Linear measurement system uses camera and barcode tape

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Linear measurement system uses camera and barcode tapeSick is launching the OLM100 camera-based optical linear measurement sensor that uses barcodes for accurate, high-speed, non-contact linear position monitoring on straight and curved tracks. This system is suitable for use in the automotive, textile and film industries, where overhead conveyors, rotary tables, turntables, rail-mounted shuttles, slewing rings, hoisting systems and robots are commonly used.

The optical linear measuring sensor detects position via a barcode tape that is installed along a travel section measuring up to 10km. The read head is mounted on the moving part, at 80-120mm from the tape. By reading the barcodes printed on the tape at 3cm intervals, the read head determines the current position with a resolution of up to 0.1mm.

Because the sensor continually reads up to three barcodes to build an absolute positional value, performance is assured even if a barcode is missing or a number of barcodes are damaged.

No moving parts

Darren Pratt, distance sensor product specialist for Sick (UK), comments: "The OLM100 illuminates the barcode using a red LED and a CMOS array reads the illuminated barcode. This means that the sensor does not have any moving parts - in contrast to conventional barcode scanners, which use a rotating mirror containing a number of moving parts.

"As the read head is generally situated on an automated machine, such as a crane, or vehicle, it is often subject to shock and vibration. By negating the need for moving parts, which can suffer wear and damage, the life expectancy of the sensor can be greatly increased.

"In addition, LED illumination has a life expectancy of almost twice the length of a good quality laser diode. This means that you can expect to get 100,000 hours of use, as opposed to the average 50,000 hours expected from a laser diode."

Harsh environments

The OLM100 is designed to ensure maximum performance and availability. It provides high-resolution measurement and a high output, enabling precise and fast positioning. In addition, the sensor is extremely hard-wearing, as it boasts a rugged metal housing, and the durable polyester barcode tape is 100 microns thick, with a high tear strength.

To cope with applications in industrial environments, the barcode tape is impervious to most oils, greases, fuels, solvents and weak acids. Furthermore, the system accommodates temperature fluctuations between -30 and + 60degC, making it suitable for use in extreme temperatures such as in cold stores and steelworks.

To simplify installation, it is only necessary to apply the barcode tape where positional information is required. In case of damage, replacement barcode tape can be created quickly by downloading and printing the code from the Sick website.

With easy alignment, simple mounting and no need for continuous calibration, the OLM100 saves end users both time and money on installation and maintenance. Using Sick's SOPAS software, the optical linear measurement system is also easy to program via an Ethernet connection. Multiple output types are available, including SSI, RS422, RS485 and CANopen. No gateways are required for most platforms.

Follow the link for more information about Sick's OLM100 camera-based optical linear measurement sensor system.

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