arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.08420cs.RO
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基于非线性优化的机械手视觉运动学标定方法

A Visual Kinematics Calibration Method for Manipulator Based on Nonlinear Optimization

School of Artificial Intelligence and Automation, Huazhong University of Science and Technology(华中科技大学人工智能与自动化学院);School of Automation, South East University(东南大学自动化学院)

Peng Gang, Wang Zhihao, Yang Jin, Li Xinde

摘要:

传统的机械手运动学标定方法需要精确的三维测量仪器来测量末端位姿,不仅测量仪器价格昂贵,而且不适用于所有机械手。另一种标定方法是使用摄像机,但摄像机参数引起的系统误差影响了机械臂运动学模型的标定精度。为此,本文提出了一种基于单目视觉的机械臂运动学模型几何参数标定方法。首先,采用经典的Denavit-Hartenberg(D-H)建模方法建立机械手的运动学参数。其次,进行非线性优化和参数补偿。将实际运动学模型和经典D-H运动学模型对应的各机械手姿态下标定板特征点的三维位置映射到像素坐标系中,以两者像素坐标的欧氏距离误差之和作为待优化的目标函数。实验结果表明,本文提出的优化D-H运动学模型对应的末端位姿与实际运动学模型对应的末端位姿在像素坐标系中的像素偏差为0.99个像素。与经典D-H运动学模型计算的像素坐标与实际像素坐标之间的7.9个偏差像素相比,偏差减少了近7个像素,误差减少了87%。因此,该方法能有效避免视觉标定中摄像机参数引起的系统误差,提高机械臂末端的绝对定位精度,具有良好的经济性和通用性。

英文摘要:

The traditional kinematic calibration method for manipulators requires precise three-dimensional measuring instruments to measure the end pose, which is not only expensive due to the high cost of the measuring instruments but also not applicable to all manipulators. Another calibration method uses a camera, but the system error caused by the camera's parameters affects the calibration accuracy of the kinematics of the robot arm. Therefore, this paper proposes a method for calibrating the geometric parameters of a kinematic model of a manipulator based on monocular vision. Firstly, the classic Denavit-Hartenberg(D-H) modeling method is used to establish the kinematic parameters of the manipulator. Secondly, nonlinear optimization and parameter compensation are performed. The three-dimensional positions of the feature points of the calibration plate under each manipulator attitude corresponding to the actual kinematic model and the classic D-H kinematic model are mapped into the pixel coordinate system, and the sum of Euclidean distance errors of the pixel coordinates of the two is used as the objective function to be optimized. The experimental results show that the pixel deviation of the end pose corresponding to the optimized D-H kinematic model proposed in this paper and the end pose corresponding to the actual kinematic model in the pixel coordinate system is 0.99 pixels. Compared with the 7.9 deviation pixels between the pixel coordinates calculated by the classic D-H kinematic model and the actual pixel coordinates, the deviation is reduced by nearly 7 pixels for an 87% reduction in error. Therefore, the proposed method can effectively avoid system errors caused by camera parameters in visual calibration, can improve the absolute positioning accuracy of the end of the robotic arm, and has good economy and universality.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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