Unique Approach to High-Speed Machine Control

For applications that are, literally, at the cutting edge of machine technology, Osai 10/Series controllers offer a unique mathematical approach to the science of machine-tool control that produces faster cutting with no reduction in surface accuracy.

The concept combines the mathematical modelling of both the component's shape and the dynamics of each of the machine's axes to provide the best possible path possible for each axis. This means that conventional cutting vectors are translated into smooth spline polynomials to which the machine is capable of reacting, giving real world high-speed cutting that is much closer to the idealised mathematical CAD model required.

Osai recognised that there were two possible approaches to solve the problem - either by regulating the dynamics of the movement or the geometry of the trajectories and chose to pursue both options - tackling the problem from both the dynamic and the geometrical points of view.

The geometrical approach looks at part co-ordinates, tool co-ordinates and machine co-ordinates simultaneously and is capable of using all different types of CAD data output. Starting from the programmed values, with exclusive algorithms, the trajectory is split into sets of fifth-power polynomial functions (splines), consisting of a number of elements that correspond to the number of programmed elements; each set representing a section of the program.

The dynamic approach looks at the machine's envelope of capability eg. maximum speed and acceleration supported by the kinematic mechanism connected to the axis. The aim of the dynamic part of the programming is to determine a new spline, in the time domain, which enables parameters to be calculated in respect of the characteristics of the single axes.

"This approach effectively extends the useful capability of virtually any machinetool," concludes Duncan Hudson. "It maximises the machine performance without sacrificing quality of finish and, we believe, gives Osai controllers a performance superior to that of any other equivalent CNC on the market.