基于近红外双目立体视觉的悬臂式掘进机定位研究

Research on the cantilever roadheader positioning based on near-infrared binocular stereo vision

  • 摘要: 针对现有掘进机无法实时定位、定位不准确、视觉定位中相机视野被遮挡导致定位失败等问题,提出了一种将基于近红外双目立体视觉的悬臂式掘进机定位方案。在悬臂式掘进机机身与机臂安装近红外LED标靶,以LED作为近红外标靶构建掘进机特征信息,通过图像处理、位姿解算实现掘进机机身与截割部的三维空间定位。双目立体视觉相机安装在巷道顶部,随着掘进机不断推进,掘进机与双目立体视觉相机距离逐渐增加,造成双目图像获取失败,进而导致视觉解算截割部位姿失败。针对该问题,引入基于一维卷积神经网络(1D−CNN)的掘进机截割部磁场辅助定位方法。在掘进机机身两侧安装三轴数字磁场计,并在机臂处安装永磁体,以磁场的强度分量和双目立体视觉相机获取的位姿数据作为训练数据,构建1D−CNN模型,输出在视觉测量失效情况下掘进机截割部位姿。从深度信息和掘进机机身及截割部位姿2个方面对基于近红外双目立体视觉的悬臂式掘进机定位方案进行实验,结果表明:机身测量误差在±11 mm以内,相对误差在0.4%以内。截割部测量误差在±50 mm以内,相对误差在1%以内;掘进机机身与截割部间的相对位姿误差在±2.5°以内,俯仰角的均方根误差为根0.930 1°,偏航角的均方根误差为0.922 0°。上述误差在巷道作业允许范围内,验证了该方案的有效性和可靠性。对基于1D−CNN的掘进机截割部磁场辅助定位方法进行了有效性验证,为模拟井下复杂磁场环境,在掘进机附近随机添加干扰磁源,结果表明:该方法对掘进机截割部俯仰角、偏航角、翻滚角的预测值与测量的真实值基本吻合,预测的俯仰角、偏航角、翻滚角决定系数分别为0.992 4,0.995 9,0.917 4,说明基于1D−CNN的掘进机截割部磁场辅助定位方法能够较好地满足在视觉定位失效下的掘进机定位需求。

     

    Abstract: The existing roadheader has problems, such as unable real-time positioning, inaccurate positioning, and positioning failure caused by camera view occlusion in visual positioning. In order to solve the above problems, a positioning scheme of the cantilever roadheader based on near-infrared binocular stereo vision is proposed. A near-infrared LED target is arranged on the fuselage and arm of cantilever roadheader. Taking LED as the near-infrared target, the characteristic information of the roadheader is constructed. The three-dimensional spatial positioning of the roadheader fuselage and the cutting part is realized through image processing and pose calculation. The binocular stereo vision camera is arranged at the top of a roadway. The distance between the roadheader and the binocular stereo vision camera gradually increases as the roadheader continues to advance. It leads to the failure of binocular image acquisition, which leads to the failure of the visual solution of the pose of the cutting part. In order to solve this problem, a magnetic field assisted positioning method of the cutting part based on one-dimensional convolution neural network (1D-CNN) is introduced. Three-axis digital magnetometers are arranged on two sides of the fuselage of the roadheader. The permanent magnet is arranged on the machine arm. The strength component of a magnetic field and pose data obtained by binocular stereo vision camera are used as training data to construct the 1D-CNN model, and the pose of a cutting part of the roadheader is output under the condition that vision measurement fails. The cantilever roadheader positioning based on near-infraared binocular stereo vision scheme is tested from the aspects of depth information and its fuselage of the roadheader and the cutting position are verified. The results showed that the measurement error of the fuselage is within ±11 mm, and the relative error is within 0.4%. The measurement error of the cutting part is within ±50 mm, and the relative error is within 1%.The relative pose error between the roadheader fuselage and the cutting part is within ±2.5°, the root-mean-square error of the pitch angle is 0.930 1°, and the root-mean-square error of the yaw angle is 0.922 0°. The errors are within the allowable range of roadway operation. The results show that the cantilever roadheader positioning scheme based on near-infrared binocular stereo vision is effective and reliable. The effectiveness of the magnetic field assisted positioning method based on 1D-CNN is verified. In order to simulate the complex magnetic field environment in coal mine underground, the interference magnetic source is randomly added near the roadheader. The results show that the predicted values of the pitch angle, yaw angle and rolling angle of the cutting part of the roadheader by this method are basically consistent with the measured real values. The determination coefficients of the predicted pitch angle, yaw angle and rolling angle are 0.992 4, 0.995 9 and 0.917 4 respectively. It shows that the magnetic field assisted positioning method of the cutting part of the roadheader based on 1D-CNN can better meet the positioning requirements of the roadheader in the case of visual positioning failure.

     

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