The Servo Dynamic Stiffness Analysis And Testing Technology Of Linear Motor Servo System

Linear motor servo system has no mechanical conversion structure, thus it has many advantages, such as high response, high accuracy, high speed, high stiffness and low noise. Therefore, it has been widely used in numerical control machine. The servo stiffness is an important index to evaluate the performance of linear motor servo systems, and it reflects the ability of servo systems to prevent the position deviation caused by the loading force fluctuation. In numerical control machine, the value of the servo stiffness affects the manufacturing accuracy. This thesis focuses on the theoretical analysis and testing technology of this concept.First, the simulation of typical linear motor servo system has been built in Simulink, based on which, the factors that affect the servo dynamic stiffness under the step loading force are analyzed. The factors include drive hardware parameters, control parameters, nonlinear factors and the mover mass.Furthermore, the transfer function has been derived by analyzing the disturbance model of the linear servo system. Based on that, the thesis explores the influence of the control parameters and the mover mass on the servo dynamic stiffness under the sinusoidal loading force. The comparison result shows that the influence trends on the two servo dynamic stiffness are the same, which validates the coherence between the two definitions. The theoretical analysis for the coherence is also done in the thesis.The traditional method to test the servo dynamic stiffness under the step loading force is not suitable for the case of large force and repeated experiment. This thesis proposes a new testing method based on linear motor loading. The factors that can influence the measuring accuracy of the method have been explored.Last, the whole test platform has been built based on the linear loading method, which includes the design of the whole system and the linear DC loading motor. Temperature and thrust experiments have been made on the loading motor before the test of the dynamic stiffness. The influence of the control parameters on the servo dynamic stiffness has been validated in the experiment. The error analysis of the test result is also done in the thesis. Finally, the test result has been compared with that of the traditional method, which proves the high accuracy of the proposed test method.