategories
– Some Beach Agencies Do Not Report to USLA
Rip Current, 79%
High Surf, 7% Sneaker
Wave, 3% Other, 6%
Unknown, 5%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
Fatalities
Surf Zone Fatalities 2014 Total
Rip Current High Surf Sneaker Wave Other Unknown
y = 0.6x - 1176.2
0
20
40
60
2000 2005 2010 2015Num
ber
of
People
Year
Rip Current Unguarded Deaths
y = 0.0545x - 20.436
0
50
100
150
2000 2005 2010 2015
Num
ber
of
People
Year
Total Unguarded Deaths
y = 0.1909x - 379.16
0
5
10
2000 2005 2010 2015
Num
ber
of
People
Year
Rip Current Guarded Deaths
y = 0.6727x - 1332.4
0
5
10
15
20
25
30
2000 2005 2010 2015Num
ber
of
People
Year
Total Guarded Deaths
NOAA, 2015
USLA, 2014
5
Rip Current Circulation Diagram
Surf Zone
Feeder
Current
Neck
Head Width Speed Length
Rip Current
Measurements
Width [10,200] feet
Length ~[100,1000] feet
Speed [1,8] feet/second
USLA, NOAA
http://floridadisaster.org/EMTOOLS/Severe/document
s/Rip%20Current%20Brochure.pdf
Shore
line
6
Rip Currents Formation
Waves travel from deep to shallow water, they break near the shoreline • Generate currents flow offshore (rip)
and alongshore (feeder)
Waves flowing through sandbars
Rip currents form between cusps
Hard Structures • Reefs, jetties, piers, or other man made
structure
• Deflect longshore current in an offshore direction
Some last for many days or months
Some form quickly and last hours or days to disappear
(NOAA, 2004)
(Next Media Animation, 2011)
Rip Current
7
SEQUENCE EVENTS IN DROWNING
Dry-Drowning
Victim Panics
Body
accumulates
carbon dioxide
Water reaches
airway Throat Spasms
Water flows into
the lungs
Victim is caught
in a rip current
Victim tries to
fight rip current
Victim gets
exhausted or
is dehydrated
or has trouble
swimming
Lungs seal &
water
accumulates in
stomach
Throat relaxes Victim becomes
unconscious
Secondary Drowning – Pulmonary Edema
1. 2. 3. 4. 5.
6. 7. 8. 9. 10. 11.
(Forensic pathology online, 2013)
8
Process of Lifeguard rescuing victim
LG swims to drowning victim
LG Rescues
LG Guides victim to shoreline
Victim out
of water
Identify
Drowning
Victim Radio
Control
RM
max 20 s
max 90 s
max 30 s
max 90 s
max
2 s
max 10 s
LG keeps an
eye on Rip
Currents
Emergency
Care
Provided
max 4 min
Victim Panics
Body
accumulates
carbon dioxide
Water reaches
airway
Throat Spasms
4. 5. 6. 7. 8.
Victim
Lifeguard
… 9
Performance Gap
There is a gap between victim survival
time and lifeguard rescue time.
Reduce the rip current-related
fatalities to X/yr from the current
average of 51/yr.
Time (s)
Max Victim Survival Time
*not in scale
60 93
Max Victim
Survival if
fighting against
current
Lifeguard
Reach Time
Time (s)
Red area = victims in danger of drowning
10
1. Context
2. Stakeholders 3. Problem/Need Statements
4. Requirements
5. Con-Ops
6. Alternatives
7. Method of Analysis
8. Management
9. Thanks
Stakeholders
Lifeguarding Associations
• usla.org (United States Lifesaving Association)
• Redcross.com
• Jellis.com (Jeff Ellis & Associates-International Lifeguard Trainings)
Lifeguards
• Sarah Litowich, an aquatic director of the Aquatic Fitness Center at George Mason
• Captain Butch Arbin III, Ocean City beach patrol officer in Maryland
• Captain Barry Kirschner, Virginia Beach Dep. of EMS emergency medical technician-enhanced
• Dane Underwood, Red Cross and Ellis and Associates certified instructor
Beach Goers
• Want least restrictions
• Want lifeguards to be 100% effective at their jobs
Manufactures
• Produce equipment to lifeguards who pay the manufactures money
• Ex: Swimoutlet, Marine Rescue Products, USLA
Municipalities
• Beach owners have to warn non-trespassers about dangerous conditions on their property
• States own land seaward of the high tide line
1.
2.
3.
4.
5.
12
Tensions
Beach Goers
Municipalities (Beach Owner)
Life guarding associations
(Certification company)
Equipment Manufactures
Lifeguards
Municipalities (Beach Operator)
Feedback Loops
LG protection/ rescue services
Accident/Injury Liability
Provide revenue Provide clean beaches
13
Liability
Beach Goers
Municipalities (Beach Owner)
Lifeguards
Municipalities (Beach Operator)
Accident/Injury Liability
Provide revenue Provide clean beaches
Beach owner is liable for beach goers
Beach owner is protected under the catastrophic
umbrella insurance for huge damage
Beaches are kept clean by the revenue BG
generate
LG protection/ rescue services
14
Certification
Municipalities (Beach Owner)
Life guarding associations
(Certification company)
Lifeguards
Municipalities (Beach Operator)
LG Associations train professional
LGs
Beach operator documents yearly
certification and training of LGs
15
Feedback for Manufacturers
Life guarding associations
(Certification company)
Equipment Manufactures
Lifeguards
Municipalities (Beach Operator)
Feedback Loops
LG associations, Beach operator
and LGs provide feedback of
equipment manufactures produce
16
Win-Win
Lifeguarding
Operators • Reduce legal actions and save lives.
Lifeguards • Improve rescue process and save lives.
Beach Goers • Increase safety of beaches without added regulation
• Decrease rip current-related deaths
Manufactures
• Allow system to use any life ring/ lifesaving device
• Let beaches use the devices they want within a
certain weight limit (no switching manufacturers)
Municipalities • Increased safety leads to more beach goers, which
lead to more beach services used
No stakeholder is against this Life-Ring Drone Delivery System
17
1. Context
2. Stakeholders
3. Problem/Need Statement 4. Requirements
5. Con-Ops
6. Alternatives
7. Method of Analysis
8. Management
9. Thanks
Problem/Need
Problem Statement
Rip tides are, on average:
• Annual beach rescues: 81% (USLA,2014)
• Annual beach fatalities: 79% (NOAA,2014)
• Average annual fatalities: 51 (NOAA,2015)
Lifeguards can reach victims in a max time of 92 seconds (Butch,2015)
• Some victims have survival times as low as 60 seconds.
