Interpolation standard gets moving

The open controls organization PLCopen has embarked on a project to develop a standardised approach to interpolated multi-axis motion control. It is developing a set of extensions to its existing multi-part standard that defines function blocks for motion control.

The first two parts of the standard have focused on single-axis and master-slave motion controls, where the position of a master axis generates one or more slave axis position commands, for applications such as electronic camming and gearing. One drawback of this approach is that if an error occurs, the coupled axes may continue to move.

The new Part 4 of the standard will tackle this problem by combining the axes into groups and linking them by interpolation.

"Interpolation brings the motion control work to a new level," says PLCopen`s managing director, Eelco van der Wal. "The support for synchronised motion with multiple axes will open new markets for us - like pick-and-place - with control structures closer to robotics, machine tools and CNC."

A first public draft of the interpolation proposals is due in April 2006. Other parts of the PLCopen Motion Control standard cover homing extensions and user guidelines.