Transcript Detailed Design Review Presentationx

P13027: Portable Ventilator
Team Leader: Megan O’Connell
Matt Burkell
Steve Digerardo
David Herdzik
Paulina Klimkiewicz
Jake Leone
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Technical Review Overview
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Engineering Specs
Proposed redesign
Battery and Power Calculations
Power: Electrical
Electric Board Layout
SPO2 Sensor
CO2 Sensor
Pneumatic Design
Pressure Sensor Testing
Housing Vision-Casing Structure
Project Comparison
System Testing
BOM
Risk Assessment
Project Passover
Questions?
Engineering Specifications
Portable Emergency Ventilator
Engineering Specifications - Revision 1 - 03/19/13
Specification
Number
Source
Function
Specification (Metric)
Unit of Measure
Marginal Value
S1
PRP
System
Volume Control
Liters
S2
PRP
System
Breathing Rate
BPM, Breaths per Minute
S3
PRP
System
Pick Flow
Liter/Min
S4
PRP
System
Air Assist Sensitivity
cm H20
0.5 ± 0.5
S5
PRP
System
High Pressure Alarm
cm H20
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S6
PRP
System
DC Input
Volts
6 - 16
S7
PRP
System
DC Internal Battery
Volts
12
S8
PRP
System
Elapsed Time Meter
Hours
0 - 8000
S9
PRP
System
Pump Life
Hours
4500
S10
PRP
System
O2 / Air mixer
O2
S11
PRP
System
Secondary Pressure Relief
cm H20
75
S12
PRP
System
Timed Backup BPM
S13
PRP
System
Weight
Kg
≤8
Drop Height
meter
S14
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Robustness
Ideal Value
Comments / Status
0.2 ± 0.2
4 -15
15 - 60
21% - 100 %
1
Due to battery, must be
greater than 9V
Revision B- Proposed Redesign
Update:
1.
Battery Size-> Reduce Size & keep same capacity
2.
Reduce Circuit Board size-> Create custom board for all electrical connects
3.
Reduce Electrical Drive Motor
4.
Display Ergonomics
5.
Reduce Size and weight of PEV
6.
Instruction manual
Additions:
1.
Visual Animated Display-> Moving Vitals
2.
Memory capabilities
3.
USB extraction of Data
4.
Co2 Sensor as additional Feature to PEV
5.
Mechanical Overload Condition due to Pump Malfunction
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Battery Choice: Tenergy Li-Ion
 14.8 V
 4400mAh
 0.8375 lbs
 7.35cm x 7.1cm x 3.75cm
 Rechargeable up to 500 times
 Price: $50.99
 Bulk pricing
 Each cell: $3.18 = $25.44 (8 cells)
 $10 Protection Circuit Module
 ~$40 with packaging and connectors
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Power Calculation
Current (A)
Voltage (V)
Power (W)
Pump
3
11.1
16.65
MCU + electronics
0.5
3.3
1.65
LCD
0.15
10
1.5
Total
3.65
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19.8
Battery Voltage (V)
14.8
Battery Capacity (Ah)
4.4
Battery Capacity (Wh)
65.12
Expected Battery Life (Hrs)
3.29
Charger (Brick)
 HP AC Adapter
 18.5V
 3.5Amps
 Power: 65W
 Max power: 70W
 Price: $14.35 (Amazon)
 Bulk pricing: $6.48 when
quantity of 1000 is bought
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DC-DC Boost Converter
T.I. TPS55340
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Component Calculations
 Designed for Vin = 12-18V, Vout=18V, Iout= 2.5A
 Most components were chosen using TI’s WEBENCH component
selection tool
 Calculating RFREQ
 RFREQ(kΩ) = 57500 × ƒsw(kHz)-1.03
 Calculating minimum Inductance required for CCM
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Voltage Regulation
•Input and output capacitors were chosen with regard to
values on datasheets.
