Development and characterization of a side scan sonar towfish stabilization device

The attitude of a side scan sonar towfish may introduce artifacts into the imagery when the towfish attitude exhibits a significant mean offset from horizontal and/or exhibits significant variations over time. The Smart Tail was designed by Boeing Australia for stabilizing the attitude of a Klein System 5000 towfish. This report describes the development and testing of a closed-loop controller for towfish attitude based on the Smart Tail's movable elevators. Transient and steady state response of the towfish pitch and roll motion were evaluated in a tow tank at speeds up to 6 knots. Mathematical modeling and simulation were used to design and build a PD controller for the Smart Tail. Performance of the towfish/Smart Tail assemblage was evaluated via an instrumented field test conducted in a typical seaway. This study concludes that closed-loop active control of a side scan towfish is feasible using controllable elevators.