Research On The Measurement Method For The Spatial Structure Pose Of Hydraulic Support Based On Depth Vision

The real-time and effective monitoring of the spatial pose of the hydraulic support is an important prerequisite for the realization of automatic and intelligent mining of the working face.Aiming at the problems of traditional contact measurement of the current hydraulic support height and top beam attitude angles,such as the large number of sensors,large calculation errors,and poor visibility,this paper studies a measurement principle and method based on depth vision.By installing a depth camera on the top beam of the hydraulic support,using computer vision and image processing technologies,the real-time measuring of the support height and the azimuth angle,roll angle and pitch angle of the top beam is achieved.The research results of this paper mainly include the following aspects:(1)Firstly,the working conditions and poses of the hydraulic support in the actual work process are classified and analyzed.According to the characteristics of the change of the hydraulic support’s pose,the full spatial pose state of the hydraulic support is divided into two aspects:the overall pose and the structural pose.Then,according to the environmental characteristics of the working face and the needs of the spatial structure of the hydraulic support for pose measurement,comprehensively considering the measurement method,measurement dimensions,measurement accuracy and speed,etc.,a depth vision-based measurement principle and method for the support height and the top beam attitude angle parameters is proposed.(2)Based on the rigid body space transformation theory,a description method of the pose transformation of the spatial structure of the hydraulic support is proposed.By expressing the support height and the azimuth angle,roll angle and pitch angle of the top beam with a spatial four-dimensional vector L=[h,α,β,γ],and then using a method of combining translation matrix,rotation matrix and Euler angles,the pose transformation process between the camera coordinate system which is fixed on the top beam and the base coordinate system was analyzed,and the mathematical description of the pose and transformation process of the spatial structure of the hydraulic support was realized.(3)Based on the depth vision measurement technology,the visual measurement algorithm of the pose parameters of the spatial structure of the hydraulic support is studied.The algorithm mainly includes two parts:the initialization of the hydraulic support structure and the calculation of the structural pose parameters during the movement of the hydraulic support.Among them,the initial value of the hydraulic support structure pose initialization is mainly through the calibration of the depth camera,the alignment of the RGB map and the depth map,and the acquisition of the three coplanar point coordinates of the hydraulic support base plane to complete the initial value calculation of the support height and the top beam attitude angles.The calculation of the structural pose parameters of the hydraulic support during the movement process is achieved by visual odometry(VO),using the image ORB feature point extraction,feature point matching and optimization,and ICP pose calculation.(4)By building a four-degree-of-freedom system that simulates the movement of the top beam of the support indoors,the stability,reliability and accuracy of the algorithm in this paper were compared and analyzed.Then,taking the laboratory ZY12000/28/63 real hydraulic support as the experimental object,the hydraulic support structure pose parameter measurement experiment was carried out.The experimental results show that the average error of the support height measurement in this algorithm is 0.015 m,the average measurement errors of the azimuth angle,roll angle and pitch angle of the top beam are 0.25°,0.22° and 0.69° respectively,which can fully meet the measurement requirements for the pose parameters of the spatial structure of the hydraulic support in terms of accuracy.(5)Through the downhole field test,the feasibility of the spatial structure pose measurement method of the hydraulic support in this paper was further verified.At the same time,the movement process of the hydraulic support was described based on the time sequence,and the cause of the measurement disturbance during the actual work of the hydraulic support was analyzed preliminarily...