Research On A Typical Part Of Non-circular Cross Section For CNC Cutting Tool Servo System Based On Iterative Learning Control

With the rapid development of information industry and economic globalization, CNCmachine plays an increasingly important role in the national economy and the application ofhigh-speed, high-precision CNC machine has become an important symbol of a country’sscientific technological level. Servo system is the middle section of CNC equipments andmachine tool. Therefore it is an essential part of the CNC machine. Starting from the controltheory, the technical requirements of the high-speed, high precision modern CNC system canbe summarized as the stability and dynamics and other quality indices requirements of theservo system. As for a real servo system, the control accuracy is a crucial aspect of itsperformance. Therefore, the reasonable control method has captured wide attention ofdomestic and foreign scholars.The main works are shown as follows:1. This paper presents the current stage of iterative learning control, including theprinciple, process descriptions, current situation of research and application, with a close lookupon the iterative learning control convergence and learning speed.2. After the in-depth research of the CNC cutting tool servo system, the principle ofCNC cutting part has been stated and the tracking accuracy of CNC cutting part is the maincause of processing error has been pointed out. Furthermore, this paper has established themathematical model of CNC feed servo cutting system, the versatility and the applicability ofthe model is relatively strong.3. According to the long cycle, complex adjust, low processing efficiency and processingaccuracy of profile machining for non-circular cross section, this paper proposes the necessityof using CNC machine for the processing of such part, the processing principle andprocedures can be clearly seen in the thesis.4. Combined with the principle of iterative learning control and the processingprocedures of non-circular cross section, the feasibility of the iterative learning controlapplied to the processing parts of the typical non-circular cross-section has been successfullyanalysised and the control method to improve the machining accuracy for the processing ofnon-circular cross section has been proposed.5. Comparing the simulation results with learning laws of the D, PD and the PID, thefeasibility of the iterative learning control applied to the processing parts of the typicalnon-circular cross-section has been successfully verified. The simulation lays specialimportance on the deviation of the initial error state, parameters of the learning law and the learning structure and their consequent impact on the system performance which approved theimpact of these factors on the learning speed of iterative learning.