曲面复合材料缝合机器人自动路径规划技术

为提高复合材料预制件缝合机器人的灵活性与加工柔性,针对缝合机器人自动路径规划问题,研究了基于三维光栅扫描技术的曲面复合材料缝合机器人视觉接缝提取技术.针对三维扫描摄像机视场固定的特点,对摄像机进行标定实验,改进传统的手眼标定方法,提出一种用于求解手眼关系矩阵的四点标定新方法,建立了机器人坐标系与摄像机坐标系的位姿映射关系.经过手眼关系标定,三维光栅扫描仪采样得到的缝合预制件点云数据可转化为机器人坐标系下的点云数据坐标.进一步对采集的预制件点云数据进行接缝中心线提取,提出了一种缝合轨迹及姿态规划算法,采用三次多项式对接缝中心线进行空间曲线拟合,采用最小二乘法对缝合微切平面进行平面拟合,完成机器人操作空间前进矢量及接近矢量的计算.最后,将规划结果应用于缝合机器人的离线编程仿真与实验中.实验结果表明,该系统精度高,线迹成型良好,可以满足机器人缝合系统的要求.

Automatic path planning technology of stitching robot for composite fabric with curved surface

In order to improve the flexibility of the stitching robot for composite preforms, a novel visual joint extraction technology was studied, for solving the automatic path planning issues of the stitching robot. The visual joint extraction technology is based on 3-D raster scanning technology and is applied in composite fabric with curved surface. Consider the characteristics of the fixed view field of 3-D scanning camera, the calibration experiment of the camera was carried out. This can improve the conventional hand-eye calibration method, propose a novel four-point calibration method to solve the hand-eye relation matrix, and then establish the posture mapping relation between the robot coordination and camera coordination systems. Through the improved hand-eye calibration and sampling with 3-D raster scanner, the point cloud data from the stitched preforms can be converted into the point cloud data coordinates in the robot coordination system. With further center-line extraction on the collected point cloud data of preforms, an algorithm for the stitching trajectory and posture planning was proposed. The proposed algorithm uses cubic polynomial to fit the center line of joint and the least square method to fit the stitched micro tangent surfaces, and completes the calculation for the tangent and approaches vectors in robot operational space. Finally, the planning result was applied in an off-line programming simulation and experiments of a stitching robot. The experimental results indicate that the system has high precision and excellent stitch forming, which can satisfy the requirements of a stitching system with robot.