DoD 2018.A STTR BAA Modifications
Announcement Text Changes
For AF STTR Topic AF18A-T012, the ITAR restriction was removed on 12/19/17.
Posted — December 19, 2017
For AF STTR Topic AF18A Instructions, page4, 5th paragraph, 1st sentence have been amended to include Oasis Systems.
Posted — December 21, 2017
Air Force STTR Topic AF18A-T008 DESCRIPTION, 2nd paragraph, has been amended to read:
The first issue is due to the mechanical constraints of a point-actuated deformable mirror (DM) with continuous facesheets from which each point-actuator is limited in its range of stroke ,. From a control algorithm perspective, the stroke limit is effectively viewed as a nonlinear saturation limit that can potentially induce instability. A conventional approach to this control problem is to design a high-stability-margin controller implemented at the expense of sacrificing control bandwidth or an optimal/robust controller that penalizes the commands to avoid saturation , which can result in having similar effects in terms of bandwidth. Adaptive optics (AO) through DM implementation offers a more challenging problem as the stroke limits for each point actuator depends on the relative position of the neighboring actuators that change every time step. In other words, due to spatial coupling of the facesheet, the so-called inter-actuator stroke limit effectively imposes point-in-time saturation limits to each actuator , which manifests the complexity of the MIMO control problem. The secondary constraint of interest is the DM resonance mode that is an inherent structural property associated with the mirror itself. The current state-of-the-art AO technology chooses to limit the control bandwidth so it does not excite these modes. The multi-channel nature of the device makes a standard notch filter a less viable option and calls for a MIMO controller that can account for the spatial and temporal dependencies of the mirror modes. The research problem here is to design a control algorithm that operates beyond the physical limits to provide sufficient AO bandwidth (BW) when addressing aero-optical effects while maintaining mechanical and control stability. Requirements for this research effort can be made by first establishing a baseline case where an AO simulation is conducted without any DM inter-actuator stroke limits. The limiting factor for performance is frame rate, open-loop BW for DM, severity of the disturbance source, and the closed-loop BW of the control algorithm. Candidate performance metrics are wavefront error (WFE), Strehl, peak irradiance, and power-in-the-bucket. The baseline case isolates that inter-actuator stroke limit problem from the AO simulation, and shows the best achievable performance. Although not completely necessary, it is good to show performance contrast by implementing the same controller in the presence of inter-actuator stroke-limits. It is highly anticipated that the performance metrics would show significant degradation. The SBIR awardee would address this issue with a novel control scheme that maximizes control BW and avoids instability.
Posted — January 9, 2018