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1. Error characteristics of stepper motor servo drive system The reason for the low accuracy of conventional open-loop stepper motor servo system is mainly caused by the following error factors: (1) For stepper motor, due to process manufacturing and other reasons The step angle cannot be made too small, there is manufacturing error between the pitch of the stator and the rotor, and the pitch is uneven, causing the movement to have a step feeling, causing oscillation, and there is a step error between the steps. (2) Since the power of the general stepping motor is small, the stepping servo system generally includes transmission pairs such as gear pair and screw nut pair, and there is a gap between them, causing multiple values ​​between the displacement of the moving parts and the command value. Nonlinear relationship. (3) The manufacturing error and wear of the transmission components in the system transmission chain cause transmission errors and vary nonlinearly with displacement. (4) The rigidity of each transmission component in the servo system is insufficient, and elastic deformation and plastic deformation occur under load, and the load is different, and the deformation amount is different, thereby causing the feed pulse to be “eaten”. In severe cases, even crawling occurs. , so that the input and output also exhibit a nonlinear relationship. It can be seen that the influence of various nonlinear error factors will inevitably cause the actual displacement of the actuator to deviate from the command value, exhibit a deviation, and exhibit strong nonlinear and uncertainty characteristics. 2. Determination of closed-loop control method Modern control theory develops rapidly and there are many control methods. The closed-loop control system should be designed with the simple scheme and the best control effect. Because of the stepper motor servo system as the controlled object, it has strong Error nonlinearity and uncertainty, such as radome antenna base tracking and measuring instrument, when tracking targets, there is uncertainty due to the influence of outdoor wind load, which makes the relationship between input and output difficult to accurately express with a mathematical function, so it is very It is difficult to obtain a mathematical model of an accurate stepper drive system for use in such situations. In this way, the closed-loop controller is designed according to the conventional control theory and method, and the control effect is obviously not good, and even can not meet the requirements. For the controlled object with many ambiguity factors, the best way to effectively control is to use fuzzy control theory. The rise of fuzzy cybernetics has opened up new avenues for the resolution of these problems. In recent years, modern fuzzy control theory based on artificial intelligence and neural networks has become a powerful mathematical tool for solving complex, random, uncertain, time-varying system control.