September 1997, Issue 86

PC/104 Quarter:
Motion Control with PC/104

MOTION-SYSTEM TOPOLOGIES

Three basic load-driving topologies, or a combination thereof, define all motion-control applications. In each system type, if more than one axis of motion is involved because of mechanical design, you must coordinate the calculations of each axis. Small load changes in one axis can have a substantial dynamic effect on the others.

The inline system consists of a load moving in an axial direction to the load driver. For instance, when a lead screw is directly attached to the load and followed by a screw follower, the load is transported in the axial direction of the lead screw (load driver) as the screw rotates, as shown in Figure 1a.

The rotary system in Figure 1b consists of a motor attached directly or through a gear train to a load rotating about the load center. The load needn't be balanced or move in a path around the load-driving device, but it must move in a radial fashion.

A rotating spindle exemplifies a typical rotary system. It either rotates the work (e.g., a lathe) or the tools that contact with the work.

The tangential system consists of a load moving in a direction perpendicular to the axial direction of the load driver (see Figure 1c). In a simple conveyor belt, the motion is perpendicular to the axial direction of the drive roller.