Multiple-Model Adaptive Fault-Tolerant Control of a Planetary Lander

摘要

In this paper we present an approach to fault-tolerant control based on multiple models, switching, and tuning andnits implementation to a hardware-in-the-loop simulation of Delta Clipper Experimental dynamics. The Delta ClippernExperimental is characterized by large control input redundancy, which made it an ideal test bed for evaluation ofnadvanced fault-tolerant and adaptive reconfigurable control strategies. The overall failure detection, identification,nand accommodation architecture is an upgraded version of our Fast Online Actuator Reconfiguration Enhancementn(FLARE) system. The FLARE approach is based on representing different possible fault and failure scenarios usingnmultiple observers, such that the case of nominal (no-failure) operation is covered along with the loss-of-effectiveness,nlock-in-place, and hardover failures of the flight control effectors. Based on a suitably chosen performance criterion,nthe FLARE system quickly detects single or multiple failures and reconfigures the controls, thus achieving either thenoriginal desired performance or graceful performance degradation. In the first stage of the project, the FLAREnsystem was tested on a medium-fidelity simulation of Delta Clipper Experimental dynamics, resulting in excellentnperformance over a large range of single and multiple faults and failures. Following that, in collaboration withnBoeing Phantom Works, the FLARE run-time code was installed at their site and tested on a hardware-in-the-loopntest bed consisting of an electromechanical actuator actuating a gimballed engine as a part of a simulation of the DeltanClipper Experimental dynamics.Alarge number of hardware-in-the-loop simulations were run to cover a dense testcasenmatrix, including cases of up to 10 simultaneous control effector failures. In all cases FLARE was able to quicklynand accurately detect the failures and reconfigure the controls, resulting in excellent overall system performance. Innthis paper we describe the Delta Clipper Experimental and its dynamics model, along with the multiple models,nswitching, and tuning based modification of our FLARE system. This is followed by a description of the experimentalntest bed and a discussion of the results obtained through hardware-in-the-loop testing.