Task 4: Techniques for passive underwater locomotion


On the basis of the research carried out at ATL (SUBMAR) and on an active EU project (SWARM), there is a clear interest in continuing the study of passive underwater locomotion techniques. The word passive means here that there will be no active systems (i.e. propellers or thrusters) used for the locomotion. So far the study has been focused on Lagrangian drifter-type robots. These robots can only adjust their specific weight but are otherwise moved by the surrounding sea currents. In the future this research task will also study some other ways to move under water. One of the most promising research areas is the use of a glider-type robot for long-term and large-scale oceanographic research purposes. The glider is a drifter that, when adjusting its buoyancy, will, in a way, fly through the water columns. In that way it can cover quite large distances and stay operational for a long time, thanks to its low power consumption.

In order to produce coherent locomotion in a multi-robot case, novel locomotion algorithms must be developed. These algorithms will use the knowledge (a priori and estimated) that they have about the strengths and directions of the sea currents at different depths. The centre point of the swarm is calculated and a watchdog software module will sound the alert if some member of the swarm is getting too far from the centre point. If so, the unit will initiate locomotion procedures aimed at reducing the distance to an acceptable level. It is a highly complex research task with many constraints.

Expected results

Expected results include algorithms for effective passive locomotion techniques for underwater conditions. They will be tested with simulators and with real robotic systems.