串并联超声肿瘤治疗床误差模型与参数识别

Error Model and Parameter Identification for Serial-Parallel Cancer Curing Machines Using Ultrasonic

建立动、静平台和伸缩杆实际误差模型的基础上,采用过约束参数识别方法,分析了高强度聚焦超声治疗机5自由度串并联机构的实际定位精度,并以3-RPS机构平台为例,进行了误差参数识别和定位精度分析,以调整控制器中的模型参数,可实现较高的定位精度,满足高强度聚焦超声治疗的要求.仿真研究表明在实际测量中约50个测试点即可满足设计要求,最大焦点总误差不超过0.5mm,测量数据误差不超过0.2mm,甚至可控制为0.05mm.该串并联机构参数识别不需要额外的姿态传感器,就能够方便地在实际工作环境中在线应用.

The actual position accuracy of the 5-DOF (Degree of Freedom) serial-parallel manipulator of a HIFU (High-Intensity Focused Ultrasonic) curing machine is analyzed on the basis of the actual error models of the mo-ving platform, the stability platform and the extension pole, as well as by means of the redundant restriction parameter identification. With a 3-RPS serial-parallel manipulator as the research object, the model parameters of the controllers of the curing machine are adjusted via the error parameter identification and position accuracy analysis, and a higher position accuracy is achieved, thus meeting the positioning requirements for HIFU treatment more satisfactorily. The simulated results indicate that, during the practical measurement, about 50 test points are enough, with a maximum total error of the focus less than 0.5mm and a maximum measurement error less than 0.2mm, even within 0.05mm. The most remarkable merit of the proposed method is that no more extra configuration transducers or sensors are needed during the parameter identification, which makes it possible for the manipulator to run on line in practical situations.