基于运动路径靶标的空间机器人视觉标定方法

Space Robot Vision Calibration with Reference Objects from Motion Trajectories

  • 摘要: 针对空间缺少标定靶标物的难题,基于空间机器人机械手的精确末端定位能力,提出了一种通过规划机械手运动路径生成靶标从而实现在轨视觉标定的方法.首先介绍了视觉标定方法的总体框架.然后对该标定方法进行了误差分析,根据棋盘靶标标定误差与控制点图像坐标误差满足线性关系的先验知识,推导了从机械手末端定位到控制点图像坐标的误差传递关系,并对两类误差进行合成得到了等效的控制点图像坐标误差.最后利用仿真实验验证了标定误差与等效误差满足线性关系,分析了靶标尺寸、相对距离、控制点密度和靶标结构因素对标定精度的影响.

     

    Abstract: For lack of reference objects in space, an on-orbit vision calibration method is proposed based on the precise localization of manipulator end of space robot, which generates reference objects through programming motion trajectories of the manipulator. Firstly, a general framework of the method is introduced. Secondly, error analysis is applied to the calibration method. According to the prior knowledge that the calibration error of the chessboard target is linear to the image coordinate error of the control point, the error transfer from localization of manipulator end to the image coordinate of the control point is derived, and an equivalent error of the image coordinate of the control point is further derived by the combination of the two kinds of errors. Finally, the linear relationship between the calibration error and the equivalent error is validated by simulation experiments, and the effects of reference object size, relative distance, control point density and structure factors on the accuracy of the proposed vision calibration method are analyzed.

     

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