An Approach to QP-based Thrust Allocation considering Inflow

One essential subtask in Dynamic Positioning is the optimal thrust distribution onto all available propulsors - the thrust allocation. Current thrust allocation algorithms support a variety of different propulsor types, but usually only under bollard pull conditions, hence ignoring water inflow. However, there are marine control tasks in which severe relative motion through water is present. In such conditions zero-inflow models may suggest wrong thrust vectors, which may lead to degraded positioning performance. In this paper an approach for dynamic thrust allocation is presented that utilizes available information on water inflow. The method is inspired by stochastic optimization and uses a set of achievable thrust points to construct convexified constraints for an underlying Quadratic Programming optimization algorithm. The workflow of the proposed method as well as simple simulations are shown on the example of thrust generation with cycloidal propellers. Copyright (C) 2021 The Authors.