Modular CNC design for intelligent machining .1. Design of a hierarchical motion control module for CNC machine tools

An hierarchical motion-control design strategy is presented to integrate various intelligent machining modules to CNC systems. There are two independent buses in the CNC system. Modular and independent processor boards reside in the primary bus which is global for manufacturing process monitoring, control and machine tool position commands. A digital signal processing board provides a secondary CNC bus, which has one imbedded microprocessor for the position control of each axis. The system is open to integration of new hardware and software modules. Any process control and monitoring task in the system can manipulate the feed, acceleration control law parameters and position commands in real time. New process control, monitoring and position control algorithms can be integrated to the system by using globally available CNC parameters. The process control and monitoring functions are executed in the real-time multi-tasking environment within 1 ms time intervals without disturbing the position control system. The proposed design provides an open development platform for parallel testing of intelligent manufacturing algorithms on machine tools and robots.