ROBOTIC BOAT

PRESENTER: JACLYN TARNAI, GRAHAM WILLIAMSON , DAVID WONG, YIRAN ZHOU

PRESENTATION FORMAT

1. Introduction and Background

2. Identify Needs and Set Specifications

3. Generate, Evaluate and Select Concept

4. Critical Function Prototype

5. Design in Detail

6. Validation of Design

7. Construction Process

8. Final Prototype Testing

9. Final Specifications and Recommendations

INTRODUCTION AND

BACKGROUND

ABOUT UBC

University located in

British Columbia (45

mins away)

Consistently ranked

among the 40 best

universities in the

world

ABOUT THE CAPSTONE COURSE

A 2-term, 6 credit course

for mechanical engineering

students in their senior

year

Required for graduation

Problems are proposed by

industry clients, and

students design a solution

BACKGROUND OF THE PROJECT

• Stratus Aeronautics designs UAVs

for aerial mapping applications

• Geophysical mapping (local

magnetic field)

• Light Detection And Ranging

terrain mapping

• Would like to enhance existing

mapping solution with bathymetry

PRIMARY FUNCTION

Bathymetry survey

Example of Bathymetry Survey Post Analysis

Note: Alberto Romani and Pierluigi Duranti(2012), "Autonomous Unmanned Surface Vessels for Hydrographic Measurement and

Environmental Monitoring"

DATA COLLECTION PROCESS

Example of a Mow the Lawn Path

Note: Christopher Kitts, Paul Mahacek, Thomas Adamek, Ketan Rasal, Vincent Howard, Steve Li, Alexi Badaoui, William Kirkwood, Geoffrey

Wheat and Sam Hulme (2012), "Field operation of a robotic small waterplane area twin hull boat for shallow-water bathymetric

characterization”

BENCHMARKING OF EXISTING ALTERNATIVES

YSI EcoMapper (AUV) Kingfisher USV by Clearpath Robotics

Long operating time (8-14 hrs)

Can be carried (45kg)

Expensive ($50,000)

Small measuring depth (100m)

Can fit in helicopter/truck

Easily carried (28kg)

Expensive ($50,000)

Low operating time (2.5 hrs)

IDENTIFY NEEDS AND SET

SPECIFICATIONS

PRIMARY REQUIREMENTS

FUNCTION DECOMPOSITION

Determinative functions:

1. Maintain device on top of water

2. Increase speed of device relative to water

3. Change orientation of device relative to water

4. Prepare device for transport

5. Decrease speed of device relative to water

6. Support components relative to device

7. Identify position of device relative to surrounding

8. Send and receive data from device to shore

9. Protect electronics from water contact

Non-determinative functions:

Store power in device

Modify power stored in device

Display information to user

Receive control parameters from user to device

Generate route device’s current position to destination position

Notify user of device’s hazardous situation

Monitor device’s status

Correct device’s current position relative to desired position

Return device to “home” position

Store “home” position in device

Store sensor data in device

GENERATE, EVALUATE, AND SELECT

CONCEPTS

EVALUATION PROCESS

Winnowing

Needs and Requirements (Thresholds)

Feasibility

Technical Readiness

Ranking(Pugh Chart)

Scoring

Weighted Decision Matrix (with AHP weightings )

Value Equations

WINNOWING

F1 Maintain device on top of water

• Dual outrigger floats

• Tupperware boat

• Partially inflated hull

• Catamaran

• Hovercraft

• Semi-submersible

• Inflatable float

• Single hull

• Raft

• Hydrofoils

• AUV

F2 Increase speed of device relative to

water

• Thruster(s)

• Impeller water jet

• Ducted fan

• Shafted propeller through hull

• Water wheels

• Air propeller

• Variable pitch propeller

• Sail

F3 Change orientation of

device relative to water

• Rudder

• Variable direction propulsion

• Differential propulsion

• Lateral propulsion

• Air rudder

• Shifting CG

F4 Prepare device for transport

• Folding floatation device

• Removable parts

• Pivoting floatation device on rail tracks

• Sliding with positioning

• Partially hollow floatation device

F5 Decrease speed of device relative to

water

• Regular drag

• Reverse propulsion

• Air brakes

• Water brakes

• Rudder braking

WINNOWING

F6 Support components relative to device

• Enclosure attachment

• Components inside floatation device

• Tow

• Bonded to vibration absorber

• Fixed to suspension platform

• Bonded to floatation device

• Suspended in air

• Suspended between hull(s)

