Carefree Handling Using Reactionary Envelope Protection Method

Abstract

The operational envelope of a flight vehicle is constrained by a number of critical parameters known as limit parameters. These parameters are constrained to remain within certain bounds to ensure operational safety and in some cases performance of the vehicle. In the case of manned vehicles the task of maintaining vehicle operation within the operational flight envelope by monitoring limit parameter values vests with the pilot. In most situations this task of envelope protection increases pilot workload. Envelope protection systems reduce operational workload by monitoring and informing the pilot of approaching envelope boundaries. Recently, envelope protection methods that translate limit proximity information to its equivalent in the control channel have gained more acceptance. Reactionary envelope protection method is an approach developed for automatic envelope protection in Unmanned Aerial Vehicles. The approach relies on prescribing a safe-response profile for the limit parameter response near the limit boundary and then providing appropriate corrections to the control channel so that limit parameter response tracks the safe-response profile. In this paper, an extension to the reactionary envelope protection method is presented that allows control margins to be calculated for envelope protection. The development of this extension will allow the reactionary envelope protection method to be utilized within an envelope protection system for piloted vehicles. The proposed extension is used to implement a reactionary envelope protection system for R22 manifold pressure limit protection. Results comparing estimated reactionary envelope protection control limits againts previously validated envelope protection methods are also presented.