Feedforward control for the MAPS adaptive secondary mirror

The MMT Adaptive optics exoPlanet characterization System (MAPS) has entered its second year of commissioning on Mount Hopkins, Arizona, with continued development of its magnetic voice coil actuated adaptive secondary mirror (ASM). While previous work focused on actuator tuning and control law refinement, this paper presents a status update on the implementation of feedforward control, a critical but as yet undeployed functionality due to safety concerns surrounding the thin shell and uncharacterized oscillatory behavior in the outer mirror rings. We describe the current limitations preventing feedforward activation, including the need for damping control. In parallel, we report on a magnet debonding incident likely caused by modal torque, motivating a deeper investigation into mirror eigenmodes and their role in dynamic behavior. We outline a theoretical framework for modeling these modes and discuss their implications for control system safety and performance. Additionally, we introduce an effort to formulate an analytic term for the wavefront error budget that captures the reduction in error due to tuning and feedforward — an open modeling challenge with promising implications.