1. MSD 1 Weeks 7-9 Critical Subsystems Design Phase End State

2. Typical MSD Accomplishments Wks 1-6 Problem Definition: Wks 1-3 – 80% complete after week 3; – >95% complete after week 6 System Design: Wks 3-6 – Team created a functional decomposition >80% complete – Team has proposed a system level solution (or several candidates for further development) – Proposal is supported by qualitative information with some quantification – Team has approval to continue refinement and specification of the system. Did you ask for it? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 2

3. Questions to Answer – end of phase Do requirements “flow down” to subsystems & are all requirements addressed? Have you demonstrated “proof-of-concept”? What analysis/prototyping have you done to demonstrate feasibility of critical subsystems? How are you going to test that requirements are met? Has your design been adequately reviewed? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 3

4. Deliverables Critical subsystems & interfaces: alternatives considered, demonstrate feasibility w/ greater specificity and quantification Requirements flow-down to subsystems (subsystems requirements): allocation process Next level decomposition (sub- subsystems) Goal: Proof-of-concept (analysis, simulation, prototyping) of critical subsystems End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 4

5. How do you identify critical subsystems? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 5

6. Identification of Critical Subsystems Consider your risk list – Highest technical risks: review with team Consider your functional decomposition – Most challenging technically: review with team Consider your engineering requirements – Most important 4-8 system level requirements Consider the required system-level behavior – Most important behaviors Other considerations?? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 6

7. What is “Proof-of-Concept” ? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 7

8. What is “Proof-of-Concept?” Technical feasibility: – Analysis (what questions are you answering?) Simple models first to get approximate magnitudes Estimate complexity to answer key questions Several analyses to answer all key questions – Demonstration or prototyping (what behaviors are you trying to show?) Functional demonstration (cause-effect) that proposal should work Physical mock-up – Experimentation (what questions are you answering?) Controlled and measured to quantify feasibility – Description of system behavior (what behaviors are you describing?) Logic based flow charts Feature descriptions, use cases, operating modes End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 8

9. Feasibility: What is it going to look like? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 9

10. Feasibility: What is it going to look like (inside)? 10 Critical Subsystems are located in 3D space. Volume, shape factor and weight distribution are considered

11. Feasibility: What is it going to look like? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 11

12. How does it work? 13026 PEV System Block Diagram End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 12

13. How does it work? 13026 PEV Major Items End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 13

14. 13026 PEV Pneumatics Mass Flow Sensor Feasibility End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 14

15. Tubing Head Loss Analysis (Between Pump outlet and Ventilator outlet) Bernouli’s Equation Assumptions Constant velocity, height and air density Major Head Loss: Dependent on length of tube between ventilator and pump exit Minor Head Loss Dependent on the expansion and contraction for two T-joints End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 15 What is the pressure drop in the mainline?

16. Mass flow sensor analysis Color Code Blue = Tubing Black = T-Joint Red = Mass Flow Sensor Orange = Control Volume for Mass Flow Route Green = Control Volume for Main Route Cross Sectional View of Mass Flow Junction End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 16 The main line and the mass flow sensor path are parallel flow paths.

17. Mass flow sensor analysis Color Code Orange = Control Volume for Mass Flow Route Green = Control Volume for Main Route Analogy Explanation Current ≈ Flow Rate Resistance ≈ Head Loss Voltage Drop ≈ Pressure Drop → Constant through each path ! Circuit Analogy End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 17 Consider Analogous Behavior

18. Mass flow sensor analysis Head Loss Through Main Tubing Path (Green) Minor Expansion from first T-Joint to Tubing Contraction from Tubing to second T-Joint Major Frictional loss along length of tubing Head Loss Through Mass Flow Path (Orange) Minor Contraction from Original flow to first T-Joint Expansion from first T-Joint to Tubing Two curves (approximated as 90 degree angles) Contraction from Tubing to second T-Joint Expansion from second T-joint to original flow No Major Losses (length of tubing is negligible) Mass Flow Sensor Pressure Drop End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 18

19. Mass flow sensor analysis Pressure Drop Assuming constant height, density and velocity Major Head Loss Total Head Loss Minor Head Losses Contraction and Expansion Curves End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 19

20. Mass flow sensor analysis Mass Flow Sensor Pressure Drop Calculated by interpolating from provided table Assumed flow would be between 200 and 400 sccm (based on educated guess) Final Calculations Only unknown is Q 2 Plugged all equations into an excel sheet and changed value of Q 2 until the difference between the pressure drops in each path was negligible (8.49e-8) End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 20

