Terminology

Accuracy

The term accuracy is probably on of the most misunderstood specifications in the positioning field. Accuracy is always understood as absolute accuracy in terms of theoretically exact distance relative to a machine coordinate system. No positioning system can truly create an absolute accurate position due to error of various magnitude.

Typical specifications would read "Accuracy ± 5 µm/300 mm" the interpretation of this specification is that the maximum error of position this stage will have is  ± 5 µm over 300 mm travel range. 

Repeatability

Repeatability is a term used to describe the ability of a positioning machine to repeat a target position within a certain range of error. There are two principal ways of describing repeatability;

Uni-Directional Repeatability: in this scenario, the targeted position is approached from one direction only. The deviation of true position on a series of repetitive moves to that targeted position, is expressed as uni-directional repeatability. 

Bi-directional Repeatability: In this scenario the targeted position in approached from both directions and the recorded deviation or error from true position is expressed as bi-direction repeatability. 

The values for bi-directional repeatability are always larger then the uni-directional repeatability because they include the composite hysteresis of the electronic, position feedback ,electro-mechanical drive and mechanical hysteresis. For the end user, the bi-directional repeatability is usually more relevant and meaningful unless the motion patter for which the stage is used is a single direction step and repeat mode requiring an optimized repeatability capability. 

Resolution

The smallest achievable positioning increment that can be achieved by a stage or system. Resolution is determined by the stages mechanical capability and its feedback device. 

About Us

NUTEC Mechatronic Systems' positioning is based on perfection. Engineering and design are focused on details and balanced design, flawless fabrication and precision machining to exacting standards and consistent quality.

Nutec Components
631-242-1225
[email protected]
81 Jefryn Boulevard East
Deer Park, NY 11729

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