Friction Parameter Identification And Synchronous Control Research Of A Machine Tool Worktable With Double Drives

With the continuous development of NC technology, traditional single drive is difficult to meet the practical needs under the condition of that the equipment is becoming larger-scale and the space is limited. Therefore, the gravity drive technology which is the NC shaft driving force for the moving parts is more and more important. China is developing the biaxial synchronous control technology as a key part of High-grade CNC machine tool and CNC system in the national strategic emerging industries to narrow the gap between our country and developed countries. Therefore, the research of biaxial synchronous control technology is of great significance.This paper takes the double drive worktable system as the research object to achieve rapid and accurate control. The dynamic model of this double drive worktable system is established based on its dynamic and distribution of friction features. Getting the experimental data through the HMC500 high-speed horizontal machining, identifying the parameters of the friction model by genetic algorithm. Using Simulink to simulate this system by designed biaxial synchronous control method.The main content of this paper are as follows:(1) The model of single drive worktable system is established with mechanism modeling method by analyzing the composition and working principle of biaxial drive worktable system and the transmission principle and features of ball screw assembly. The flexible model of single drive worktable system is established by analyzing the stiffness of this system. The flexible model of biaxial drive worktable system is established by analyzing the relation between the double driving force and the worktable displacement, in which nonlinear friction is divided into three parts.(2) Describing the friction of system by the Stribeck friction model. Using the genetic algorithm to identify the parameters of the friction model based on the friction distribution features of biaxial drive worktable. Using genetic algorithm to identify the parameters of Stribeck friction model with the biaxial drive worktable system forward and reverse motion. The results show that the genetic algorithm can identify the parameters of friction model rapidly and accurately.(3) The three-loop PID biaxial synchronous control method which position loop and velocity loop is PI controller and current loop is P controller is put forward. Using this method to simulate the system, the results show that it can control the system effectively. No friction compensation for the system simulation, simulation results show that the friction can cause the increase of system tracking error and adjust time.(4) Separately using the friction feedback compensation method and the friction feedforward compensation method to compensate the friction of system. The results show that the tow method can control the friction compensation; in which the former method is better in rapidly response features and overshoot, the latter method better in stability; generally, the former method is better than the latter in control performance.