21. HONEYWELL AWM2300V FEATURES Bidirectional sensing capability Actual mass air flow sensing Low differential pressure sensing The AWM2000 Series microbridge mass airflow sensor is a passive device comprised of two Wheatstone bridges. Data is transmitted via analog. A typical application is in medical respirators and ventilators. End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 21 Selected Sensor

22. Honeywell AWM2300v cont. Performance Characteristics @ 10.01 +/- 0.01 VDC, 25°C CharacteristicValue Flow Range (Full Scale) +/- 1000 sccm Accuracy2.5% Weight10.8g Power Consumption 30mV – 50mV Sensor CurrentMax. 0.6mA Response Time1msec – 3msec Temp. RangeOper. -25°C to +85°C Storage: -40°C to +90°C Dimension31.5mm x 54.4mm x 15.5mm End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 22

23. Mass flow sensor feasibility Typical engineering analysis to demonstrate “feasibility” of the mass flow sensor. Other analysis may be required to demonstrate that the sensor will meet engineering requirements (eg. flow rate accuracy, etc.) End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 23

24. Feasibility of achieving critical requirements Examples Power, Cost, Weight, etc Allocate to critical subsystems Rollup from the bottom as you build the system – Quantified critical subsystems ??? – Estimated critical subsystems??? – Unknowns / Risks??? Iterate, converge, monitor: assign responsibility End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 24

25. Consider the Power System P13026 PEV End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 25

26. Engineering Specifications Portable Emergency Ventilator Engineering Specifications - Revision 5 - 2/8/13 Specification Number Importance Sourc e FunctionSpecification (Metric)Unit of MeasureTarget ValueAccuracyComments / Status S13CN1System OperationVolume ControlLiters0.2 - 1.210% S23CN1System OperationBreathing RateBPM, Breaths per Minute4 -15 S33CN1System OperationPeak FlowLiter/Min15 - 2410% S43CN1System OperationAir Assist Senitivitycm H 2 00.5 - 1.510% S53CN1System SafetyHigh Pressure Alarmcm H 2 010 - 7010% S63CN1System OperationDC InputVolts6 - 16 S73CN1System OperationDC Internal BatteryVolts12 S83CN4System OperationBattery Operation TimeHours1 S93PRPSystem SafetyElasped Time MeterHours0 - 2000 S103PRPSystem LongevityPump LifeHours2000 S113PRPSystem SafetySecondary Pressure Reliefcm H 2 075 S123PRPSystem SafetyTimed Backup BPMseconds15 S132CN8System OperationBlood Oxygen Level%88-100±2 S152 System RobustnessOperational TemperatureDegrees Celsius0 - 40 S162CN2System PortabilityVolumecm 3 10,000 S173CN2System PortabilityWeightKg<8 Importance Weight: 3 = Must Have, 2 = Nice to Have, 1 = Preference Only What defines battery operation time? End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 26

27. Power Flow End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 27

28. Tekkeon MP3450i 12V, 5V Li-Ion 60 Wh < 1 lb. 3.3" x 6.8" x 0.9" (20.2 in 3 ) Built in charging port, prevents overcharging Comes with 90-240VAC charger, can also be charged with 9-24VDC Low battery audible alert Price: $200, inc. tax & shipping Operating temps: -10°C to 60°C Charging temps: 0°C to 45°C Capacity reduces to 70% after 300 charge/discharge cycles End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 28 PProposed Battery

29. Feasibility - Power Analysis Current (A)Voltage (V)Power (W) Pump*3.81222.8 MCU (K70P256M120SF3)0.33.81.14 NEC 4.3" LCD (NL4827HC19-05B)0.276451.382 Total25.322 Battery Voltage (V)12 Battery Capacity (Ah)5 Battery Capacity (Wh)60 Expected Battery Life (Hours)2.37 *Assumes pump is running at 50% duty cycle End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 29 Engi Engineering Requirement is 1 hour. The proposal is “Feasible”

30. Feasibility - Battery Lifetime Battery capacity (Wh)60 Power draw (Wh)25.322 Battery capacity after 300 charge cycles70% Number of charge cycles550 New expected battery life (Hours)1.07 Average number of uses per week*5 Battery lifetime (years)2.12 *Estimated number of uses per week End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 30

31. Summary What questions do you need to answer to demonstrate feasibility of your critical subsystems? What are the most efficient and effective means to answer questions? Add-up key contributors to critical system requirements. Can system requirements be achieved thru your critical subsystems? Iterate and converge as needed Update your risk assessment End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 31

32. Have fun being an Engineer! End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 32

33. Questions End State:Critical Subsystems Design Phase 10/08/13 Hanzlik 33