mm-act.htm; created: 09 DEC 1999

MicroMag Actuator

Our magnet servo’s, or rather actuators as they don’t have feedback,are fully proportional, the current in the coil generates a magnetic field that is proportional to the current. The magnetic field generates a moment on the magnet that is again proportional to the current. This moment balances with the neutralizing moment. This is generated magnetically, one magnet attracts the other and forces it to neutral. As the two coils and thus the axes of movement of the magnets are under 90 degrees, the coil only acts on its own magnet and does not influence the movement of the other magnet. This is the reason that the two servo's are mounted on a balsa board at the right distance to get the correct neutralising force. When placed closer to each other the neutralising force increases, which increases the positional accuracy of the servo's but reduces the available force. When placed further apart the positional accuracy reduces but the force increases. This yeild more a force control than a positional control.

As The force is limited, the elevator shall be 20 to 25 % of the total surface and the rudder 25 to 30 %. They shall move very free as well as their linkages. A mass balancing of the elevator is recommended unless it is of an ultralight construction. See more info on this under applications.

We can supply two sizes of magnet servo’s small and very small. For very small models up to about 35 grams flying weight you can use the micro actuators of 0.7 gram, the mini’s of 1.7 gram are fine for models up to about 60 grams. Use the mini’s when you want aerobatic performance.

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