基于进给系统动态特性的多轴协调运动自适应前瞻控制

With the aim to solve the problems of feed shaft oscillating caused by mismatched feed system dynamic characteristics and acceleration and deceleration parameter, trajectory error caused by different dynamic characteristics of feed shaft, the multi-axis coordinated motion adaptive prospective control method was proposed. According to the dynamic characteristics of different structure feed shaft, the response characteristics of feed shaft influenced by the method and parameter of acceleration and deceleration was researched, and the trajectory accuracy influenced by different dynamic characteristics of feed shaft was researched. According to identifying each feed axis characteristic parameters and pre-reading trajectory instruction in real time, it was easily to predict the tracking error and the knife-axis error of the output oscillation of single-axis and multi-axis machining and to optimize the velocity curve and the trajectory curve. The interpolator used the prospective control method which acceleration and deceleration parameters could adjust adaptively and processing track was optimized. It could solve the problems of the oscillation caused by mismatched feed system and trajectory error caused by uncoordinated multi-axis.It was based on the open CNC system developed adaptive prospect control module. The CNC system could be adaptive adjustment acceleration and deceleration parameters and optimize processing track when the machine feeding system dynamic characteristics changing. And it could guaranteed the multi-axis CNC machine tools could be rapid and stable processing ,and it could improved the accuracy of multi-axis machining at the same time.

针对进给系统动态特性与加减速参数不匹配造成的进给轴振荡以及机床各进给轴动态特性不同造成的多轴联动轨迹误差问题，提出了基于进给系统动态特性的多轴联动协调运动自适应前瞻控制方法。根据不同结构进给轴的动态特性，研究加减速方法和加减速参数对进给轴响应特性的影响规律，建立进给系统动态特性特征参数与加减速参数的最优匹配，解决加减速参数不合理造成的进给系统振荡或降低加工效率的问题；研究进给轴间不同动态特性对轨迹误差的影响规律，实现基于进给系统动态特性的轨迹重构方法，解决多轴联动不协调造成的轨迹误差问题；研究进给系统动态特性特征参数的实时辨识方法，解决进给系统动态特性未知或时变条件下的加减速参数自适应调整和指令轨迹自适应重构的问题。基于开放式数控系统开发自适应前瞻控制模块，确保多轴联动数控机床在快速稳定加工的同时提高多轴联动加工精度。

目前数控机床中的控制参数、加减速重要参数基本通过工程人员根据经验反复尝试来设定，参数设置不合理就会造成系统振荡影响加工质量或者造成系统响应过慢，影响加工效率。而在前瞻运动控制中，速度规划和轨迹平滑仅仅通过指令的速度变化和轨迹的平滑程度进行几何运算，没有考虑进给系统动态特性对加工效率和加工精度的影响。而在数控加工中机床进给系统的动态特性会导致各轴不能协调运动产生较大轨迹误差，针对以上问题，本项目的主要研究内容和成果如下：.在伺服系统参数整定和最大加速度参数设置方面：通过建立三惯量机械传动系统动力学模型，建立了机械传动环节动态特征参数与控制器速度环、位置环控制参数的整定匹配关系；用于指导不同类型伺服系统的控制参数自整定；根据最大加速度参数与伺服系统的速度波动和位置跟随特性的关系，确定了伺服进给系统动态特性与伺服系统最大加减速参数设置的匹配关系.在自适应前瞻控制方面：根据多轴联动加工中敏感区域的轨迹误差预测，确定了保证轨迹精度的最小速度限定，用于前瞻控制中的自适应速度规划，在保证加工精度的前提下，保证了最大的加工效率。在联动轨迹误差补偿方面：针对多轴联动轨迹加工时轨迹误差与轨迹方向和轨迹类型的关系，项目组提出了基于轨迹误差预测的轨迹规划方法；针对系统封闭难以实现轨迹误差补偿的工程现状，提出了基于轨迹误差预测的轨迹指令预处理方法，根据伺服系统动态特性，预测轨迹误差并对加工指令进行重构，显著减小了多轴联动加工的轨迹误差。为了研究进给系统动态特性对参数整定及轨迹误差的影响，验证本项目的研究成果，搭建了基于PMAC运动控制器的三轴动态特性试验台，开发了系统辨识模块，进行各轴进给系统动态特性的辨识；开发了速度前瞻规划模块，用于自适应速度前瞻控制的测试和实验验证。基于MATLAB建立了三轴加工轨迹误差仿真模型，用于预测典型零件加工的轨迹误差以及验证基于轨迹误差的指令预处理方法的有效性