【作者】 丁海峰；

【导师】 路长厚；

【作者基本信息】 山东大学 ， 机械电子工程， 2008， 硕士

【摘要】 随着高精密加工技术的不断发展,人们对机床的加工精度提出了越来越高的要求。而机床的定位精度是影响其加工精度的主要因素之一,所以如何方便实用的提高机床的定位精度成为现在各个方面都在研究的重要课题。特别是对于开环和半闭环数控系统,由于开环环节的存在,使得定位精度的进一步提高受到了限制。对于这类机床其定位精度主要取决于电机的控制精度与进给丝杠的加工精度,以及受导轨副和丝杠副的摩擦和热变形等因素的影响。本研究课题主要从螺距丝杠累积误差的动态测量与补偿这个角度来提高数控机床的定位精度,从而满足人们对数控机床越来越高的加工精度要求。本文首先综述了国内外电机运动控制算法的研究现状及最新发展,以及螺距滚珠丝杠误差的动态测量及补偿方法的有关研究。电机的控制精度对螺距丝杠累积误差的动态测量影响非常大,要想准确的测量出丝杠的螺距累积误差,首先应该解决X-Y工作台的控制问题。常规PID控制算法因其原理简单,使用方便,鲁棒性较强,在工业过程控制中得到了广泛的应用,并取得了良好的应用效果。但它仅适用于线性系统,而实际工业生产过程中往往具有非线性、时变不确定性,应用常规的PID控制不能达到理想的控制效果。现代控制理论如模糊控制、神经网络控制等智能控制算法还处于仿真阶段,在线调整比较困难,很难在线实现高精度控制。综合分析,本文决定对原有PID控制算法进行改进来提高系统的控制精度,从而减小控制对定位精度的影响。积分分离PID控制算法既能消除系统的稳态误差,又能提高系统的响应速度,减小超调,并且在线调整也比较简单。仿真和实验结果都证明该控制方法能有效地减小X-Y工作台系统的超调和振荡,提高稳态精度。滚珠螺距丝杠的累积误差是影响X-Y工作台定位精度的主要因素。要想减小它对定位精度的影响,首先应该正确的测量出它的数值,并采取合适的方法进行补偿。现在常用的动态测量仪器主要是高精密的长光栅,但由于安装等各方面因素的影响,测量时存在较大的平行度误差。而激光测量仪较精密长光栅具有动态响应好、平行度误差较小等优点,所以本课题选用激光测量仪代替精密长光栅进行螺距丝杠累积误差的动态测量和分析。并基于此通过前馈补偿的方法减少螺距丝杠累积误差对工作台定位精度的影响,提高工作台的定位精度。实验结果证明该方法能准确的测出丝杠的累积误差,从而能够进行正确的误差补偿,提高工作台的定位精度。更多还原

【Abstract】 With the development of high exact machining technology, people have advanced more and more high request for the machining precision of machine tool. Moreover the orientation precision of machine tool is one of the mostly factors which affect its machining precision, so that how to advance tool position precision expediently and practicality is an import task which is studied in every respect now. Especially for the open loop and the half closed loop numerical control system, because the exist of the open loop tache, position precision improved more is limited. For this kind of machine tools their orientation precision mostly lies on the control precision of electric motor and the machining precision of cutting feed screw rod, along with the infection of friction and hot distortion of the guideway fit and screw rod fit and so on. This study task improves tool’s position precision mostly through the dynamic measure and compensate of screw rod cumulated error, sequentially to satisfy people with more and more high machining precision of numerical control machine tool.First of all we summarize the study status in quo and up to the minute development of the control arithmetic of electric motor inside and outside country, as well as the relational study of the dynamic measure and compensation of screw rod error in this text. The control precision of electric motor affects the dynamic measure of screw rod cumulated error greatly. The general PID control , because of its simple principle、convenience、robustness, has been used in the industry process control widely, and acquire upstanding apply effect. But it is the same with linearity system only, and that the practice industry produce process is provided with non-linearity、time-varying nondeterminacy, difficult to constitute accurate math model, the perfect control result can’t reach under the routine PID control. Modern times control theories , such as fuzzy control、NN control and so on, still locate in simulation stage, adjusting on lie and realizing high degree of accuracy control with difficulty. This text uses integral separate PID control arithmetic to improve inhere PID control arithmetic, it can not only removes steady error, but also improves systemic respond velocity, minishes overshoot. So systemic control precision is improved effectually. The experiment validate this means can minish the overshoot and surge of X-Y table effectually.The cumulation error of screw rod is the primary factor which affects the position error of the X-Y table. If want to minish its effect on the position precision ,we must measure its value firstly. Now high exact long grating linear is the dynamic measure apparatus in common use. But because of the factors such as installation and so on, the parallel error exists in the measure process. Because the laser vibration measurer is provided with dynamic respondent quickly、less parallel error, so this task uses the laser vibration measurer in stead of the long grating linear to measure and analyse the cumulation error of screw rod. Based on this, we use the feedforward compensatory means to minish the cumulation error of screw rod, improve the position precision of the table. The experiment validate this means can measure the cumulation error of screw rod well and truly, so that the error can be compensated accurately, and the position precision of the table can be improved.更多还原