2. Smiha Sayal

3.  Left Ventricular Assist Device (LVAD)  Mechanical device that helps pump blood from the heart to the rest of the body.  Implanted in patients with heart diseases or poor heart function.

4. All team members

5. CorAide (NASA)

7.  “Black box” architecture used during development  Large, not portable  Runs on AC power

8.  Miniaturize the existing LVAD system to achieve portability while retaining its safety and reliability.

9.  Has both internal / external components  Equivalent to our “Option 2”  Unfinished implementation

10.  Microcontroller used in the last year’s project did not work.  The wires and the system were not robust enough to perform testing of the system. Testing of levitation and rotation was not performed.  Space in the internal enclosure could have been optimized by better placement of internal components.  The enclosure was not ergonomic and nor was it the most physically biocompatible shape.

11.  System needs to work  Safe  Robust  Affordable  Easy to wear and use  Interactive with user  Controllable by skilled technician  Comparable performance  Compatible with existing pump

12. Control system all external

13. ADC internal only

14. Amplifiers + MCU internal

15. All electronics and battery internal

16. Amplifiers internal

17. See Handout

18. Option 1 Smallest internal volume Feasible within timeline Easiest to maintain Minimum 20 wires Option 2 Relatively small internal volume Slightly higher risk of internal failure Minimum 10 wires Option 3 Large internal volume Difficult to design Electronics failure is fatal Minimum 3 wires Option 4 Large internal volume Difficult to design Electronics failure is fatal Minimum 3 wires Option 5 Moderate internal volume Difficult to design Electronics failure is fatal Minimum X wires Best Option 350 273 200 153 249

19. Nicole Varble and Jason Walzer

20.  Needs  The external package should be lightweight/ robust/ water resistant  The devices should be competitive with current devices  The device should fit into a small pouch and be comfortable for user and be comfortable for the user  The external package should resist minor splashing  The device should survive a fall from the hip  Risks  Housing for the electronics is too heavy/large/uncomfortable  Water can enter the external package and harm the electronics  The housing fails before the electronic components in drop tests  The electronic components can not survive multiple drop tests

21. Concept Generation- Material and Manufacturing Processes Manufacturing Processes Rapid Prototyping (ABS Plastic)StereolithographyInjection MoldedMachine Metal or Polymer Selection CriteriaWeightRatingNotesScoreRatingNotesScoreRatingNotesScoreRatingNotesScore Cost94 361 91$30k for mold92 18 Feasibility within timeline105 504long lead time401 103 30 Strength6437 MPa24558 MPa30535-70 MPa305~580 MPa30 Material Interaction with water42 84resin based165 204 16 Ease of Manufacturing35 155 3 93 9 0 0 0 0 20 wires0 10 wires0 3 wires0 0 Net Score 133 110 78 103 Rank 1 2 3 4 Continue? yes No no weight1- low importance 10- high importance rating1- does not meet cirteria 5- meets cirteria See Handout

22. Machinable  Material can be drilled and tapped (carefully) Accepts CAD drawings – Complex geometries can be created easily – Ideal for proposed ergonomic shape Builds with support layer – Models can be built with working/moving hinges without having to worry about pins Capable of building thin geometries ABSplus – Industrial thermoplastic Lightweight - Specific gravity of 1.04 Porous – Does not address water resistant need http://www.dimensionprinting.com/

23. Mechanical Property Test Method ImperialMetric Tensile StrengthASTM D6385,300 psi37 MPa Tensile ModulusASTM D638330,000 psi2,320 MPa Tensile ElongationASTM D6383% Heat DeflectionASTM D648204°F96°C Glass TransitionDMA (SSYS)226°F108°C Specific GravityASTM D7921.04 Coefficient of Thermal Expansion ASTM E8314.90E-5 in/in/F Important Notes Relatively high tensile strength Glass Transition well above body temperature Specific Gravity indicates lightweight material

24. Need: The external package should resist minor splashing Specification: Water Ingress Tests – Once model is constructed, (user interface, connectors sealed, lid in place) exclude internal electronics and perform test – Monitor flow rate (length of time and volume) of water – Asses the quality to which water is prevented from entering case by examining water soluble paper Risk: Water can enter the external package and harm the electronics Preventative measures:  Spray on Rubber Coating or adhesive  O-rings around each screw well and around the lid  Loctite at connectors Preliminary Tests without protective coating show no traceable water ingress Spray on Rubberized Coating Loctite

