Contents I. Introduction
A large portion of the earth is covered by the ocean. To explore the complex underwater environment, the AUVs have been widely used [1][2]. However, long-term deployment of the AUVs is constrained by limited data transmission bandwidth and battery capacity. As a result, the AUVs need to be recovered every several hours for recharging and data uploading. Various methods have been adopted to accomplish the recovery mission [3][4][5][6][7]. A cone shape docking station was proven to be an effective design for the recovery of AUV when the docking station is static [4]. When the AUVs were recovered by moving platforms such as USV and submarine, latching bar and rope were used as their low resistance profile can guarantee the movement efficiency of the recovery platform [5][6]. However, the small docking area can lower the success rate. In addition to the passive recovery methods mentioned above, active recovery approaches where the docking devices can adjust their position to compensate for the limited movement capability of the under-actuated AUV were also studied[8][9]. While most of the docking devices maintain a fixed shape through the recovery process, little attention has been paid to the transformable design. In this paper, we propose an active recovery method by designing a deployable underwater robot. The robot is equipped with eight thrusters and can transform between open and closed states to fulfill the different movement requirements during different recovery stages (Fig. 1). It can maintain a low resistance profile with a large propulsion force in the forward direction as it approaches the AUV. When the robot is ready for recovery, the origami-based structure deploys to form a pyramid opening which lowers the requirement of AUVs’ movement ability and localization accuracy. Meanwhile, the thruster’s configuration changes with the deployment of the robot, which results in high maneuverability of the DUR.