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Battery Charging Circuit
 Suggested Solution:
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Our Solution
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Battery Charging Circuit
 Many discrete components suggested by proposed solution were used
 Determining the values of R8 and R9:
 Timing Capacitors changed in order to set longer charging times for larger battery
 Thermistor not needed for our application, replaced with resistor.
 Current sense resistors set by: IFSS = 0.1V/R12 and IFSI = 0.2V/R18
 Dual-channel Power MOSFET chosen for power switch – rated well for our
application
 All components chosen with safety margins in order to achieve proper operation
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Electrical Schematics
Refer to Electrical Schematics (confidential)
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Revised Board Layout
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Connections to PCB
User Inputs
and Power
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Sensors
and Audio
LCD
SpO2 Sensor
• Difference in Absorption between Red and Infrared is
used to determine SpO2
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SpO2 Sensor Continued
Simplified Design:
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SpO2 Flow Chart
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Source: Freescale Pulse Oximeter Fundamentals and Design
CO2 Sensor
1. Original Target -> Telaire 6004 OEM Module
Problem: Supplier went out of business, similar models
are not being sold by GE Sensing
2. GE SENSING: Does not sell CO2 OEM Module within
concentration range needed
Upon Further Investigation:
The average exhale returns ~ 40,000 ppm of CO2
Dollar Range for CO2 OEM Concentration Modules (using NDIR)
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Cheapest option:
CO2 Meter- K-30 10% CO2 Sensor
Cost $249 for 1
$163 for 250+
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Programmable Range: 0-100,000 ppm
Accuracy: ± 30 ppm ± 3 % of measured value (up to 3% CO2)
Sensor Life Expectancy: > 15 years
Sampling Method: Diffusion
Current Consumption: 40 mA average
Simple analogue output sensor transmitter signal directed to
OUT1 and OUT2
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Electrical Bill of Materials
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Total Cost:
For 1:
$311.94
For 100:
$193.43
(This includes PCB, MCU, Sensors, and LCD)
Refer to Electrical BOM for complete parts list
(confidential)
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Initial Test Plan for PCB Assembly
Weeks 1 and 2: PCB Assembly
 First two weeks will be spent soldering PCB.
1.
Check that all pads match component footprints
 If any component(s) do not match footprint, attempt to solder
jumper wire to pins.
 If jumper wire is not possible or if component overlaps another
component, make changes to PCB and reorder (2 week lead
time +$66)
2.
Solder components in CIMS using heat gun and solder
paste. Larger components such as connectors will be handsoldered
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Week 3: Power System I and Hello
World Program
Power System I: Powered from only external or only Battery
1.
Apply 18V to external input power using Lab Power Supply. Set Current
Limit to 500 mA to prevent damage to circuits.
2.
Measure voltage on 10V, 5V and 3.3V nodes to confirm outputs are as
expected.
3.
Disconnect external power and connect charged battery.
4.
Measure voltage on 10V, 5V and 3.3V nodes to confirm outputs are as
expected.
Hello World Program:
1.
Plug in JTAG connector. Ensure correct orientation.
2.
Test to see if JTAG Debugger has connection to MCU.
3.
Download Test Program to MCU.
4.
Connect LED to output pin. LED should start blinking.
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Week 4: Power Systems II Motor Drive
Testing
Power Systems II: Battery Charging and various DC inputs
1.
Connect depleted battery and attach oscilloscope across battery and battery
current sense resistor.
2.
Apply external Power with Current Limit set to 2.5 A.
3.
Observe that current stays less than or equal to 2 A and voltage on battery
steadily increases up to but not over 16.8V. Monitor battery temperatures
and discontinue temperatures if battery exceeds 110 F in Ambient.
Motor Drive Testing:
1.
Download PWM program to MCU
2.
With Motor Disconnected, observe proper pulsing from MOT_PWM
3.
Connect Motor
4.