26.  Need: The device should survive a fall from the hip  Specification: Drop Test  Drop external housing 3 times from 1.5 m, device should remain fully intact  Specify and build internal electrical components  Identify the “most vulnerable” electrical component(s) which may be susceptible to breaking upon a drop  Mimic those components using comparable (but inexpensive and replaceable) electrical components, solder on point to point soldering board  Goal  Show the housing will not fail  Show electronics package will not fail, when subjected to multiple drop tests  Risks  The housing fails before the electronic components in drop tests (proved unlikely with prototype enclosure)  The electronic components can not survive multiple drop tests  Preventative Measures  Eliminate snap hinges from housing (tested and failed)  Test the housing first  Design a compact electronics package

27.  130 ° C is absolute maximum for chip junction temperature in order to function properly  Goal: comfort for the user  Assumed steady state, heat only dissipated through 3 external surfaces  Maximum heat dissipation: ~25W  Actual heat dissipation: ~5W t, k Q Tin Tout h

28.  Survived drop test  Water resistant  Plastic is machinable  Drilled, tapped, milled  Helicoils should be used to tap holes  Constant opening and screwing and unscrewing of lid will result in stripped threads  Approximate wall thickness (6mm)  Distance between center of holes and wall needs to be increased  Some cracking occurred  Latches are not feasible

29. LED Backlit display with waterproof bezel and o-ring G/R/Y LEDs with O-ring and waterproof bezel Waterproof buttons with O-ring

30. Current Model: Part # EGG 2K 326 CLL Proposed: Part # EEG 2K 326 CLV Straight-Through Right-Angle, PCB mount

31. See Handout on IP Ratings

35. Zack Shivers

36. See Handout

37.  Interfaces:  26-pin pump connector ▪ Will be directly compatible with old connector!  JTAG (for direct programming)  FTDI USB-to-serial converter  Reset pushbutton See Schematic Page 2

38. Transient voltage protection USB connection FTDI USB-to-Serial converter RX / TX LEDs

39.  Microcontroller requires little electronics design  MCU needs:  Clean 3.3V supply voltage  I/O connections  Programming interface (JTAG or BSL)  Oscillator (optional) See Schematic Page 5

40. + _ LPF Anti- aliasing filter Hall Effect + Hall Effect - ADC Input Voltage Clamping + Reference Voltage See Schematic Page 6

41. Buffer circuit used as voltage reference for ADC

42.  Worst case voltage swing = 4V – 2.5V = 1.5V  Differential output = +3V  Resolution  12-bit ADC  3.3V / 2^12 = 3.3V / 4096 = 0.806 mV / bit  Full Swing Digital  3.0V / 3.3 V * 4096 = 3723 bits

43.  Using TI DRV8412 Dual Full-Bridge PWM Motor Controller  Heat dissipation PCB considerations  Package is able to take 5W at 25 degrees C  Worst case power calculation: ▪ Ptotal = VDD * Iq + 2( Icond^2 * RDS(on) ) = 12V (10.5 mA + 16 mA) + 2 * (1A)^2 * 120mΩ = 0.558W  Worst case power calculation does not exceed case  No heatsink required, use grounded pad for heatsink See Schematic Page 7 & 8

44.  Per customer request, we will continue to use the COTS PHX-35 controller from Castle Creations  Added connectors to board to interface with this part See Schematic Page 9

45.  Require multiple voltage supplies  +3.3V, +5V, +12V  Typical input voltage from batteries ranges from 12V – 15V  Step-down voltage converters  Efficiently (upwards of 90%) convert large voltage to smaller voltages  Disadvantage: injection of switching noise into supply voltages

46. SwitcherPro from TI

47. Linear Technology “AN101: Minimizing Switching Regulator Residue in Linear Regulator Outputs”. July 2005. Switching supply regulates from 12-15V to 3.75V with added switching noise Linear regulator attenuates switching noise, leaving clean 3.3V output See Schematic Page 10

48.  Why will the electronics work?  Difference amplifiers with filter worked for last team  Brushless controller is COTS  MCU crystal and JTAG circuitry taken directly from TI development boards  Professionally created tool SwitcherPRO used for design of voltage regulation circuits

49.  How will we verify electronics meet spec?  Header breakouts for all signals allows for debug and verify at each subsystem  Unit tests  AWB amplifier test  HESA signal acquisition  PHX-35 test with MCU input  Power regulation test  LED + Button test  Graphic LCD test

