面向新型并联机床的CNC系统

【作者】 倪田荣；

【导师】 范守文；

【作者基本信息】 电子科技大学 ， 机械电子工程， 2003， 硕士

【摘要】 以两种新型并联机床为研究对象，对新型并联机床的主进给机构运动学分析、NC自动编程技术、数控插补算法、后置处理算法以及误差分析与补偿等方面的理论与方法进行了较深入系统的研究。通过建立运动等效模型，对2TPS+2RPS型并联机床的主进给机构进行了运动学分析，推导出了一阶和二阶影响系数矩阵规格化的表达式。利用最小二乘法和NURBS曲线对刀触点轨迹进行拟合，重新确定了拟合曲线的权因子，提高了曲线的拟合精度。推导出了刀位轨迹算法和切削行距算法，建立了面向新型并联机床的CAM系统框架模型。 基于粗、精插补相结合的插补策略，构造了基于时间均匀分割恒速进给的插补算法。通过对一阶台劳级数的优化，消除了插补曲线曲率半径对插补精度的影响，同时简化了插补计算，并对插补误差进行了分析。通过对并联机床的机床坐标系、动平台坐标系以及工件坐标系之间关系的分析，建立了封闭形式的矢量关系表达式， 推导出了新型并联机床刀位数据后置处理的计算方法，其中包括控制空间伺服驱动腿精插补所需要的位置和速度计算公式以及工件平台位置坐标计算公式。运用误差摄动法建立起了并联机床的误差模型，提出了基于模糊神经网络的误差补偿控制方法，对网络结构、功能和训练算法进行了讨论，并对基于模糊神经网络的误差补偿控制方法进行了仿真研究。更多还原

【Abstract】 Aiming at two new type parallel machine tools (PMTs), the theory and method of kinematic analysis,NC automatic programming, interpolation algorithm ，post-processor algorithm，error analysis and compensation of PMTs are studied extensively and systematically in this thesis．Kinematic analysis for main feed mechanism of 2TPS+2RPS type PMT is done by establishing kinematic equivalent model, One and two order effect coefficient matrixs for main feed mechanism of 2TPS+2RPS type PMT are derived. Cutter traces are fitted by least square method and NURBS curve, Weight factors are modified and curve fit accuracy is increased.Algorithms for tool path calculation and cutter path interval calculation are derived.Frame model for CAM system of PMTs is established. Based on time equal division and strategy of coarse interpolation combines with fine interpolation,constant feederate interpolation algorithm for new type PMTs is constructed. With optimum treatment of one order Taylor series, the influence of curvature radius to interpolation accuracy is elimated,and interpolate calculation is simplified.The error of interpolation algorithm is analyzed．A special post-processor that can automatically transfer the cutter location data (CL-data) into machine specific NC commands is essential for real machining applications of PMT.The vector relationship expressions are established through analyzing relations among machine tool coordinate system，movable platform coordinate system and workpiece coordinate system.Post processing method of cutter location data including the position and speed<WP=5>calculation needed for fine interpolation and the position calculation of workpiece platform is presented.Error model for new type PMT is established based on perturbation method，Strategy of error compensation control for new type PMT,which is based on fuzzy neural network,is proposed. Network structure and train algorithm of network model are discussed.Simulation results show that this strategy can reduce machining error effectively.更多还原