Application of industrial image processing

The possible uses of digital image processing in industrial applications are wide-ranged and are therefore on the focus of many different industries. One main area of application is industrial quality assurance in manufacturing or outgoing inspection etc.

The spectrum of technologies ranges from the inspection and characterization of surfaces, optical 3D measurement methods and X-ray technology to heat flow thermography, terahertz measurement technology, methods of non-destructive testing or hyperspectral image processing.

Defect detection of complex structures

In the field of surface inspection the challenges nowadays are in the detection of defects on complex patterns and structures, for example in the inspection of leather. Among other things, a particular difficulty is distinguishing defects from permissible surface deviations, which are the ok for a natural product such as leather.

Detection of contamination

The method of fluorescence measurement technology is used to detect contamination on surfaces. Integrated into an inline measuring system, a 100 percent inspection is carried out in production, even on complex components with an area of 50 x 50 cm². Unwanted residues such as lubricants, cleaning substances or photo coatings are detected.

Deflectometry of reflecting surfaces

Deflectometry is a suitable method for the inspection of reflective or partially reflective surfaces. The picture shows the height deviations in a 1m x 1m chassis part compared to the CAD data set; deviations of clearly less than 0.1 mm can be seen.

With the new technology of inverse deflectometry objects on both sides can now also be inspected, e.g. progressive lenses.

Geometric quality inspection of wheels

The laser cutting method is used for example in the automatic quality inspection of wheels. The system shown in the picture inspects all functionally relevant geometric features on aluminum wheels fully automatically and inline within the production cycle.

Defect inspection of belt material

When inspecting belt material such as wire, it is important that deviations (defects) can be detected quickly and are reported  back  to the process immediately. The system shown in the picture detects defects bigger than 50 μm on wire surfaces at a speed of max. 30 meters per second.

Sorting of bulk material

Multi- and hyperspectral image processing has established itself as an alternative to pure color inspection for the sorting of bulk material, such as food, plastic granulates or stones, with which very good sorting results can be achieved. This takes advantage of the fact that many products exhibit differences in the ultraviolet and infrared wavelength range that cannot be detected in the visible wavelength range.

Identification and tracing of components

In modern productions based on Industry 4.0 all parts and components must be clearly identifiable. The picture shows a track & trace fingerprint system that identifies mass-produced parts on the basis of their individual surfaces. This is based on random features visible under the microscope such as microstructures or color textures.

Inspection of carbon fibers

A polarization camera can be used to inspect carbon fibers. Incoming unpolarized light is linearly polarized by carbon fibers, with the polarization direction depending on the fiber direction. With the polarization camera the polarization direction of the reflected light can be measured and the fiber direction can be obtained directly from it. The image shows the color-coded polarization image of a defective carbon fiber scrim.

Evaluation of point clouds

The point clouds generated when using optical 3D measuring systems for dimensional accuracy tasks can be automatically evaluated, e.g. by means of best-fit methods of control geometries. The picture shows the measurement data of an exhaust gas converter.

Support for individualized productions

In highly individualized productions and the resulting small quantities, e.g. aircraft fuselage shells, assembly assistance systems can support the worker and provide appropriate assistance.

Left: Add-on part and joint are in order

Right: Attachment is incorrectly twisted

Real-Time 3D Person Measurement

Example of a real-time 3D person measurement by means of fast, irritation-free pattern projection in the near infrared. Corresponding 3D sensors can be used to detect body posture, gestures or facial expressions for human-machine interaction, interactive training systems, vehicle interior monitoring, security technology in public spaces and motion analysis on humans.

Characterization of complex microstructures

3D image processing enables the geometric characterization of complex microstructures. In particular, parameters are calculated that cannot be determined from 2D images, such as the grain shape in rock fills for high-performance mortars. The evaluation enables conclusions about the material properties (flow properties) and is thereby used for material optimization.

Visualization of internal structures

X-ray computer tomography can be used to  visualize the complete internal structures of components. The areas marked in red represent detected defects.

Heat flow thermography for the inspection of material interiors

Heat flow thermography is another possibility for inspecting the near-surface areas of the material interior of components. In the left half of the image a clutch disc can be seen; in the thermogram on the right colored bonding defects between the friction coating and the steel beam can be seen.

Distance and position determination

High-frequency or radar sensors have the advantage that they can operate in demanding environmental conditions such as high temperatures, vibrations or zero visibility due to smoke, steam or fog. In addition, protective measureslike for X-ray are not necessary. A main application area of such systems is distance or position determination.

Magnetic resonance for industrial quality assurance

Magnetic resonance (MR) technology that has been known up to now primarily from medical diagnostics is on the threshold of being used as a method for industrial quality assurance with image processing. In industrial quality assurance it can be used for example in the field of polymers and adhesives. The picture shows MR tomograms of silicone samples.

Millimeter waves for detecting objects in packaging

With millimeter waves near the terahertz limit it is possible to examine objects through packaging. Possible applications can be found in the food, plastics or pharmaceutical industries. The image below shows the inside of a nut chocolate, recorded at 240 GHz through the opaque cardboard packaging. Due to the different reflection properties the detection of the nuts in the chocolate through the packaging is possible.