50. Andrew Hoag and Zack Shivers

51.  Requirements  Selecting suitable embedded control system  Designing port of control logic to embedded system architecture  Customer Needs  Device is compatible with current LVAD  Device is portable/small  Allows debug access

52.  Impeller must be levitating or “floating”  Electromagnets control force exerted on impeller  Keeps impeller stabilized in the center  Position error measured by Hall Effect sensors

53.  Algorithm complexity influences microcontroller choice  Electronics choices affect volume / weight  Proportional – Integral – Derivative (PID)  Very common, low complexity control scheme http://en.wikipedia.org/wiki/PID_controller

54.  Requirements:  Can handle PID calculations  Has at least 8x 12-bit ADC for sensors at 5000 samples/sec  Multiple PWM outputs to motor controller(s)  Same control logic as current LVAD system  Reprogrammable

55.  Custom Embedded  dsPIC Microcontroller ▪ Blocks for Simulink ▪ Small ▪ Inexpensive (<$10 a piece)  TI MSP430 ▪ Inexpensive (<$8 a piece) ▪ Small, low power  COTS Embedded  National Instruments Embedded ▪ Uses LabVIEW ▪ Manufacturer of current test and data acquisition system in “Big Black Box” ▪ Large to very large ▪ Very expensive (>$2000)

56. Microcontroller Setups Selection CriteriaWeight dsPICMSP430 Notes RatingScoreRatingScore Cost 6 4244 Similar Feasibility within timeline10220550Zack has more MSP430 experience A/D8540432MSP430 ADC is 3.3V, sensors are 5V Ease of design64244 Similar Ease of manufacturing64244 Similar Net Score 132 154 Rank 2 1 Continue? No Yes Weight Scale 1 - Low importance 10 - High importance Rating Scale 1 - Does not meet cirteria 5 - Meets cirteria Best Option See Handout

57.  Specifications  Max Frequency: 25MHz  Operating voltage: 1.8V – 3.3V  Package: 100 pin LQFP  Flash Memory: 256 KB  RAM: 16 KB  87 General I/O pins  ADC: 12-bit SAR  4x USCI_A (UART/LIN/IrDA/SPI)  4x USCI_B (I2C/SPI)  Timers  1x 16-bit (5CCR)  1x 16-bit (3CCR)  1x 16-bit (7CCR)  Watchdog  RTC

58.  Greater than 200- ksps maximum conversion rate  Able to acquire all 4 HESA signals in one shot without CPU intervention

59.  How does this chip meet the specifications?  Fast ▪ Dedicated peripherals like timers and UART reduce CPU usage ▪ Able to execute full PID algorithm with minimal CPU usage  Spacious ▪ Large RAM and program space ▪ Able to execute programs much larger this application  Able to generate 12 PWM signals (only need 5)  Physical Size ▪ Small portion of expected PCB layout (only 16x16 mm) ▪ Marginally larger than 80 pin 5xx devices with much more I/O and other peripherals

60.  Confidence in ability to program and interface with hardware  Was able to program an actual chip with breakout board  Standard high-end TI MCU  Hundreds of code examples available for this specific chip  Previous experience  Over 3 months of experience at TI with this specific chip

61.  Optional / Cool Future Features  Ability to program using bootstrap loader (BSL) over USB instead of JTAG  Data dump to USB ▪ Temperature, current, RPM  PONG (not really…)

62. Graphic LCD Buttons LEDsBuzzer

63. See Handout

64.  Why use an LCD?  Display much more information  Interactivity  Allows interface modes for technician and user  Buttons  Up, Down, and Menu for interaction  IP67-rated  LEDs  Provide basic, robust indicators  Buzzer  Loud, high importance warnings  Audible button feedback (beep when pressed)

65. See Handout

66.  How do we know UI will work / meet specs?  Portable, proven example code online for LCD display  Buttons / LED interfacing is standard and very simple  If graphic menu system is too complex, can fall back to simpler modes ▪ LCD text only ▪ LED and button interaction only

67. Andrew Hoag

68.  Described in Software Design Plan/Software Design Document  Coding Standards – ANSI C, File headers, comments  Code Reviews – EE/CE team will review all changes  Unit and Integration testing See Handout

69.  Software unit and integration tests using Gtest (Google Testing Framework) – an open source test framework for C/C++  Results/artifacts for coverage, pass and failure.

