DESIGN AND DEVELOPMENT OF A MULTIPROCESSOR-BASED CNC SYSTEM

Abstract

The system developed in this project was targeted as a. computer numerical controller (CNC). With the suitable control software implemented, it was customised to perform control functions for a 3-axis vertical milling machine. A general-purpose microcontroller device was used as the processor of the system. Based on the microcontroller device, a software-programmable controller hoard, 1196, was developed. The controller included a memory unit and an I/O unit, so that control software could be loaded into it and the I/O control functions could be realized. A multiprocessor architecture was adopted for the overall system design. In the supervisory control unit (SCU1, a general-purpose microcomputer was employed. Dedicated system control software functions were developed for user interface and device control functions pertaining to interface with the machine control unit (MCU). In the MCU, three 1196 microcontroller boards were connected together to perform control tasks for the 3-axis vertical milling machine. Software tool-path interpolations were also developed for the multiprocessor system. Simulation tests were conducted for the tool-path interpolation functions implemented in the MCU. Non-cutting interpolation tests were performed on a simple stepper-driven 3-axis system to verify the functionality of the controller. Actual machining tests were subsequently done on an industrial-scale milling machine using the multiprocessor system as the controller. Dimensional measurements were taken of the machined workpieces to evaluate the performance of the system.