Fault-tolerant control of dynamic positioning vessel by means of a virtual thruster

This paper presents a method for on-line reconfiguration of fault-tolerant control to dynamic positioning (DP) vessel by means of a virtual thruster after the occurrence of thruster failures. First, a brief review of the main idea of a virtual actuator is presented. Then a suitable linear state-space model of DP vessel is derived which consists of motions in 3 DOF. A virtual thruster design is finished which combines with virtual actuator and DP vessel model. The reconfiguration block of virtual thruster generates suitable inputs for the faulty vessel based on the output of the nominal controllers. At last, the feasible and effective of this method are demonstrated by a simulation of a DP vessel.