| In order to achieve the strategic goal of becoming a powerful manufacturing country,the state puts forward the strategic plan of “Made in China 2025”.High-end CNC machine tools and robots are one of the top ten key areas for China to achieve the strategic goal of “Made in China 2025”.As the “brain” of high-end CNC machine tools,high-end CNC system should become a key research topic.In particular,China’s transformation from a large manufacturing country to a powerful manufacturing country is more urgent.Focusing on the development of intelligent manufacturing equipment and accelerating the intelligent upgrading of production process are important means to achieve the goal of “Made in China 2025”.The Ministry of industry and information technology has funded a series of special topics related to intelligent manufacturing through special funds.During the 13 th Five-Year Plan period,the subject of "Research,development and application verification of intelligent technology for domestic high-end CNC system" was specially set up.This subject realizes the intelligent upgrading of domestic high-end CNC system by developing intelligent CNC system(CNC device and servo unit).The task of this major national science and technology special project has been fully implemented and successfully passed the acceptance of the special project.The developed new products have passed the product inspection of the national machine tool quality supervision and inspection center,and the technical indexes of the products have reached the level of international mainstream intelligent CNC system.This thesis relies on this special subject and is an important part of the research content of this special subject.The main research contents and innovations of this thesis are as follows:1.Research on the architecture of CNC system based on CPS.The overall architecture of CNC system(including CNC device and servo unit)based on CPS is analyzed and studied.CNC device and several servo units form system level CPS through industrial network.The CNC device accurately senses the state of the controlled machinery through multiple servo units and multiple intelligent sensors,analyzes the sensing data in real time,and makes intelligent decisions according to the analysis results.Then,multiple servo units realize accurate execution,and finally complete the intelligent functions of the CNC system,such as precision surface machining,built-in optimization and diagnosis,intelligent compensation for reversing impact,and feed rate adaptation.2.Design of intelligent servo unit based on CPS.Based on the detailed analysis of the CNC system based on CPS,the software,hardware and network interface design of the intelligent servo unit based on CPS are completed from the perspective of the specific application requirements of the CNC system.The software of intelligent servo unit is the core to realize intellectualization.It realizes high-performance servo control through high-precision state sensing,real-time analysis of system status,and autonomous decision of control strategy.The network interface is the data and information exchange channel between the intelligent servo unit and the NC device.Through the support of a variety of fieldbus protocols and high-precision synchronous control,it supports the state perception and accurate execution of the NC device.3.Current control software design of intelligent servo unit.A data-driven on-line decoupling control strategy for permanent magnet synchronous motor(PMSM)is proposed to solve the problem that the decoupling control of PMSM is easily affected by the change of motor parameters,which makes it impossible to achieve complete decoupling.The decoupling control module estimates the parameters of the module according to the input and output data of the permanent magnet synchronous motor,and outputs the decoupling control quantity in the way of voltage feedforward.Aiming at the problem that the motor parameters in the current control loop are time-varying,the inverter dead time,the motor cogging torque and other parameters are unknown,and it is impossible to establish an accurate control system model,resulting in the low control accuracy of the traditional model-based current control method,a current control method with self-learning adjustment of controller parameters is proposed.The data-driven model identification module identifies the model parameters of the current loop in real time according to the input and output data of the current loop and calculates the evaluation function value.When the evaluation function value does not meet the requirements,the parameters of the PI controller are adjusted in real time to meet the stability and rapidity of the control system.4.Speed control software design of intelligent servo unit.In order to solve the problem that the speed control performance of permanent magnet synchronous motor is easily affected by the uncertainty factors such as load inertia change,external disturbance and unmodeled dynamics,a speed control method based on self-learning adjustment of controller parameters based on optimal reference curve is proposed.The data-driven model identification module identifies the model parameters of the speed loop in real time according to the input and output data of the speed loop and calculates the evaluation function value.When the evaluation function value does not meet the requirements,the PI controller parameters are adjusted in real time.In order to improve the speed of parameter self-learning adjustment of PI controller,a method based on optimal reference curve is proposed to adjust the parameters of PI controller.5.Application verification of intelligent servo unit.The experimental verification platform is built in the laboratory,and the data acquisition host computer software of the intelligent servo unit is developed to verify the intelligent servo unit developed in this thesis.After the experimental verification,the intelligent servo unit and the intelligent numerical control device developed in this thesis are applied in the machining center. |
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