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Systems Design Review P15044 Intelligent Mobility Cane Allan Andranikian Marisa Ashour Dan Chianucci Andrew Greeley Justine Nichols Ben Stewart
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Agenda • Project Overview
• Project Background • Deliverables • Customer Requirements • Engineering Requirements • House of Quality
• Functional Analysis • Functional Decomposition • Function-Requirement Mapping • Functional Architecture
• Research • Benchmarking • Background Research
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• System Analysis • Morphological Table • Preliminary Concepts • Concept Selection Process • Pugh Charts • System Architecture • Morphological Elimination • Power Feasibility • Weight Feasibility
• Risks and Next Steps • Test Plan • Risk Analysis • Risk Management • 3 Week Plan • Action Items • Lessons Learned
Project Background • A ‘Smart Cane’ is a device
that is designed to improve the usage of a mobility cane by the visually impaired.
• Our team aims to build an Intelligent Mobility Cane that detects obstacles and drop offs in front of the user and provides haptic (vibrational) feedback while being low-cost.
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Deliverables
• A prototype that fulfills all Customer Requirements
• User’s Guide for the prototype • Engineering documentation for the
reproduction of the prototype (Bill of Materials, Test Plan, etc.)
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Customer Requirements Customer Rqmt. # Importance Description
C1 3 Accurately detects overhangs, obstacles, and walls
C2 3Accurately detects drop offs in front of the cane through a
swept arc
C3 3 Adequate detection range
C4 3 Haptic feedback
C5 3 Low manufacturing cost
C6 2 Easy user assembly
C7 2 Lightweight
C8 2 Long battery life
C9 2 Ergonomically designed for the average American male
C10 1 Rechargeable
C11 1 Cane collapses for easy storage
IMPORTANCE
LEGEND
HIGH 3
MEDIUM 2
LOW 1
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Engineering Requirements rqmt. # Importance Source Function Engr. Requirement (metric) Unit of Measure
Minimum
Value
Target
Value
Maximum
Value
S1 3 C1 Detection Differentiates between obstacles, overhangs, and walls yes/no
S2 3 C1 Detection Response time seconds 0 0.25 1
S3 3 C1 Detection
Percentage of false negatives/positives (accuracy of
detection) % 0 5 10
S4 3 C2 DetectionDetects drop offs in front of the cane through a swept
arcyes/no
S5 3 C3 Detection Detection range (length) feet 6 7 13
S6 3 C3 Detection Detection angle/arc (at maximum length) degrees (°) 2 3 3
S7 3 C4 Feedback Percentage of feedback correctly interpreted by user % 80 90 100
S8 3 C5 Fabrication Materials cost $ 0 125 125
S9 2 C6 Use User assembly time seconds 30 60 90
S10 2 C7 Fabrication
Maximum weight of feedback and detection
components ounces 4 4 16
S11 2 C8 Battery Battery life hours 8 8 /
S12 2 C9
Dimension
s Cane length (when in use) centimeters 129 134 139
S13 2 C9
Dimension
s Cane handle circumference centimeters 10.8 11.4 12
S14 1 C10 Battery Battery recharge cycle hours 2 2 3
S15 1 C11 Storage Cane length (when collapsed) centimeters 0 20 20
S16 1 C11 Storage Cane width (when collapsed) centimeters 0 20 20
yes
yes
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IMPORTANCE LEGEND
HIGH 3
MEDIUM 2
LOW 1
House of Quality P
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Major Takeaway from House of Quality: The deflection angle arc is the most important engineering requirement, as it maps to all of the critical customer requirements.
Functional Decomposition P
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Constraints: •
Function – Requirement Map Function Customer Requirement Engineering Requirement
Enable navigation of the external environment ALL ALL
Differentiate between different types of obstacles C1,C2 S1, S4
Detect obstacles C2, C3 S2, S3, S4, S5, S6
Provide feedback C4 S7
Provide ability to use and store cane C6, C7, C8, C9, C10, C11 S9, S10, S11, S12, S13, S14, S15, S16
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Functional Architecture P
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The cane will be split into multiple subsystems:
• Power Distribution: Provides power and
recharges the battery
• Detection: Senses obstacles and drop offs.