Need Statement
There is a need for a system that can reach and assist a victim in under 60 seconds (while
the victim are still an active drowner) in order to increase the victim's survival time.
By decreasing flotation device delivery time, we can reduce drowning deaths by X%.(TBD)
19
System Scope
Design a rescue drone delivery system • Reach victims using camera systems
• Drop flotation device using 1st tether release
• When victim grabs lifesaving device, 2nd tether release drops the lifesaving device and tether, allowing drone to return home.
Determine the best possible design to: • Motor
• Drone Platform (quad/hexa/octo)
• Battery
• Flotation Device
Design a tether holding/releasing system
Tether Hold/Release System
Tethered Lifesaving Device
Front and Down Cameras
In the end, deliver:
1. Drone System Design
1. Business model and Cost Model
2. Rescue System Design
1. Draft training methods and user manual 20
1. Context
2. Stakeholders
3. Problem/Need Statements
4. Requirements 5. Con-Ops
6. Alternatives
7. Method of Analysis
8. Management
9. Thanks
Mission Requirement
MR.1 The system shall reduce the
average annual number of rip current
deaths by a minimum of X%.
22
Functional Requirements
F.1 The system shall hover at a minimum altitude of 3m above the ground.
F.1.1 The system shall hover at an altitude of 3m with a minimum payload of 2.268kg.
F.2 The system shall be operable within X m of the home point.
F.3 The system shall reach a victim within X seconds.
F.3.1 The system shall increase the victim survival time by an average of X seconds, if the
system does reach the victim.
F.4 The system shall be able to restock its payload within X seconds.
F.5 The system shall be able to deploy its payload within X seconds.
F.6 The system shall do the entire rescue process at a maximum time of X seconds.
F.7 The system shall be able to hover within a horizontal distance of 0.5m from the target.
23
Design Requirements
DR.1 The system shall attach the lifesaving device to the drone through a tether.
DR.1.1 The system may have a disconnect method to cut or release the tether in order to deliver the
lifesaving device.
DR.1.2 The system shall have a tether release system that weighs under X kg.
DR.1.3 The system shall be able to release the tether within X seconds of the request to release.
DR.2 The system shall have a camera system pointing downward.
DR.3 The system shall have a camera system pointing forward.
24
Ilities Requirements
Usability
U.1 The system shall be usable by a person that has less than 12 hours of training.
Availability
A.1 The system shall be available to at least any beach on U.S territory
A.1.1 The system shall comply with all federal drone regulations.
A.2 The system shall be available for rescues over 95% of the time.
A.3 The system shall be usable in X rescues a day when balanced charged.
A.4 The system shall have a minimum lifetime of 5 years
Reliability
RE.1 The system will have MTBF of X months
RE.2 The system shall have a tether system error MTBF of 7 days
Resistability
RS.1 The system shall resist sand conditions of an average beach.
RS.2 The system shall resist humiditity conditions of an average beach.
RS.3 The system shall resist temperature conditions.of an average beach.
25
FAA UAS Regulations
Current Advisories UAS flight altitude below 400 ft.
UAS weighs under 55 lbs.
Maintain visual line of sight of the UAS • Spotter allowed
– Minimum 1 spotter per UAS
UAS operator must have a pilot's license
UAS may not be operated in restricted airspace • (grey area)
• not applicable to government
UAS may not be operated for commercial purposes
No Overhead Operation !!!
Proposed Regulations
UAS flight altitude below 500 ft.
UAS weighs under 55 lbs.
UAS may not exceed 100 mph
Maintain visual line of sight of the UAS
• Spotter allowed
– Minimum 1 spotter per UAS
UAS operator:
• Be licensed
• Report incidents in less than 10 days
• Make UAS available for inspection
3 mile visibility from control station
Inspect UAS prior to flight
No Overhead Operation !!! Source: http://www.faa.gov/uas/
26
1. Context
2. Stakeholders
3. Problem/Need Statements
4. Requirements
5. Con-Ops 6. Alternatives
7. Method of Analysis
8. Management
9. Thanks
Rescuing Process with Drone
28 (Butch,2015)
Control Rm
receives
Coordinates Drone
leaves
home point
Drops
tether w/
ring buoy Victim grabs
buoy, tether
is released Drone
returns to
home point
Drone
travels to
victim
LG swims to drowning victim
LG Rescues
LG Guides victim to shoreline
Victim out
of water
Identify
victim Radio
Contr
ol Rm
max 20 s
max 30 s
max 90 s
max 2
s
max 10 s
LG keeps an
eye on Rip
Currents
Emergency
Care
Provided
NO
YES
max 90 s
Stage
1
Stage 2
Con-Ops
Precondition: Lifeguard has identified a drowning victim. Lifeguard is prepared for rescue process. Lifeguard radios control room of the section # or victim’s
general direction. Victim is located somewhere on the rip current and is attempting an escape method. Drone is ready to deploy. Flotation device is stocked
on drone.
Primary: Stage 1
Controller is informed by lifeguard of general area of the victim
Controller takes off drone • Confirm victim location by eyesight if near tower
The system takes off to a height of X meters.
The system accelerates to X m/s towards the section given.
Controller confirms specific location in that section through camera or eyesight. • Relative to Drone
The system maintains X m/s towards the victim's location.
Once the system is within X m of the victim’s location, system shall decelerate to victim’s speed and position. At the same time, the system will reduce
height until the flotation device is just above the water (confirmed by controller).
Primary: Stage 2
The system drops the flotation device and positions it by the victim
Once the victim is about to grab the the flotaton device, system detaches the tether.
The system maintains a X m hover over victim until lifeguard has reached the victim. • Controller uses camera to visually determine victim state (active or passive)
• If necessary Controller inform medical personnel of victim status
Primary: Return
Once lifeguard has reached the victim, or drone has been determined to be of no further use, or drone has reached critical battery charge, system will
be flown back to the home point.
System lands on home point.
Post-Condition: Lifeguard is enacting the rest of rescue process starting with rescuing the victim. Drone has landed back at the home point and awaits
restocking of ring buoy. Victim is being helped by the lifeguard.
29
Identify
•Prepared for rescue
•Identify Victim
•Radio control room
•Flotation device stocked
•Prepared to deploy
•attempting escape method
Beach
Area
Shore
line
30
•Lifeguard swims to drowning victim.
•Leaves homepoint
•Travels to victim
Stage 1
Beach
Area
Shore
line
31
•swims to drowning victim.
