Research On Vision Driven Control Method Of UUV Approaching Target

UUV approaching operation target at close range is the premise for UUV to undertake underwater operation tasks,UUV mainly uses the binocular vision system to obtain pose feedback information in the process of approaching target.To this end,this paper carries out the study on vision-driven control methord of UUV approaching target.This paper takes Z UUV as the research object.The geodetic coordinate system and the hull coordinate system are established;The kinematics model and dynamic model of ZU UUV are deduced according to the knowledge of kinematics,the momentum theorem and the momentum moment theorem respectively;the hydrodynamics,gravity,buoyancy and propulsion thrust are analysed.The pose feedback informatiion that guides UUV approaching target is constructed.The pose feedback information is divided into relative pose information and secondary pose feedback information.The secondary pose feedback information is obtained directly through the inertial navigation system,and the relative pose information is the main pose feedback information in the process of UUV approaching the target,which is obtained indirectly through the binocular vision system.In order to obtain relative pose information,firstly,this paper introduces the structure,working process and fitting scheme of binocular vision system.Secondly,this paper introduces the camera imaging model and Zhang Zhengyou calibration method.Thirdly,the relative pose information and its image characterization method are introduced in detail.Finally,the formula of relative pose information is deduced based on the camera imaging model and the characterization of relative pose information.The visual servo controller is designed according to the pose feedback information that guides UUV approaching target.At first,the PD controller is designed in the ideal situation,and the PD controller is proved to be correct and valid by the simulation experiment,thus proving the correctness and validity of the pose feedback information.Then,for a real underwater operating environment with large external disturbance,based on the assumption that the upper and lower bounds of the disturbance are known,a robust sliding mode controller based on reaching law is designed.Simulation is performed in the same simulation experiment scenario as the PD controller’s.The simulation results show that under the control of the sliding mode controller,the UUV can accurately approach the specified position,maintain the specified relative attitude with the operating target,and the dynamic quality is good,thus proving the validity of the sliding mode controller.In order to verify the correctness of the relative pose information formula,a UUV binocular vision simulation experiment system is built,and the experiment of obtaining relative pose information of the operation target is designed.Firstly,the binocular vision simulation system is calibrated by Zhang Zhengyou calibration method.The calibration results show that the binocular vision simulation system can fulfil the requirements of fitting scheme.Then,based on the calibration experiment,the experiment of obtaining the relative pose information of the operation target is performed.Based on the acquired image features,the relative pose information is calculated by relative pose information formula,and the results are compared with the actual relative pose information.Within the tolerance of error,the experiment verifies the correctness of the relative pose information formula.