Adaptive dynamic control allocation for dynamic positioning of marine vessel based on backstepping method and sequential quadratic programming

It is generally assumed in dynamic positioning of over-actuated marine vessels that the control effectiveness matrix (input matrix) is known and constant, or, in case of fault information, it is estimated by the fault detection and diagnosis system. The purpose of the study is to develop the adaptive dynamic positioning control system for an over-actuated marine vessel in the presence of uncertainties and with emphasis on limited information about thruster forces. The proposed approach bases on the MIMO adaptive backstepping method to design the high-level control law and then to give inputs to the control allocation unit. An adaptive solution allows to accommodate the unknown time-varying control effectiveness matrix and to update the thrust distribution due to actuator losses and failures. The effectiveness and correctness of the proposed control schema is demonstrated by simulations involving a redundant set of actuators when some of them have lost partially their efficiency or failed. The evaluation criteria include energy consumption, robustness and accuracy of dynamic positioning during typical vessel operations. Based on simulation tests results, the generated control inputs stabilize the ship position and orientation violated by thruster faults.