Hexapod Coordinate Measuring Machine (HCMM)

Coordinate measuring machines are quality control inspection tools used in industry to verify the dimensional measurements of a part or product. Inspections are typically the slowest parts of a manufacturing process. As the economy demands higher throughput and more efficient manufacturing, industry's focus has shifted to concentrate on improving the inspection process.

The HCMM is a parallel architecture machine with five actuated legs and a passive leg. Each actuated leg has a frameless, brushless DC motor, an encoder, over-travel and home sensors, and a brake. Additionally, the hollow legs of the HCMM provide a pathway for a laser interferometry system. This laser system determines the length of each leg to sub-micron accuracy.

A PMAC2 motion controller controls all of the motion, safety, and human-machine interface functions on the HCMM. Because of the HCMM's configuration, in order to do Cartesian Coordinate moves, inverse kinematics must be performed. Since the movement of each leg on a HCMM both translates and rotates the probe tip, it takes the simultaneous coordinated movement of all actuators to produce a pure translation or pure rotation motion. The HCMM software performs these calculations so that this process is transparent to the user and part programmer.

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This HCMM is part of the Machine Tool Research Center at the University of Florida. Perry Automation was involved in all aspects of the controller design and installation.