IPP&T Magazine Online

Absolute positioning with just one sensor

November 5, 2018  

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Pepperl+Fuchs has developed a new generation of positioning systems that-for the very first time-achieve SIL 3/PLe compliance with a single sensor, making them uniquely safe and highly efficient. While previously associated with high cost and time investment, this safety level can now be attained more simply than ever before.

The new safePGV and safePXV systems from Pepperl+Fuchs achieve maximum safety in the form of a single-sensor positioning system. This new generation of security solutions is based on a technology that has been used for many years-the particularly reliable combination of a 2-D reader and Data Matrix code. New superimposed Data Matrix codes, one in red and one in blue, are the hallmark of the safety version.

The 2-D reader is also equipped with red and blue LEDs. The two-colour Data Matrix codes, in combination with two-colour LEDs on the reader, are the basis for this unique security solution. Each individual code contains position and safety information, which is made visible by red or blue LED illumination and can therefore be read by the camera.

The safePXV positioning system offers unparalleled reliability for linear absolute positioning. Due to its easy handling, the system is suitable for a variety of applications, such as ensuring exact positioning of monorail conveyors in a production line. Additionally, it can be used for stacker cranes in material handling, rotary tables, elevators, and skillets.

The new safePGV system is the ideal solution for navigation with automated guided vehicles (AGV) in the fields of warehousing and material handling, supply, and production. In addition to the safe X position, the sensor supplies all values required for reliable vehicle control.

In automotive manufacturing, for example, a minimum distance can be guaranteed between vehicles at all times, protecting all the employees working in that area. In addition to the safe data, the plant operator can also access angular feedback and Y positions in order to correct track deviations easily at any time. The new positioning system is the ideal solution for all navigation tasks.

An innovative new firmware is the mastermind behind these positioning systems. It controls the different LED colors with a safe-rated algorithm. Each code is then directly checked for plausibility in the safety section of the sensor. The 2-D read head of the new absolute positioning systems reads the color codes of the Data Matrix code band. The advanced firmware processes the received information based on a safe algorithm in the sensor and forwards it as safe data according to SIL 3/PL e to the safety PLC.

This progressive sensor technology performs continuous self-checks, making it the ultimate in reliability. Most importantly, however, this system is the first of its kind to meet the high SIL 3/PLe safety requirements with a single sensor.

The sensor’s scan window has been considerably enlarged, now measuring 120 mm x 80 mm, and provides multiple levels of redundancy.

Major benefits come with the significantly larger reading window. Coupled with the enormous depth of focus, it guarantees optimal readability and the highest possible tolerance level during production-tight curve radii, uphill and downhill gradients, and distances of up to 100,000 metres can therefore be achieved without any problem. Gaps or interruptions of up to 75 millimetres in the code tape without any loss of position. This is particularly useful in plants with extremely long routes. For example, expansion joints in buildings can be bridged without any loss of absolute position.

The Data Matrix code band is self-adhesive and is available in customized lengths. Following approximate alignment of the reader, additional parameterization can be carried out directly via the safety control system using the PROFINET-GSDML file. The 2-D camera can be easily parameterized with this file via the safety PLC. Fieldbus variants are direct via the controller. Additionally, interfaces included in the sensor’s housing facilitate system integration.

The safePGV and safePXV innovative safety technology from Pepperl+Fuchs can be used in all industries. The latest generation of positioning systems means that SIL 3/PLe-compliant safe absolute positioning is possible using a single sensor for the very first time, offering reliable protection for both human and machine at the highest level of ease and efficiency.


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