ICTINEU-AUV was designed for the SAUC-E competition held in London in 2006. Since then, it has been used as a research testbed for inspection tasks close to the sea bottom or artificial structures like dams, harbours or later tanks. In these applications, manoeuvrability is certainly an important issue.
Mechanical Design
The main design principle of ICTINEUAUV was to adopt a cheap structure simple to maintain and upgrade. For these reasons, ICTINEUAUV was designed as an open frame vehicle. The robot is actuated by four thrusters. It can move in the vertical and transversal directions depending on the composition forces generated by the vertical thrusters. On the other hand, horizontal thrusters are used to move forward (surge DOF) as well as to change the heading (yaw DOF). Hence, the prototype is a fully actuated vehicle in four DOF (surge, sway, heave and yaw), while being passively stable in Rol l and Pitch DOFs (its meta-centre is above the centre of gravity) .
The robot’s chassis is made of Delrin material. Three pressure vessels are used to hold the electronics. The two bigger cylinders are made of aluminium while the smaller one is made of Delrin. One of the cylinders contains the computers, another the thruster controllers and batteries, and the last contains the Motion Reference Unit (MRU). The thrusters were built using MAXON DC motors (250 Watts) with planetary gears and are contained in stainless steel housings. Brass propellers are linked to the motor by a stainless steel shaft providing around 14.7/14.2 newtons of forward/backward thrust. Buoyancy is provided by technical foam located on the top with 10.5 litres of volume and a weight of 0.6 Kg.
Computer Module
Two PCs, one for control and the other for image and sonar processing, are connected through a 100 MBs switch, in the core of the robot hardware. The control PC is an AMD GEODE-300MHz PC-104 form factor powered by a 50 W power supply module. The PC104 stack also incorporates an A/D and digital I/O card with 8 analogue input channels, 4 analogue output channels and 24 digital I/O. The vision computer is a mini- ITX Via C3 1 GHz Pentium clone used to process the data from the imaging sonar and the video cameras. A cheap PCTV110 from Pinnacle is used as a frame grabber.
Power Module
The power module contains four power drivers for the thrusters as well as a pack of 2 inexpensive, sealed lead-acid batteries which have been dimensioned to provide an autonomy of 2 hours. In addition, the vehicle can also be supplied with external power through an optional umbilical cable for long term work in ROV mode. These two power modes are commuted by a simple relay circuit. Finally, a DC-DC converter is included to provide a stabilised voltage to the rest of components.
Sensor Suite
The vehicle is equipped with a complete sensor suite composed of a forward-looking colour camera, a downward-looking B&W camera, a Motion Reference Unit (MRU) MTi from XSens Technologies, a Miniking imaging sonar from Tritech, a smart echo sounder from Airmar, a hydrophone and an Argonaut Doppler Velocity Log (DVL) from Sontek including a compass/tilt sensor, a depth sensor and 3 altimeters. Temperature, pressure and water leak sensors are installed inside the pressure vessels for safety purposes.
