Pepperl+Fuchs: Easy-to-Use Laser-Line Triangulation Technology

Easy SmartRunner parameterisation using control codes

Integrated sensor solution for many applications

The line triangulation method is a frequently underestimated sensing mode for monitoring presence, completeness, position, and similar tasks. In many applications, compact intelligent light section sensors deliver results that are more precise and reliable than those delivered by other types of sensors. Line triangulation technology is not only unaffected by extraneous light, it also reliably detects objects with minimal contrast or no contrast to the background. The potential of the line triangulation method will be demonstrated using a number of application examples from different industrial fields and sectors.

The primary goal of all automation is high throughput and the elimination of downtime and scrap production. Therefore, an increasing number of sensors in production, processing, and logistics applications ensure that the necessary requirements are met. They are used to check the presence, completeness, and accuracy of supplied parts. Slides and components must be in the correct position and orientation to be filled, processed, or picked up by a robotic arm. Many of these typical detection tasks can be performed reliably and elegantly using line triangulation technology.

Light section sensors combine all the required components in one compact device and are usually easier to parameterise than 2-D vision sensors. They work on the principle of triangulation, using a projected laser line to detect height profiles and edge contours with high precision: The known distances and angles of the triangle formed by the light source, camera, and object are used to calculate the exact positions of all points along the line projected on the target object.

Precise and Resistant to Interference

The use of a sharply defined laser beam provides some decisive advantages when compared to normal vision sensors. Light section sensors can clearly detect low-contrast objects and even zero-contrast objects. They only require differences in height to detect surfaces. Furthermore, the light section method is much more resistant to extraneous light and fluctuating lighting conditions.

In 2-D vision sensors, (unexpected) changes in lighting in particular can dramatically reduce or even completely disable detection performance, for instance if daylight enters a window. When using vision sensors, the exposure time, arrangement of the device, and, where necessary, external lighting must always be precisely adapted to the conditions of the application. In contrast, the automatic exposure time control function with which light section sensors are ideally supplied is perfectly sufficient for the vast majority of applications.

From the Automotive Industry…

These properties predestine high-performance laser-line triangulation sensors, such as the SmartRunner Matcher from Pepperl+Fuchs, for use in numerous applications in the automotive industry, packaging technology, logistics, and in mechanical and plant engineering. When manufacturing car bodies, it is vital to check that fixing elements such as rivets, screws, clips, and dummy plugs are present and installed in the correct position. These small parts often differ only slightly from the background and the contrast is very low.

The light section solution can easily overcome this challenge. The sensor detects height profiles regardless of color and surface structure and issues a good or bad signal via the switching outputs depending on the detection result. If the sensor is mounted on a robot arm, diverse elements or scenes can be verified using the same device. Only one sensor is required as it can store multiple detection profiles.

Other applications in the automotive industry include checking anchorages on skids (skid bolts), checking the precision of sheet metal parts before welding, and checking whether anti-vibration pads (stickies) are correctly glued in place. Laser-line triangulation technology always ensures reliable detection in all applications. Its function is not affected by extraneous light, low contrast, or reflections.

…to Packaging Technology

The packaging industry also benefits from line triangulation technology. For instance, plastic trays with multiple compartments are often used to package ready meals. These allow the main course and side dishes to be kept separate until consumed for reasons of taste and esthetics. Proper separation of the components is a prerequisite for customer acceptance as well as for correct, air-tight sealing.

Therefore, it is necessary to check the orientation of the trays before filling. Here too, the light section sensor can prove its worth, as the plain, mostly white trays naturally offer only little contrast. The Matcher always delivers reliable and unambiguous results by detecting the height profiles.

Ready-to-Use Line Triangulation Solution

Laser-line triangulation technology is often superior to other solutions and has much untapped potential that users should exploit in their applications. All of these applications can be implemented with the SmartRunner Matcher laser-line triangulation sensor.

The Pepperl+Fuchs device combines a high-precision light section sensor and a vision sensor in one compact unit. The Matcher is factory-optimised to recognise a previously learned reference contour, can store up to 32 profiles, and can be integrated immediately into applications as a plug-and-play solution. The evaluation results are output via switching outputs as good or bad signals that any control panel can process. Fieldbus solutions and gateways are also available for PROFINET, PROFIBUS, EtherNet/IP, and EtherCAT.

One interesting feature is the option to output the deviation of the current position from the learned X position and Z position. If an application does not allow accurate sensor triggering, standard sensors such as light sensors or ultrasonic sensors are not suitable for presence detection. In this case, laser-line triangulation sensors can deliver geometric displacement results to the control panel.

A powerful LED lighting system is also integrated for generating image documentation of faults, process states, and quality characteristics. Alternatively, the sensor can be easily parameterised using Data Matrix control codes, so that no PC is required.