The Tri-Dog 1 AUV was developed as a shallow water test bed for operations close to structures. It is equiped with six thrusters to independently control surge, sway, heave and yaw motion. The Fiber Optical Gyro (FOG) measures heading angle and rate, and the Doppler Velocity Log (DVL) reads ground speed. The AUV also has Attitude Heading Reference Sys-tem (AHRS) and depth meter for motion compensation and navigation. The AUV has four obstacle avoidance sonars, one profiling sonar and one light-section ranging system.
Directivity of the obstacle avoidance sonars is about 20deg and its resolution is 0.01m. Coverage is set to be 5m. Frequency of sampling is 4Hz. The profiling sonar has directivity of about 2deg with a resolution of 0.01m. It mechanically scans 360deg on a horizontal plane with a step size of 2.4deg. Coverage is set to be 40m and rotation period is about 17sec. The light-section profiling system consists of a TV camera and a sheet laser device, providing continuous shape of target structures by light-sectioning.
There are three TV cameras onboard. Cam1 is mounted on AUV’s nose directing forward, Cam2 is on its left. Cam3 is mounted on its bottom looking forward with 55deg depression. As well as being an observation tool Cam2 is also a component of LS and to enhance its performance it is mounted with 20deg elevation. There is another sheet laser device on AUV’s nose, looking downward with the laser plane orthogonal to surge direction for bathymetry mapping.