F7 Identify position of device relative to

surrounding

• GPS

• Home reference (DGPS)

• Transmission latency

• Compass + math model

• Sonar sensor(s)

• Camera

• Wire/cord

• Signal tracking

• Flare tracking

• Drone

• Visually tracked from shore (laser)

• Inertia sensor

F8 Send and receive data from device to shore

• Antenna tower

• Omnidirectional antenna

• Balloon antenna

• Relay

• Transmit to third party

• Wired (no transmitting)

• Laser

• Sound transmission

• Wi-Fi

F9 Protect electronics from water contact

• Waterproof enclosure

• Waterproof spray

• Umbrella

SCREENING

(PUGH CHART)

CRITERIA

Concept

#1

Concept

#2

Concept

#3

Concept

#4

Concept

#5 Example Justifications

Concept

#6

Concept

#7

Concept

#8

Cost 0 -1 -1 1 0 -1 -1 -1

Transport-

ation Size 0 -1 1 -1 1

Inflated hull significantly shortens

the length of boat and allows

folding -1 0 -1

Endurance 0 -1 -1 0 -1

Inflated hull creates additional

water resistance compared to

streamlined hull 0 -1 -1

Robustness 0 -1 0 1 -1

Partially inflated hull may need

more maintenance than rigid hull 0 1 0

Weight 0 1 -1 -1 1

Weight of hull and simpler

shafted propellor are lighter 0 -1 -1

Controll-

ability 0 1 -1 0 -1

inflated hull lowers the

predictive behavior of device -1 1 -1

sum 1's 0 2 1 2 2 0 2 0

sum -1's 0 4 4 2 3 3 3 5

sum 0's 6 0 1 2 1 3 1 1

overall rating 0 -2 -3 0 -1 -3 -1 -5

rank 1 5 6 1 3 6 3 8

CONCEPT #1

Tupperware Boat -Thrusters - Rudder - Folding - Reverse Propulsion - Mechanical Attachment

- DGPS - Antenna Tower - Waterproof Enclosure

CONCEPT #4

Catamaran Dual Outrigger Float - Thrusters - Rudder - Removable - Regular Drag -

Mechanical Attachment - GPS - Antenna Tower - Waterproof Enclosure

CONCEPT #5

Catamaran Partially Inflated Hull - Shafted Propeller - Rudder - Folding - Rudder Braking -

Vibration Absorber - DGPS - Omnidirectional Antenna - Waterproof Enclosure

Folding hinge

Cross section

CONCEPT #7

Semi-submersible (catamaran style) - Impeller Waterjet - Differential Thrust - Sliding with

Positioning - Regular Drag - Fixed to Suspension Platform - GPS - Antenna Tower -Waterproof

Enclosure

EVALUATION STRATEGY

Weight

6%Transportation size

9%

Endurance

15%

Controllability

16%

Robustness

17%

Cost

37%

0

50

100

0 500 1000 1500

Sat

isfa

ctio

n (%

)

Cost ($)

Customer Satisfaction % vs Cost of Robotic Boat

CRITICAL FUNCTION PROTOTYPING

CRITICAL FUNCTION

FUNCTION: Correct device's current position relative to desired position.

Will the Pixhawk autopilot be able to correct the devices position accurately after a

disturbance?

Actual Path

Disturbance

Desired Path

Acce

pta

ble

devia

tion

Image from https://www.youtube.com/watch?v=4Y7zG48uHRo

RATIONAL FOR CFP

Three main categories in the project:

Mechanical Design: Well-developed with existing solutions

Data Collection: Scope is limited to researching, selecting, and integrating sensor

Autonomous Navigation System: Integration is complex

Autopilot importance:

Most complex feature

Significant project cost and lead time

Lack of team familiarity

WHICH CONCEPT WILL BE TESTED ?

