EHPV

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EHPV TechnologySponsored by HUSCO Intl. the
FPMC Center
PATRICK OPDENBOSCH Graduate Research Assistant
NADER SADEGH Ph.D. Mechanical Engineering
Professor
WAYNE BOOK Ph.D. Mechanical Engineering Professor
Georgia Institute of Technology
George W. Woodruff School of Mechanical
Engineering
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AGENDA

• Purpose
• Valve overview.
• Principle of operation.
• Mathematical modeling.
• Simulation results.
• Non-linear controller.
• Hardware-In-the-Loop (HIL)
• Future work.

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PURPOSE

• Development of a trainable nonlinear controller
  for flow control through a 4-way EHPV
  arrangement that compensates for inherent system
  non-linearities such as hysteresis.

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VALVE OVERVIEW

• Electro-Hydraulic Poppet Valves (EHPV) are pilot
  operated valves used for flow control in
  hydraulic machinery.

• The flow control is achieved by changing the
  valve restriction coefficient via a PWM input
  current acting on a pilot and a poppet type
  orifice with pressure compensation.

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VALVE OVERVIEW

• Bi-Directional Capability
• Pressure compensation for consistent current at
  flow initiation.
• Adequate Dynamic Response (Step Response 80ms
  10-90)
• Zero leakage (lt 0.5 cc/min)
• Low Hysteresis (lt 5)
• 12 Volt System 1.5 Amp max current per solenoid.

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VALVE OVERVIEW
Compact View
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VALVE OVERVIEW
COMPONENTS
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PRINCIPLE OF OPERATION

• Forward Flow
• Pressure at port A
• is higher than that
• at port B.

Port A
Port B
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PRINCIPLE OF OPERATION

• Forward Flow
• Pilot pin and armature
• displaced due to hydraulic
• imbalance

Pressure compensating spring acts to balance
pilot pin
Port A
Port B
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PRINCIPLE OF OPERATION

• Forward Flow
• Solenoid is activated and hydraulic fluid is
  drained to low pressure side

Port A
Port B
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PRINCIPLE OF OPERATION

• Forward Flow
• Main poppet is displaced to a new equilibrium
• position allowing a
• direct connection
• between ports A and B

Port A
Port B
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MATHEMATICAL MODELING

• The mathematical modeling is based on the
  interaction of three subsystems

Electromagnetic
Mechanical
Hydraulic
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MECHANICAL SYSTEM
Modulating spring
Pilot pin mass
Armature mass
Bias spring
Piston mass
Pressure compensating spring
Main poppet mass
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MECHANICAL SYSTEM
Pilot Armature Piston Combined

• MODE 1 (closed)

• Pilot-Armature-Piston Dynamics

• Main Poppet Dynamics

Main Poppet
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MECHANICAL SYSTEM

• MODE 2 (open)

Pilot Armature
Piston
Main Poppet
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MECHANICAL SYSTEM

• MODE 2 (open)

• Pilot-Armature Dynamics

Pilot Armature
Main Poppet
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MECHANICAL SYSTEM

• MODE 2 (open)

• Piston Dynamics

Piston
Main Poppet
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MECHANICAL SYSTEM

• MODE 2 (open)

• Main Poppet Dynamics

Pilot Armature
Piston
Main Poppet
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MECHANICAL SYSTEM

• State Constraints

- Main Poppet
Pilot Armature
- Pilot Armature
Piston
Main Poppet
- Piston
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MECHANICAL SYSTEM

• State Constraints

- Main Poppet
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HYDRAULIC SYSTEM
FLOW MODES

• Forward Flow

• Reverse Flow

Port A
Bi-Directional Capability
Port B
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HYDRAULIC SYSTEM
Pilot Head Chamber
Control Pressure Chamber
C2
C1
C
A
B
C1
C2
FORWARD FLOW DIAGRAM
A
C
B
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HYDRAULIC SYSTEM
Pilot Head Chamber
Control Pressure Chamber
C2
C1
C
A
B
C1
C2
REVERSE FLOW DIAGRAM
A
C
B
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HYDRAULIC SYSTEM
Pilot Head Chamber
FORWARD FLOW
Control Pressure Chamber
C
A
B
C1
C2
A
C
B
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HYDRAULIC SYSTEM
A
A
View A-A
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HYDRAULIC SYSTEM
Pilot Head Chamber
Control Pressure Chamber
C
A
B
C1
C2
Neglecting compressibility effects
A
C
B
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ELECTRO-MAGNETIC SYSTEM
Rsol
Vsol
isol
gmax
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ELECTRO-MAGNETIC SYSTEM
Rsol
Vsol
isol
gmax
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ELECTRO-MAGNETIC SYSTEM
Rsol
Vsol
isol
gmax
Hysteresis
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SIMULATION RESULTS

• EHPV Step Response (0-90 capacity)

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NON-LINEAR CONTROLLER

• Motor Speed Control

CONTROLLER
EHPV
Pump
M
M
Load Motor
Tank
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NON-LINEAR CONTROLLER

• Two Possibilities

Closed-Loop Control
Open-loop Control
Vs.

• Look-up table
• Generate Kv for given pressure differential
• Trainable/tailored

• PI type
• Generates duty cycle for PWM driver
• Needs control variable measurement feedback

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NON-LINEAR CONTROLLER

• Closed-loop Control

EHPV
PI Controller
Load Motor
Reference
PWM Driver
Sampled Error
100
0
(Duty Cycle)
PI Controller
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NON-LINEAR CONTROLLER

• Closed-loop Control

Set
PWM Driver
Regulate
V i
Pull
Terminate
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NON-LINEAR CONTROLLER

• Response w/o PI
• 50Hz PWM 99 Duty cycle current regulated at 1A

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NON-LINEAR CONTROLLER

• Open-loop Control

EHPV
Controller
Load Motor
Converter/ PWM Driver
Look-UpTable
Controller
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HARDWARE-IN-THE-LOOP

• The Hardware-In-the-Loop (HIL) simulation
  facility located at the Intelligent Machine
  Dynamics Laboratory (IMDL) will be exploited for
  model validation, controller training, and
  control implementation.

Hydraulic Circuit for Single Valve Identification
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HARDWARE-IN-THE-LOOP
Hardware-In-the-Loop Facility at IMDL
Hydraulic Circuit for 4-Way EHPV Control Training
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FUTURE WORK

• 1. Tune-up and test controllers.
• 2. Model validation for single and 4-way
  directional valve arrangement.
• 3. Simulation and testing of four different flow
  metering modes, and study their effects.
• 4. Development of a more sophisticated and
  trainable nonlinear controller to compensate for
  inherent system non-linearities such as
  hysteresis.

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CLOSURE

• EHPV design features, capabilities, and usage
  were exposed.
• Based on the EHPV s principle of operation, a
  complete non-linear model was developed.
• Preliminary work on the Non-linear controller has
  been started.
• The test facility Hardware-In-the-Loop (HIL) will
  be employed for model validation as well as for
  controller training and testing.
• Future work has been established.