Test Motor from DC=.05 to DC=.66
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Initial Testing
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Initial Testing- Differential Pressure
Sensor Model
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Differential Pressure Sensor
 System Architecture
 No Capacitor
 No Backpressure
Differential Pressure Sensor
 Capacitor
 Backpressure
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Static Pressure Sensor
 System Architecture
 No Capacitor
 No Backpressure
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Screen Shots
 System Architecture
DP
Sensor
GP
Sensor
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Screen Shots
 Mechanical Capacitor
DP
Sensor
GP
Sensor
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Screen Shots
 Electrical RC Circuit
 10 kΩ Resistor
 Capacitor 100 μF
DP
Sensor
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Screen Shots
DP Sensor
GP Sensor
 Results of temporarily resisting flow and then
releasing
 Pressure builds
 Flow spikes and then quickly levels
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Video Proof
 Impact of mechanical
capacitor in system
 Flow speed
 Sensor dampening
 Proof of flow sensor accuracy
Conversion of Mechanical Flow Sensor:
Cheat: 12 = 20 l/min
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Human Trials Determine if sensor can observe human backpressure
 System Architecture
 No Capacitor
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Voltage to Pump
Flow
Pressure Sensor
Free Reading
V
3
6.5
7.5
l/min
8.5
25
31
mV
223
310
344
Max Patient
Capacity
Pressure
mV
425
375
400
Pressure
Observed by
Patient
mV
202
65
56
Mechanical Relief Valve
Pressure Release at 1 psi  Reusable
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Rough Correlation to Factory
Specifications
 System Pressure
 Patient Pressure
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0-4.5 kPa (0-.65 psi)
0.5-2 kPa (.07-.29 psi)
Concerns- Calibration
 Currently have no way of measuring pressure
accurately
 Mechanical gauge cannot handle pulsation
 Uncertainty as to whether we can calibrate
against another digital sensor
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Housing Modifications
 13026 Physical Extremes:
 15in long X 10in high X 7in deep
 Projected 13027 Physical Extremes:
 12in long X 7.5in high X 7in deep
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Team: 13026
Team: 13027
Housing Vision
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Housing Vision
Speaker
Mode
O2 Sensor port
CPR Compression #
CO2 Sensor port
Manual
Mask tube ports
Power
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BPM
Flow Rate
Pressure Limit
Housing Vision
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Housing Vision
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Housing Vision
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Housing Vision
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Project Comparison
GOAL: Analyze the size and weight reduction between major contributing components of MSD
13026 PEV to our projected design.
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Summary:
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Casing Assembly
Material: Plastic, Styrene for molding with rubber soles to protect damaging case
Goal:
Create an enclosed structure for our system components.
Problem: Limiting the capabilities to ability/ access vacuum molding machine to
produce similar appearance result as MSD 13026
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Option 1- Recruit RIT Industrial Design Major to recreate vision
Option 2- Create a paneled assembly from plastic
Cons:
-Visual appearance would degrade
- Casing would not be seamlessly enclosed
- Expense for sheet plastic
(ranges from $50-$200 based on thickness)
Option 3- Purchase premade casing
Cons:
- Visual appearance would degrade
- Casing would make entire device be
larger & heavier than intended
- Expense (~$158)
System Testing
1.
Usability Study
-Imagine RIT
-Medical Personnel Discussions
2. Vibration Testing
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1. Usability Study Breakdown
1
2
3
INSTRUCTIONAL
INTERACTION
LIKERT SCALE RATING
COMPONENT
COMPARISON
Goal:
Gain user feedback from actual
interaction with device.
Goal:
Gain a mass feedback on
overall look and operation
of the device.
1. Guide user through medical
scenario and operation.
