Adaptive mirrors based on voice-coil technology have force actuators with an
internal metrology to close a local loop for controlling its shape in position.
When actuators are requested to be disabled or slaved, control matrices have to
be re-computed. The report describes the algorithms to re-compute the relevant
matrixes for controlling of the mirror without the need of recalibration. This
is related in particular to MMT, LBT, Magellan, VLT, ELT and GMT adaptive
mirrors that use the voice-coil technology. The technique is successfully used
in practice with LBT and VLT-UT4 adaptive secondary mirror units.Comment: 12 pages, 1 figure, INAF Technical Report n.68 (2021),
http://hdl.handle.net/20.500.12386/2976
