Research On Docking Process Based On ADRC Control Strategy For Air Cushion Vehicle

The rapid development of science and technology has led to more intense competition of marine resources,so the high performance ships emerge as the times require. Air cushion vehicle (ACV) has been focused on civil and military fields with its characteristics of high speed, amphibious and good seakeeping etc. But ACV consumes the fuel quickly, it usually is loaded in dock landing ship to complete the task of remote sea area, thus the research of docking process of ACV is necessary. Currently the docking process of ACV is manually operated and the external facilities easily damaged by collisions. Therefore, according to the mechanism of ACV sailing, this paper designs a control strategy for ACV docking, which aims to ensure the ACV safely and accurately.In this paper, active disturbance rejection controller (ADRC) is the core controller in ACV docking because of its ability that does not depend on accurate model in controlled object. The docking process is divided into two consecutive steps: the first is docking guidance process, based on the algorithm of way-point tracking to complete the path planning for ACV; the second is docking control process, based on the cross-track control to finish the docking process, and there needs to control the speed and heave position of ACV during the second step. The specific research process is as follows:Firstly, the fixed and body coordinate system are established and the conversion method of the two coordinates is described in order to complete the kinematics model for ACV. Then the force and moment of each part of the ACV is analyzed by the method of separation, so the six degree of freedom differentia equations can be established by superposition principle. In the end the established model of ACV is verified by direct and rotary simulation.Secondly, the ADRC of docking process is introduced in detail. With the principle of separation the ADRC is divided into four parts: tracking differentiator (TD), extended state observer (ESO), nonlinear state error feedback law (NLSEF) and linear dynamic compensation. At last, the simulation experiment of the course control for ACV is carried out by changing the parameters of each part. From the results we can know the influence of each parameter on the control system for ACV.Then, the control strategy of the docking guidance process is designed, and the path of the guidance process is determined by the way-point guidance algorithm. This section mainly includes the introduction of genetic algorithm and the method of setting the key parameters for ADRC. And the path control and way-point tracking control is completed by the ADRC guidance controller.Finally, the control strategy of the docking control process is designed. The cross-track control based on virtual course is used as the control algorithm for this stage. This section designs the module of speed control and heave control, pitch angle can be controlled to complete reduction process of ACV and setting desired cushion pressure to ensure the heave position stably. Both of them aim to meet the requirements of the docking process. Above of all, combined with the two consecutive steps of docking process, the whole process is completed by ADRC for ACV automatic control.