An experimental model and a prototype model were made for the developement of underwater inspection robot. The experimental model is a overground test robot that is not made watertight. The model was used for basic research and a debug tool for program developement.
　The prototype model made watertight was developed after tests of the experimental model. The model is the first walking robot in the world that has succeeded in walking on sea bed.
　The hardware and software of the robots are described herein. The principal features of the models are as follows.
　The robots are six-legged articulated insect type robots named AQUAROBOT. Each leg has three articulations and has a touch sensor on the foot. The articulation is driven semi-directly by a DC motor that is built in the leg. All the motions are controlled by a micro-computer. Therefore, the robots can walk on uneven ground and can walk in any direction without changing its quarter.