•Drops tether with ring buoy
•Releases tether when victim grabs ring buoy
•Victim grabs flotation device
Stage 2
Beach
Area
Shore
line
32
Return
•Lifeguard continues rescue process
•Drone returns to homepoint
•Drone is ready to be resupplied
Beach
Area
Shore
line
33
1. Context
2. Stakeholders
3. Problem/Need Statements
4. Requirements
5. Con-Ops
6. Alternatives 7. Method of Analysis
8. Management
9. Thanks
Design
Alternatives
Set A
• Location of drone station
Set B
• Design of drone
Set C
• Choice of flotation device
Design of Experiment
DoE A
• Location of drone station (TBD)
DoE B
• Design of drone (TBD)
35
Set A: Drone Location
Option 1: main control room. • Operation range of multiple
lifeguard towers.
• Easier to charge drone. Safer for the drone.
Option 2: near guard towers. • Operation range of the nearest
lifeguard towers.
• Closer to shore and allows eyesight to confirm victims.
Option 3: At Sea • Avoid Regulatory problems
Section
2. Tower
Victim
Tower
1.
Control
Room
3. Boat
36
Set B: Design of Drone
Motors
Drone Platform (quad/hexa/octo)
Battery
37
Set C: Flotation Device
Flotation
Device Cost Weight Dimensions Buoyance
Effectiveness
(5 Star)
Usability
(5 Star)
Ring Buoy
(Jimbuoy
JBW-20)
$85.98 3 lbs. 20 in 16.5 lbs. 5 5
Rescue Can
(Jimbuoy
model 8t)
$139.99 4 lbs. 29.5x9.5 in 18.2 lbs. 2 2
Lifejacket
(First Mate –
Stearns
flotation)
$74.99 1.5 lbs. 24x12x3 in 15.5 lbs. 4 4
Ultra 3000
(Auto
inflating life
jacket)
$204.99 3 lbs. 30x52 in 37.7 lbs. 3 3
38
Set C: Floatation Device AHP Analysis
Buoyance
Time of
Delivery Effectiveness Usability Dimensions
Buoyance 1 1/2 5 5 5
Time of
Delivery 2 1 7 7 7
Effectiveness 1/5 1/7 1 1/2 1
Usability 1/5 1/7 2 1 3
Dimensions 1/5 1/7 1 1/3 1
• Comparing 5 factors
• AHP Analysis to find
the best alternative
• Found weights of
each factor
• Still need to
calculate the best
alternative by using
weights
39
• Time of Delivery & Buoyance most important
• Highest rated
• Used Intensity of importance scale to rate others
1. Context
2. Stakeholders
3. Problem/Need Statements
4. Requirements
5. Con-Ops
6. Alternatives
7. Method of Analysis 8. Management
9. Thanks
Drone Info
•Quadcopter = 4 rotors
•Hexacopter = 6 rotors
•Octocopter = 8 rotors
•Opposite rotors have same spin. •2 rotors rotate counterclockwise
•the other 2 rotate clockwise
•This allows drone body to choose to rotate, or not rotate,
depending on the rotational velocity of the rotors.
•Picture on left shows clockwise spin being stronger, thus the
drone rotates counterclockwise.
Stronger clockwise motors =
Body rotates counterclockwise
41
Orientation
Positive x-axis = front side (direction of motor 2)
Positive y-axis = left side (direction of motor 3)
Positive z-axis = top side
Body frame = body reference = drone reference
Inertial Frame = our reference = our point of view
Controller
X
Y
Inertia Frame
Body Frame
42
Axis's of Rotation (Euler Angles) Roll, Yaw, Pitch
φ (roll)
θ (pitch)
ψ (yaw) Counterclockwise = positive http://theboredengineers.com/2012/05/the-quadcopter-basics/
X Y
Z
cossin0
sincos0
001
cos0sin
010
sin0cos
100
0cossin
0sincos
R
R
R
coscoscossinsin
cossincossinsinsinsinsincoscossincos
cossincossinsincossinsincossincoscos
RRRR
coscossin0
cossincos0
sin01
Z
Y
X
Combined
Rotational
Matrices
Rational
Matrix for
Angular
Velocity 43
Electrical-Mechanical Power
Torque produced by motor
• τ = torque generated by motor
• Kt = torque proportionality constant
• I = input current
• I0 = current when there is no load on motor – Considered Negligible
Voltage drop across motor
• V = voltage
• I = current
• Rm = motor resistance – Considered Negligible
• Kv = back-EMF per rpm (coefficient)
• ω = angular velocity of the motor
Manufacturers use inverse of Kv
)( 0IIKt
vm KIRV
t
v
K
KP
TK
KKP
TK
t
v
Now that we have terms for current and voltage, we
can find power produced by motor
P = power = I*V
Assuming that Kt*I0 << τ and negligible motor
resistance.
Variable 1 Relation Variable 2 Proportionality
Coefficient
Equation
τ ∝ I Kt τ = Kt * I
τ ∝ T Kτ τ = Kτ * T
V ∝ ω Kv V = Kv* ω
44
Linear Dynamics
R = body-to-inertia transformation matrix
TB = Thrust in body-frame
FD = force of drag due to air
Frope = force due to rope interaction
Flifevest = force due to vest interaction
-mg = force due to gravity
FD= drag force (from fluid)
CD= drag coefficient (determined experimentally)
v = velocity of body in perspective of fluid
A = reference area
PD= power needed to overcome drag
Tbody = total thrust on body of drone
ωi = angular velocity of ith motor (in the reference of the body)
T = Thrust
D = diameter of propeller
ρ = density of air
P = power produced by propeller
lifevestDbody FFRT
mgz
y
x
m
0
0
A
v
v
v
CF
z
y
x
DD
2
2
2
2
1
2
2 0
0
*)(2
i
t
vbody
K
KKDT
2
2
0
0
*
)(2
i
body
T
v
kT
K
KKDk
3
1
22 ]2
[ PDT
Force of lifevest =
Force of lifevest drag +
Force of lifevest weight (mg)
m*a = ∑F
45
Free Body Diagram
Side-view
46
Z-axis Torque per motor
Each propeller can spin the body of the drone AKA provide torque from drag forces from the air onto the body.
A = propeller cross section (not swept area)
r = radius of the propeller.
CD = constant
τD = torque due to drag
τZ= torque in z-axis (in reference of body)
ω= angular velocity
ωdot= angular acceleration • Considered neglible
IZ= moment of inertia around the motor Z-axis
2
22
)(2
1
)()(2
1
rACrb
rACr
D
DD
ZZ Ib 2
47
Torque of body
Torque = Σ(Thrust x radius)
Opposite rotors have spin
• To have the same thrust while rotating, one rotor must decrease and one must increase in angular velocity in a rotor pair.
