2 years ago



Sustainable generation

Sustainable generation of positioning systems AUTOMATION Large reading window and codes guarantee SIL 3/PLe-compliant safety applications, or in other words adherence to the most stringent safety guidelines and optimum protection for human and machine at all times. Achieving this level of safety previously entailed a great deal of time and money, but these problems will no longer affect future users of a new positioning systems. I n 2011, Pepperl+Fuchs celebrated the first launch of its PCV (Position Coded Vision) sensor, combining a 2-D camera as a reader with a Data Matrix code tape for absolute positioning. The reader extracts the information in the Data Matrix code, identifies the current location, and then calculates the exact position in relation to the center of the camera. The system is innovative in that it offers the highest possible level of data security by always reading several codes at the same time. In 2014, the newly developed PGV (Position Guided Vision) system – a navigation solution for automated guided vehicles (AGV) – was released using the same technology. The method of using a 2-D code to tackle the task of positioning remains unique, and offers major benefits over solutions using 1-D codes. For example, the user can evaluate the Y axis as well as the X axis and use this data for positioning purposes. Both of these systems have undergone continuous optimization and development over the past few years. The second generation of the PCV successor model - the new PXV system - was presented late last year. Yet despite the continuous efforts to enhance these positioning devices, operators frequently reported a need for additional safety solutions for absolute positioning and safe navigation. Machines and plants which can be controlled by electrical or elec- Author: Armin Hornberger, Head of Product Management for Industrial Vision Components, Pepperl+Fuchs GmbH in Mannheim, Germany tronic systems and sensors present a hazard to the humans working with them. In order to protect these individuals, stringent statutory requirements must be met. They are set out in the Machinery Directive, and are intended to ensure that all the machines and plants placed on the market are safe. With the safePGV and the safePXV systems, Pepperl+Fuchs has developed a new generation of positioning systems which achieves the required SIL 3/PLe compliance for the first time – all with a single sensor. What is so ground-breaking about this safety solution? To start with, SIL 3/PLe-compliant safe absolute positioning has been virtually unachievable for plant operators to date owing to the substantial amounts of time and money involved. Redundant systems with different sensors or different technologies needed to be constructed. It was furthermore necessary for the safe control system to carry out plausibility checks of the data, and the overall development process needed to be monitored by TÜV and ultimately approved. A single positioning system with just one sensor achieves all of this in the new safePGV and safePXV systems from Pepperl+Fuchs. The new safety technology is based on the particularly reliable combination of a 2-D reader and the Data Matrix code, which has been popular for many years. The new system however introduces a special tape with two superimposed red and blue Data Matrix codes. The 2-D reader is equipped with two different colored LED rings - also red and blue. The two-color codes, in combination with twocolor illumination, form 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. Direct and safe data transfer to safety PLC The real brain of these positioning systems can be found in the innovative new firmware. It controls the different LED colors with an algorithm rated as safe. Each code is then independently checked for plausibility in the safety section of the sensor. The mathematically random flash sequence must match the actual position. Since the different LEDs are controlled via the safety section, the camera 36 WORLD OF INDUSTRIES 2018

Benefits n Safe absolute positioning according to SIL 3/PL e with only one single sensor n Multiple-redundant technology combines safe firmware, 2-D read head, and two-color Data Matrix code band 01 The 2-D camera can be easily parameterized with Profinet-GSDML file via the safety PLC Absolute positioning system detects the data matrix codes regardless of radius size n Direct and safe data transfer to safety PLC via Profinet Profisafe protocol—without any additional function block needed evaluation system does not know the illumination color currently being used for recording. It therefore only compares the data actually recorded for the code against the expected value. This means that checks are constantly being carried out to ensure that the software in the camera is still functioning properly. The system firmware only transmits all the data to the safe control system via Profisafe once it has carried out plausibility checks within the sensor itself. The safe X position can then be directly processed by the safe control system without additional checks and used for process control. The result is a unique and absolutely reliable sensor technology which continuously performs selfchecks. The system also meets the stringent SIL 3/PLe safety requirements for the first time, with a high level of efficiency - and just a single sensor. Suitable for many versatile fields of application Based on a multi-redundant technology, safePXV and safePGV enable safe absolute positioning according to SIL 3/PL e with one single sensor for the first time. Armin Hornberger The new safePXV system is ideally suited for linear safe absolute positioning in electric overhead conveyors, stacker cranes in the field of warehousing and material handling, rotary tables in mechanical engineering, elevator construction, and wind turbines in the field of renewable energies. As well as safety and reliability, ease of handling was also of enormous importance when developing the system. The mounting procedure could not be quicker or easier. The code tape is already supplied in the appropriate length and simply needs to be adhered in place. Following approximate alignment of the reader, additional parameterization can be carried out directly via the safety control system using the Profinet- GSDML file. The new safePGV system has been optimized for navigation with automated guided vehicles (AGV) in the field of warehousing and material handling, supply, and production. The solution goes far beyond simple positioning in this respect. 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. As well as the safe data, the plant operator can also access angles and Y positions easily and flexibly. This means that track deviations can be corrected easily at any time. The new positioning system is therefore the ideal solution for all navigation tasks, as well as being a safe investment in the future. A crane system with a crucial safety advantage The new safety technology makes it possible to increase levels of occupational safety for employees working on crane systems efficiently and without significant effort. The safePXV system can be used to achieve the absolutely reliable definition of a safety zone in which the goods can be lowered without any hazard. In the case of gantry cranes in large halls, for example, the new safety technology must be affixed to the side rails. The sensors then reliably report their precise position to the safe control system using the Data Matrix code tape. Since both sides of the crane system are fitted with the safePXV system, synchronization can be ensured. The trolley and the axis on which it moves are also fitted with a sensor and the Data Matrix code tape, with a view to guaranteeing the exact position of the load within the crane system and safe absolute positioning. The new technology can also significantly increase safety during unloading and reloading of containers in port facilities. Portal cranes are frequently used in these situations to load the cargo onto trucks. Safe absolute positioning is a crucial factor in placing the container accurately and avoiding damage to vehicles and hazards to workers. The new safePXV system can also be fitted onto crane systems of this kind with very little effort, ensuring that safe X and Y positions are determined from the system’s two directions and transmitted to the safe control system. Photographs: Pepperl+Fuchs WORLD OF INDUSTRIES 2018 37