## 3 Description of the Selected Proposals
### Technologies for Reliable Autonomous Control (TRAC)  
The technologies for reliable autonomous control (TRAC) of UAVs was developed as part of a DARPA effort under the Software Enabled Control (SEC) initiative [78]. It was created to enable greater mission capability, higher reliability and safety, and greater adaptability to vehicle and mission environment variability, and was in essence the same as the reliable autonomous control technologies (ReACT) for AUVs created by the same authors as a NASA effort for the revolutionary concepts (RevCon) initiative [79]. TRAC/ReACT were developed and demonstrated through simulations [80] and real scenarios demonstrations [79]. As with CPEF, TRAC was not intended for being used in underwater missions. However, some of the concepts introduced by TRAC could be of interest when designing a mission planning and management architecture for underwater operations. Figure 19 illustrates the functional architecture of TRAC. The components of the TRAC architecture include: \begin{table}
\begin{tabular}{c c c} \hline \hline
**Feature** & **Category** & **Explanation** \\ \hline Plan & 1 & The description of CPEF does not include a reference of how the plan has to be specified. Further, the proposal of CPEF predates the specification of PDDL and its updates and extensions, as well as RDDL \\ \hline Adaptation & 3 & The plan manager in CPEF is able to adapt the plan to the events if they trigger the need for repairing the plan. However there is no mention about the use of adaptation in the agents executing the plan. \\ \hline
**Virtualization** & 1 & There is no mention in the proposal about the use of virtualization or abstraction of the agents executing the plan. \\ \hline Dispatching & 3 & Although there is no specific mention on how the plan is dispatched to the agents, CPEF proposal mentions that the plan manager uses a flow model in which it waits for the status reports of each individual action in the plan. \\ \hline \hline \end{tabular}
\end{table} 
Table 10: CPEF assessment. Figure 19: The TRAC functional architecture. * A beacon-based exception analysis for maintenance (BEAM) that monitors the data bus and detects anomalies, and isolates and characterizes failures. * A spacecraft health inference engine (SHINE), used in conjunction with BEAM for diagnosis and prognosis. * A closed loop execution and recovery (CLEaR) that provides high-level mission plan management and generates the sequence of commands to the UAV to execute the mission plan. * An autonomous command executive (ACE) that supervises the execution of the mission plan created by the CLEaR component. These four components are linked together through the active state cache, which is a data exchange repository for keeping and synchronizing all global information regarding the mission. The CLEaR component later evolved as an independent framework [81], is just in charge of generating the mission plan and coordinate a goal-driven and event-driven behavior. This is partially done by sharing plan information and continuous status updates both with the planner and the executive. The decision about if a plan conflict must be handled by the planner or by the executive is provided by some heuristics that depend on the mission and the domain. The other relevant component from the mission management point of view is the ACE [80]. Figure 20 shows the functions performed by ACE, and how they are related to each other. As illustrated, ACE includes an action manager that receives the actions from the planner requests and the unplanned events to be handled. The action manager is responsible for the execution of the actions in the vehicles through the VMS, and for the decision making about the unexpected events. If an event prevents the normal completion of an action, the action manager will notify the planner, so a new plan can be generated if required to fulfill the mission. Figure 21 shows the components of the action manager within ACE.