Fault detection for autonomous multirotors using a redundant flight control architecture

Within the last years unmanned aerial vehicles (UAV) have found their way into several industrial applications and are currently considered to be a highly efficient solution to deliver parcels to end costumers. However, a power shutdown or emergency stop of the propulsion system in the case of a failure is compared to stationary or mobile ground robots no suitable reaction as it leads to a fall of the UAV and hence creates a safety hazard for persons in the surroundings. Thus it must be ensured that the UAV is not only capable of detecting occurring failures but also of remaining airworthy and navigable at any time.Within this work we therefore present a fault detection approach for autonomous multirotor systems using a redundant flight control architecture. The presented fault detection methodology is capable of analysing flight control units (FCU) based on different hard- and software and does not require a precise time synchronization. To deal with different and unsynchronized FCUs we design and implement an inexact voter to continuously compare states and functionalities of the individual FCUs. In the case of a failure or break down of the active FCU the developed architecture has the ability of switching to one of the fallback systems.The approach and algorithms used for failure detection are presented in detail and afterwards the overall system is evaluated using a hexarotor in different flight states and conditions.