2009 Seawolf III Journal Paper

Seawolf III is our latest competition AUV. The idea for SW3 was to build a modular, expandable and cost-effective vehicle. The frame is built with 80/20 aluminum stock for durability and easier mounting options. Each thruster mount and accessory are attached to the vehicle along the integrated T-slots, allowing for quick thruster repositioning in the field. All of the electronics sit inside of a medium-sized waterproof Pelican case - The electronics are easily accessible without the need to disassembe the craft like other competition vehicles.

Frame
Seawolf III's frame is composed of 80/20 extruded aluminum with integrated T-slots. The thruster mounts, camera enclosures, electronics case and dropper assembly can all be relocated within seconds by loosening the bolts and sliding the unit along the T-slots.

Electronics
The Pelican case houses all of Seawolf's electronics. Currently, we are using a Lenovo Netbook (temporary replacement) in place of a smaller form factor PC-104. The Netbook sports an Intel Atom single-core processor running a stripped version of Debian Linux. All of the external components interface to the Netbook via USB and ethernet.

Embedded Controllers
The Netbook communicates with external microcontrollers to interface with the thrusters and various sensors. Specifically, we have implemented Arduinos, a community-driven open source microcontroller platform based on the Atmega uC. The custom Arduino boards are equipped with on board FTDI USB to Serial controllers which are used as the primary communication channel with Netbook.

Vision
Seawolf uses three Logitech CCD webcams in custom waterproof enclosures for vision. One camera is oriented forward, the second is oriented downward to aid with the bombing run, and the third camera looks towards the surface. Each camera is connected to the netbook which runs both Intel's OpenCV library and custom written software for vision processing. The custom functions are derived from OpenCV's library, but are customized for improved performance.

Acoustics
The acoustics system is composed of three sub-systems, an ADC, FPGA and Blackfin DSP. All three boards are part of a Blackfin evaluation kit provided through a sponsorship by Analog Devices. The ADC continuously grabs hydrophone data samples and passes them to the FPGA which downsamples and buffers them in memory. The Blackfin grabs the data, runs a filtering scheme and calculates a target heading which is passed over to the Netbook via an ethernet interface.