ADAPTIVE THRUSTER ALLOCATION AND INTEGRATED PERFORMANCE EVALUATION FOR DYNAMIC POSITIONING OF SEMISUBMERSIBLE DRILLING UNITS

Thruster allocation significantly affects the power consumption and operational efficiency of dynamic positioning (DP) systems on semisubmersible drilling units. This paper presents an adaptive thruster allocation model that continuously updates power coefficients based on measured consumption, integrated with a complete DP simulation framework. The allocation problem is formulated as a constrained optimization minimizing total power subject to force and moment requirements. Three allocation methods are compared: 
•    Pseudo-inverse allocation, 
•    Power-optimized allocation with fixed coefficients, and 
•    Adaptive allocation with online coefficient updates. 
Results show that the adaptive allocation achieves 14.7% power saving compared to pseudo-inverse and 5.9% compared to fixed-coefficient optimization. Thruster utilization ranges 42–55% for adaptive allocation versus 38–62% for pseudo-inverse, indicating more even load distribution. Average thruster efficiency improves to 0.158 kN/kW from 0.142 kN/kW (11.3% improvement). When integrated with an adaptive controller, the complete system achieves 4–19% total power reduction compared to conventional PID control, with cumulative savings of 1,620 kWh over a 1-hour simulation. Power demand variation is reduced (std = 580 kW vs. 740 kW for PID), reducing stress on power generation systems. The results demonstrate that adaptive thruster allocation provides significant operational cost savings and reliability improvements for deepwater drilling operations.