Motion Control Systen And Its Applications To NC Retrofit Of Traditional Machine Tools

Motion control, originated from the early electric drive control, has been evolved into an integrated multi-disciplines interacting technology with the development of motor control, sensor, power electronics, automatic control and micro processing.In the current automation technologies, motion control represents the most complicated task with the broadest applications. Servo-control systems, as an essential component of the NC systems, belong to the motion control systems to some extent. Alternating current servo systems is an important research direction, and represents the trends of the development of current technologies. The main contribution of this paper is as follow:1. Proposed a scheme for NC retrofit of traditional milling machine. Economic and applicable NC retrofit of the traditional machineries is a pressing task in the present and/or in the future, owing to the sole function of traditional machineries, complexity of the mechanical transmission systems, low stability, low accuracy, heavy workload in fault maintenance and low productivity. This paper proposed a scheme for NC retrofit of traditional milling machine. The motion control of machine tools is realized by connecting special NC system with the servo-control system. The functions of the retrofitted NC milling machine are expended, and the accuracy of the system is improved significantly. In the meantime, the productivity of machine tools is improved, the intensity of labor is reduced, the cost on new equipments is saved, and the fault of equipments is reduced. The NC retrofit of traditional machine tools is economical and efficient, and is good way for the enterprises to carry out technology renovation.2. Servo system is a major component of the NC machine tools, whose fine performance is the foundation and significant guarantee for the NC machine tools to realize the processing in high speed and high accuracy. Based on analyzing the components and control of the servo-system of the NC machine tools, this paper studies the methods for setting parameters in each loop to guarantee the performance of the machine tools.3. Performance requirements of the servo-control system in the NC machine tools mainly include the accuracy of the steady state, stability and swiftness of the dynamic response, and robustness to the varying parameters and uncertain disturbance. High performance can be achieved through the selection of actuators, sensors, and control strategies. The study and application of advanced control strategies is very important to the improvement of the performance of systems. In this paper, we analyze and compare the PID control and compound control. The performance of the control strategies is studied through simulation, which provides a guide line for the practical applications. Furthermore, this paper also explores the application of the intelligent control theory to the servo system of machine tools. A fuzzy PID controller is designed for the position control of machine tools. Simulation results show that advanced control theory can improve the steady-state accuracy and the dynamic performance of the system.