Title: Coupling a Standard Hydraulic Valve and Advanced Control to Achieve a Motion Compensation System
Author(s): Jeff Woodacre, Woles Wahidi, Robert Bauer and Rishad Irani
Abstract: The work highlights how a standard hydraulic valve can be coupled with a model-predictive controller (MPC) to achieve active-heave compensation. The system contains a common hydraulic proportional valve where the hysteresis, dead-band and non-linear properties have been overcome to control a radial piston motor that emulates an unloaded winch. Additionally, the MPC controller uses a set-point prediction algorithm and the results are compared to a tuned Proportional-Integral-Derivative (PID) controller operating the same test setup. Furthermore, a MATLAB Simulink model of the experimental setup is created and, within the simulator, a load is applied to the winch to test how the MPC and PID performance compare under loaded operating conditions. The MPC system is found to track a variety of test cases and references while outperforming the tuned PID controller. When high frequency components were added the to the reference signal, the MPC is able to maintain an acceptable level of accuracy, while the PID performance decreases dramatically with the addition of these high frequency components. It was found that, with constant parameters for the MPC and PID systems, the MPC was more robust for a wide range of operating conditions. As a result of this work, it is foreseen that the MPC controller and the signal modifiers have the potential to replace complex hydraulic circuits or components for a wide range of marine applications. The implementation could be used as an add-on to a standard winch to achieve active heave compensation and even help to mitigate anti-pendulum/sway in future systems.