HUSCO Electro-Hydraulic Poppet Valve Project Review

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HUSCO Electro-Hydraulic Poppet Valve Project
Review
George W. Woodruff School of Mechanical
Engineering
Presented by
PATRICK OPDENBOSCH
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AGENDA

1. Components
2. Opening Sequence
3. Related Work
4. Mathematical Modeling
5. Control Schemes
6. Future Work
7. Conclusions

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1. COMPONENTS
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2. OPENING SEQUENCE
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2. OPENING SEQUENCE
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2. OPENING SEQUENCE
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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.
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• Valve Modeling

States

• .

(3.1)
Output
(3.2)
Figure 3.2 Electro-proportional flow valve
(3.3)
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• Jacobian Linearization and Model Reduction

(3.4)
Assumptions
(3.5)
(3.6)
(3.7)
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(3.8)
Figure 3.3 Simplified Second Order Model
Figure 3.4 Flow valve identification test setup
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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.

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4. MATHEMATICAL MODELING

• Flow Distribution

uv
Q2
Qp
Qa
Q1
Qb
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Pa
(4.2)
(4.1)
xp
Pp
xm
Qp
Pb
(4.3)
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• 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)
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• Second Order Systems

Pilot Dynamics (from equilibrium state)
(4.11)
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Main Poppet Dynamics (from equilibrium state)
am,1 Poppets Large area am,s Poppets Small
area
(4.12)
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Letting
(4.13)
and
EHPV State Space Representation about Equilibrium
Point
(4.14)
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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)
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5. CONTROL SCHEMES

• Jacobian Linearization
• Input-output Linearization

u
y

BL
CL
Int

AL
BL
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• Jacobian Linearization

Assumption Incompressible fluid
(5.1)
(5.2)
(5.3)
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Figure 5.1 Output flow for PWM input about
nominal value.
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Figure 5.2 Control diagram.
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• Input-Output Linearization (Model Reduction)

Assumption Pilot dynamics are fast and can be
considered as the Input to the system (i.e. xpW)
(5.4)
(5.5)
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(5.6)
(5.7)
Equation 5.7 gives a direct mapping between
fictitious input V and output flow.
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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

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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