Trusting Learning Based Adaptive Flight Control Algorithms

摘要

Autonomous unmanned aerial systems (UAS) are envisioned to become increasingly utilized in commercial airspace. In order to be attractive for commercial applications, UAS are required to undergo a quick development cycle, ensure cost effectiveness and work reliably in changing environments. Learning based adaptive control systems have been proposed to meet these demands. These techniques promise more flexibility when compared with traditional linear control techniques. However, no consistent verification and validation (V&V) framework exists for adaptive controllers. The underlying purpose of the V&V processes in certifying control algorithms for aircraft is to build trust in a safety critical system. In the past, most adaptive control algorithms were solely designed to ensure stability of a model system and meet robustness requirements against selective uncertainties and disturbances. However, these assessments do not guarantee reliable performance of the real system required by the V&V process. The question arises how trust can be defined for learning based adaptive control algorithms. From our perspective, self-confidence of an adaptive flight controller will be an integral part of building trust in the system. The notion of self-confidence in the adaptive control context relates to the estimate of the adaptive controller in its capabilities to operate reliably, and its ability to foresee the need for taking action before undesired behaviors lead to a loss of the system. In this paper we present a pathway to a possible answer to the question of how selfconfidence for adaptive controllers can be achieved. In particular, we elaborate how algorithms for diagnosis and prognosis can be integrated to help in this process.