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HUSCO Electro-Hydraulic Poppet Valve Project Review

George W. Woodruff School of Mechanical Engineering. HUSCO Electro-Hydraulic Poppet Valve Project Review. Presented by :. PATRICK OPDENBOSCH. AGENDA. Components Opening Sequence Related Work Mathematical Modeling Control Schemes Future Work Conclusions. Input. Pilot Spring. Pilot.

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HUSCO Electro-Hydraulic Poppet Valve Project Review

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  1. George W. Woodruff School of Mechanical Engineering HUSCOElectro-Hydraulic Poppet Valve Project Review Presented by: PATRICK OPDENBOSCH April 07, 2003

  2. AGENDA • Components • Opening Sequence • Related Work • Mathematical Modeling • Control Schemes • Future Work • Conclusions

  3. Input Pilot Spring Pilot Solenoid Core Control Chamber Main Spring Feed Line Main Poppet Inlet Outlet 1. COMPONENTS

  4. 2. OPENING SEQUENCE

  5. 2. OPENING SEQUENCE

  6. 2. OPENING SEQUENCE

  7. 3. RELATED WORK Performance Limitations of a Class of Two-Stage Electro-hydraulic Flow Valves1 • Done by: Rong Zhang. Dr. Andrew Alleyne. Eko Prasetiawan. Figure 3.1 Vickers EPV-16 Valvistor (1) Zhang, R.,Alleyne, A., and Prasetiawan, E., “Performance Limitations of a Class of Two-Stage Electro-hydraulic Flow Valves”, International Journal of Fluid Power, April 2002.

  8. Valve Modeling: States: (3.1) Output: . (3.2) Figure 3.2 Electro-proportional flow valve (3.3)

  9. Jacobian Linearization and Model Reduction : (3.4) Assumptions: (3.5) (3.6) (3.7)

  10. (3.8) Figure 3.3 Simplified Second Order Model Figure 3.4 Flow valve identification test setup

  11. Figure 3.6 Root-locus of a Valvistor-controlled system Figure 3.5 Time domain experimental validation • Main Results: • Pilot flow introduces open-loop zeros that limit the closed-loop bandwidth. • Pilot flow can be re-routed to tank trading performance by efficiency. • Open-loop zeros can be moved leftwards by altering valve parameters.

  12. 4. MATHEMATICAL MODELING • Flow Distribution: uv Q2 Qp Qa Q1 Qb

  13. Dr xm Q2 Pp Pa xm Q1 Pb Pa (4.2) (4.1) xp Pp xm Qp Pb (4.3)

  14. small small small • Compressibility: (4.4) am,1 xp (4.5) xm Q2 xo (4.6) (4.7) Qp (4.8) r : Fluid density V: Chamber volume e : Equivalent length of pilot inside control volume b : Bulk modulus (4.9) (4.10)

  15. Second Order Systems: Pilot Dynamics (from equilibrium state): (4.11)

  16. Main Poppet Dynamics (from equilibrium state): am,1 : Poppet’s Large area am,s : Poppet’s Small area (4.12)

  17. Letting: and (4.13) EHPV State Space Representation about Equilibrium Point (4.14)

  18. Reduced Order EHPV State Space Representation about Equilibrium Point From (4.10): (4.15) 0 Then, solving for X3 and substituting in (4.14): (4.16)

  19. 5. CONTROL SCHEMES • Jacobian Linearization • Input-output Linearization u y BL + Int CL + AL BL

  20. Jacobian Linearization: Assumption: Incompressible fluid: (5.1) (5.2) (5.3)

  21. Figure 5.1 Output flow for PWM input about nominal value.

  22. Dist F Plant R Ki Int BL Int CL Qb AL Integral Controller L Int CL -1 AL Observer -1 K -1 Figure 5.2 Control diagram.

  23. Input-Output Linearization (Model Reduction): Assumption: Pilot dynamics are fast and can be considered as the Input to the system (i.e. xp=W) (5.4) (5.5)

  24. (5.6) (5.7) Equation 5.7 gives a direct mapping between fictitious input V and output flow.

  25. 6. FUTURE WORK • Complete control scheme for jacobian linearized system. • Extend input-ouput linearization theory to full order system. • Perform system parameter identification (hardware) • Compare simulation results to experimental results. • Determine control solutions to EHPV operational problems

  26. 7. CONCLUSIONS • Review of valve components and opening sequence • Determination of valve limitations: • Pilot flow introduces open-loop zeros • Re-route flow to tank (efficiency/performance) • Alter valve parameters • Evaluation of 5th order EHPV mathematical model • Control alternatives: • Jacobian linearized system • Input-Output linearization

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