Model Predictive Control of a Shipborne Hydraulic Parallel Stabilized Platform Based on Ship Motion Prediction

Hongbin Qiang,Xinyu Feng,Dapeng Xue,Song Jin,Lijie Zhang

doi:10.1109/access.2020.2992458

Hongbin Qiang, Xinyu Feng + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.2992458

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Abstract

Shipborne stabilized platform is an important equipment to ensure the stability of shipborne equipment relative to inertial coordinate system. This paper presents a model predictive control strategy based on ship motion prediction (MPMPC) for ship stabilization platform. Firstly, the ship motion is simulated, and the autoregressive prediction model (AR model) is used to predict the ship motion. Then the kinematics analysis of the Shipborne stabilized platform is carried out and the mathematical model of the hydraulic drive unit (HDU) of the stable platform is established. Then the predicted ship motion is combined with model predictive control (MPC). The predicted trajectory of HDU can be obtained by the kinematics calculation of predicted ship motion. One part of the predicted trajectory is used to compensate the time delay of HDU, and the other part is used as the reference trajectory of the rolling optimization of MPC, instead of the reference trajectory using the measured ship motion at the current moment in traditional model predictive control. Compared with the reference trajectory using the measured ship motion at the current moment, the predicted trajectory of AR model can reflect the future state of the system better, and a better control sequence will be obtained by minimizing the objective function. Finally, the simulation and experiment show that the MPMPC has higher tracking accuracy than traditional MPC.

Highlights

In the actual marine environment, due to the action of wave, current, wind and other environmental factors, a ship constantly generates the movement of six degrees of freedom including surge, sway, heave, roll, pitch and yaw, and the motion of each degree of freedom has certain regularity and prediction [1]
Many scholars have studied ship motion prediction based on AR model [2], [3], neural network [4], [5], grey theory [6] and other methods
Essa et al [21] studied the application of model predictive control (MPC) for high force control precision in a real industrial electro-hydraulic servo system (EHSS), and the results showed that the performance of MPC controller is VOLUME 8, 2020 considerably improved compared with the traditional and fractional order controllers

Summary

INTRODUCTION

In the actual marine environment, due to the action of wave, current, wind and other environmental factors, a ship constantly generates the movement of six degrees of freedom including surge, sway, heave, roll, pitch and yaw, and the motion of each degree of freedom has certain regularity and prediction [1]. Compared with the reference trajectory using the measured ship motion at the current moment, the predicted trajectory of AR model can reflect the future state of the system better, and a better control sequence will be obtained by minimizing the objective function. The stability analysis of closed-loop MPC system based on state observer is as follows: The optimal control sequence U is obtained as. Compared with the reference trajectory R using the value of r(k), AR predicted trajectory RAR can reflect the future state of the system better, and a better control sequence U can be obtained by minimizing the objective function JAR, and has higher tracking accuracy. The eigenvalues of the closed loop MPMPC system remain the same as those of the traditional closed loop MPC system, i.e. the stability of the system remains the same

SIMULATION VERIFICATION

SIMULATION AND EXPERIMENT OF YDRAULIC PARALLEL STABILIZED PLATFORM