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Linear Motion Tracks For Robotic Positioning

2019-04-09

By Lisa Eitel • Robot-positioning tracks can add flexibility to manufacturing spaces, but must be fast, accurate, and safe to be truly useful. Here we take a look at drives that deliver.

Robot positioning systems are long tracks in warehouse, aerospace, and automotive facilities to let one robot perform multiple tasks. Also called robot-transfer units or RTUs, these motion designs are increasingly common for assembly, large-scale welding, and warehousing.

In contrast with typical setups in which a robot bolts to a floor, RTUs move robots through work-cells and factories and shuttle them between stations. The best setups for RTUs are those just being built or ones where processes and related machines can be put in a straight row. Where RTUs move six-axis robots, the linear tracks are also sometimes called the seventh axis (or less commonly, when the robot itself has seven degrees of freedom, the eighth axis). When these tracks are part of a frame, including frames from which the robot hangs, they’re gantries.

No matter the robot or track morphology, the point of the extra axis is to add translational motion. This either extends the work envelope or lets a robot transport work-pieces or tools. In some arrangements, the former lets a robot tend multiple machines or pick pallets from rows, or machine very large components. For the latter, common applications are packing, welding, plasma-arc cutting, and other mechanical tasks.

Here we focus on drive options for RTUs. However, note that engineers must also decide between an array of guides and bearings (usually in the form of cam followers or profile guides).