Integrated Vision Platform for 3-D Applications
Published on : Friday 06-05-2022
Armin Hornberger explains how the new 3-D sensor series masters stereo vision and time-of-flight processes work.
Where packaging is automated, driverless industrial trucks are often on the move. The new sensor series SmartRunner Explorer 3-D from Pepperl+Fuchs supplies the 3-D vision data for controlling different applications. It includes two device variants with their own measurement methods on one platform: Stereo Vision and Time-of-Flight. Housed in the same housing, with uniform user software and data output, the integration effort for 3-D applications can be significantly reduced.
Conventional vision sensors usually derive various control-relevant features from a captured 2-D image. Most devices specialise in specific, narrowly defined applications. For example, they can be used to check the completeness of beverage crates and determine whether all compartments are occupied. However, there is at least one more relevant question for the quality control of the bottling plant: Are the crown caps or screw caps correctly positioned on the bottles? It is very difficult to answer with a 2-D sensor from the same perspective, since the z-axis depth information is missing. A 3-D device, on the other hand, can supply the data for both control tasks in one automated run.
Complex situation mapping in Stereo Vision 3-D
The stereo vision device has a range of one meter and a resolution of 1.4 megapixels. The size of the detection area is 400 x 350 mm at a distance of 600 mm and 550 x 500 mm at a distance of 900 mm. With these parameters, it is optimised for the high-precision detection of objects in this close range and is particularly suitable for inspection applications. For example, it can be used for checking and counting of defined objects or for volume acquisition. The additional depth information in the z-direction opens up completely new application possibilities that remain closed with conventional sensors.
The device works with two cameras. Using the high-resolution 2-D data, the sensor can be precisely aligned with the target object, which makes it easier to interpret the measurement results. In the first step, your 2-D images are automatically superimposed to form a disparity image, which forms the basis of the 3-D point cloud. It should also be mentioned that all devices are factory calibrated.
A typical field of application is the detection of an amorphous mass in a packaging unit, for example bananas in an open shipping box. This should be as full as possible, but without anything protruding. After all, a single damaged fruit could rot the entire contents of the box. Each overhang is reliably displayed on the 3-D image of the SmartRunner 3-D Explorer, while the degree of filling is recorded at the same time.
Dynamic data output with time-of-flight
With the ToF variant, the focus is on range and signal frequency. Signal acquisition and output are optimised for applications with a larger measuring range where short response times are important. The device has a single camera with a VGA resolution of 640x480 pixels and a measuring rate of 30 Hz. The detection range is 7.5 meters long. The infrared light emitted by the sensor's DuraBeam illumination has a wavelength of 940 nanometres. It keeps a large distance from the spectrum of daylight and conventional lighting. The sensor is therefore highly insensitive to extraneous light, even outdoors.
A typical application can be the control of an automated guided vehicle (AGV). The SmartRunner 3-D provides the 3-D point cloud, which shows the recesses in the pallet foot and also the contours of the pallet loading.
All in one
Both device variants are raw data sensors that are delivered, calibrated. They use an identically standardised data structure and the same ViSolution user software with a uniformly designed, intuitive user interface. The software is provided with the devices free of charge. The task-specific visualisation of 2D and 3D data is set up with just a few clicks.
After commissioning a first device of the SmartRunner Explorer 3-D series, further devices in both variants and for different application ranges can be integrated by duplicating. An Ethernet gigabit interface ensures fast data transmission. The uniform, highly stable aluminium housing dissipates the operating heat and compensates for unwanted temperature influences.
Commissioning and parameterisation can be carried out intuitively with ViSolution using live data. Plug&Play applies when replacing devices, there is no need for recalibration. Mounting is aided by an alignment ruler and alignment holes on the housing. Together, the two device variants of the SmartRunner Explorer 3-D series can cover the vast majority of 3-D applications for vision sensors in industrial practice, from precise object measurement on conveyor belts to the exact positioning of robot arms. Thanks to the uniform platform, the integration effort is reduced.
Armin Hornberger is Head of Product Management for Industrial Vision Components at Pepperl+Fuchs.
Article courtesy: Pepperl+Fuchs SE – Lilienthalstrasse 200 – 68307 Mannheim. Phone: +49 621 776-1111. Email: [email protected]