Research On ACC/DEC Control,Servocontrol And Contour Control Of CNC System

The open-architecture and high-performance CNC system not only has flexible configuration , but also should machine with high federate, high precision and high reliability using the new computer technology, automation and machining technology. In the thesis several key technologies, such as Acceleration /Deceleration control, curve interpolation, servo control and contour control are researched in details aimed at the development of high-performance CNC system.A new Acc/Dec approach in which the jerk is planned by Trapezoidal ACC/DEC is put forward in the thesis, improving contouring accuracy and reducing the impact on machine greatly. And the contour motion control equation of this approach is developed in details.After analyzing the weakness of the linear interpolation approach aimed at the complex profile parts' high speed and high accuracy CNC machining, the NURBS curve interpolation algorithm and the feed rate controll self-adaptively approach are researched in the thesis, which can achieve high and smooth feed motion on the basis of meeting the need of Acc/Dec rule, contouring error limitation and maximal centripetal acceleration.The rapidity, stability and accuracy of CNC system are determined by the servo system. A nonlinear PID controller is developed to enhance the servosystem accuracy on the basis of analyzing PID controller and feedforward control in details.After analyzing the influence of electric disturbance on servo system precision, a electric disturbance observation and compensator is developed to minish track error and enhance the system accuracy. The simulation results reveal the electric disturbance observation and compensator could enhance the interference rejection performance greatly.After analyzing the weakness of the conventional machine contour control scheme, a multi-axis cross-coupled control approach based on NURBS curve interpolator is put forward in the thesis aimed at the demand of complex profile...