L = distance between motor and center of body.
Assume angular acceleration is negligible
yaw
pitch
roll
b
Lk
Lk
B
)(
)(
)(
2
4
2
3
2
2
2
1
2
4
2
2
2
3
2
1
4
7
3
5
1
2
8
6
X
Y
X
Y 1
2
3
4 2
5
4
3
1
6
X
Y
48
Rotational Dynamics
Euler’s Equation on Torque
• τ = torque
• I = moment of inertia
• ω = angular velocity
• m = mass
yx
ZZ
YYXX
zx
YY
XXZZ
zy
XX
ZZYY
ZZ
YY
XX
z
y
x
ZZ
YY
XX
I
II
I
II
I
II
I
I
I
II
I
I
I
I
1
1
1
1 ))((
00
00
00
i
ii
c
iii
m
rmr
IrmI2
)( II
49
1. Context 2. Stakeholders 3. Problem/Need Statements 4. Requirements 5. Con-Ops 6. Alternatives
7. Method of Analysis DoE / Simulation
8. Management 9. Thanks
Drag DOE
Determine the force of drag acting on the S900. • Needed to accurately create a simulation of the drone.
To determine the force of drag: • Perform a flight test of the drone.
• Collect its telemetry.
• Broken down into: – Horizontal force of drag.
– Vertical force of drag.
• At different speeds – To know how much /if Cd materially changes.
51
Drag DOE
Inputs
Outputs
Procedure Height Flight Speed Pitch Roll Velocity
Wind
speed Altitude Distance
Horizontal
CD test
1. fly 30 m north
2. fly 30 m east
3. fly 30 m south
4. fly 30 m west
Maintain
constant
10 m
# 1 1 m/s
# 2 5 m/s
# 3 10 m/s
# 4 15 m/s
Vertical
CD test
1. Ascend 30 m
2. Descend 30 m
At least
10 m
above
ground
# 1 1 m/s
# 2 5 m/s
52
Motor Parameter DOE
To simulate the DC electric motors of the S900 we need to determine:
• Torque-Speed curve
• Power-Speed curve
• Torque-Current curve
The curves will be used to find:
• No load current
• Torque constant
• Torque to thrust constant
53
Motor Parameter DOE
Inputs Outputs
Voltage Torque Current Speed (RPM) Resistance
http://www.micromo.com/technical-library/dc-motor-tutorials/motor-calculations
54
1. Context 2. Stakeholders 3. Problem/Need Statements 4. Requirements 5. Con-Ops 6. Alternatives
7. Method of Analysis DoE / Simulation
8. Management 9. Thanks
Simulation
• MATLAB and Simulink
• Goal: Simulation verify that the system meets the requirements
o MR.1 The system shall reduce the average annual number of rip current
deaths by a minimum of X%.
o Design of Experiments will verify the simulation.
56
Simulation Requirements
SR.1 The system shall be able to fly towards a waypoint and maintain position
within 0.5m of the waypoint.
SR.2 The system shall have one run simulated under 1 minute.
SR.3 The system shall simulate wind and weight interactions with the drone.
SR.4 The system shall model drone rotational and translational dynamics.
SR.5 The system shall model the lifeguard-victim rescue process up until the
lifeguard reaches the victim.
SR.5.1 The system shall model the three victim escape methods (swim
parallel to neck, swim against the neck, float)
SR.5.2 The system shall model riptides of length 100/200/300/400/500
meters.
SR.5.3 The system shall model the lifeguard speed on land and on water as
an average velocity of X m/s and Y m/s respectively.
57
Simulation Requirements conti.
Input Requirements
IR.1 The system shall inputted a victim swimming method. It will pick between floating, swimming parallel
against the shore, and swimming parallel to shore.
IR.1.1 The system shall model the swimming methods as velocities.
IR.1.2 The system shall be inputted a random victim survival time
based on the swimming method chosen.
IR.2 The system shall be inputted a random rip current speed. The speed will be chosen by a random distribution
with mean X and variance X.
Output Requirements
OR.1 The system shall output the victim position over time.
OR.2 The system shall output the lifeguard position over time.
OR.3 The system shall output the drone position over time.
OR.4 The system shall output 1 or 0 depending if the lifeguard rescue time is under victim survival time.
OR.4.1 The system shall detect if the drone reached the victim before
the lifeguard and increase victim survival time by X seconds.
58
Simulation Model
1. Generate victim
position over time
3. generate drone
position over time
2. generate lifeguard
position over time
4. Pass judgment
a. If drone reached victim before survival
time ended and before lifeguard, drop life
ring (increase survival time by X seconds).
b. If lifeguard reaches victim before survival
time, victim is saved.
c. If lifeguard does not reach victim before
survival time, victim is lost.
d. Save result 59
Victim Model and Lifeguard Model
60
Drone Model
61
62
Linear Dynamics
63
64
Rotational Dynamics
65
66
67
Hexacopter Base Model D
eri
ved t
hro
ugh o
nline d
ocum
enta
tion
and f
light
experi
ments
Constants Meaning Value
Kt Propor. Const.
Kτ Propor. Const.
Kv Porpor. Const. 1/400
D Rotor diameter
ρ Air density 1.225kg/m3
CD Drone drag coeff.
AX Drone Area X-view
AY Drone Area Y-view
AZ Drone Area Z-view
m Drone mass
L arms Radius of arms
from center
b Rotor Yaw Const.
Ar Rotor Cross Section
Constants Meaning Value
LR Cd Ring drag coeff.
LR Ax Area of ring horiz.
LR Az Area of ring top
LR m Ring mass 2.268kg
Ixx Mom. of Iner. X-axis
Iyy Mom. of Iner. Y-axis
Izz Mom. of Iner. Z-axis
Battery Mass
Battery Capacity 15000mAh
Tether Syst. Mass 0.5kg
Tether Density
Tether Length
Camera Mass 1.0kg
68
Two Simulation Models
GPS Mode
• Maximum tilts and velocities
• Maintains altitude for
horizontal movement inputs
and no inputs
• Simplified Model
• Pro
• Simpler to implement
• Con
• Settle time is longer
• Does not care about max speed (unrealistic)
• Vigorous Model
• Pro
• Reaches and maintains max speed (until close to
victim)
• Con
• More unstable movements
• Takes longer to run simulation
Current Simulation has:
• 9 PID controllers per model
• 350 lines of code per model
• 6 models
(simplified/vigorous)
(quad/hexa/octo)
69
Stationary Target Moving Target 5m/s
70
71
Stop & Move, Overshoot Stop & Move, Jumping
Victim – Lifeguard – Drone Simulation
Victim – spotted 10m ahead, 25m to the left of lifeguard, floating
Lifeguard – already spotted victim, runs on land to current, swims ahead, 3m/s
Drone – Lifts off when lifeguard starts to run, overshoots some.
