Remote control of a deep-seabed mining robot crawling on extremely cohesive soft soil

Abstract

This paper presents a deep-seabed mining robot developed in pilot scale and the test results from the in-situ tests performed in water depths of 130m and 1,370m. The pilot mining robot, named MineRo, was developed to operate in 5,000m deep seafloor and recover the polymetallic nodules half-buried in the soft sediment bottom. MineRo is the combination robot of two unit-robots in lateral direction, which are identical in functions and mirror symmetric in shape. Each unit-robot is capable of crawling on seafloor by two tracks. MineRo is driven by independent controls of the four tracks. Underwater navigation algorithm was developed by sensor-fusion for localization and driving control of MineRo. Basic driving performances of MineRo were investigated: relationships between slips and driving speeds, between steering ratios and turning radii, and between steering ratios and slip angles, etc. Using the basic test results, the path tracking performances were tested for various conditions: lane changes, U-turns and keyhole turns, and complex paths. The constant speed control was successfully performed even in the path tracking control. The driving performances of seafloor crawling robot (MineRo) were thoroughly tested, and it was shown that the four-tracked robot vehicle can be effectively applied for sweeping the polymetallic nodules on extremely soft cohesive soil.