**6. References**

16 Will-be-set-by-IN-TECH

(a) Submerge and Float up (b) Submerge Only

From Fig.21(a) and Fig.21(b), we can see, the experimental results does not fit well with simulation results very well, errors exceed 100%. When we analyze the reasons, we find that, the simulation experiment does not consider the variation of water pressure. The control voltage to the thrusters is 7*V* as a constant. That means, the propulsive force will not change. But with the increasing of depth, water pressure increases. As a result, the effective propulsive

We let the vehicle rotate about 90*<sup>o</sup>* then stop. From Fig.22(a) and Fig.22(b), the maximum error between simulation results and experimental results happens at about 2.8*s* where is nearly the maximum angular velocity. The reason of this result is that, we simplified the model of our vehicle, especially the hydrodynamic damping forces. Only linear damping force and quadratic damping force are taken into account in our case. But in the real experiment, there are many other velocity related hydrodynamic damping forces, therefore, when the angular

(a) Angular Velocity of Yaw (b) Angle of Yaw

In this paper, we proposed a spherical underwater vehicle which uses three water-jet propellers as its propulsion system. We introduced the design details of mechanical and

velocity increasing, the damping effect of ignored forces become obvious.

step 2. Move downward in Z axis for about 7*s* ;

Fig. 21. Experimental Results of Vertical Motion

force are weaken by water pressure.

Fig. 22. Experimental Results of Yaw

**5. Conclusions**

electrical system.

**4.3 Experiment of yaw**

step 3. Stop the vehicle.


**2** 

**Development of a Hovering-Type Intelligent** 

**Autonomous Underwater Vehicle, P-SURO** 

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

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 1-

axis 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.

**1. Introduction** 

of basic function for hovering AUVs (Li et al., 2010).

Ji-Hong Li1\*, Sung-Kook Park1, Seung-Sub Oh1, Jin-Ho Suh1,

Gyeong-Hwan Yoon2 and Myeong-Sook Baek2

*1Pohang Institute of Intelligent Robotics* 

*2Daeyang Electric Inc. Republic of Korea* 

