| This thesis deals with key issues in the process of the construction of the CNC system of a parallel kinematic machine including the software programming development,velocity control strategy and error compensation.The following achievements have been obtained.Considering the structure of the parallel kinematic machine and aging problem of CNC system,the CNC system is upgraded in aspect of the hardware and software.The structure of “IPC + Turbo PMAC” is as the building core of the hardware platform.The “operating system of Windows + internal program system of Turbo PMAC” is as the building foundation.The basic modules are developed with the LabVIEW software including the main interface of the human and machine,JOG,Auto,MDI,and tool setting.In view of the motion control characteristics of parallel kinematic machine,the acceleration and deceleration control method based on workspace and joint space are adopted.A hybrid S curve acceleration and deceleration control method combining five and seven segments is designed in the workspace.A velocity transfer strategy between continuous segments is proposed.Then the flexibility of the system is improved.In the joint space,the global search method is used to estimate the spatial position and the contour error caused by the PVT interpolation algorithm.According to the two-stage velocity control method,a stability prediction method for velocity control is proposed,and the simulation comparison is carried out.An embedded geometric error compensation scheme is proposed for the open CNC system of parallel kinematic machine.The compensation parameters in the error compensation model are calculated according to the error Jacobian and parameter source in the geometric error mapping and parameter identification models.An independent embedded geometric error compensation module is developed based on the design idea of hierarchy and modularization.The validity of the error compensation model is verified by simulation. |
