基于可变向测头的未知自由曲面数字化测量

为了消除曲面倾斜对点激光测头测量精度的影响,针对连续的未知自由曲面,提出一种基于可变向测头的数字化测量方法.设计一种摆动机构安装点激光测头,使测头方向可以在一定范围内变动.在测量过程中,首先使测头竖直,对被测曲面进行等间距逐行扫描,并对扫描数据进行及时处理与曲线拟合,根据拟合曲线外法线与X轴正方向所成角度α值的大小,找出α∈0°,60°)、α∈(120°,180°]的曲线段所在位置.一次扫描结束后,将测头向左倾斜,对α∈0°,60°)的曲线段进行二次测量,将测头向右倾斜,对α∈120°,180°)的曲线段进行二次测量.通过多次测量数据组合,获得被测曲面的整体形貌数据.实验结果表明,该方法能够有效实现α∈0°,180°)的未知自由曲面的数字化测量,同时保证测量精度.

Digitalization of unknown free-form surface based on variable-direction point laser sensor

In order to eliminate the influence of surface inclination on measurement accuracy of point laser sensors, a new digitalization method for continuous unknown free-from surface based on a variable-direction point laser sensor was proposed. In this strategy, a hinge structure was designed to fix the point laser sensor, so the direction of the probe could be changed in a certain extent. At first, the probe was fixed vertically , and scanned the surface with equal step line by line until the whole surface was finished. The derived data was processed and fitted into curves immediately, and the angle value α  between the exterior normal of the curves and the positive direction of X-axis was figured out to find out the location of the curves with α∈\0°,60°) or α∈(120°,180°\]. Then second time measurement was performed to rescan the curves of  α∈\0°,60°)   with the probe  tilting to the left and to rescan the curves of  α∈\120°,180°)  with the probe tilting to the right. Finally, the data generated by different measuring directions was merged as the final result. The experimental results indicate that this method can completely measure the unknown free-from surface with  α∈\0°,180°)   while the measurement accuracy maintains good.