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Abstract | ||
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This paper demonstrates optimal rejection of laser beam jitter by a variable-order adaptive control scheme based on a recursive least-squares lattice filter. The performance of the adaptive controller in a beam-steering experiment is compared to that of the theoretically optimal linear time-invariant con- troller. The benefits of adaptive control over optimal LTI control is demonstrated by experimental results for both stationary and non-stationary jitter. The variable-order adaptive controller is based on an adaptive lattice filter that implicitly identifies the disturbance statistics from real-time sensor data. In steady- state, high-order adaptive controller exerts control authority over a broad spectrum of frequencies. Moreover, compared to a fixed-order adaptive controller, the variable-order adaptive controller exhibits significantly improved transient. I. INTRODUCTION In emerging technologies such as high-energy laser sys- tems and wireless optical communications precise pointing of laser beams and high-bandwidth rejection of disturbances produced by platform vibrations and atmospheric turbulence are critical. Also, some fast steering mirrors have lightly damped elastic modes that produce beam jitter. Because of the multiple sources and complex structural dynamics of typical platforms, jitter often is composed of multiple bandwidths. Optimal performance of a beam steering system requires an adaptive control system because the disturbance charac- teristics often change with time. Recent research on jitter control has produced adaptive control methods that employ least-mean-square (LMS) (1)-(3) adaptive filtering and recur- sive least-squares (RLS) adaptive filtering (4)-(6). The trade off is between a simpler algorithm (hence computational economy) with LMS versus faster convergence and exact minimum-variance steady-state performance with RLS. The adaptive controller in this paper is based on a recursive least-squares lattice filter, and the the order-recursive struc- ture of the lattice filter is exploited to produce a variable- order adaptive control scheme. The capability to vary the order of the filter in the adaptive controller is important because optimal gains can be identified faster for lower- order filters while higher-order filters are required for optimal steady-state rejection of broadband disturbance. Thus, low filter orders can be used initially for fast adaptation without undesirable transient responses, and the filter order can be |
Year | DOI | Venue |
|---|---|---|
2006 | 10.1109/CDC.2006.377253 | Conference on Decision and Control |
Keywords | DocType | ISSN |
adaptive control,beam steering,jitter,lattice filters,least squares approximations,adaptive lattice filter,laser beam steering,least-squares lattice filter,optimal LTI control,optimal jitter rejection,variable-order adaptive control | Conference | 0743-1546 |
Citations | PageRank | References |
1 | 0.39 | 3 |
Authors | ||
4 | ||
Name | Order | Citations | PageRank |
|---|---|---|---|
| Pawel K. Orzechowski | 1 | 5 | 1.36 |
| Neil Chen | 2 | 12 | 2.64 |
| Steve Gibson | 3 | 17 | 3.43 |
| Tsu-Chin Tsao | 4 | 135 | 37.12 |