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The Streamliner Artificial Heart

The Streamliner Artificial Heart. Brad Paden University of California, Santa Barbara & LaunchPoint Technologies LLC. Outline. LVAD’s for artificial heart assist Background Next generation devices Design & Prototypes Actuators Sensor Control Commercialization.

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The Streamliner Artificial Heart

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  1. The Streamliner Artificial Heart Brad Paden University of California, Santa Barbara & LaunchPoint Technologies LLC XIV Brazilian Automatic Control Conference

  2. Outline • LVAD’s for artificial heart assist • Background • Next generation devices • Design & Prototypes • Actuators • Sensor • Control • Commercialization XIV Brazilian Automatic Control Conference

  3. Need for Mechanical Circulatory Assist • 15,000,000 heart disease deaths/yr. • 5-10% could be saved with circulatory assist • Several options: • Transplant (limited supply) • Ventricular assist device • Total artificial heart (not needed in general) XIV Brazilian Automatic Control Conference

  4. Heart Transplants in the US 2500/yr 2000/yr 1500/yr 1000/yr 500/yr XIV Brazilian Automatic Control Conference

  5. Left Ventricular Assist Devices (LVAD) are the Leading Alternative to Transplants XIV Brazilian Automatic Control Conference

  6. XIV Brazilian Automatic Control Conference

  7. Lumped-element model of the cardiovascular system XIV Brazilian Automatic Control Conference

  8. 1st Generation LVADs are in use and are pulsatile XIV Brazilian Automatic Control Conference

  9. 1st Generation Devices • Increase 2-year survival from 8% to 23% in end-stage heart failure patients* • Issues remain: • Thrombus (clot) formation, • Mechanical reliability. • Energy efficiency. *Rose et al, “Long-term use of a left ventricular assist device for end-stage heart failure,” The New England Journal of Medicine, Vol 345(20), 2001 XIV Brazilian Automatic Control Conference

  10. 1st Generation (pulsatile) 2nd Generation (rotary) 3rd Generation (maglev) XIV Brazilian Automatic Control Conference

  11. XIV Brazilian Automatic Control Conference

  12. Background on 3rd GenerationLVADs • Extracorporeal Prototypes (Olsen and Bramm, 1981; Allaire, Maslen, and Olsen, 1995; Chen et al, 1998) • Implantable devices in animal trials (StreamLiner 1998, TCI/Sulzer 1999, Berlin Heart ?) • Human Trials (Berlin Heart AG, June 16th 2002)

  13. Utah/UVA Mag-Lev LVAD XIV Brazilian Automatic Control Conference

  14. Cleveland Clinic/Mohawk LVAD XIV Brazilian Automatic Control Conference

  15. LVAD Design Objectives • Avoid mechanical shearing of the blood • 6 Liters/min and 100 mmHg • High reliability and efficiency • … hence magnetic bearings • low power • ~10 g loading XIV Brazilian Automatic Control Conference

  16. Shear-Induced Hemolysis:a design constraint L.B. Leverett et al, “Red Blood Cell Damage by Shear Stress,” Biophysical Journal, Vol. 12, pp. 257-273, 1972. XIV Brazilian Automatic Control Conference

  17. 1st Streamliner Concept (HemoGlide 1) XIV Brazilian Automatic Control Conference

  18. Conical Bearing Prototypea wonderful 8x8, 10-state nonlinear multivariable control problem. Stabilized using static linear decouplers and and 5 SISO lead-lag controllers. XIV Brazilian Automatic Control Conference

  19. This is too complicated! Can we just use permanent magnets? Earnshaw’sTheorem (1842) • In a divergence-free electric field there are no stable • equilibria for charged particles. • Similarly for ideal permanent magnets in a • static magnetic field. XIV Brazilian Automatic Control Conference

  20. more formally… XIV Brazilian Automatic Control Conference

  21. Design Corollary: We can’t use all permanent magnet levitation... XIV Brazilian Automatic Control Conference

  22. But we can eliminate all but one active axis... HG3 concept XIV Brazilian Automatic Control Conference

  23. Final Design JA Holmes XIV Brazilian Automatic Control Conference

  24. Section View and Final Device XIV Brazilian Automatic Control Conference

  25. Jarvik-7, Novacor LVAD, HG3b XIV Brazilian Automatic Control Conference

  26. HG3b Animal Trial (July ‘98)first fully maglev pump sufficiently compact and energy efficient for implantation XIV Brazilian Automatic Control Conference

  27. 34 Day Animal Trial (August 24, 1999) XIV Brazilian Automatic Control Conference

