EMA Technology Overview

ElectroMagnetic Actuator – EMA4K

• Peak Force = 19kN• Peak Vel = 4m/sec• Typical Damper Pk

Performance: 10kN @ 4m/sec

• Freq response up to 300Hz

• 200mm stroke• All Electric Motion• Also avail in 1K, 2K, 6K

configurations

Electromagnetic Actuator Fundamentals•U-Channel Brushless Linear Servo Motor

•Consists of a non-contacting forcer coil and a U-channel rare earth (Neodymium) magnet track

•Ironless forcer means there are no attractive forces and no disturbance forces generated between forcer and magnet track

•Ironless forcer has low mass resulting in high acceleration forces

•Three phase coil winding with sinusoidal brushless commutation

•U-Channel design reduces magnetic flux leakage

•Non-contact design supported by standard bearings to handle off-axis loading

Electromagnetic Technology – Where Used

• Assembly• Automotive• Data Storage• Electronic

Manufacturing• Machine Tool• Medical• Military/Aerospace

• Fiber Optics• Photovoltaics• Packaging• Engineered

Systems• Test & Inspection

Electromagnetic Actuator (EMA)Major Components

U-Channel Rare Earth Magnets

Optical Encoder Read head with 1um resolution

Forcer block attached to 3-phase forcer coils on each side (inside U-channel magnets)

Lower T-rail bearing support – 1 each side

Drylin actuator shaft bearing with replaceable inserts

End of Travel Limit Switches

U-Channel Magnet Assembly bolted to column supports both sides

Actuator motion generated here

EMA Comparisons – Damper Testing

Typical shock absorber performance as obtained from published literature

EMA Comparisons – General Performance

0.1

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10

100

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1 10 100 1000

Dis

pla

cem

ent m

m (P

k-P

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Frequency (Hz)

Actuator Performance Comparison

Hyd HS EMA4K

Estimates based on the following assumptions:

• 2500kg GVW, 40kg unsprung, 650kg sprung mass, 6N/mm/sec viscous loading, 50N/mm spring load.

• Hyd HS = Typical hydraulic actuator with hydrostatic bearings, dual 50l/min servovalves, 200l/min 210 bar hydraulic supply

EMA Comparisons – General PerformanceDisplacement (Pk-Pk)

Freq(Hz) Hyd HS EMA4K

1 150 177

2 150 177

3 143.5 177

5 86.22 161

7 61.33 113

10 42.67 76

20 19.76 26.3

30 11.16 12.5

50 4.6 4.68

70 --  2.41

150 --  0.53

200 --  0.26

*Peak Acceleration

Hyd HS EMA4K

23.14 24.25

* = peak acceleration based on unsprung mass of 40kg, wheelpan 20kg, and mass

of actuator

Actuator Mass

Hyd HS EMA4K

25.56kg 19kg

Estimates based on the following assumptions:

• 2500GVW, 40kg unsprung, 650kg sprung mass, 6N/mm/sec viscous loading, 50N/mm spring load.

• Hyd HS = Typical hydraulic actuator with hydrostatic bearings, dual 60l/min servovalves, 200l/min 210 bar hydraulic supply

EMA2K Performance – Road Data

Plot of Track Data Command and Feedback Profiles – Direct file Playback(No transfer function compensation required)

EMA2K Performance – Road Data

Zoom In on portion of Command AND Feedback Track Data (there are 2 plots)

EMA2K Performance – Road Data

Plot of Error throughout Entire Track File (Command – Feedback) RMS Error less than 0.001” (0.025mm)

EMA2K Performance – Road Data

Plot of Actual Forces Achieved during dynamic Track Data Playback on EMA2K

EMA2K Performance – Road Data

Zoom Plot of Dynamic Force - Track Data

EMA Benefits Summary Higher performance / frequency response due to:

No oil column resonance Lower actuator mass Lower friction (no seals) Tighter closed loop control

Direct file playback often 10X better than hydraulic system with

transfer function compensation! Independent of operating temperature

No oil viscosity variables to affect control loop Independent of waveform content

Can accurately run low velocity/low force and high velocity/high

force without changeover from 2stage to 3stage, etc Independent of accumulator charging/discharging cycles

EMA Benefits Summary Less Maintenance and Downtime

No seals, accumulators, servovalves, filtration, oil contamination DryLin bearings only contact points – easily replaceable No system degradation due to component wear (pumps, valves,

etc) Modular design and less components makes troubleshooting

easier

Lower Operating Costs Increased efficiency over servohydraulics means annual

electrical operating costs are 30% of comparable hydraulic systems

No filters, accumulators, servovalves, seals, hoses, pumps to repair/replace

Service and Support fees a fraction of major hydraulic competitors!

The new leader in dynamic testing