Slaving and disabling actuators with voice-coil adaptive mirrors

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.