Assessing Vehicle Health Management Requirements for Unmanned Air Systems

Abstract

Unmanned air systems (UAS) have replaced the pilot of an aircraft with a set of sensors in order to fly. This often leads to lack of remote pilot situational awareness due to the physical and psychological distance and that the sensors do not fully recreate the sensory capacity of a human. One way in which this problem manifests is identifying and responding to faults on-board the aircraft. If there is no sensor in place to identify the fault it will go detected with the remote pilot having to infer what the fault might be from information that is available and take the appropriate contingency action. This problem becomes more apparent as the level of autonomy increases, with less human reasoning in the loop. Integrated Vehicle Health Management (IVHM) uses sensors to provide information on the state of systems within the UAS. To ascertain the amount, type and location of these sensors, the information required from the health monitoring system need to be established. This paper presents a requirements analysis procedure to capture the high-level requirements for an IVHM system, on-board an aircraft, that will be acting as an advisor to the human pilot. The requirements analysis is conducted using a systems engineering approach to capture requirements beyond the technological needs, identifying the interactions of the IVHM system with other systems on-board the aircraft, within the UAS and external to the UAS. This process of requirements analysis and capture will enable a designer of an IVHM system for a UAS to be aware of the needs, their importance in relation to each other, the interactions of the IVHM system with the rest of the UAS, and implications external to the UAS. The designer can make the necessary informed trade-offs between the more and less important needs, and limit negative interactions. In addition, the paper will discuss the difference in the high-level requirements for an IVHM system acting as an advisor to a human on a UAS with a low level of autonomy and one of a high level of autonomy and a low level of human interaction.