Motion control considering the effects of cable deflection caused by gravity and fluid resistance for Cable-restricted Underwater Vehicle

For efficiently observing the marine resources, we developed an observation device with low operational risk and a wide observable area. The observation device consists of a seafloor station and an underwater vehicle tethered by a cable. As experimental validation result, we found that the vehicle tethered by a cable was able to navigate with an error of less than 0. 071m compared with the planned trajectory. The vehicle is controlled using the cable restraint condition and the forces exerted by the thrusters while considering the effect of the cable slack, without the need of any feedback signal.