Constrained fault-tolerant thrust allocation of ship DP system based on a novel quantum-behaved squirrel search algorithm

Abstract

The thrust allocation (TA) of ship dynamic positioning (DP) systems is to determine the desired thrust force and direction of each thruster of a ship such that all the thrusters jointly produce the generalized control forces commanded by DP controllers. Thruster faults inevitably occur because thrusters operate in the complex ocean environment for a long time. In addition, due to physical limitations of thrusters, the desired thrust force and direction of thrusters both have magnitude and rate constraints. In the presence of loss-of-effectiveness (LOE) faults as well as magnitude and rate constraints of thrusters of ships, the TA of their DP systems can be formulated as a constrained fault-tolerant optimization problem. This paper creates a novel quantum-behaved squirrel search algorithm (QSSA) by combining the squirrel search algorithm with a quantum Delta potential well model, and whereby solves this constrained fault-tolerant TA optimization problem. Simulation studies on a scale model supply ship verify the effectiveness of the QSSA-based constrained fault-tolerant TA of the DP ship under thruster LOE faults.