• Processing: Interprets sensors and determines the correct feedback
• Feedback: Produces the vibration felt by the user
• Enclosure: Secures other subsystems in place
Cane Benchmarking Brand Ambutech Drive Medical ILA NFB Revolution WCIB
Model GG3040W-90-4 10352-1 MIN100 8498(inches) #REV-4 #WCPB
Seller Ambutech Medihub USA/ Amazon Independent Living Independent Living Independent Living Independent Living
Diameter .5 inch .5 inch Not Listed .25 inch Not Listed Not listed
Lengths 36"-60" (in 2 " inc) OR 90-150 cm( in 5 cm
inc) 46 1/4 inches 48" 32"- 61"(2 in inc) 36"-44" (2 in inc) 26"-60" (2 in inc)
Cost 18 + $10 SH + $2 TX= $30 $13.89+ FREE SH+ $2 TX=
$15.89 $39.95 +FREE SH+ $2 TX=
$41.95 $25 + FREE SH+ $2 TX= $27
$36.95+ FREE SH+ $2 TX= $38.95
$24.95+FREE SH + $2TX= $26.95
Weight Not Listed .18 lbs Not Listed Not Listed Not Listed Not listed
Material Aluminum Aluminum Carbon Fiber Fiberglass Graphite Aluminum
Shipment Location Winnipeg, MB Canada Crosby Texas, US Buffalo, NY US Buffalo, NY US Buffalo, NY US Buffalo, NY US
Collapsibility 4 different section selections 4 sections Telescoping to 8.75" NO 4 Sections NO
Features Tight Fitting Joints,
Hook and Slip on Tips Available Comes w/strap,
tape for night visibility Fits in backback, Travel
size Durable Flexible, Rubber Handle
Straight or Curved Handle, Long life
Tip Material Several Different Choices Available Nylon Nylon Carbon Fiber Long Life Polymer Nylon
Color 12 colors available Red White/black Silver/black Red/White/Black Silver/Black/Red
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Sensor Type Benchmarking
Parameter IR sensor Ultrasonic sensor (transducer) Laser sensor
light type infrared n/a laser (visible spectrum)
light frequency 300 GHz - 430 THz n/a 430 - 790 THz
sound frequency n/a >20 kHz n/a
typical maximum range 5+ ft 10+ ft 100+ ft.
typical average cost $5-$20 $25+ $50+
expected interference can be influenced by indirect and direct sunlight can be influenced by the reversing sensors in
some cars and other sensors
can be influenced by light of a similar wavelength, which is
common.
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IR Transmitter Benchmarking Parameter IR Distance Sensor (TX + RX) IR emitter (TX only)
Typical Drive Current (mA) 30 Anywhere between 50 and 500
Supply voltage (V) 4.5 to 5.5 3 to 5
Range of detection (m) 1 to 5 in ideal conditions Up to 5 depending on sensitivity and LED type
Emission angle (°) between 15 and 60 depending on narrow or wide-
beam
Cost ($) 24.95 0.005
Part Availability Available through multiple sources Available through multiple sources
Ease of implementation modular, only would need to do signal processing and minimal
conversion through circuitry would need driver circuitry , in addition to a separate
receiver module
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IR Receiver Benchmarking Parameter Passive IR Thermocouple Intrinsic Extrinsic
Detection Mechanism Energy detection and use of
signal processing Converts temperature to
electrical signal Photoconduction/Photovoltaics Photoconduction
Operating Temperature (°C) Range of -40 to 60 Range of 0 to 60 Range of -50 to 600 (depending
on type) -260
Detection range Infrared detectors used for
motion detection can reach up to 15ft in low sensitivity modes
Mostly used to detect objects at close range, no more than 1-2"
away from point of measurement (Part availability is low) (Part availability is low)
Cost $200 (Part availability is low) (Part availability is low)
Weight (oz) >.25 ≤1 (Part availability is low) (Part availability is low)
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Ultrasonic Sensor Benchmarking MB7267 MB1010 UM30-21511
USTR40-14A
(no driver)
Cost $99.95 $29.95 Upon Request ($100+) $5.90 + driver circuitry (
Drop-off Detection Benchmarking
IR Ultrasonic (Stereo Setup) Thermal 2*IR + Ultrasonic
Cost ~$15 ~$50 $2,500+ $83
Response Time 40mS 50mS 33mS 50mS
Accuracy Testing Required Testing Required Testing Required Testing Required
Max Range 4ft 8ft 35ft 8ft-Ultrasonic
4ft- IR
Power Consumption 150mW (can PWM IR for lower
consumption) 25mW 65W
400mW (can PWM IR for lower
consumption)
Weight 0.2oz 0.4oz ~20lbs 0.8oz
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Drop-off Detection Research P
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Source What we learned
“Nighttime Negative Obstacle Detection For Off-road Autonomous
Navigation”
Thermal imaging is great at drop-off detection, but is not feasible for our
application.
