Nonlinear differential and integral sliding mode control for wave compensation system of ship-borne manipulator

Zhiqiang Xu,Zhixin Shen,Yougang Sun,Zhiyong Wang

doi:10.1177/0020294020944956

Abstract

Ship-borne manipulator system is extremely unstable under the complex marine environment, which seriously threatens the safety of operating equipment and operators. In this paper, the dynamics and robust control of wave compensation system for ship-borne manipulator are studied. First, based on the oil circuit variable amplitude control of ship-borne manipulator, the coupling dynamic model of valve-controlled cylinder parallel accumulator is established. Then, since traditional sliding mode needs high-order derivative of feedback angle, it is difficult to implement traditional sliding mode in real hardware system. To solve these problems, a nonlinear differential and integral sliding mode control strategy is proposed. The integral term is introduced to reduce the influence of unmodeled disturbance and parameter perturbation. The stability analysis proves that the system state can track the desired target signal, and the tracking error e( t) tends to zero. In addition, in order to weaken the phenomenon of system chattering, this paper introduces a nonlinear differential control to increase the damping coefficient of the system. The simulation and experimental results show that the control law has good dynamic performance, high control accuracy, and strong anti-disturbance ability without chattering phenomenon. It is of great significance to improve the efficiency and safety of ship-borne manipulator operation, and this paper also provides useful reference for wave compensation system of other marine equipment.

Highlights

Ship-borne manipulator system is the most important tool for marine cargo trans-shipment and salvage.1–4 As shown in Figure 1, it can greatly reduce manual labor, improve operational efficiency, and achieve safe production
Sun et al.7 proposed a double-layer sliding mode control law to eliminate the influence of the sea condition on the cargo sway
The controller outputs have high-frequency oscillation, which is called chattering, the chattering phenomenon can be reduced significantly with nonlinear differential and integral sliding mode controller (NDISMC). These results show that the proposed improved sliding mode controller is robust facing external disturbances and parameter perturbations

Summary

Introduction

Ship-borne manipulator system is the most important tool for marine cargo trans-shipment and salvage.1–4 As shown in Figure 1, it can greatly reduce manual labor, improve operational efficiency, and achieve safe production. In order to address the problem of non-existence of the feedback variable high-order derivative, a nonlinear differential and integral sliding mode control strategy is proposed to compensate disturbance of waves.

Results

Conclusion