Rip current – 8m/s
•Victim
•Lifeguard
•Drone
72
Future Work
WBS 7 DoE
• WBS 7.3 Design
– 7.3.1 Motors
– 7.3.2 Drone Platform
(quad/hexa/octo)
– 7.3.3 Battery
• WBS 7.4 Location
WBS 11 Rescue System
WBS 8.1.8, 8.1.9, 8.2, 8.3 -
Complete Simulation
WBS 6.3 - Sensitivity Analysis
WBS 6.5 Utility Model
73
1. Context
2. Stakeholders
3. Problem/Need Statements
4. Requirements
5. Con-Ops
6. Alternatives
7. Method of Analysis
8. Management 9. Thanks
WBS
Top level WBS
The project’s major tasks and
subtasks
Stakeholder analysis, DOE, and
especially the simulation are
the most important of the
work.
75
Critical Path # WBS Task Name Start Finish
18 3.2.3 Rescue Process Diagrams 10/8/15 1/23/16
21 4.2 Functional Requirements 10/30/15 11/27/15
22 4.3 Design Requirements 10/31/15 11/27/15
29 5.1.4 Evaluate Drone Battery Alternatives 3/31/16 4/2/16
31 5.1.6 Evaluate Drone Motor Alternatives 3/17/16 3/19/16
33 5.1.8 Evaluate Drone Rotor Alternatives 3/19/16 3/23/16
35 5.1.10 Evaluate Drone Location Alternatives 3/14/16 3/17/16
36 5.1.11 Research Drone Configuration Alternatives 10/1/15 10/3/15
37 5.1.12 Evaluate Drone Configuration Alternatives 10/3/15 10/27/15
40 5.2.2 Evaluate Flotation Device Alternatives 10/15/15 4/28/16
52 6.3 Sensitivity Analysis 3/25/16 4/3/16
56 6.4.3 Simulation Risk Analysis 11/27/15 12/5/15
77 8.1.7 Create Rip Current Model 2/13/16 2/27/16
79 8.1.9 Create GUI 2/27/16 3/14/16
80 8.2 Simulation Testing 3/14/16 3/25/16
81 8.3 Perform Sensitivity Tests 3/25/16 4/3/16
89 9.2.1 Faculty Presentation Creation 11/14/15 11/19/15
90 9.2.2 Faculty Presentation 11/20/15 11/20/15
97 9.4.3 Spring Brief 3 3/14/16 3/14/16
102 10.1.2 Proposal Final Report 12/9/15 12/9/15
104 10.2.1 Draft Conference Paper 12/9/15 12/9/15
105 10.2.2 Draft Poster 12/9/15 12/9/15
106 10.2.3 Final Reports and Stuff 11/23/15 12/8/15
76
Schedule
77
Schedule
78
Schedule
79
Cost, Schedule Variance & CPI, SPI
80
Earned Value
Actual cost (ACWP)
Has been above our Earned Value
(BCWP).
Currently below Earned Value.
Planned Value (BCWS)
Has been roughly equal to Earned
Value
Currently below Earned Value
Currently we are under budget
Currently we are ahead of schedule
81
Project Risks
Risk Severity Likelihood Detectability Score Mitigation
Simulation Control Structure is not
done by Nov. 15th (2 weeks behind
schedule) 8 10 1 80
Revert to old model with no control. Manually
adjust voltages in order to get the right distance
and other values needed.
Simulation Testing is Delayed by X
days beyond scheduled due date 10 3 5 150
Do primary analysis of the drone’s effectiveness in
reducing fatalities. Forgo all other simulation
tests until we find time again.
Evaluate life saving device
alternatives is not done, ring buoy
information is wrong 9 3 5 135
Find other life saving devices with accurate
information about them and evaluate them/
Gather accurate information about
force, pitch, roll, yaw, velocity,
height and wind speed 7 4 4 112
Perform the flight experiment again until we get
accurate data. Use pocket money to get program
and tablet that can watch the instruments.
Unable to acquire tools to perform
experiments 10 6 1 60
Use the University’s lab experiments to get the
tools.
82
1. Context
2. Stakeholders
3. Problem/Need Statements
4. Requirements
5. Con-Ops
6. Alternatives
7. Method of Analysis
8. Management
9. Thanks
Special Thanks
Brett Vilcovoch and Brian Yi of Expert Drones
• For the use of one of their drones
Dane Underwood
• For helping us understand lifeguarding
UAS Collision Avoidance System Project Team
• For help understanding FAA regulations
Professor Lance Sherry and Barham Yousefi
• For the guidance in making this project
84
Special Thanks
Professor Peggy Brouse
• For the sweet PowerPoint theme
All our Teachers
• For the knowledge to complete this project
George Mason Faculty and Staff
Fellow Systems Students
85
Sources
EPA, LEARN: Beach Basics, 2015. [Online]. Available: http://www2.epa.gov/beaches/learn-beach-basics. [Accessed: 14- Nov - 2015].
EPA, National List of Beaches, 2015. [Online]. Available: http://ofmpub.epa.gov/apex/beacon2/f?p=117:12:6598228724511::NO::P12_YEARS:Current. [Accessed: 14- Nov - 2015].
American Shore and Beach Preservation Association, New study shows beaches are a key driver of U.S. economy, 2014. [Online]. Available: http://www.asbpa.org/news/Beach_News/080814Houston.pdf. [Accessed: 14- Nov - 2015].
Ocean City Maryland, Town of Ocean City Adopted budget, 2015. [Online]. Available: http://oceancitymd.gov/City_Manager/BudgetBook.pdf. [Accessed: 14- Nov - 2015].
USLA, 'Primary Cause of Rescue at Surf Beaches', 2015. [Online]. Available: http://arc.usla.org/Statistics/Primary-Cause-Analysis.pdf. [Accessed: 18- Oct- 2015].
USLA, 'Statistics', 2015. [Online]. Available: http://arc.usla.org/Statistics/public.asp. [Accessed: 18- Oct- 2015].
National Oceanic and Atmospheric Administration, 'U.S Surf Zone Fatalities 2015', 2015. [Online]. Available: http://www.ripcurrents.noaa.gov/fatalities.shtml. [Accessed: 18- Oct- 2015].
86
Sources cont.
National Oceanic and Atmospheric Administration, 'List of Severe Weather Fatalities', 2015. [Online].
