ange, driven implementing agencies , given the speed of elimination of bias towards the direction of movement, until a given position feedback and the actual location of the margin of zero. Feed the closed-loop system in the structure than to the open-loop system into the complex, high-cost, strict requirements on the environment at room temperature. Design and debugging difficult than open-loop system. However, can be compared to the open-loop system into higher accuracy, faster speed, greater power drive characteristic indicators. Under the technological requirements and decide whether or not to adopt this system.
该系统与开环系统的区别是：由光栅、感应同步器等位置检测装置测得的实际位置反馈信号，随时与给定值进行比较，将两者的差值放大和变换，驱动执行机构，以给定的速度向着消除偏差的方向运动，直到给定位置与反馈的实际位置的差值等于零为止。闭环进给系统在结构上比开环进给系统复杂，成本也高，对环境室温要求严。设计和调试都比开环系统难。但是可以获得比开环进给系统更高的精度，更快的速度，驱动功率更大的特性指标。可根据产品技术要求，决定是否采用这种系统。
5.3, AC / DC servo motor drive, the semi-encoder feedback loop NC system
5.3、交/直流伺服电机拖动，编码器反馈的半闭环数控系统
Semi-closed-loop system detection devices installed in the middle of transmission, the implementation of indirect measurement components position. It can only be part of the internal loop compensation system components of the error and, therefore, it compared the accuracy of the closed-loop system of low accuracy, but its structure and debug than simple closed-loop system. Will be in the angular displacement detection devices and speed detection devices and make a servo motor when there was no need to consider the overall position of the installation of detection devices.
半闭环系统检测元件安装在中间传动件上，间接测量执行部件的位置。它只能补偿系统环路内部部分元件的误差，因此，它的精度比闭环系统的精度低，但是它的结构与调试都较闭环系统简单。在将角位移检测元件与速度检测元件和伺服电机作成一个整体时则无需考虑位置检测装置的安装问题。
NC system for the current production companies more manufacturers, such as the famous German company SIEMENS, Japan FANUC companies; Everest domestic companies such as China, Beijing Aerospace CNC System Corporation, Shenyang and the central high-grade companies NC National Engineering Research Center.
当前生产数控系统的公司厂家比较多，国外著名公司的如德国SIEMENS公司、日本FANUC公司；国内公司如中国珠峰公司、北京航天机床数控系统集团公司、华中数控公司和沈阳高档数控