Tupperware boat

Thruster(s)

Rudder(s)

Regular Drag

WHAT WAS USED FOR TESTING?

Pixhawk Autopilot

Autopilot suggested by client

GPS ublox LEA-6 w/compass

Provided for Testing

More accurate Swift or Novatel GPS for project

Image from http://www.robotshop.com/ca/en/3dr-px4-pixhawk-advanced-autopilot.html

http://www.robotshop.com/ca/en/3dr-gps-module-ublox-lea-6-compass.html

EXECUTION OF CRITICAL FUNCTION PROTOTYPE

MAPPING OF FEATURES OF CFP TO

VERIFICATION CRITERIA

Hovercraft CFP Features

Rudder system

Throttle controlled thruster

Operating in fluid

GPS waypoint navigation

CFP BUILD QUALITY

Cost (“small expenditure” = $30)

Limited time & budget available

Material used

Material available at-hand

Robust

Used for 2 days w/o significant wear

Consistent performance

Re-usable for further testing

PID tuning and path testing

Electrical connections must be

temporary

TYPICAL SCENARIO

Positional Shift of the boat

Ref: http://ngm.nationalgeographic.com/u/TvyamNb-

BivtNwcoxtkc5xGBuGkIMh_nj4UJHQKuorle-82rIjPED3j1K-

sgp7vZ4QwrDy0gkuBKjQ/

Angular Shift of the boat

Top View:

Top View:

ASSUMPTION FOR SCENARIO

Positional Shift of Hovercraft

Angular Shift of Hovercraft

6ft

3ft

-3ft

ASSUMPTIONS

Behavior of the hovercraft is comparable to a boat

Autopilot behavior using current GPS is comparable to a more accurate GPS

PID for hovercraft is not usable as PID for boat

More time will be spent to tune PID for boat

LIMITATIONS

Hovercraft is a different system

Less friction from air therefore less damping

More prone to skidding/drifting

Smaller scale

PID control is not perfectly tuned

Testing conditions

Minor slopes/debris on ground

Accurate GPS for final prototype is not available during CFP stage

- Slight drifting of GPS is expected

RESULTS

-4

-3

-2

-1

0

1

2

3

4

-5 0 5 10 15 20 25

Devi

atio

n (

m)

Distance from starting point (m)

Deviation of various offsets

Control

-3 ft position offset

-6 ft position offset

3 ft position offset

15 deg offset

30 deg offset

45 deg offset

60 deg offset

RESULTS

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

0 5 10 15 20 25

Devi

atio

n (

m)

Distance from starting point (m)

Deviation of various offsets with drift corrected

Control

-3 ft position offset

-6 ft position offset

3 ft position offset

15 deg offset

30 deg offset

45 deg offset

60 deg offset

CONCLUSION OF RESULTS

Met verification criteria within limitations

30 deg. & -6ft results were influenced by testing environment

Pixhawk autopilot is suitable

Responsiveness can be improved with further PID tuning

Drift shows that improved accuracy of DGPS is worthwhile

RESULTS/LESSONS LEARNED

Result

Autopilot will work for the final prototype

Lessons Learned

PID controller tuning

Start with suggested PID control parameters for boats

Autopilot has not been used extensively with hovercraft

Procedure to analyze GPS data

DESIGN IN DETAILDESIGNING THE HULL

CALCULATION PARAMETERS

EXAMPLE CALCULATIONS

HULL OPTIMIZATION

Plotted various parameters as a function of hull length and hull width

Draught

Drag force

Max speed

Stability

Endurance

Final dimensions:

Length – 2m

Width – 18cm

Draught – 9.4cm

Center-to-center distance of hulls – 1m

612

1824

3036

4248

5460

0

1

2

3

4

5

6

7

8

9

1 1.2 1.4 1.6 1.8 2 2.2

HU

LL W

IDT

H (C

M)

MA

X S

PEED

(K

M/H

)

