## 1 Introduction  
More and more underwater robots are taking the place of human beings in the areas of sea-water fishery, safety search and rescue, scientific investigation and so on [1, 2, 3]. The control system of the underwater robot in near shallow seas is hampered by various disturbances--some of which are derived from the outside of the system, such as waves, ocean currents and wind; and some of which are derived from the inside of the system, such as highly nonlinear dynamics and coupling, deviation of model parameters and noise of sensors [4]. Although various disturbance observers and antidisturbance algorithms have been developed by scholars [5, 6], it is difficult for underwater robots to obtain disturbance information from inside and outside of the system only by relying on inertial sensors, underwater acoustic sensors and visual sensors. The performance of the underwater robot system is strongly affected by this situation, which makes it difficult to complete fixed-point hovering and track tracking tasks, especially in waters with poor lighting conditions or complicated terrain. From a biological point of view, the lateral-line system is the water-environment sensing organ distributed around the body of fish and other aquatic organisms. The lateral-line system of fish uses a mechanical sensing unit, the nerve colliculus, to perceive the hydrodynamic characteristics around itself and obtain the surrounding environment information through central nervous calculations [7]. Through the bionics principle, the lateral line of aquatic organisms is simulated to perceive the water-environment information, and the lateral-line system of aquatic organisms is transplanted into the underwater-robot system, which will improve the ability of the underwater robot to observe the external-interference information of the system. It is still urgent to solve how to use the existing sensors and computer technology to realize the imitation of the fish lateral-line system and develop the corresponding data-processing methods, so that the underwater robot can obtain the ability to sense the movement and force of the surrounding water, so as to counter the interference from the external water of the robot. The first application of underwater robots was in the 1950s. After the Americans developed the \"CURV-1\" underwater robot, they tried to use underwater robots to salvage hydrogen bombs on the seabed, an extremely dangerous and complex task. After the success of this task, researchers all over the world saw the great national defense research value of underwater robots. Since then, underwater robots have attracted people's attention. They are now widely used in the offshore oil and gas sectors, underwater target search and salvage, underwater patrol inspection and offshore fishery. The earliest studies of lateral-line systems of fish date back to the 17 th century [8]. [PERSON] first conducted functional research on the lateral line in article [9], and speculated that the lateral line is a receptor to feel the stimulation of water motion. [PERSON] initiated the study of the current line-measurement system in 1963 and learned that the lateral line was a kind of independent sensory system, and proposed that the lateral line could feel the vibration stimulation generated by water fluctuation or fluid stimulation generated by the movement of objects [10]. Later researchers have conducted a lot of research on the biological morphology, distribution and function of the lateral-line system, and proposed that the lateral-line system can assist these species in performing various functions such as schooling, prey detection, communication and rheotaxis [11; 12; 13].