【作者】 范良志；

【导师】 李培根； 喻道远；

【作者基本信息】 华中科技大学 ， 机械电子工程， 2005， 博士

【摘要】 本文将并联机器人技术引入到HIFU(HIFU -High Intensity Focused Ultrasound)肿瘤治疗机设计之中,提出了以3PRS并联机构为基本构型的串并联HIFU肿瘤治疗机设计,开发完成了一台原型样机。分别建立了基于3PRS 并联机构的串并联机构名义模型和带有运动学误差项目的实际运动学模型的正/反解,求解得到了用动平台法矢表达的初等函数形式的3PRS 并联机构名义反解解析解。串并联治疗机的控制系统设计以Pmac 运动控制卡为核心。运动控制为两级运动插补模式,利用指数前加减速作为粗插补计算的基础,分别设计实现了基于直线精插补模式和PVT 精插补模式的运动控制算法。粗插补时间片长度大约取为电机轴以最大加速度加速到最高速度所需时间的一半。在保证机器运动性能的前提下,降低了运动指令处理计算及通讯负载。应用奇异值理论,分别进行了典型运动模式下两种运动控制算法的插补原理精度分析,结果表明本文所选择的插补参数合理有效。在以上理论工作基础之上,提出了基于辅助测试钢套的运动约束平面法矢计算方法,结合平面运动约束的机器人运动学自标定原理,完成了串并联治疗机中3PRS 并联机构的运动学参数标定。针对实际测量约束平面法矢和完全不测量约束平面法矢两种实验配置,通过数值仿真证明,采用优化计算方案能够得到接近于机构运动学参数真值的解。实际标定实验中采用了完全不测量约束平面法矢标定方案,计算得到了实际3PRS 并联机构的运动学参数。更多还原

【Abstract】 This paper introduces robotic technology into the design of HIFU (HIFU –High Intensity Focused Ultrasound) treatment machine and puts forward a serial-parallel HIFU cancer treatment prototype based on 3PRS parallel mechanism. Both nominal and practical kinematic models have been set up with respect to the existance of kinematic errors. Analytical resolution has been obtained according to the 3PRS mechanism mobile platform normal vector in the form of elementary functions by the derivation of nominal inverse kinematic equations. Control system of this machine takes Pmac (Programmable Multi-Axis Card) as its hardware kernel. Motion control works in a 2-grade interpolations mode, in which exponential pre-acceleration/deceleration law is employed for rough interpolation. Precise interpolation is fulfilled by linear mode and PVT mode specificly. Rough interpolation sample time is about half of the time that each motor axis accelerates to its maximum speed by its maxium acceleration. Motion codes processing and communication workload could be lowered down while overall performance be ensured. Interpolation accuracy analysis has been carried out according to above two motion control modes by singularity value analysis under classical movement modes. Results show that selected interpolation parameters are reasonable and effective. With theoretical works above, this paper puts forward a constraint plane normal vector evaluation method which is based on the motion constraints of auxiliary cap. Together considering about self kinematic calibration method for robots, this paper carried out kinematic calibration for the 3PRS paralle mechanism in studied serial-parallel HIFU treatment machine. Numeric simulations show that kinematic parameters could be reasonably approximated by optimization calculation for two different calibration experiment configurations which tests or does not test constraint plane normal vectors. Practical calibration experiments were carried out without any measurement of constraint plane normal vectors. Kinematic parameters have been achieved for practical 3PRS paralle mechanism in the prototype machine without measured constraint plane normal vectors.更多还原