Product category:
Vision and Colour Sensors
News Release from: Cognex UK | Subject: In-Sight 5100 vision sensor
Edited by the Engineeringtalk Editorial
Team on 17 August 2007
Vision sensors help maintain filter
production
A complete pick and place system was in place within four weeks.
Anyone producing in large quantities for the motor-vehicle industry has to ensure that their production processes run particularly smoothly and reliably The major global manufacturers of soot particulate filters for the motor-vehicle industry now use In-Sight vision sensors for greater efficiency on the production lines
This article was originally published on Engineeringtalk on 12 Mar 2001 at 8.00am (UK)
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The decision - at the Nienburg plant of the Engelhard Technologie company - to rationalise the handling processes by using robots went hand-in-hand with the desire to control this precisely and reliably by means of image processing.
In December the entire system controlled by image processing underwent initial start-up by the robot system integrator.
Thanks to the efficient co-operation and the comfortable In-Sight Explorer development environment it was possible to have the 'pick and place' system up and running in less than four weeks.
With this handling task, difficult facts had to also be reliably mastered.
Immediately after the furnace the ceramic filters are forwarded automatically to the transport conveyor and then the robot cell.
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Special purpose machine tools and assembly systems, with Cognex machine vision systems as an integral part, are being supplied to the automotive industry by Douglas Curtis Machine Tools
Complex vision technology in an affordable unit
Cognex have introduced the In-Sight 2000, an entirely new type of industrial machine vision sensor at a cost usually associated with "smart cameras"
Cognex unveils online support and learning centre
Cognex has unveiled a new internet-based Support and Learning Center that provides 24-hour access to a wide range of learning and technical support resources.
The robot must be able to detect, for example that the gripping of the type 3 part is done precisely and that it is then placed on Line 2 for further processing.
The soot filter product variants differ from each other only in minor terms, however they have to be handled absolutely reliably by the image processing system.
The In-Sight 5100 vision sensor used in the robot cell must be absolutely reliable in recognising each shape amongst the roughly 25 different filter variants and also determine their exact position.
To enable the robot to grip faithfully the measuring accuracy must be +/- 1mm.
Because there are also filter variants of identical design but slightly different lengths, the image processing system must also be capable of reliably detecting these parts on the conveyor with their differing heights.
Only then will the robot know which part has been picked up.
The rotation angles of the mainly asymmetrically shaped parts are to be provided to the robot as extremely precise data.
This has to be performed accurately as the subsequent reading of the 2D codes always has to take place at the same point for reasons of process reliability.
A great advantage in implementing this demanding task was the extraordinary reliable operation of the vision tools and algorithms that are integrated as a library into In-Sight.
They are parts of the powerful PatMax vision software from Cognex.
In contrast to edge detection through grey-scale correlation these tools operate using geometry-oriented object recognition.
The selected ceramic filters are then placed by the robot onto the conveyor belt that forwards them to packaging.
The accurate position data supplied by the In-Sight vision sensor then immediately controls the robot.
Programming, configuring and organising the installation of the image processing system within the company enables short communication paths to be set up.
Thomas Wente of Engelhard Technologie, responsible for project execution, said: "On the one hand, we considered it to be very important to be able to execute projects quickly and reliably, yet on the other hand we also wanted to be able to immediately perform any necessary changes to the process ourselves".
It was also possible to master additional control tasks with regard to packing the soot particulate filters.
By using an In-Sight 5100C colour vision sensor it is possible to verify whether the green quality label is available on each filter and whether the cardboard box contains the prescribed number of parts.
By continuously checking the number of packed parts and by comparing the number actually produced it is possible to determine the amount of rejects/loss.
The support of Cognex employees at the production line itself made it possible to completely solve the control task in only two days.
Here too the benefit of having a very simple image processing programming process for the vision sensor using a spreadsheet operator interface was once again demonstrated.
Right from the start an additional expansion of the image processing system was planned for the production lines.
This is why work was done straight away with the In-Sight Explorer development environment.
This proved to be advantageous in terms of reducing time and costs for setting up as well as programming the networked vision sensors.
The extremely user-friendly graphic working platform based on the Windows environment enabled a time-saving and application-specific solution for the complete vision tasks to be achieved.
This serves to guarantee all aspects of the implementation including the continuous administration and communication of the vision sensor network with the production network.
The fact that the staff learnt very quickly how to use the In-Sight Explorer resulted in a significant reduction in vision development time.
Another In-Sight has been integrated into the existing robot cell and two further vision sensors control the second robot cell which has now been installed.
In the past the localisation of objects or edges in the image processing system was based on grey-scale correlation.
During this analysis procedure the image pixel grey stages are compared against the reference object whereupon the position is then calculated.
This procedure soon reaches the limits of its capabilities when utmost precision is called for and where influences such as rotation, scaling or fluctuating illumination and contrast ratios have to be mastered.
In contrast to the grey-scale correlation process, the Cognex vision software PatMax procedures use the geometric basic structures of objects in a three-stage procedure.
Firstly, the most important individual characteristics of an object such as the edges, dimensions, shapes, angles, arcs and shades, are isolated and identified.
The three-dimensional relationships between these central features of the practised image are compared against the real-time image.
By analysing the geometrical data and the features and their three-dimensional relationship it is possible to clearly define the object's position with maximum accuracy.
The overall recording image no longer needs to undergo linear analysis.
This in turn simplifies the feature detection process, rendering the vision system very fast, highly flexible and extremely reliable.
PatMax records extremely high resolutions down to the subpixel range and provides reliable angular determinations of objects to 0.02 degrees.
The vision tool is invariant to the object's position, orientation and change of scale.
Through simultaneous examination of the outline and structure of the object pattern it is possible to eliminate alternating illumination and contrast ratios. Request a free brochure from Cognex UK ...
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