Implementation and flight test assessment of an adaptive, reconfigurable flight control system

Abstract

During the summer of 1996 a series of¯ight tests demonstrated a new indirect-adaptive approach to recon-®gurable¯ight control known as the self-designing controller (SDC). The SDC achieves improved, appropriately decoupled responses during arbitrary effector or airframe impairment scenarios, and successful SDC¯ight tests culminated with smooth landing of the VISTA/F-16 in crosswind conditions with a (simulated) missing primary control surface (left horizontal tail). The SDC couples modelfollowing receding-horizon optimal control with an on-line parameter identi®cation (ID) algorithm designed to provide smooth, accurate estimates of possibly time-varying system parameters, even under conditions of low excitation. The adaptive model-following approach is designed to reduce control law development costs and improve system performance in the presence of gradual or abrupt changes, including unforeseen events. This paper provides (1) a brief summary of the SDC algorithms, (2) a discussion of SDC implementation on the VISTA/F-16¯ight control hardware, (3) a summary of¯ight test results, and (4) suggestions for further research in recon®gurable/adaptive controls. This work has been supported

Handling Qualities Evaluations of Low Complexity Model Reference Adaptive Controllers for Reduced Pitch and Roll Damping Scenarios

“…Examples that do exist include the first flight tests of a model reference adaptive system on the F-94A aircraft (Lockheed Martin, Bethesda, Maryland), 1 an experimental adaptive flight control system evaluated on the F-94C aircraft (Lockheed Martin, Bethesda, Maryland), 2 the implementation of an adaptive flight control system on the X-15 aircraft (North American Aviation, Inc., Downy, California), 3,4 testing of an indirect-adaptive self designing controller (SDC) on the F-16 VISTA (General Dynamics, now Lockheed Martin, Bethesda, Maryland) 5 and the intelligent flight control system (IFCS) research on the highly-modified NASA F-15 aircraft (McDonnell Douglas, now The Boeing Company). 6,7 By the mid-2000s, experiments such as SDC and IFCS had demonstrated that adaptive flight controls can be an effective technology for improving aircraft safety in the event of failures or damage.…”

Adaptive control of Bayesian network computation

“…Second, as one decreases the forgetting factor, the size of the data window gets smaller and it is more likely that there will exist data collinearities within the data window. To deal with this issue, the Modified Recursive Least Squares (MRLS) algorithm prevents singularities in the covariance matrix by reformulation of the least squares problem [13]. The cost function to be minimized includes additional penalties on changes in the parameter values in the form of temporal and spatial constraints.…”

Historical Overview of Research in Reconfigurable Flight Control

“…Bodson later showed that this was equivalent to using an adaptive forgetting function that varies the size of the data window used by the identification algorithm based on the amount of excitation [51]. Barron associates under the USAF Self-Designing Flight Control System program combined the two approaches in a modified sequential least-squares (MSLS) algorithm [52]. MSLS attempts to optimize a cost function that includes both the more conventional predicted squared error of the estimate over a weighted window of data, and a term that penalizes the estimate for deviations from a constraint of the form…”