New magnetic positioning system offers 0.1mm resolution over distances to 548m

Sensor Review

ISSN: 0260-2288

Article publication date: 28 March 2008



(2008), "New magnetic positioning system offers 0.1mm resolution over distances to 548m", Sensor Review, Vol. 28 No. 2.



Emerald Group Publishing Limited

Copyright © 2008, Emerald Group Publishing Limited

New magnetic positioning system offers 0.1mm resolution over distances to 548m

Article Type: Mini features From: Sensor Review, Volume 28, Issue 2.

The KH53 absolute linear encoder system (Figure 6) from SICK (UK) Ltd, is now available in a new advanced version that offers a position resolution of 0.1mm with an increased mounting tolerance ±20mm.

Capable of operating in harsh conditions, the KH53 Advanced is available in two variants with measurement lengths up to 54 and 548m, respectively; typical applications include crane position detection, in handling and warehousing systems, or the detection of rail-mounted vehicles in both indoor and outdoor environments.

Figure 6 The KH53 absolute linear encoder system from SICK (UK) Ltd

In operation, the KH53's read head determines the absolute position of the crane or vehicle using non-contact scanning of permanent magnets. During manufacture, the individual magnets, referred to as measuring elements, are fixed inside aluminium profiles that are approximately 2m long with the separation distance between each magnet being unique. Furthermore, the position of the magnets is unique within each measuring element, with a code identifying how the magnets have been installed and in which order the measuring element should be mounted. Once the measuring elements are fitted in the application, the distance between each magnet is unique and not repeated over the whole length of travel. This magnet separation is then identified by the read head's magneto-resistive sensors the result being the accurate calculation of the absolute linear position.

In the case of the new KH53 Advanced, the nominal separation between the read head and measuring element is 55mm with a tolerance of ±20mm twice the tolerance of the standard KH53. This increased mounting tolerance ensures that positions are reliably detected even if the distance between the read head and the measurement elements vary to a greater extent in applications with harsh environmental conditions or on older installations with worn wheels or bent rails.

With its non-contact technology, the KH53 Advanced system is completely free of wear. If necessary, the robust measurement elements can be installed under the floor of the drive path to protect them from mechanical damage. A reference run is not required when the plant is started up due to the absolute position determination.

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