| With the rapid development of modern manufacturing industry,the demand for the performance and precision of numerical control equipment has improved constantly.Meanwhile,as the key transmission parts of numerical control equipment which has an effect on precision properties,the requirements for the performance and precision of feeding system are becoming higher and higher.Compared with the traditional feeding system driven by single motor and single ball screw,the dual-drive feeding system achieved through two sets of parallel motor and ball screw has more advantages including higher stiffness and faster response performance.Therefore,dual-drive feeding system has already been widely used in all kinds of advanced numerical control equipment.However,two motors bring a new problem to the control system: how to reduce the synchronization error between two motors.Moreover,friction in the dual-drive feeding system will seriously affects the tracking error and synchronization error of the system and therefore the final control effect which makes it difficult to guarantee the synchronization performance of the dual-drive feeding system through traditional control strategies.In conclusion,the study of how to improve synchronization performance and eliminate the adverse effects caused by friction has important significance whether in theoretical research or in practical application.In this paper,the dual-drive feeding system of two dimensional worktable is studied as the main research object.This paper focuses on friction compensation and synchronous control strategy of the dual-drive feeding system based on two performance indexes: tracking error and synchronization error.The main research contents and results are listed as follows:1)Firstly,the system was divided into two parts: servo-drive part and mechanical transmission part and then corresponding mathematical model was built based on the analysis of the composition and principle of the dual-drive feeding system.Secondly,the influence of stiffness and mechanical coupling was considered in the model.Then the integral model of the dual-drive feeding system was established which finally lay the foundation for the following research and simulation analysis of synchronous control technology.2)Firstly,the effect of friction on the synchronization performance of the dual-drive feeding system was analyzed.Then Stribeck friction model was selected for the use of friction compensation.The undetermined parameters in the model are identified by least square and genetic algorithm based on the results of multiple groups of uniform acceleration and uniform motion experiments.And the effect of friction was validated through simulation.Secondly,the research on synchronization control strategy for synchronization error was expanded and then the control effect of the master-slave and cross coupling control strategy was compared and analyzed through simulation.Finally,a cross coupling synchronization control strategy based on friction compensation was proposed by bringing friction compensation into cross coupling control.And the result was proved through simulation.3)A dual-drive feeding system test setup was built.The overall architecture of the dual-drive feeding system test setup and the selection of key devices were described in detail.And the closed-loop control was realized by integrating grating ruler with motion control software TwinCAT.4)The experiment scheme was designed,and the process of realization of friction compensation and cross coupling controller was described.The effectiveness of the proposed cross coupling control strategy based on friction compensation was verified with the experiment of synchronous control strategy and friction compensation. |
PDF Full Text Request