2. Instruct user to operate with
system inputs
3. Ask questions about the
user/device interaction
1. Create handout to be
1. Knob Board Comparison
filled out by on-viewers
with physical examples
2. Scaled rating (1-10) of 2. Overall geometry
critical components of
comparison (using David’s
design.
sketches)
3. Original MEDIRESP III to
MSD 13026 hands on part
Mass feedback from overall
comparison
system aesthetic
Direct Feedback of liking to a
specific individual component
Conversational Feedback from
direct system operation
Goal:
Understand and Maximize
usability of critical user
operated components.
Likert Survey for Imagine RIT (5/4/13)
FOR IMAGINE RIT
13027 will provide:
1. Survey Print Outs
2. Clip boards
3. Folder for
completed forms
4. Pens
5. Knob Board
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2. Vibration Analysis
 Performed pump vibration testing with the assistance of Dr.
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Lam.
Pump was run at 100% duty cycle at 12v.
Mono-axis accelerometer used
Data was collected in Labview.
Data collected on 3 axes.
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Vibration Analysis- Part 1
 Raw data in volts
 Volts
G’s
Acceleration
Force
 Force=V*exp factor*gravity*mass of pump
 For worst case, maximum voltage was .1V in any direction
 F(N)=.1V*1G/100mV*9.81m/s^2*1.731kg
 Maximum Force = 1.69795 N
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Vibration Analysis- Part 1
 This force then used in failure analysis.
 1st failure scenario: vertical tear-out
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*not to scale
Vibration Analysis-Part 1
 Static Analysis
𝐹
𝜏=
𝑡∗π∗𝐷
 Ultimate strength of polystyrene is 40 MPa.
 Evaluated at a factor of safety of 2.5X
 The calculated minimum nut diameter is
1.3299e-5in
 This is significantly smaller than any practical nut and bolt
combination that would be used.
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Vibration Analysis- Part 1
 Fatigue Analysis
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Source: Characterization and Failure Analysis of Plastics, ASTM, 2003
Vibration Analysis- Part 1
 Designing for infinite life
 Assumed completely reversing stresses
 For polystyrene 𝜎𝑎 =10 Mpa (infinite life)
 For safety factor of 2.5X, evaluate at 4MPa
 Evaluating using the previous formula….
 The calculated minimum nut diameter is .00209in
 This is significantly smaller than any practical nut and bolt
combination that would be used.
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Vibration Analysis- Part 2
 2nd failure scenario: lateral tear-out
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*not to scale
Vibration Analysis – Part 2
 Static Analysis
𝜏=
𝐹
2∗𝑙∗𝑡
 Ultimate strength of polystyrene is 40 MPa.
 Evaluated at a factor of safety of 2.5X, evaluate at 16MPa.
 Stress concentration factor for plate with circular hole, Kf=2
 The calculated minimum distance to the mounting plate edge is
8.14715e-4in
 This is a very reasonable distance to design to.
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Vibration Analysis –Part 2
 Designing for infinite life
 Assumed completely reversing stresses
 For polystyrene 𝜎𝑎 =10 Mpa (infinite life)
 For safety factor of 2.5X, evaluate at 4MPa
 Evaluating using the previous formula….
 The calculated minimum distance to the mounting plate edge
is .00652in
 This is a very manageable distance to design to.
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Bill of Materials (BOM)
See ‘BOM REV 5_1_13 within Confidential Folder.
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Manufacturing Cost Analysis
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Revised Technical Risk Assessment
Revised Operational Risk Assessment
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13027 Fall Staffing Request
1. Industrial Design Major
Contributions:
a. Case Construction
b. Create improved case vision
c. Improve user interface design (based on usability study)
2. Computer Engineer Major(s)
Contributions:
a. Programming of PEV system functions
b. Integrate hardware outputs on display for visualization
c. Design further advanced logic for software components
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13027-Project Passover
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13028 Staffing Proposal
1. Mechanical Engineer (1-2)
2. Electrical Engineer (1-2)
3. Computer Engineer (3-4) **
4. Industrial Engineer (1)
5. Industrial Design Major (1)
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