HULL LENGTH (M)

MAX SPEED

0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9

STABILITY CALCULATIONS

𝐼𝑇𝑟𝑎𝑛𝑠𝑣𝑒𝑟𝑠𝑒 = 2 ∗ (𝐿𝑒𝑛𝑔𝑡ℎ ∗𝑊𝑖𝑑𝑡ℎ3

12+ 𝐴 ∗ 𝑑2)

𝐵𝑀 =𝐼𝑇𝑟𝑎𝑛𝑠𝑣𝑒𝑟𝑠𝑒

𝑊𝑒𝑖𝑔ℎ𝑡

KG = Draught

KB = Draught / 2

𝐺𝑀 = 𝐵𝑀 + 𝐾𝐵 − 𝐾𝐺 = 1.8𝑚

Longitudinal Static StabilityTransverse Static Stability

𝐼𝐿𝑜𝑛𝑔𝑖𝑡𝑢𝑑𝑖𝑛𝑎𝑙 = 2 ∗ (𝑊𝑖𝑑𝑡ℎ∗𝐿𝑒𝑛𝑔𝑡ℎ3

12+ 𝐴 ∗ 𝑑2)

𝐵𝑀 =𝐼𝐿𝑜𝑛𝑔𝑖𝑡𝑢𝑑𝑖𝑛𝑎𝑙

𝑊𝑒𝑖𝑔ℎ𝑡KG = DraughtKB = Draught / 2

𝐺𝑀𝐿𝑜𝑛𝑔𝑖𝑡𝑢𝑑𝑖𝑛𝑎𝑙 = 𝐵𝑀 + 𝐾𝐵 − 𝐾𝐺 = 3.04𝑚

HULL DESIGN

Recommendation from Client

– simple hull to limit manufacturing time

Approx. Length = 2m

Polystyrene and Fiberglass Hull

Construction

STRESS CALCULATIONS

CALCULATED PERFORMANCE

Assumptions

Weight = 45.04kg

Drag Coefficient = 1.2

Batteries: 1x90Ah at 12V

Overhead Power Loss=50W

Performance

Dimensions of device below surface:

approx. 2m x 18cm x 8.5cm per hull,

center-to-center spacing =1m

Max. speed: 6.6 km/hr (3.56 Knots)

Battery life: 3.2 hr

VALIDATION AND VERIFICATION

¼ SCALE MODEL VERIFICATION

Tested at scale speed:

0.83m/s, survey speed

1.25m/s, mid speed

1.67m/s, top speed

Tested with:

1/4 scale sensor

Sensor fairing

Reduced weight

FLUME TESTING

Scale Model

DAQ System

Pulley

Tank

FLUME TESTING

Include Video/GIF

RESULTS

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7

Dra

g Fo

rce (

N)

Scale Speed (m/s)

Model Drag Force

No Load

Sensor

Fairing

Light Model

RESULTS

Average Drag CoefficientNo Load 0.719Sensor 0.603Fairing 0.324Light Model (-14.3%) 0.335

MAPPING TO EVALUATION CRITERIA

Cost

24%

Manufacturability

22%

Robustness

8%

Weight

2%

Endurance

6%

Controllability

9%

Stability

29%

APPROPRIATENESS OF EVALUATION CRITERIA

Manufacturability and cost reflects the design of the boat hulls

Hand calculations were done for speed, endurance, stability, and robustness

The hand calculation results show that the design was barely meeting the minimum requirements for

speed and endurance, so a physical scale testing needs to be done

As well, the sonar may pose significant drag force due to its geometry, so a comparison

between the sensor and sensor with fairing was needed.

