Feature Sensors & transducers


ensors are used across all industry sectors – from food and beverage to manufacturing. Whether it’s for presence detection, distance and positioning, code detection or quality control, we depend on the capabilities of sensing technology every day. In fact, sensors are so widely employed in our daily lives, both in industry and person- ally, that it is difficult to imagine how we would cope without them. The technology is continually devel- oping, enabling more accurate sensing, not only over greater distances but also in 3D and in colour. This continued innovation is enabling industry to make savings, not just financially, but also in terms of time, quality and safety. Over the past year we have seen some significant developments, and some of the most notable innovations have enabled the detection of colour and 3D in parallel. There have also been


Sensing the way forward S


Vision and quality control Vision systems used for industrial quality control, pick and place, and positioning applications have been progressing from 2D to 3D over the last decade. Now, however, we have seen vision system technology develop to another level.


Progress – from simple detection of where an object is on a belt to giving ever more complex informa- tion about the object parameters of size, shape and profile – has enabled industrial processors, especially in the food and pharmaceutical indus- tries, to select the degree of detection best suited to their process.


Here, too, the precision of lasers has enabled better information to be captured by vision cameras. Just as important has been the increase in the capability of the cameras, and we have seen an important step forward in this technology that enables even better quality control data capture.


developments in LED technology, con- siderably improving presence detection.


Measurement and safety Continued developments in laser technology, enabling high precision over greater distances, have improved safety and security applications, as well as distance measurement. Laser technology can now provide precision with resolution down to just millime- ters, and power for ranges of up to 30m. This delivers significantly enhanced security in industry, enabling the user to establish safe distances for collision avoidance, for example.


Double pulse technology and sophis- ticated time-of-flight measurement are some of the techniques now being used. This technology enables accurate control under difficult conditions, such as rain or water spray, dirt and dust, and with transparent surfaces including sheets of glass or plastic.


While many of these developments are based on the power and coherent light of lasers, which have been extend- ing the role of laser sensors in tough conditions, breakthroughs with other light sources also arrived in 2010.


Instrumentation FEBRUARY 2011


Using colour image data, 2D and 3D information as well as grey scale values in industrial applications, has required the use of multiple camera and lighting set ups, with associated calibration and data integration diffi- culties. This barrier has now been broken, however, with vision systems that combine the profiling and surface detail capabilities of line scanning lasers with a further colour scanning ability in the vision processing camera. The digital assessment of shape, contrast, colour, volume and height provides five different measure- ments for quality control comparison with set parameters. With a single camera capable of providing this wider range of data, investment, maintenance and set up time are reduced. Benefits can be found in electronic, food processing, pharma- ceutical, cosmetic and building material production, amongst others.


Presence detection While low power lasers have been


This Array sensor is used to detect paper and film positioning to high accuracy


David Hannaby, imaging & measurement specialist at SICK (UK), highlights some of the exciting developments in the world of sensors and the resulting benefits for industry


widely used for switching devices with motion, security, distance measurement and quality control functions, the latest breakthrough in LED design offers a significant step forward in presence detection. Although lasers produce a tightly focused and intense beam of light which enables high precision sens- ing and a useful detecting range, LEDs have a significantly longer life span of up to 100,000 hours, nearly twice as long as a laser, while also being economic to purchase and operate. LEDs are also robust and


operate over a wider ambient tempera- ture range, making them useful in a wide variety of process conditions. Until now, conventional LEDs have had a major drawback, due to an inherent design characteristic that puts one of the diode bonding wires at the tip of the diode, creating a very distinctive central black spot and a halo of lower intensity light.


Left:


Baked goods such as this burger bun are ideal for colour vision quality control


Reconfiguring the LED and enabling it to emit a pin-point of light has virtu- ally diminished the halo effect. The light spot intensity of the Pin-Point LED is concentrated on a much smaller area, giving it greater functional reserves. This also offers the ability to detect objects down to 1mm, and distances are improved from around 100mm to 500mm. This increased capability enables sensor detection systems with the new LED to overcome contamina- tion and dirt, and have wide applica- tions in the processing industries. This level of precision detection makes the pin-point style of LED ideal for some photo-electric switching appli- cations, enabling significantly lower purchasing and whole-life operational costs, with reduced process downtime.


A developing technology The capabilities of modern sensing systems now significantly surpass the expectations of traditional sensors, enabling benefits in areas as diverse as energy efficiency, waste reduction, security and control precision. The advances we are seeing demon- strate how far the technology has come and how it is continually changing, pushing the boundaries of current per- formance and functional expectations. The possibilities are endless.


The PinPoint LED eliminates the halo effect


SICK (UK) T: 01727 831121 www.sick.com/uk


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