Cooperative Mission Execution

The key objective for the work related to Cooperative Mission Execution is to develop a set of tools and methodologies to aid in the formulation and execution of cooperative mission plans involving groups of vehicles and humans in the loop. Here, only a very short overview of selected contributions during year 2 of the project is given. Please check the publications for more detailed info.

In the 2nd year of the CO3AUVs project, steps have been taken to advance the development of a new breed of off-line as well as on-line, event-driven motion planning systems that address explicitly inter-vehicle collision avoidance, together with a number of criteria that may include simultaneous times of arrival at assigned target points, energy minimization, acoustic communication constraints, and the maximization of terrain information along the vehicle paths for terrain-based navigation purposes. The theoretical framework adopted borrows from optimization and dynamical systems theory.

Fig 1: A cooperative path planning system for multiple autonomous marine vehicles (AMVs).

It is also crucial in the scope of the CO3AUVs project that new methods are developed to localize one more divers or targets simultaneously, based on acoustic range information received on-board a set of autonomous surface vehicles. As a contribution towards meeting this goal, we have addressed the problem of computing the optimal geometric configuration of a mobile surface sensor network that will maximize the range-related information available for multiple target localization in three-dimensional space. In contrast to what has so far been published in the literature, we addressed explicitly the localization problem in 3D using a sensor array located at the sea surface (2D). Furthermore, we have incorporated directly in the problem formulation the fact that multiple targets must be localized simultaneously. Clearly, there will be trade-offs involved in the precision with which each of the targets can be localized; to study them, we resorted to techniques that borrow from Pareto optimization and estimation theory.

Fig 2: Multiple Target Localization: performance achievable.

During the second year of the project, work also progressed towards the development of advanced geophysical navigation systems for autonomous marine vehicles. As the logic corollary of the work done in Year 1 on Terrain-Aided Navigation, the problem that we tackled was that of combining terrain-aided with single beacon-based navigation. Terrain-Aided Navigation (TAN) has recently come to the fore and holds promise for the development of cost effective means to navigate underwater. In this set-up, an underwater vehicle combines dead reckoning strategies (based on the integration of the vehicle´s velocity based on measurements provided by a Doppler unit plus a Heading and Attitude Reference system) with terrain altitude data obtained with one more down-looking echosounders.

Fig 3: AUV Terrain / Single Beacon-Aided Navigation.