Objective In complex Marine environment, the vertical movement of ships often has a significant impact on the safety of offshore engineering operations. Active heave compensation devices can compensation for the vertical movement of ships, and all of its compensation commands need to be based on the vertical vessel attitude motion (roll, pitch,heave) as an input. Therefore, a ship attitude prediction method based on low-cost inertial measurement unit is proposed.

Methods Based on the mathematical model between quaternion and ship rotating motion, the linear acceleration of the ship when it is in the dynamic state is taken into account, and a virtual yaw measurement value is introduced, an ship attitude observer is designed. The extended Kalman filter algorithm is used to predict the ship attitude.

Results By simulation analysis and six-DOF platform experiments, and the prediction errors of the ship's roll angle and pitch angle are within 5%, which are comparable to the prediction errors of commonly used motion reference units. In addition, the method can also predict the relative change of yaw angle with an prediction error of no more than 8%, the analysis experiments under different sea conditions verified the accuracy and effectiveness of the ship attitude prediction method.

Conclusions The research results can provide high-precision ship attitude data for wave compensation equipment, enhancing the safety and efficiency of marine engineering operations.