Available: http://www.nws.noaa.gov/om/hazstats/resources/weather_fatalities.pdf. [Accessed: 18-
Oct- 2015].
USLA, About Rip Currents. [Online]. Available: http://www.usla.org/?page=RIPCURRENTS.
[Accessed: 25- Oct- 2015]
http://floridadisaster.org/EMTOOLS/Severe/documents/Rip%20Current%20Brochure.pdf
National Oceanic and Atmospheric Administration, Rip Currents. [Online]. Available:
http://www.ripcurrents.noaa.gov/resources/Final%20Talking%20Points%20and%20Fact%20Sheet_041
707.pdf. [Accessed: 25- Oct- 2015].
National Oceanic and Atmospheric Administraion, Rip Current Science, 2004. [Online]. Available:
http://www.ripcurrents.noaa.gov/science.shtml.[Accessed: 25- Oct- 2015]
https://www.youtube.com/watch?v=d8c7RJx5pBg
NOAA's SciJinks, 'How to Escape Rip Currents', 2015. [Online]. Available:
http://scijinks.jpl.nasa.gov/rip-currents/. [Accessed: 18- Oct- 2015].
87
Sources cont.
V. Gensini and W. Ashley. An examination of rip current fatalities in the United States, August
2009. [Online]. Available:
http://weather.cod.edu/~vgensini/files/pubs/Gensini%20and%20Ashley%202011a%20NH.pdf.
[Accessed: 25- Oct- 2015].
A. Gibiansky, 'Quadcopter Dynamics and Simulation', Andrew.gibiansky.com, 2015. [Online].
Available: http://andrew.gibiansky.com/blog/physics/quadcopter dynamics/. [Accessed: 18- Oct-
2015].
S. Litovich, 'Drowning Information and Drone Considerations', GMU AFS, 2015.
B. Arbin III, 'Lifeguarding Information', 2015.
D. Underwood, 'Lifeguarding Litigation and Insurance', GMU, 2015.
Jimbuoy, ‘Marine Product List’, 2015. [Online].Available: http://www.jimbuoy.com/index.htm.
[Accessed:18- Oct- 2015].
CreateDJI, 'Spreading Wings S900 - Specs | DJI', 2015. [Online].
Available:http://www.dji.com/product/spreading-wings-s900/spec. [Accessed: 24- Sep- 2015].
88
Sources cont.
CreateDJI, 'Inspire 1 - Specs | DJI', 2015. [Online]. Available: http://www.dji.com/product/inspire-
1/spec. [Accessed: 24- Sep- 2015].
CreateDJI, 'Phantom 3 Professional & Advanced - Specs | DJI', 2015. [Online]. Available:
http://www.dji.com/product/phantom-3/spec. [Accessed: 24- Sep- 2015].
CreateDJI, 'Spreading Wings S1000+ - Specs | DJI', 2015. [Online]. Available:
http://www.dji.com/product/spreading-wings-s1000-plus/spec. [Accessed: 24- Sep- 2015].
Store.3drobotics.com, 'X8+ - 3DRobotics Inc', 2015. [Online]. Available:
http://store.3drobotics.com/products/x8-plus. [Accessed: 24- Sep- 2015].
Indeed.com, 'Systems Engineer Entry Salary | Indeed.com', 2015. [Online]. Available:
http://www.indeed.com/salary?q1=Systems+Engineer+Entry&l1=Fairfax. [Accessed: 20- Oct- 2015].
Forensic pathology online, ‘Drowning’, 2013. [Online]. Available:
http://www.forensicpathologyonline.com/E-Book/asphyxia/drowning. [Accessed: 20- Oct- 2015].
89
Drone Component Alternatives: Battery
Source Cost Battery
Mass
(g)
Energy
Output
(mAh)
Volume
(mm^3)
Discharge
Rate
Current
(A) http://www.buildyourowndrone.co.uk
/6s-lipo-battery-10400-mah-35c.html $233.23 Desire Power 10400 1524 10400 744310 35C 182
http://www.buildyourowndrone.co.uk
/6s-lipo-battery-12400-mah-35c.html $302.71 Desire Power 12400 1680 12400 850640 35C 217
http://www.buildyourowndrone.co.uk
/6s-lipo-battery-20000-mah-35c.html $347.74 Desire Power 20000 2492 20000 1177677 25C 500
http://www.buildyourowndrone.co.uk
/6s-lipo-battery-8300-mah-35c.html $186.15 Desire Power 8300 1115 8300 536256 35C 290.5
http://www.buildyourowndrone.co.uk
/6s-lipo-battery-16000-mah-35c.html $360.67 Desire Power 16000 2162 16000 950000 35C 320
http://www.all-battery.com/li-
ion18650222v7800mahrechargeablebat
terypackpcbprotectionwith18awgbarel
eadscustomize.aspx $135.59 AT: Tenergy 866 7800 433620 6
http://smile.amazon.com/gp/product
/B00LF3QJYW?keywords=6s%20LiPo&qi
d=1446401259&ref_=sr_1_3&sr=8-3 $72.32 Turnigy 816.47 5000 589934 20C 100
http://smile.amazon.com/gp/product
/B00USY1FES?keywords=6s%20LiPo&qid
=1446401259&ref_=sr_1_4&sr=8-4 $129.90 Multistar High Capacity 1189 10000 537420 10C 100
http://smile.amazon.com/gp/product
/B0027G87K0?keywords=6s%20LiPo&qid
=1446401259&ref_=sr_1_5&sr=8-5 $87.99 Venom 547 3200 230748 30C 96
http://smile.amazon.com/gp/product
/B00USQY3KO?keywords=6s%20LiPo&qi
d=1446401259&ref_=sr_1_6&sr=8-6 $84.82 Turnigy Heavy Duty 864 5000 421850 60C 300
http://smile.amazon.com/gp/product
/B00QPNXS4Q?keywords=6s%20LiPo&qi
d=1446401259&ref_=sr_1_9&sr=8-9 $109.90 MultiStar 956 8000 438354 10C 80
http://www.batteryspace.com/tattu-
22000mah-6s1p-25c-lipo-battery-pack-
--un38-3-passed.aspx $479.00 Tattu 22000 2630 22000 1177600 25C 550
http://www.batteryspace.com/tattu-
16000mah-6s1p-15c-lipo-battery-pack-
--un38-3-passed.aspx $320.00 Tattu 16000 1932 16000 865800 15C 240
http://www.batteryspace.com/tattu-
12000mah-6s1p-15c-lipo-battery-pack-
--un38-3-passed.aspx $248.00 Tattu 12000 1620 12000 796904 15C 240
http://www.batteryspace.com/custo
m-li-ion-18650-battery-22-2v-13-6ah-
302wh-20a-rate-rechargeable-battery-
pack.aspx $395.50 Custom 18650 13.6Ah 1250 13600 865800 20
http://www.batteryspace.com/custo
m-li-ion-18650-battery-22-2v-10-2ah-
226wh-7a-rate-rechargeable-battery-
