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MACHINE BUILDING, FRAMEWORKS & SAFETY FEATURE


Breaking new ground in inspection speed and accuracy


Paul Wilson, managing director at Scorpion


Vision, looks into the advantages of combining line-scan cameras with AI and examines how the company built an AI-powered line scanning system to detect burgers for defects


L


ine-scan cameras are often used for inline quality control of web printing processes where they are used for


inspecting printed sheets or textiles for defects such as ink spot marks, embossing defects and mis-registered colours. Outside of the printing industry, however, their use has been limited to such applications as inspecting printed circuit boards, and in the food industry on nut sorting lines, for example. Line-scan cameras will generally provide


a better solution than conventional area-scan cameras where a moving, continuous material, needs to be analysed for faults or defects. Area-scan cameras capture


the data for an entire image in one go and the dimensions of the resulting image correspond to the number of pixels on the sensor; whereas line-scan cameras use a single row of light-sensitive pixels to constantly scan moving objects at a high frequency, capturing lots of ‘slices’ of an image which it then combines to construct the final image. Area-scan cameras are


therefore not as suited to very fast web based applications but, being easier to install and use, are ideal for straightforward machine vision tasks. Despite this, the advent of


bigger, faster and more sensitive area-scan sensors means that it is not unusual to see a CMOS area-scan sensor being used where a line-scan camera would have been the default option. The ability to adjust the active area on the sensor means that a line-scan camera can be emulated in some cases.


HigH perFormance


Although capable of higher speed processing, line-scan cameras are more complicated and costly to install, mainly because the line rate of


the camera must be synchronised to the speed of the object being detected. However, advancements in the technology mean


that industries such as food, pharmaceuticals, e-commerce and logistics can no longer afford to ignore their performance advantages. Advancements in Image Signal Processors


(ISPs) are facilitating higher quality and faster processing of 3D images in more demanding environmental and lighting conditions. This enables the cameras to detect more critical detail


Fast inspection


Scorpion Vision’s AI-powered line


scanning system inspects IQF


burgers for visual abnormalities and defects


In a recent application, Scorpion Vision designed a bespoke AI-powered line scanning system to inspect IQF burgers for visual abnormalities and defects. The system incorporates two Scorpion 3D Stinger cameras above and below the conveyor belt which check each frozen burger is exactly the correct shape and size, shows no signs of discolouration, freezer burn or ice crystal formation, and is free from visual abnormalities such as large lumps of fat. A line-scan was best for this application


as the inspection needs to take place while the frozen burgers are being transported to a robotic pick & place packing system on a very fast moving conveyor belt. The line-scanning system designed by Scorpion is able to locate, inspect and measure the burgers in real time. In addition, an area-scan camera would


only be able to image the surface that faces upwards, not the underside of the burger. With the line-scan system, the burgers are passed over a very narrow gap between two conveyors and two cameras (one above and one below) which build up a 3D image of the complete burger as it passes over the gap. The scanning unit incorporates two 3D


Stinger cameras built into enclosures with internal polarised light sources, an arrangement that enables robust acquisition of images on reflective surfaces. Scorpion Vision’s proprietary


and capture higher resolution images. As an example, HIKROBOT, represented


by Scorpion Vision in the UK and Ireland, launched a 16K line-scan camera that is capable of detecting minute defects in PCB, EV battery, semiconductor, print and film inspection applications. At the same time, system designers are harnessing GPUs (Graphics Processing Units)


AI-optimised software analyses these images in real-time for reference features that have been established through deep learning, and any burgers that exhibit abnormalities are immediately rejected from the line.


Scorpion Vision T: 01590 679333 www.scorpion.vision


MARCH 2023 DESIGN SOLUTIONS 21


from the gaming industry for image processing. This hardware can reduce algorithm and data processing time and enables the use of AI-powered analysis. Using AI to improve pattern matching


capabilities improves and accelerates inspection performance. The combination of advanced image sensor technology and AI is enabling line-scan cameras to infer increasingly complex insights from the vast amounts of vision data they capture. Sophisticated sensor technology has also


provided solutions to the problem of adjusting the line rate to match the speed of the material under inspection, enabling accurate, meaningful 3D analysis of the image at high frequencies using software algorithms.


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