Fast Visual Servo for Rapidly Seafood Capturing of Underwater Delta Robots

In this paper, we propose and design an underwater delta robot for fast seafood grasping. First, the hardware structure of the robot is described in detail. After that, a visual servo control method for fast catching of this underwater delta robot is proposed. The method is able to generate real-time radial trajectories so as to realize the catching based on the swaying of the robot body as well as the movement of the object to be caught. In the actual grasping test, the moving platform and the slave arm can occlude to the target resulting in the loss of target position information. Therefore, we propose a position prediction method to predict the position of the grasped object when occlusion occurs, thus improving the success rate of grasping and ensuring a smooth robot trajectory. Finally, several land and underwater experiments were conducted with good results, which verified the feasibility of the robot structure and algorithm.