Development of a Hovering-Type Intelligent Autonomous Underwater Vehicle, P-SURO

Abstract

P-SURO(PIRO-Smart Underwater RObot) is a hovering-type test-bed autonomous underwater vehicle (AUV) for developing various underwater core technologies (Li et al., 2010). Compared to the relatively mature torpedo-type AUV technologies (Prestero, 2001; Marthiniussen et al., 2004), few commercial hovering-type AUVs have been presented so far. This is partly because some of underwater missions of hovering-type AUV can be carried out through ROV (Remotely Operated Vehicle) system. But the most important reason is of less mature core technologies for hovering-type AUVs. To carry out its underwater task, hovering-type AUV may need capable of accurate underwater localization, obstacle avoidance, flexible manoeuvrability, and so on. On the other hand, because of limitation of present underwater communication bandwidth, high autonomy of an AUV has become one of basic function for hovering AUVs (Li et al., 2010). As a test-bed AUV, P-SURO has been constructed to develop various underwater core technologies, such as underwater vision, SLAM, and vehicle guidance & control. There are four thrusters mounted to steer the vehicle's underwater motion: two vertical thrusters for up/down in the vertical plane, and 3DOF horizontal motion is controlled by two horizontal ones, see Fig. 1. Three communication channels are designed between the vehicle and the surface control unit. Ethernet cable is used in the early steps of development and program/file upload and download. On the surface, RF channel is used to exchange information and user commands, while acoustic channel (ATM: Acoustic Telemetry Modem) is used in the under water. A colour camera is mounted at the vehicle's nose. And three range sonar, each of forward, backward and downward, are designed to assist vehicle's navigation as well as obstacle avoidance and SLAM. An AHRS combined with 1axis Gyro, 1-axis accelerometer, depth sensor consist of vehicle's navigation system. In this chapter, we report the details of to date development of the vehicle, including SLAM, obstacle detection/path planning, and some of vehicle control algorithms. The remainder of this chapter is organized as follows. In Section II, we introduce the vehicle's general specifications and some of its features. Underwater vision for P-SURO AUV is discussed in Section III, and the SLAM algorithm in the basin environment is presented in Section IV. In Section V, we discuss some of control issues for P-SURO AUV. Finally in Section VI, we make a brief summary of the report and some future research issues are also discussed.