Moving Coil explained

How Moving Coil Actuators work?

At the heart of all SMAC actuators is the moving coil, also described as a voice coil actuator. The essential principle is the same as you will find in any permanent magnet loudspeaker. The voice coil sits in a strong magnetic field, and by passing a current through the coil a force is generated in either direction. With SMAC actuators, the moving coil makes an ideal linear motor.

The amount of force generated is governed by the equation: F N I B

where:
  F is the force generated
  N is the number of turns in the winding (Constant)
  I is the current flowing through the winding and
  B is the magnetic flux (Constant)

Therefore, by controlling current we can accurately control the force output.

Other voice coil acuators give no proviison for position feedback, but all SMAC actuators include a precision, non-contact linear encoder. This allows closed-loop servo control of motion in position in velocity modes and real time monitoring of position in all operating modes.

This unique features allowed SMAC to develop the Soft-Land™ routine, which has permitted applications simply not possible with other technologies.