70.  Code Coverage – the degree to which source code has been covered in software tests. It is required in safety-critical systems.  FDA has released guidelines and recommendations for code coverage.  DO-178B

71.  The software shall sample HESA values at f s =5000, input to the control loop, and update the AMB PWM outputs.  The software shall report battery level, faults, and status to the user.  The software shall respond to user input to adjust pump motor speed.  The software shall provide a verbose technician/engineering debug output.  The software shall be robust and reliable for a safety-critical system. See Handout

72.  Each of the HESA analog channels is sampled at 5 kilo-samples/second.  The software shall make use of the ADC timers and interrupts provided by the microcontroller architecture to control the sampling. See Handout

73.  Pulse-width Modulation is a digital signal that is used to simulate an analog output by varying high and low signals at intervals proportional to the value.  The AMB is controlled using 4 PWM signals. The pump motor is controlled using a single PWM output. See Handout

74.  PID: common feedback control loop that is currently used in the LVAD control system.  The output signal is a function of the error, the error’s history, and the error’s rate of change. See Handout

75. Startup and Main Loop A/D Interrupt Service Routine

76.  The current baseline is available on the team’s EDGE subversion repository: https://edge.rit.edu/dav/P11021/design/software https://edge.rit.edu/dav/P11021/design/software  This includes 3 rd party packages (Gtest), environment setup, and makefiles.

77. Juan Jackson

78. Higher power to load Low efficiency Linear High frequency switching Capable of higher power than the linear amplifier Better performance at higher frequencies High efficiency PWM

79. Four Degrees of freedom, Front X, Front Y, Rear X, Rear Y, which pushes rotor DAC Microcontroller PWM Control Signal Full Bridge Power Amplifiers Active Magnetic Bearing System Impeller Front X Front Y Rear X Rear Y Hall Effect Sensors (Senses Position)  Closed loop system  Stabilized by negative feedback  Power amplifiers increase power of PWM signals

80. Linear Amplifier PWM Amplifier Selection CriteriaWeightRatingNotesScoreRatingNotesScore Cost53 155 25 Feasibility within timeline105 505 Fits Customer Requests102 205 50 Ease of Design64 244 Net Score 109 149 Weight1-Low importance 10-High importance Rating 1-Does not meet criteria 5-Meets criteria Best Option

81. AMB Amplifier Selection LMD1800TLE6209RDRV8412 Selection CriteriaWeight Specificatio nRatingScoreSpecificationRatingScoreSpecificationRatingScore Continuous Current Output (A) 10 35 5035 65 Switching Frequency (kHz) 10 1005 50 2000 550 500 550 Rdson (mΩ) 10 3302 20 150 550 80 550 Operating Supply Voltage (V) 10 12 to 555 50 up to 45 550 5 Temperature (°C) 10 -40°C ~ 125°C5 50 -40°C ~ 150°C 550 -40°C ~ 85°C 550 Package Type 8 Through hole 216 Surface mount 540 5 Net Score 236 290 Rank 2 1 1 Designer Choice 3 rd 2 nd 1 st Customer Choice 1 st 2 nd 3 rd See Handout Best Option

82. Texas Instrument Application Diagram for Full Bridge Mode Operation

83. Motor Control - DC Brushless BLDC motors are more efficient, run faster and quieter, and require electronics to control the rotating field. BLDC motors are also cheaper to manufacture and easy to maintain Recommended :MSP430F5438 Also consider: Stellaris 5000 /8000 Series C2000 - Fixed Point / Piccolo, Delfino MSP430 - F2xx /5xx 25MHzMSP430F54385000 8000 C2000Fixed Point / Piccolo, DelfinoF2xx5xx ADS7953ADS7953 - 1ch, 12 bit ADC BQ2000TBQ2000T - Battery Charge Management SN65HVD23 3SN65HVD23 3 - 3.3V CAN Transceiver TPS40305TPS40305 - DC/DC Controllers DRV8412DRV8412 - PWM Power Driver TPS54620TPS54620 - Step- Down Regulators Texas Instruments Microcontroller for Motor Control Applications : Component recommendation "MCU4Analog." Texas Instruments. Texas Instruments, n.d. Web. 4 Nov 2010. <http://focus.ti.com/mcu/docs/mcuorphan.tsp?contentId=73295&DCMP=MCU_other&HQS=Other+OT

84. Help us improve our design!