基于双屏视觉标靶的掘锚机机身位姿测量技术

Position and orientation measurement technology for bolter miner body based on dual-screen visual target

针对掘锚机在煤矿巷道掘进过程中难以实现机身位姿的实时精确测量,进而导致难以实现定向掘进的问题,提出一种基于双屏视觉标靶的掘锚机导向方法。由2块竖直安装的感光成像屏组成双屏视觉标靶靶面,巷道中的激光器发射指示激光并在前、后靶面上呈现光斑,利用视觉测量、高精度栅格标定等技术,建立光斑质心的图像坐标与三维空间坐标的映射关系,以形成坐标点云数据;再根据栅格索引、坐标变换、欧拉角解算等原理,结合标靶底部的双轴倾角仪来获得掘锚机机身的实时位姿,并解算出机身关键点相对于巷道设计轴线的横向/纵向偏差,为掘进过程中的偏差纠正提供数据支撑。通过构建数学模型对系统脱靶问题进行了分析,同时搭建实验平台验证了该导向方法的有效性。实验结果表明:该方法能够实现机身六自由度空间位姿的精确测量;在9 m测试距离下偏航角重复性测量精度优于0.01º、偏航角绝对测量误差小于0.05º;在15~40 m测量范围内,用全站仪与矿用激光器设置计划线时机身关键点横向/纵向偏差测量误差分别小于5、15 mm。基于该方法研发的导向系统已成功应用于煤矿井下巷道掘进中,满足了巷道施工与掘锚机机身定位的精度要求。该导向方法的误差特性与测试距离无关,且该方法中涉及的所有光学测量功能均在标靶内部实现,可有效屏蔽井下复杂环境对测量功能的影响,大幅提升了现场应用时的抗粉尘干扰能力。

Aiming at the problem that it is difficult to achieve the real-time and accurate measurement of the bolter miner’s position and orientation during the excavation process in coal mines,which leads to the difficulty in achieving directional excavation,a guidance method for bolter miner based on dual-screen visual target is proposed.Using two vertically in-stalled light-sensitive imaging screens to form the dual-screen visual target surfaces and the indication laser emitted by the laser instrument presents light spots on the front and rear target surfaces.Combining with the visual measurement,high-precision raster calibration and other technology are applied to establish the mapping relationship of the spot centroid between 2D-3D coordinates,which is used to form the point cloud data of the coordinates.Based on the principle of grid indexing,coordinate transformation and Euler angle solving,combining with the biaxial inclinometer at the bottom of tar-get to obtain the bolter miner body’s real-time position and orientation,the key points’horizontal/vertical deviations relat-ive to the roadway axis are calculated,which can provide data support for deviation correction during the excavation pro-cess.The off-target problem of the system is analyzed by constructing a mathematical model.Meanwhile,the effective-ness of the guidance method is verified by building an experimental platform.The experimental results indicate that this method can achieve a precision measurement of six-degrees-of-freedom spatial pose for the machine body.When the measurement distance is 9 m,the repeatability measurement precision of the yaw angle is better than 0.01ºand the error of absolute measurement is less than 0.05º.Within the measurement range of 15−40 m,which uses the total station and min-ing laser to set the planning line,the measurement errors of key points’horizontal/vertical deviations are less than 5 mm and 15 mm,respectively.The guiding system developed based on this method has also been successfully applied to the un-derground roadway excavation in coal mine,which fully meets the requirements of underground roadway excavation and the positioning of the machine body’s key points.The error characteristic of the guiding method is independent of the test distance.Also,all optical measurement functions involved in the method are realized inside the target,which can effect-ively shield the influence of the underground complex environment for the measurement function,and greatly improve the capacity of anti-dust interference in field application.