“An Inexpensive, Alternative Drop-off Detection Solution”
IR sensors are feasible to use for short range drop-off detection.
“Advanced Augmented White Cane with Obstacle Height and Distance
Feedback”
Battery Benchmarking Battery Type
Parameter Lithium ion Lithium polymer Nickel cadmium Nickel metal hydride
Rechargeable (yes/no) yes yes yes yes
Average number of charge cycles (#) 400 - 1200 500 - 1000 2000 500 - 2000
Charge/discharge efficiency (%) 80 - 90 97 - 99 70 - 90 66
Nominal cell voltage (V) 3.2 or 3.7 3.6 1.2 1.2
Average capacity range (mAh) 2500 - 3300 1500 - 2700 2000 - 3000 1300 - 2900
Part Availability (high/low) high high high high
Weight Lithium ion and lithium polymer are mostly comparable in weight
20% lighter than conventional batteries
Heavier than Nickel metal hydride Heavier than lithium-ion/lithium
polymer
Memory effect no no yes no
Weight energy density (Wh/Kg) 125 170 50 80
Volume energy Density (Wh/l) 320 400 150 200
Self discharge (%/month) 9 5 25-30 30-35
Average cost ceiling ($)
Feedback Benchmarking P
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Morphological Table P
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Preliminary Concepts Concept #
Team
Definition
Detect
obstacles
Detect
drop offs
Provide
feedbackProcess detection
Enclose
system
Power
system
Recharge
systemCollapse cane
1 Best Guess Ultrasonic IR ERM MCUModular
one unitLiPO USB tent pole
2 Cheapest IR IR Voice coil MCU
Modular
multiple
unit
LiPO USB tent pole
3 Lightest no effect no effect piezo no effect single unit LiPO no effectmanually
telescope
4Highest
PerformanceUltrasonic IR piezo FPGA no effect LiPO wall wort
automatically
telescope
5 Easiest Ultrasonic IR ERM MCU single unit no effect wall wort tent pole
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Selection Criteria • Response Time • Cost • Weight • Power Consumption • Sensor Accuracy • Feedback Amplitude • Part Availability • Ease of Mechanical Implementation • Ease of Electrical Implementation
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Pugh Charts P
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Pugh Charts P
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Pugh Charts P
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Pugh Charts P
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Pugh Charts P
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System Architecture P
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• Obstacle detection: Ultrasonic • Drop off detection: Infrared • Provide feedback: ERM • Process detection: MCU • Enclose system: Modular one unit or single unit • Power system: LiPO • Recharge system: USB or wall wort • Collapse cane: tent pole
Morphological Elimination P
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Power Feasibility Conservative Power Estimates
Component Voltage (V) Current (mA)
Ultrasonic Sonic Up 5 20
Ultrasonic Sonic Front 5 20
IR Dropoff 5 30
MCU 3.3 10
ERM 1 3.3 54
ERM 2 3.3 54
ERM 3 3.3 54
Misc 3.3 60
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Power Feasibility Cont.