pack-18-4.aspx $360.00 Custom 18650 10.2Ah 877 10200 577860.48 7
http://www.batteryspace.com/custo
m-li-ion-18650-battery-pack-22-2v-
17ah-377wh-40a-rate-with-customer-
provide-pcm.aspx $345.50 Custom 18650 17Ah 1900 17000 900900 32
http://www.atomikrc.com/collections
/lipo-batteries/products/venom-45c-
6s-22000mah-22-2v-lipo-battery-for-
dji-s1000-rc-hexacopter $599.99 VENOM 15145 2800 22000 1296000 45C 990
http://www.atomikrc.com/collections
/lipo-batteries/products/venom-30c-
6s-16000mah-22-2v-lipo-high-capacity-
multi-rotor-drone-and-air-battery $379.99 VENOM 15143 2300 16000 1152000 30C 480
http://www.atomikrc.com/collections
/lipo-batteries/products/venom-45c-
6s-16000mah-22-2v-lipo-high-capacity-
multi-rotor-drone-and-air-battery $429.99 VENOM 15144 2300 16000 1048320 45C 720
http://www.atomikrc.com/collections
/lipo-batteries/products/dji-
spreading-wings-s1000-rc-drone-30c-
6s-12000mah-22-2v-lipo-battery-by-
venom $329.99 VENOM 15142 1716 12000 864000 30C 360
y = 7.6183x + 352.76 R² = 0.9051
0
5000
10000
15000
20000
25000
0 500 1000 1500 2000 2500 3000
Ener
gy O
utp
ut
(mA
h)
Mass (g)
Battery Mass V. Energy Output
y = 0.0173x - 1068.1 R² = 0.8908
0
5000
10000
15000
20000
25000
0 200000 400000 600000 800000 1000000 1200000 1400000
Ener
gy O
utp
ut
(mA
h)
Volume (mm^3)
Battery Volume V. Energy Output
90
Gap
60 93
Fighting
Against
Current
Lifeguard
Reach Time
Time (s)
Max Victim Survival Time
*not in scale
91
Table of Inputs/ Outputs Simulation Table
Inputs (Random) Outputs Baseline Historic
Rip
Current
Speed
Rip
Current
Length
Rip
Current
Width
Rip
Curren
t Y-
Positio
n
Victim
Escape
Method
Base
Hex
Reach
Time
Base Octo
Reach
Time
Octo 2-ring
Reach
Time
Lifeguard
only reach
time
Victim
Survival Time
USLA Data on
Fatalities/Rescu
es
… … … … … … … … … …
Repeat above for X reps, until %Saved σ <
10%
Result
s: -> %
Saved
% Saved %Saved %Saved
without
drone
%Saved
Inputs for Alternatives Analysis (1 at a
time) (same reps as before? Or less reps?)
Outputs (add time to reach as well?)
Location Battery Type Motor Types Base Hex % Saved Base Octo % Saved Octo 2-ring
% Saved
3 locations Use battery
equation
Use motor
equations
Use Grouping for lower sigma count for % saved
92
Inputs Outputs
Drone Properties and
Base Weight
Added Payload Maneuvers Power Needed to Maintain
Maneuver
Base Hexacopter 1kg Hover
Const. Velo. Lv. Flight
Accelerating Lv. Flight
3kg Hover
Const. Velo. Lv. Flight
Accelerating Lv. Flight
Base Octocopter 1kg Hover
Const. Velo. Lv. Flight
Accelerating Lv. Flight
3kg Hover
Const. Velo. Lv. Flight
Accelerating Lv. Flight
Design Space for Weight and Power DoE
93
Location DoE
Inputs Outputs
Drone Location Random:
1. Rip position
2. Victim speed
3. Rip length
4. Identified
Victim
Drone
Velocity
% reached
within 30
sceonds
% reached
within 60
seconds
% reached
within 90
seconds
Base
Hexacopter
Location A
(Main Control
Room)
20 reps 12m/s
10m/s
Location B
(Lifeguard
Tower)
20 reps 12m/s
10m/s
Location C
(On a Rescue
ship)
20 reps 12m/s
10m/s
94
Prelim. Cost Model
95
Lifecycle Cost (2yrs)
System Acquisition Cost
Drone Platform
Camera System
Tether Release System
Tether
Environment Protection Equipment
Battery Acquisition
Location Setup
User manual/Training
Operations and Support Cost
Annual Repair Cost
Annual Maintenance Cost
Annual Battery Recharging Cost
Controller’s salary
Disposal Cost
Prelim Utility Function
ETSu ERTs
S = percent lives saved (%)
TR = mean time to reach victim (sec)
E = mean battery energy usage per rescue (kWh/Rescue)
96
Victim/LG/Rip Current Distributions
Victim Escape
Victim Survival
Rip Current Properties
• Speed ~ Unif(1,8)ft/s
• Length ~ Unif(100,1000)ft
• Width ~ Unif(10,200)ft
• Position
– Guarded ~ Uniform(0,250)ft
– Unguarded ~ 250+Expo(250)ft
165.0,
65.04.0,
4.00,
)(
)1,0(
xparallel
xfloat
xfight
xescape
uniformx
parallelescapeTBATBA
floatescape
fightescapeTBA
escapevictVelo
],,[
],0,0[
],0,[
)(
97
BACKUP SLIDES
ROPE
98
Rope Interactions
Assuming rope is tense and straight.
Tension = (rope weight per meter) * (length of rope)
Rope Drag = Tension * cos(α)
Rope Torque = radiusbody * sin(α) * Tension
α
99
Catenary Rope
If rope is slack, use catenary equations to solve for rope
form and tension.
[1] Dredgingengineering.com, 'Asymmetric Catenary Cable', 2015. [Online]. Available:
http://www.dredgingengineering.com/moorings/catenarya/asymetrische%20afleiding%20goed.htm. [Accessed:
13- Aug- 2015].
S = arc length of rope
d = height difference between ends
L = horizontal distance between ends
T0 = horizontal tension force on drone
µ = weight per length of rope (weight density)
• µ = mass*acceleration of gravity / total length
T1 = vertical tension force on drone
s = length of rope between lowest point and the end (NOT total length)
Equation 1: general form of catenary line
Equation 2: definition of a
Equation 3: definition of λ (helpful variable, no meaning)
Equation 4: A identity used to calculate T0
George Mason University LALVDS Project Team Briefing 4
/.2
)/cosh(*)(.1
0Ta
axaxf
sT
LdS
TL
*.5
/)(/).(sinh4
)2/(.3
1
222
0
100
Removing Homepoint Tether from Simulation?
