Thrust Ability Diagrams for Multi-Thruster Marine Vessels

For reliable fault-tolerant control, monitoring, and capability analysis of dynamically positioned vessel it is highly desirable to know the set of generalized force vectors possible to allocate between the thrusters in operation. Such a 3-dimensional set, referred as the Thrust Ability Diagram (TAD) may be quite complicated but is effectively approximated by unions of convex polytopes. In the present paper the methods of computation and visualization, as well as applications of TAD in the DP systems are discussed. We show that the calculation of TAD is a quite useful function of dynamic positioning system.