Dynamic modelling and control of an active autonomous wing dock for subsurface recovery of AUVs
University of New Brunswick
The development of robust autonomous launch and recovery (L&R) capabilities for autonomous underwater vehicles (AUVs) would allow a massive broadening of AUV mission scope in all fields. As proposed by Defence Research and Development Canada (DRDC) Atlantic, this project is concerned with the creation of an active third-body autonomous docking system for recovery of AUVs to submerged submarines. This thesis defines the concept of a hydrodynamically actuated wing dock as one solution, and presents the research objectives and methods surrounding its analysis. The wing dock will employ active pitch control to produce lift for motion of the docking system. The recursive Newton-Euler equations of motion typical of manipulator kinematics are used to describe the wing dock. The procedure is modified to account for hydrodynamic forces and a passive rotational joint. A new model for hydrodynamic force distribution is developed to account for asymmetric lift distributions present during docking operations. A model predictive controller (MPC) is also proposed to handle the non-linear, state dependant responses of the end effector to pitch input. Instrumentation of an existing small-scale, partial fidelity prototype was improved and calibrated for testing conducted at DRDC’s Dartmouth facilities. Collected data supports the developed hydrodynamic force models, and confirms a wing is capable of the required end effector trajectories while under motion control by an MPC. Further data is available for validation of the developed forward dynamic simulations once they are complete. The current state of these simulations, recommendations for future work, and some performance observations conclude this thesis.