On Amazon, a 5mm assessory cord over 100m (~300ft) is 1.84kg. • 7mm assessory cord over 100m is 3.02kg.
• 8.8mm hiking cord over 100m is 4.82kg.
• 9mm climbing rope over 100m is 6.3kg.
100m = 328ft (rip currents can be hundreds of feet)
Hexacopter max lift = 5kg • Octocopter max lift = 9kg
Conclusion: A drone lifting a tether from the homepoint to the drone is under heavy weight. Possibly unable to deliver a life ring. • Simulation results soon…
http://www.amazon.com/BlueWater-Ropes-Titan-Cord-Dyneema/dp/B00BCLK5CY/ref=sr_1_2?s=outdoor-
recreation&ie=UTF8&qid=1445629411&sr=1-2&refinements=p_n_feature_keywords_two_browse-bin%3A7046718011
http://www.amazon.com/Bluewater-7MM-Accessory-Cord-Red/dp/B0011W49HQ/ref=sr_1_5?s=outdoor-recreation&ie=UTF8&qid=1445629411&sr=1-
5&refinements=p_n_feature_keywords_two_browse-bin%3A7046718011
http://www.amazon.com/Sterling-Rope-Evolution-Duetto-Orange/dp/B004MXAFNS/ref=sr_1_1?s=outdoor-
recreation&ie=UTF8&qid=1445629001&sr=1-1&refinements=p_n_feature_keywords_two_browse-bin%3A7046718011
http://www.amazon.com/CAMTOA-Climbing-Survival-Downhill-Utility/dp/B014XUBYN4/ref=sr_1_11?s=outdoor-
recreation&ie=UTF8&qid=1445629133&sr=1-11&keywords=rope+4mm
101
BACKUP SLIDES
Drowning
102
Drowning
Primary Drowning (Dry Drowning)
Water reaches airway
• coughs or swallows water
Water goes to lower airways
• the throat spasms
• lungs are sealed
• Water accumulates in stomach
Large amounts of panic
• rapid movements
(sources?)
Secondary Drowning (Pulmonary Edema)
Person becomes unconscious
• throat relaxes
• allows water to flow into the lungs
Body accumulates Carbon dioxide
• stimulates to feel the need to breathe
• involuntarily draws in breath
(note, I'm not sure I got the content
in the right places) 103
Drowning
Active Drowning
Stage just before submersion
Will go under water in less than a
minute
Kicking, waving and squirming for
help
Head thrown back with face
upward
(Sources?)
Passive Drowning
Unconsciousness
Motionless
Victim floats face down
Hyperventilation
104
BACKUP SLIDES
DOE 105
DJI Spreading Wings S900
Takeoff Weight 4.7Kg ~ 8.2Kg
Total Weight 3.3Kg
Hover Time 18min • @12000mAh& 6.8Kg Takeoff
Weight
Diagonal Wheelbase 900mm
Rotor • Size 15×5.2inch
• Weight 13g
http://www.dji.com/product/spreading-wings-s900/spec
106
Horizontal Component of Drag Force
The forces at a constant velocity.
The force of gravity • Pulling the drone down.
The force of drag • Resisting forward motion.
The force of thrust • Decomposed into:
– Force of lift
• Counters gravity
– Force of forward
• Counters drag.
Decompose
Force of Drag Force of Drag
Gravity Gravity
Force of
thrust
Force of
Lift
Force of going
in the forward
direction
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Horizontal Component of Drag Force
Coefficient of drag can be found by knowing:
•The force of drag – can be found by:
• The angle to recompose lift into forward motion
– the pitch/roll of the drone
•the density of the air
•The speed of the drone(wind relative to drone)
•The area of the projection orthogonal to the drone
Coefficient of drag:
𝐶𝐷 =2 ∗ 𝐹𝐷
𝜌 ∗ 𝑣2 ∗ 𝐴
Force of Drag:
𝐹𝐷 = 𝑚 ∗ 𝑎 − 𝑔 ∗ tan 𝑝𝑖𝑡𝑐ℎ
108
Vertical Component of Drag Force
Drone Maintains no
horizontal movement
Maintains a constant vertical
velocity
h
Later
109
Vertical Component of Drag Force
By conservation of energy:
• The potential energy of the
drone = the kinetic energy of
the drone – the losses due to
friction of the air(drag)
With the force of drag the
coefficient can be found same
as previous.
Conservation of energy
𝑚 ∗ 𝑔 ∗= 12 ∗ 𝑚 ∗ 𝑣2 +𝐹𝐷 ∗ ℎ
Coefficient of drag:
𝐶𝐷 =2 ∗ 𝐹𝐷
𝜌 ∗ 𝑣2 ∗ 𝐴
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111
112
Goal
To simulate the DC electric motors of the S900 we need to determine:
• Torque-Speed curve
• Power-Speed curve
• Torque-Current curve
The curves will be used to find:
• No load current
• Torque constant
• Torque to thrust constant
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Torque-Current Curve
No load current
• Point on the torque current curve
– Where torque = 0
– Not equal to zero
Motor torque constant
• Slope of the torque-current curve
http://www.me.umn.edu/courses/me2011/arduino/techno
tes/dcmotors/motor-tutorial/
114
Torque-Speed & Power-Speed Curves
Motor torque to thrust constant
𝐾𝜏 =𝜏𝑇 ,
Relates: • Output power of the motor (P)
– Power-Speed curve
• To the torque of the motor (𝜏) – Torque-Speed curve
http://lancet.mit.edu/motors/motors3.html#torque
3
1
22 ]2
[ PDT
115
Torque-Speed Curve
http://lancet.mit.edu/motors/motors3.html#torque
116
Procedure
1. Apply Fixed Voltage to motor
• Not to exceed motor rated voltage
2. Run motor unloaded
• Record RPM
– Torque-Speed curve
• Record current
– Torque-Current curve
http://www.micromo.com/technical-library/dc-
motor-tutorials/motor-calculations
3. Apply torque to stall
• Record torque
– Torque-Speed curve
– Torque-Current curve
• Record current
– Torque-Current curve
4. Measure terminal resistance
5. Repeat for additional voltages
117
Equipment Needed
Adjustable voltage supply
Ammeter
• Current probe
Ohm meter
Adjustable Torque brake
• Small particle brake
Non contact tachometer
• strobe
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