自适应优化控制的人工髋关节磨损三坐标测量及评估方法

Optimized Adaptive Control for Evaluation of Artificial Hip Joint Volumetric Wear by Coordinate Measuring

针对目前三坐标测量在人工髋关节磨损评估上重复测量误差较大和准确性不高的突出问题,提出了一种自适应优化控制的人工髋关节三坐标测量及磨损评估方法.该方法包括臼杯表面采样点云分布的磨损自适应设计,测量点触测矢量的优化控制以及构建相同体积计算区域,并使用超高分子量聚乙烯（UHMWPE）髋臼杯对该方法进行了验证.研究结果表明：与非相同体积计算区域方法相比,在低于原来一半的测量成本下,体积评估重复性偏差减小了49.3％;与随机的触测矢量方法相比,在同样的点密度下,体积评估精度提高了32.4％～46.7％;该方法的磨损评估结果与称量法对照,表现出了有效的相关性（R2=0.922 8）;与称量法相比,该方法表现出磨损分布统计分析能力,为人工关节磨损分析和研究提供了更多的信息.

Compared with the gravimetric method,geometric method in terms of coordinate measurement （CMM） is endowed with advantage of direct determining wear volume and distribution on the articulating surfaces of artificial hip prostheses.The current volumetric measurement usually requires more measuring points and computational cost to surpass the limitations of bad repeatability and low accuracy.A new method of CMM measurement is proposed for collecting density of data adapted to the surface profile of worn area,controlling and optimizing probe contact angle and reconstructing calculative socket on the same region with better measuring accuracy and relatively lower calculating cost.UHMWPE cups are chosen to validate this approach.The results show that the repeatability error of volume evaluation is reduced by 49.3 ％ with half as much as measurement cost for previous method and the accuracy is improved by 32.4％-46.7％,a correlation （R2 =0.922 8） exists between the new method and gravimetric method,showing its effectiveness,and the developed method enables to reconstruct the worn surface with detailed distribution.