Regulators 85% Efficiency
Efficiency 85 %
Power Consumption
3.3V 880.4 mW
5V 402.5 mW
Total 1282.9 mW
Needed Capacity 10263.5 mWh
2773.9 mAh
# of Batts Needed 2
Battery Life Requirement: 8 Hours LiPo Cell Voltage: 3.7V LiPo Cell Capacity: 1500mAh
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Regulators 60% Efficiency
Efficiency 60 %
Power Consumption
3.3V 1071.8 mW
5V 490.0 mW
Total 1561.8 mW
Needed Capacity 12494.7 mWh
3376.9 mAh
# of Batts Needed 3
Weight Feasibility
*Note: Misc. is a safe estimate for total weight of smaller components such as resistors, the circuit board, and wires.
Weight Contributors
Quantity weight (oz.)
Battery (18650) 2 2
Enclosure 1 Best Estimate
ERM 3 0.1
Ultrasonic Sensor 2 0.5
Infrared Sensor 1 0.2
Misc.* N/A 1
Total Weight 7oz + Enclosure
Target Weight 6oz
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Cost Feasibility P
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Option: Cheapest
Component Type Price
Cane Base Drive Medical $15.89
Obstacle Detection 3*IR $45
Feedback 3*Cheapo ERM $7.50
Process Detection 32-bit MCU $10
Power System 3*LiPO cells $25
Recharge System wall wort/USB $7
Total: $110.39
Option: Most Expensive
Component Type Price
Cane Base Revolution 38.95
Obstacle Detection 3*Ultrasonic 120
Feedback 3*Precision Microdrives ERM $24.00
Process Detection 16-bit MCU $5
Power System 3*LiPO cells $25
Recharge System wall wort/USB $7
Total: $219.95
Option: Ideal/ Midcost
Component Type Price
Cane Base Ambutech $30
Obstacle Detection 2*Ultrasonic, 1*IR $95
Feedback 3*Precision Microdrives ERM $19.50
Process Detection 16-bit MCU $5
Power System 3*LiPO cells $25
Recharge System wall wort/USB $7
Total: $182
Test Plan Stress Test Vibrating Actuator: • Continuous use shouldn’t negatively affect the transducer • Run motor at max draw for 8hrs while monitoring vibrational intensity and
temperature Test Battery Life: • Battery should last 8 hrs. of continuous current draw • Attach a dummy load to the battery and monitor the battery’s charge level Test Feedback Intensity: • Vibration must be easily detectable by users • Blindfold user and ask them to indicate when the cane is vibrating Test Sensor Response • Sensors to detect the required obstacles at a range of 6ft • Move objects into and out of range and record the sensor’s response times.
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Risk Analysis P
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Risk Analysis- Con’t P
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3 week vision / updated plan P
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Systems Design Review
Subsystems Design Review
Action Items • Update Project Documents based on Feedback :Justine -10/3 • Begin Draft Bill of Materials : Justine, Marisa – 10/7 • Order First Parts for First Cut Testing: Andrew, Ben - 10/9 • Verify final decisions for enclosing and recharging the systems:
Allan, Dan- 10/13 • Conduct surveying with visually impaired individuals about
preferred haptic feedback. : Team- 10/25 • Reference the research from previous Multidisciplinary Senior Design
teams.
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Lessons Learned • Sometimes instincts about implementation are not correct.
• IR is not necessarily ruled out for detection. • Piezoelectrics are more difficult to implement than anticipated.
• Customer Requirements are not static. • Extensive research is needed to verify that referenced material
is correct. • Information about use of piezoelectrics for haptic feedback is
conflicting.
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Questions?
Image Processing Benchmarking
Characteristic University of Stuttgart NAVI University of Guelph TVS Tyfos FIU CompVision
Detects front obstacles Y Y Y Y Y Y
Detects drop-off obstacles Y
Requires computer Y Y Y Y Y Y
NAVI- Navigation Assistance for Visually Impaired
TVS- Tactile Vision System
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