| The underwater vehicle with cable remote control has the characteristics of long endurance and strong working ability,so it has become the most widely used underwater vehicle in ocean engineering.It can be used in safety search and rescue,underwater bridge and pipeline inspection,hull and drilling platform maintenance,underwater entertainment,scientific research and teaching,underwater archaeology and other industries.In order to achieve the good performance of the underwater robot,it is necessary to obtain its hydrodynamic coefficient and carry out motion control research,evaluate the hydrodynamic performance of the robot,and provide theoretical guidance for the follow-up research and design.In this paper,a kind of underwater detection robot is developed for underwater detection task.The first-order hydrodynamic coefficient is calculated and its motion control is predicted.The specific work is as follows:First of all,according to the underwater task,based on the modular design concept,the system composition of the flaw detection ROV is determined.And the key equipment selection,material selection of each component and the determination of each installation and fixation mode are completed.Relying on the Three-dimensional Modeling Software Solidworks,the three-dimensional drawings of each component,structural strength analysis and the assembly of the overall virtual prototype are completed.And the assembly body is also completed calculate and adjust the center of gravity and center of buoyancy.Secondly,the geodetic coordinate system and the following coordinate system of the underwater robot are established,and the coordinate transformation equation is given.Based on the premise assumption of "quasi steady motion" of the rigid body,combined with the characteristics of the robot's own structure,the rigid body motion and the hydrodynamic force of the underwater robot are described in detail respectively.According to the spatial motion equation of the common underwater robot,a four degree of freedom motion simulation mathematical model and motion control model for the underwater flaw detection robot are established.Then,based on FINE/Marine software platform,the hydrodynamic force and hydrodynamic moment of the robot are solved by numerical simulation.According to the established dynamic model of the underwater robot,the outgoing hydrodynamic coefficient is solved by MATLAB software.This paper discusses the influence of different time periods on the calculation results of hydrodynamic coefficients,and provides an effective calculation method for the acquisition of hydrodynamic coefficients of open frame complexunderwater vehicles.Finally,the hydrodynamic coefficient identified by MATLAB software is introduced into the established ROV simulation mathematical model,and the simplified dynamic equation is solved by MATLAB software programming.By giving different propeller speeds,the simulation curves of the robot's three main axes,horizontal plane motion ability and rotation motion are given.Based on the simulation platform of Simulink control and the traditional PID control technology,the depth displacement curve and heading angle displacement curve are obtained.It lays a reliable foundation for the maneuverability simulation and prediction of the complex underwater vehicle,and provides some basis for the subsequent control system design. |
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