## 3 Description of the Selected Proposals
### Teleo-Reactive Executive (T-REX)  
The T-REX [47, 48] was developed by the Autonomy Group at Monterey Bay Aquarium Research Institute (MBARI), and has been validated in several real case scenarios. For instance, it has been successfully used in some of the experiments of the Controlled, Agile, and Novel Ocean Network (CANON) initiative at MBARI [49, 50], as well as other marine and service robotics experiments [45] and simulations [51]. It also had an executive implementation as a node part of ROS up until the C Turtle release [52]. The T-REX architecture was conceived as a goal-oriented system, where the typical mission plan, instead of being a sequence of detailed tasks, it is specified by a sequence of high-level goals and constraints. The reasoning for this change is to deal with the increasing mission uncertainty in underwater environments. The essentials of T-REX are inspired by the sense-plan-act [38] adaptive model, using a number of concurrent control loops that provide the response to exogenous events and enable the distribution of the deliberation processes among the components of a T-REX agent. An example of a T-REX agent is described in [47], and illustrated in Figure 9. In this case the T-REX agent has four components, formerly named teleo-reactors, or just simply reactors: a mission manager, a science operator, a navigator, and an executive. Each of the reactors in the figure provide the goals for other reactors (full arrows), and monitors their current state through the provided observations (dotted arrows). Each reactor in T-REX is capable of planning the specific tasks to achieve the goals provided, and to dispatch them to other reactors as their own goals. [PERSON] et al. provided in [53] the example of an integrated system design with three reactors with their internal main components that is shown in Figure 10. In this example, we have three reactors in a hierarchical distribution: a vehicle control subsystem (VCS) at bottom, a navigator at middle, and a mission manager at top. As the figure illustrates, each reactor receives goals from the reactor in its upper layer reactor, and sends their own generated goals to its lower layer reactor. At the same time, each reactor receives the observations \begin{table}
\begin{tabular}{c l} \hline \hline
**Category** & **Description** \\ \hline
1 & The proposal does not mention how the mission plan or the mission plan tasks are dispatched to the vehicles and/or executed. \\
2 & The mission is fully loaded into the vehicles before launch. \\
3 & The mission plan is dispatched to the vehicles task by task, thus the global mission manager being responsible for active supervising of the task execution before dispatching \\  & the next task to a vehicle. \\
4 & The mission plan is dispatched completely to the vehicles, thus the supervision of the \\  & execution of each task in the mission plan is done at the vehicle level, and without regards \\  & of if the mission manager is also actively or passively monitoring the execution progress. \\
5 & Same as 3 or 4, but also including the possibility of updating the mission plan in real time \\  & from the global mission manager. \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Mission plan dispatching and execution assessment. from its lower layer reactor, and generates observations to its upper layer reactor. Each agent has a local database for storing the received observations, and as shown in the figure, to store also plans, models and algorithms. The reactors in the example include a planner, a synchronizer and a dispatcher. The planner uses automated planning techniques for adapting incomplete plans from the database to the current problem. The synchronizer is used to ensure plan consistency and completeness. Finally, the dispatcher is a simple algorithm used to publish goals to other reactors. The system proposed as an example in Figure 10 can be used as follows: the mission manager reactor receives the goals to fulfill a mission, for instance, a mission to survey an area.