Comparison of the Performance of Modal Control Schemes for an Adaptive Optics System and Analysis of the Effect of Actuator Limitations
Abstract
In this study, modal control with various bases has been experimentally evaluated on an experimental Adaptive Optics (AO) testbed. In most custom-built adaptive optics control problems, spatial resolution and available stroke of the deformable mirror (DM) are assumed to be sufficient for the intended performance. In practice, however, there are situations where DMs of limited capability are used and the control system is desired to make most out of the hardware even in such situations. In this paper, the effect of the hardware limitations, such as the spatial resolution of the wavefront sensor and the deformable mirror (DM) on the performance of the AO system, is investigated and several control techniques are proposed to mitigate the problem. The derivatives of Zernike polynomials do not have the orthogonal property.A simple approximate orthogonalization technique is proposed along with the method to avoid the discrepancy of minimum error in the sensor output vector space and in the vector space where the control law is applied. An anti-windup technique is also proposed to reduce the adverse effect by an integral controller when saturation of the DM occurs. Effectiveness of the proposed techniques is demonstrated by experiments on the pseudo real-time AO testbed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2012
- Accession Number
- ADA570313
Entities
People
- Brij Agrawal
- Jae J. Kim
- Masaki Nagashima
Organizations
- Naval Postgraduate School