Development of a parallel typed robot with a sensorless observer for harbor construction

This paper presents an underwater robot developed for harbor construction, which requires the robot to carry a heavy load with large workspace and high dexterity. The requirement can't be attained by a conventional serial typed robot but by a parallel typed robot. For underwater work, it is necessary to waterproof the robot and its sensors. Especially, a sensor waterproof is a main drawback to build the underwater robot. This leads us to develop a sensorless observer which gives the position information without any position sensor. We design a neural network to identify the displacement change of the hydraulic cylinder according to the voltage exerting at servo valve. This paper introduces the design strategy for the parallel typed robot and the development with hydraulic control and wireless communication. The robot is attached to the end of an excavator or a crane to carry a large stone to build a bank. This paper shows the experimental results and explains the performance of the robot.