The development of modern motor control theory makes the machine numerical control servo system realize the AC, digital and intelligent machine tool numerical control system. The commonly used servo motor and control system are: (1) Open loop control system The stepping motor is used as the driving device, and the position and speed detecting device is not needed, and there is no feedback circuit, and the control circuit is simple and the price is low. The difference between a stepper motor and a normal motor is mainly due to its pulse control. It is this feature that the stepper motor can be combined with modern digital control technology. However, the stepper motor is not as good as the traditional closed-loop controlled DC servo motor in terms of control accuracy, speed variation range and low speed performance. Stepper motors can be used where accuracy is not particularly high. Stepper motors can be characterized by their simple structure, high reliability and low cost. (2) Semi-closed loop and closed loop position control system A DC servo motor or an AC servo motor is used as the driving component, and a pulse encoder built in the motor can be used. The brushless resolver or the tachogenerator is used as the position/speed detecting device to form a semi-closed loop position control system, and can also be directly mounted. A grating or inductive synchronizer on the table serves as a position detecting device to form a high-precision full-closed position control system. In the 1970s, the United States GATTYS company invented the DC torque servo motor for machine tools. Since then, CNC machine tools have been widely used in various countries. The open loop system is gradually replaced by a closed loop system. The DC servo system with DC servo motor as the driving device has a simple control circuit and low price. The main disadvantage is that there is a mechanical reversing device inside the DC servo motor. The carbon brush is easy to wear, the maintenance workload is large, and the spark is easy to start during operation, which brings great difficulty to the increase of the motor speed and power. Although the AC asynchronous motor is cheap and simple in structure, it has not been applied to the numerical control system for a long time due to poor control performance. With the development of power electronics technology and modern motor control theory, in 1971, Blaschke of Siemens in Germany invented the vector control method of AC asynchronous machine; in 1980, the research team led by German Leonhard in the application of vector control of microprocessor Progress has been made to make vector control practical. From the late 1970s, CNC machine tools gradually used asynchronous motors as spindle drive motors. If the DC motor structure is "inverted", the armature winding is mounted on the stator, the rotor is a permanent magnet portion, and the magnetic pole position control electronic switch is detected by an encoder on the rotor shaft for electronic commutation. It constitutes a permanent magnet brushless DC motor. This AC servo motor has good servo performance. Since the 1980s, it has been gradually applied to the feed drive of CNC systems. The AC servo system uses AC servo motor as the driving device, which can form a high-precision, high-performance semi-closed loop or full-closed loop control system like the DC servo motor. Since the AC servo motor has a brushless structure, it requires almost no maintenance and is relatively compact. Small, which is conducive to the improvement of speed and power. At present, the AC servo system has replaced the DC servo system to a large extent. In the contemporary CNC system, the breakthrough in servo technology can be summarized as: AC servo instead of DC servo, digital control instead of analog control, or it is called software control instead of hardware control. The result of these two breakthroughs has resulted in an AC digital drive system for servo feed and spindle drives on CNC machine tools. Due to the rapid development of power electronics technology and control theory, microelectronics technology such as microprocessors, software computing and processing capabilities, the use of high-speed microprocessors and dedicated digital signal processors (DSP-DigitalSignalProcessor) full digital AC servo system After that, the calculation speed of the system is greatly improved, and the sampling time is greatly reduced. The original hardware servo control becomes software servo control, and some advanced algorithms in modern control theory are realized, which greatly improves the performance of the servo system. For example, the servo control loop of the OSP-U10/U100 networked numerical control system is a kind of high. Performance servo control network, which realizes distributed configuration and network connection for each servo device and component that performs autonomous control, further exerts its control ability and communication speed on the machine tool. The breakthrough of these technologies has improved the performance of the servo system, improved reliability, convenient debugging, and enhanced flexibility, which has greatly promoted the development of high-precision high-speed machining technology. The state observer and Kalman filter can be used to identify the motor parameters online. The sliding mode variable structure control can enhance the robustness of the motor control system. If we can combine various intelligent control theories organically, we will create a new world of AC servo control. For example, fuzzy control and neural network control do not require precise object models and parameters, making the system very robust. Next page Stainless Steel Hex Bolts,Hexagon Screw Head,Heavy Hex Bolt,Hex Bolt Shaoxing Grace International Trade Co.,Ltd , https://www.shaoxinggrace.com