  28. Design Approach: Computer Modeling and Optimization XIV Brazilian Automatic Control Conference

  29. Design Procedure TOPOLOGY SELECTION LUMPED PARAMETER MODELS FINITE ELEMENT MODEL OPTIMIZATION RAPID PROTOTYPE OPTIMIZATION IMPLANTABLE PROTOTYPE XIV Brazilian Automatic Control Conference

  30. Topology Selection (via design grammar) (FH,AO) Sp - PRB-DCBM-ATB-PRB-Sp || || sb - ib - sb XIV Brazilian Automatic Control Conference

  31. Motor & Thrust Actuator Lumped reluctance analysis w/FEA-derived Correction Factors Some FEA optimization PM Bearings closed form solution of maxwell’s equations FEAanalysis Rotor rigid body model linear fluid damping Controller, Actuator, Sensor finite-dimensional models Pump Meanline Analysis Empirical Formulae Computational fluid dynamics (CFD) Lumped-Element Modeling and Finite-Element Analysis XIV Brazilian Automatic Control Conference

  32. PM Bearing Design XIV Brazilian Automatic Control Conference

  33. z XIV Brazilian Automatic Control Conference

  34. z XIV Brazilian Automatic Control Conference

  35. XIV Brazilian Automatic Control Conference

  36. PM Bearing Model XIV Brazilian Automatic Control Conference

  37. Motor Design STATOR ROTOR XIV Brazilian Automatic Control Conference

  38. Motor Parameterization R5 = 13.31 R3 = 5.936 R4 = 9.58 Ls =14.66 W1 = 3.73 XIV Brazilian Automatic Control Conference

  39. 4 2 6 1 3 7 5 Motor Optimization h = 90% V = 20.3 N = 10000 RPM V = 12.4 P = 8W V = 18.2 N = 5000 RPM h = 85% P = 4W V = 16.1 N = 15000 RPM V = 11.0 P = 16W V = 20.8 h = 95% V = 40.2 XIV Brazilian Automatic Control Conference

  40. Motor redesign and re-optimization to reduce radial instability XIV Brazilian Automatic Control Conference

  41. Pump Design (CFD)(James Antaki & Greg Burgreen) XIV Brazilian Automatic Control Conference

  42. Final impeller design • 5 impeller blade refinements • 4 internal flow path refinements • 6 aft stator blade refinements • 18 month development effort XIV Brazilian Automatic Control Conference

  43. Flow visualization of early design XIV Brazilian Automatic Control Conference

  44. Hydrodynamic performance Efficiency 0.16 0.15 0.14 0.13 0.12 0.11 0.10 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 8000 RPM PRESSURE mm-Hg FLOW RATE (LPM) XIV Brazilian Automatic Control Conference

  45. Control system design • Linear actuator with optimized force/watt1/2 • Virtual Zero Power (VZP) axial control • (1.5W coil power while pumping) • Ultra low-noise eddy-current sensors • Sensorless Motor Control XIV Brazilian Automatic Control Conference

  46. Sensor System 1 MHz Osc. (-90 deg) -1 Current Driver s-a s+b -90º 90º Voltage Sense Amp LPF V(x) + offset adjust mixer x L(x) 1/(2(L(x0)C) ½) = 1MHz C XIV Brazilian Automatic Control Conference

  47. PID Controller Structure (for reference only) impeller axial disturbance force heat Eddy-Current Sensor Ka (Ms2 -Kb )-1 Ks displacement force Rotor Mass & Bearing Negative Stiffness Linear Motor ~2 N/ root watt Pos. Reference = 0 noise ~1Å / root Hz - Kp+Kd s coil current PID Controller Ki/s XIV Brazilian Automatic Control Conference

  48. Virtual Zero Power (VZP) Controller Structure* impeller axial disturbance force less heat Ks Ka (Ms2 -Kb )-1 displacement force Eddy-Current Sensor Rotor Mass & Bearing Negative Stiffness Linear Motor ~2 N/ root watt noise ~1Å / root Hz current reference = 0 Kp+Kd s - coil current s(Kp+Kd s) Ki/s Ki Kp +(1-Kd Ki)s Anti-windup included VZP Controller XIV Brazilian Automatic Control Conference *J. Lyman, “Virtually zero powered magnetic suspension,” US Pat. 3,860,300, 1975.

  49. Axial Disturbance Force 4 Newtons XIV Brazilian Automatic Control Conference

  50. 19 August 1999 Streamliner HG3C sn001 pre-implant What is next? XIV Brazilian Automatic Control Conference

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