基于标准圆柱的线激光轮廓扫描机器人手眼标定方法

A Hand-eye Calibration Method of Line Laser Profile Scanning Robot Based on Standard Cylinder

  • 摘要: 在搭载线激光轮廓传感器的机器人平台手眼标定问题中,依靠线激光轮廓传感器输出的2维点云信息进行标定,存在标定过程复杂、标定精度低的缺点。本文针对这些问题,提出一种基于圆柱侧面约束的手眼标定方法。通过改变扫描机器人末端位姿,获得不同位姿下圆柱侧面扫描数据。对于激光平面与圆柱侧面相交得到的椭圆轮廓,利用随机抽样一致性(RANSAC)算法得到椭圆轮廓中心点坐标。利用椭圆轮廓的估计中心点到圆柱中轴线的距离建立约束优化方程,将手眼标定问题转化为约束优化问题。利用粒子群优化(PSO)算法和广义拉格朗日乘子法的融合算法求解约束优化问题,得到手眼标定的变换矩阵。最后基于所提方法进行模拟仿真和扫描重建试验。分别讨论了标定数据误差、标定参照物位置和标定参数初始值对标定结果的影响,并验证了手眼标定精度。结果表明,该方法不受标定参照物位置和标定参数初始值的影响,具有操作简单、通用性强、标定精度高等特点,标定精度在0.15mm以内,适合现场标定。

     

    Abstract: For the hand-eye calibration problem of the robot platform equipped with a line laser profile sensor, the calibration relying on the 2D point cloud information output by the line laser profile sensor, is of disadvantages of complex calibration process and low calibration accuracy. To solve these problems, a hand-eye calibration method based on cylindrical side-face constraint is proposed. By changing the end pose of the scanning robot, the scanning data of the cylindrical side-face in different poses are obtained. For the elliptical profile obtained by the intersection of the laser plane and the cylinder side-face, the random sampling consensus (RANSAC) algorithm is used to get the coordinates of the center point of the ellipse section. The constrained optimization equation is established by using the distance from the estimated center point of the elliptical profile to the central axis of the cylinder, and thus the hand-eye calibration problem is transformed into the constrained optimization problem. A fusion algorithm of particle swarm optimization (PSO) algorithm and generalized Lagrange multiplier method are used to solve the constrained optimization problem, and the transformation matrix is obtained for hand-eye calibration. Finally, simulation and scanning reconstruction experiments are carried out based on the proposed method. The effects of the error of calibration data, the position of calibration reference object and the initial values of calibration parameters on the calibration results are discussed, and the hand-eye calibration accuracy is verified. The results show that the method is not affected by the position of the calibration reference object and the initial values of the calibration parameters. It is of characteristics of a simple operation, a universal versatility, and a high calibration accuracy. The calibration accuracy is within 0.15 mm, which is suitable for a robot hand-eye in-field calibration.

     

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