Bi-Directional Rotary Actuator

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Bi-Directional Rotary Actuator

• Group 9
• Sung Bae
• Robert Hooge
• Chris Imparato
• Jose Jaramillo

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• What is a Rotary Actuator?

360 deg
Upper stator
Non-energized
Rotor
Lower stator
Energized - polarity 30 deg CW rotation
- or
Energized polarity 30 deg CCW rotation
Sandia coil design Coil is constrained to one
side of actuator. Magnetic field conducts thru
can to opposite stator.
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Needs Assessment

• Replace two uni-directional solenoids with single
  bi-directional solenoid.
• Used in weapon components systems
• Should be adaptable to Micro-Electro-Mechanical
  System (MEMS) for miniaturization.

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Scope

• Design a bi-directional rotary actuator
• Compact and easy to assemble
• Rotates either clockwise or counterclockwise with
  a return to a neutral position
• Electro-magnetic with a permanent magnet rotor
• Takes full advantage of maximum moment arm
  availability (pancake style)
• Single coil design
• Directionality is controlled by coil polarity

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Constraints/Goals

• Rotor must be 2 in diameter
• No springs to return to neutral position
• Torque must be 0.31Nm or greater
• Step size of 20 - 30

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Original Designs
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Major changes

• Cylindrical housing
• Uniformly distributed magnetic field
• Inner magnets used.
• Helped to increase torque.
• Changed from 4 poles to 3
• Taller coil
• Lowered current density
• Distributed temperature over larger area.

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Final Design
N
S
Magnets left out for clarity
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Exploded View
1-64 Flat Head Screws
Outer Housing
Shaft
Lower Stator
Rotor
Bushing
Snap Ring
Upper Stator
Base Plate
Shoulder Bearing
Coil Core
Coil
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2-D Simulation
Using Maxwell 2-D SV
Off Position (No Current)
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2-D Simulation
On Position (1500A)
Shading in above figure represents magnetic
field, lines represent magnetic flux
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3-D Simulation
Using Maxwell 3-D

• De-Energized

• Energized

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Thermal Modeling

• Surface Temperature
• Surrounding objects
• Safety
• Determined materials used for coil

• E-Physics

Calculated - 72C Max
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Calculations
Calculations from Assumed Values
Calculations from Measured Values
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Fabricated Parts
Coil Core
Housing
Base Plate
Lower Stator
Rotor Shaft
Screws
Upper Stator
Winding Device
Coil Spool
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Assembly
Coil and Lower Stator Assembly
Rotor Assembly
Assembly
Full Assembly
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Assembly Problems

• Tolerances on shaft and rotor
• Remade rotor and shaft
• Made shoulder on shaft
• Used bushing in upper stator
• Press fitting 2 bearings posed disassembly
  problems

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Operational Setup
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Operation
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Torque Test
Using Torque Gauge
Generated - .068 N-m
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Thermal Tests
47.4 C
53.2 C
Temperature after 2 minutes
Temperature after 5 minutes
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Conclusions

• Proof of concept
• Single bi-directional solenoid
• Torque
• .068 N-m 1/5 Predicted value
• 2nd Test TBD
• Measure stall torque
• Step Size
• 10-15

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Recommendations

• Housing with 3 walls aligned with stators.
• Magnet spacing.
• Stators wider with larger radius than magnets.

Diagrams to be inserted
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Acknowledgments

• Sponsor - Gilbert Benavides (SNL)
• Advisors
• Dr. Masson
• Dr. Englander
• NHMFL
• Lee Marks
• Graduate Machine Shop Staff
• Dr. Luongo

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Questions?