Mission reconfiguration based on real-time system reliability assessment

Unmanned Aerial Vehicles (UAVs) must be reliable and have the ability to take appropriate action when some functionality is lost due to failure. Fast system reliability assessment techniques such as the Binary Decision Diagram (BDD) technique can be used as part of the decision making process to decide when the likelihood of the autonomous vehicle successfully performing its intended task becomes unacceptably low and what action needs to be taken to mitigate this situation. A UAV is used in this paper to demonstrate the technique. Its mission objectives are specified and the way that this will be achieved is expressed as a phased mission. If the reliability analysis of this phased mission is acceptable it will go ahead. However the UAV must have the ability to respond to changing conditions. Such changes can occur due to component failures causing loss of functionality or reduced redundancy, changing weather conditions, or the emergence of a threat such as another aircraft in the locality. When these conditions are reported the mission success likelihood is re-evaluated accounting for the new conditions and the number of phases already successfully completed. In the event that this new mission reliability is below the acceptable threshold, reconfiguration is initiated. Mission reconfiguration for a UAV selects a new route, new mission objectives, or to abort the mission and make an emergency landing. The focus of the method presented in this paper is the mission reconfiguration process which is based on optimising the mission reliability under its current conditions and environment. This is demonstrated using a UAV carrying out a search and rescue operation.