A recursive estimation algorithm to track aircraft model parameters

Abstract

On-line parameter tracking is often an attractive option for advanced FDD/FTC systems that require a global monitoring in contrast with a local (component) one. This is the case for impaired aircraft, but also for under-equipped vehicles (UAVs, small airplanes), since an updated model is a prerequisite for many indirect adaptive or reconfigurable control algorithms. Many schemes have been proposed since the 80s to deal with the tricky problem of on-line estimation. However for aircraft, their computational burden is often incompatible with the constraints resulting from onboard implementation and certification issues. As a result, this paper relies on the well-known pros of frequency domain techniques, but proposes a fully recursive algorithm simple enough to comply with those requirements. The approach is applied to the parameter tracking of a civil aircraft on view of designing an adaptive gain-scheduled flight control law.