在机测量激光测头位姿的线性标定

Linear calibration for on-machine measurement of laser probe pose

针对在机激光扫描测量中激光测头安装位置和姿态引起的测量误差,提出了一种适用于在机激光测量的测头标定方法。构造了在机激光扫描测量原型系统,建立了激光测头随机床运动的测量模型;通过多角度扫描标准球球面拟合球心,给出了一种线性求解测头安装位姿参数的算法,避免了非线性优化求解中的大量计算和不稳定问题。分析了测量过程中机床各个轴的运动误差对测量结果的影响,建立了误差模型,并给出补偿机床系统误差的方法。实验显示,对直径已知的标准球进行测量时,测头在不同摆角测得的标准球直径误差小于0.05 mm,误差补偿后球心位置误差减小了83%。实验结果验证了该标定方法的可行性,以及机床误差对测量精度影响的模型及补偿方法的正确性。

A calibration method suitable for a laser probe in on-machine laser scanning measurement was proposed to eliminate the measuring errors from installation pose.A prototype system for the onmachine laser scanning measurement was built and a model of the laser probe moved with a machine tool was established.The center of a standard ball was fitted by scanning the ball surface with multiperspective,and a linear algorithm to solve the installation pose parameters of the laser probe was given to overcome the heavy computation and un-robustness of the existing nonlinear algorithms.The influence of the machine tool movement error on the measurement was also analyzed and an error model was established and a compensation method for the machine tool error was proposed.The experimental results show when the standard ball with a known diameter was measured,its diameter error measured by the laser probe at different angles is less than 0.05 mm,and the position error of the standard ball center is reduced by 83% with the compensation method.The results illustrate the feasibility of the calibration method as well as the validity of the error model and the compensation method.