Tow-Body Control System Modeling and Tuning on a Real-World Vehicle

This paper presents a model-based approach for developing a stable, robust control system for a shallow water survey towfish. A model of the towfish system was developed based on experimental data from open-water operations. This model was then implemented in Simulink and a Bode analysis was performed on the open loop transfer functions. Once the desired phase margin crossover frequency was achieved, the system was run in Simulink to ensure the performance of the system met overshoot and stability requirements. Finally, the improved gains were tested in open water sea trials in Bedford Basin and the nearby open water. Both improved gain sets resulted in better performance that the original baseline gain set and have been demonstrated to meet the requirements for high quality Synthetic Aperture Sonar imagery and SeaVision™ 3D laser imaging. These control system improvements have since been implemented on systems worldwide as part of Kraken Robotic Systems’ ongoing product support and operational improvements were realized immediately in the field.