In the past, a manufacturer of automated storage and retrieval system (AS/RS) shuttle solutions relied on wheel encoders to indicate shuttle positions along rails. Although this solution has been used for years and continues to be used, it can be prone to positioning errors, typically caused by wheel diameter variation, roundness and slippage. These factors enable position errors to accumulate, requiring the frequent usage of a shuttle homing sequence. To eliminate these challenges, the manufacturer selected non-contact Dimetix laser distance sensors. The Dimetix D-series lasers can communicate as a serial synchronous interface (SSI) encoder, which is a common output of traditional wheel encoders. This protocol is absolute, so errors will not accumulate and the position will be saved, even if power is lost. An absolute accuracy of 0.03 to 0.11 inches has been achievable over a 16-foot range, depending on the integration method, along with the model chosen for each job.
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