Development of robust extensible architectures for machine tool control

The authors discuss their progress to date in the design of fully functional CNC systems. The major factor influencing the end cost, effectiveness, flexibility and extensibility of a control is the basic architecture. The architecture described uses a highly parallel, patented arrangement, with the process control activity being carried out over an alternate front plane communication system. Examples of the use of this system in both force and error control are given, in addition a relatively new extension of the system which allows increased flexibility is also discussed. A discussion of the use of a range of standard boards in the building of commercial systems will be used to demonstrate the flexibility which such controls should present to both OEM's and end users. Some of the potential problems which may arise are also discussed. The issue of operating software is discussed in some detail. The authors have standardized on the FORTH language for all low level software. It is believed that many in the control community are unaware of the recent ANSI and open firmware initiatives and indeed the potential of FORTH like languages in open embedded systems. The use of the FORTH interpreter allows the addition and actioning of code while the control is operating, this greatly adds to the flexibility of integration and reconfiguration.