Remote control system of a 6 DOF underwater robot

This paper presents a remote control system of a 6 DOF underwater robot using two acoustic transducers, while radio and optical waves are not used because they are strongly attenuated in a complex environment as water. Underwater robots can be controlled by cables limited by distances, environment conditions, and not flexible. Therefore, it is necessary to develop a remote control system for underwater robots. These robots are used to discover, investigate environment parameters under rivers, canals, and seashores. This paper includes two main parts: underwater communication and control system. The communication is designed with a transmitter and a receiver. The transmitter receives commands from a control station and then generates acoustic wave signals, in which usable frequencies are 8-16 KHz. The receiver receives signals from the acoustic transducer and after processing, they are converted in to pulse signals. Two coding methods for communicating are frequency coding and pulse coding which are proposed and compared to evaluate their advantages and disadvantages. Decoded pulse signals are used to control the underwater robot. Fuzzy P+ID algorithm is proposed to control depths, heading and directions of the underwater robot. Experiment results show that the signal is well processed and the underwater robot can be effectively operated.