High Order Sliding Mode Control and Observation for DP Systems

Sliding Mode Controllers (SMC) are a robust and simple strategy suitable to mechanical systems subject to structured disturbances. Such characteristics make them an interest solution as control algorithms for Dynamic Positioning Systems, providing enhanced trajectory tracking capacities even during transients. The trade-off is usually a limit in accuracy, due to smoothing methods required to reduce control chattering. This work proposes the usage of a Second Order SMC method, named Super-Twisting control as an alternative for the application of SMC in DP Systems. This algorithm provides high accuracy and robustness while eliminating chattering. The solution is completed with the introduction of a High Order Sliding Mode Observer, which performs wave-filtering, velocity and drift estimation. The controller-observer structure is tested in a high fidelity marine simulation environment, producing results that confirm the performance of the system.