DESIGN FEATURES MAPPED TO EVALUATION CRITERIA

• Cost(24%)

• $193.03 for hulls

• Manufacturability(22%)

• Straight edges, no curves

• Stability(29%)

• Catamaran design(horizontal)

• Maximized water-plane

area(longitudinal)

• Lowered CG with batteries

stored in hull

CONCLUSION

Our hand calculations are valid

Further improvements to design:

Decrease weight

Swap lead-acid battery for lighter alternative

Round off edges

CONSTRUCTION PROCESS

CONSTRUCTION PROCESS

Template for hull shape

Template for front hull shape

CONSTRUCTION PROCESS

Layout of foam layouts

Hot wire cutting for hull shape& battery compartment

CONSTRUCTION PROCESS

Plywood hard points for attaching fasteners onto hull

Made into shape for battery hatches

CONSTRUCTION PROCESS

Fiberglass layer on top of foams (fiber, epoxy, paint)

Reapplication of epoxy at corners

CONSTRUCTION PROCESS

Handles for carrying

CONSTRUCTION PROCESS

Two 2” x 2” x 1.32m horizontal struts for connecting hulls

Two 1” x 1” vertical struts for motor mounts

CONSTRUCTION PROCESS

Mounting L brackets for motor

Waterjet cut from aluminum sheet

CONSTRUCTION PROCESS

Fabrication of power system

Glands and gaskets used for waterproofing

CONSTRUCTION PROCESS

Fabrication of Pelican case, Power electronics,

signal processing and telemetry

CONSTRUCTION PROCESS

Mounting brackets for pelican case

Connection of power and signal to rudder & thrusters

FINAL PROTOTYPE TESTING

FINAL PROTOTYPE TESTING

Location: UBC Fountain

Verified stability at 7s oscillation from impulse

Verified water line at 46kg weight

Verified maneuverability requiring < 10 lbf to turn boat

FINAL PROTOTYPE TESTING

Location: Alta Lake, Whistler

Validated onsite assembly and transportation

Verified Maximum speed (7.9kph)

Less than desired, space to improve

Verified Turning Radius (1.73m)

Lessons Learned:

Need improvements on compass interference

Need improvements on control thresholds

FINAL PROTOTYPE TESTING

Location: Como Lake, Coquitlam

Successful collection of sonar data

Further PID tuning required to follow

generated path

TESTING VIDEO

FINAL SPECIFICATIONS AND

RECOMMENDATIONS

FINAL SPECIFICATIONS

Maximum Speed : 2.2 m/s (7.9kph)

Turning Radius: 1.73m

Survey Depth: 150m

Weight: 44.4 kg

Dimension: 2000mm (L) x 1180(W) x 1450 (H)

Hull Dimension: 2000mm (L) x 180mm (W) x 300mm (H)

Draught (waterline): 94mm

Material: Polystyrene Foam, Fiberglass, Plywood, Aluminum 6068 T6, Stainless

Steel 316, Polypropylene and Mild Steel

Battery Capacity: 5s x 60Ah for Boat (LiFe) & 2 x 4s x 3Ah for Sensor (LiPo)

Operation Time: 10.7h (Boat) & 2h (Sensor)

REPLACE STIFF ELECTRICAL WIRE

Stiff Wire Flexible Wire

CONTINUE TUNING AUTOPILOT

REDUCE BOAT WEIGHT

Final weight: 44.4kg

Max weight: 46.0kg

Platform weight: 7.9kg

OPERATE USING 6 BATTERIES INSTEAD OF 5

Battery Specifications

60Ah capacity

Min: 2.5V, Nom: 3.2V, Max: 3.65V

Thruster max: 6-20V

> 16V – performance unknown

15V – 21.9V range

< 20V = <3.33V per battery

LOWER THRUSTERS DEEPER INTO WATER

Observed water splashing

Improve efficiency

ADD TELEMETRY CONNECTION TO NUC

Pelican Case with NUC GPS and Heave Data for NUC

INCREASE SENSOR BATTERY CAPACITY

Current capacity: 2 x 4S LiPo

3Ah each = 6Ah total

Operating time = 2hr

REPLACE 3D PRINTED RUDDER

3D Printed Design Final 3D Printed Part

REPLACE ALL NON-STAINLESS FASTENERS

Some steel bolts and screws were included

Due to time constraints

Replace with 18-8 stainless steel equivalent

REPLACE GLANDS WITH CONNECTORS

Waterproof Cable Glands Military Grade Connectors

QUESTIONS?

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