J0202-3-3 Development of high precision depth control technique for underwater vehicle

Abstract

To accurately control depth of underwater vehicle in rather shallow water (around 1 m), we develop an underwater machine with a buoyancy control unit, and investigate methods to control depth of the machine. This machine is 1.9 kg in mass, and has a buoyancy control unit (piston) that control range is ± 29.45 cc. Experimental results show that the depth of the machine can be stabilized when time of piston shrinkage and extension is both 3 sec. and, after that, piston is extended ('overshoot') in 1.25 sec. We also conduct numerical simulations of motion of the machine, and these results show that the depth can be stabilized when overshoot time is 1.57 sec. Effects of the control line (cable) and fluid force against the machine are discussed.