Underwater robot is a device which can move underwater with vision and perception system. As Underwater robots is the kernel of ocean exploitation techniques, a modular Remotely Operated Vehicle (ROV) robot is presented using low cost compact solution for a control system. The control system, propulsion system, signal conversion system, and full observation system were designed as independent modules, which were arranged on main frame of ROV rationally, hence different kinds of robot systems were constructed for underwater conditions. A position and orientation automatic control algorithms of underwater vehicle were proposed without using the knowledge of a previous dynamic model in the control law, mainly by using a low cost embedded instrumentation. STM32F series Micro Controller Unit (MCUs) were used for sensor data acquisition, output calculation and actuator control. Experimental results for using the proposed sensing have demonstrated its good performance and are suitable for the design requirements.