/ Measuring Technology /
TechnoTeam Bildverarbeitung GmbH, Germany
Company: TechnoTeam Bildverarbeitung GmbH
Industry: Labs, measuring technology, automotive and supplier industries
DENSO products used: VS-060 and VS-087
We are surrounded by displays – on smart phones and television sets, in kitchen appliances and even in cars. The design of these user interfaces and small-sized screens not only has to follow a stylish look, touch & feel, but also has to guarantee at-a-glance readability and a high functionality. This is particularly important in cars, where the trusted visibility and use of displays support traffic safety.
A display’s technical reliability and functionality depend on the electro-optical characteristics of a screen, which have to be analyzed and tested using a precise lighting technology measuring. In the past, these processes have been carried out manually, but this method has reached its limits: Today, an ever more complex display technology, its increasing integration into a car’s service and control systems as well as a wider product, materials and design variety call for individual measuring processes. However, if carried out manually, both the setup times for measuring devices and the precise reproducibility of measurements are a highly cost- and time-consuming process for manufacturers.
The solution is an automated, robot-assisted measuring system by TechnoTeam Bildverarbeitung GmbH. Founded in 1991 in Ilmenau / Thuringia (Germany), the company develops and manufactures photometric and colorimetric measuring cameras as well as image-processing light and color measuring technologies for labs and industrial automation. Today, this measuring technology is being used in the development and manufacturing of illuminated and illuminating work parts/modules such as displays, headlights and lamps, serving as the industry standard for the automotive sector and suppliers.
For the automated light measuring of self-emitting screens such as highly integrated automotive displays (both free form and curved designs), TechnoTeam, in 2019-2020, together with DENSO Robotics, has developed the LMK Position System. Featuring a DENSO robot at its center, it’s an innovative combination of photometry, robotics and machine vision. In particular, the LMK is being used in the development and testing of pre-serial and small batch production of automotive displays. Demanding a high level of flexibility, a separate product quality control of these parts would be too inefficient.
The automated measuring process requires a six-axis robot, therefore, the LMK Position System is being operated either with a VS-060 (605 mm arm reach, 4 kg payload) or a VS-087 (905 mm arm reach, 7 kg payload). In addition, the robots need to have an open interface, i.e. offered by DENSO Robotics’ ORiN2 software. Last but not least, the VS-087 can also be equipped with the latest and biggest cameras and lenses (as the trend goes toward a higher pixel resolution).
With the robots providing an outstanding repeatability of 20-30 μm for positioning, they are guaranteeing the required precision and payload – despite their compact sizes and sleek robot arm (95 mm, axis 4, 5 and 6). In addition, the TÜV-certified “Safety Motion“ option, enabling the robot operating without any safety cell, is an advantage, as TechnoTeam was able to focus on the applications’ actual software development. Thus the software controls the robotic-arm to drive the mounted LMK correctly to the desired position.
The system’s outstanding feature, thanks to the robot, is its capability of referencing the measurement positions, required by the geometries of the regulatory norms, to be reproduced exactly – irrespective of the exact positioning of the device under test (DUT), i.e. a display. In addition, automotive displays – due to their high level of integration in a car’s system – show complex forms (3D, curved, freeform surface) that are individually designed, depending on their function, but also the manufacturer: Here, the robot-based measuring technology shows its strengths, as the LMK is fit to be used for all kinds of displays because the system conceptualization – particularly its alignment – can be directly applied to other, self-emitting displays as well.
Combing the controlled and precise robot movements with using LMK reference images, the normal vector of the DUT’s surface can be determined for each single measuring point, thus offering the possibility of an automated adjustment for a perpendicular view of the optical camera axis in relation to the DUT. The perpendicular positioning or the angular-dependent orientation of the LMK is particularly important for the industry standard “Uniformity Measurement for Displays“, used by German car makers, as well as the IDMS (“Information Display Measurement Standard“). In the first case, the alignment consists of five dimensions (three angles and two locations) – if implemented manually, the required precision would require much more effort. The high level of automation thus makes it easier to combine different images, thereby unlocking new measuring and correction methods. In addition, there are specific requirements for measuring the complex geometry of reflections (according to ISO standard 15008), where both precision and quality have been significantly optimized thanks to the robots.
“Our decision for DENSO Robotics was heavily influenced by the communications flange, an option with these six-axis robots not offered by any other manufacturer,” explains TechnoTeam General Manager Udo Krüger. “Because we don’t know the display’s position in advance, we also cannot access the required movements beforehand, so the cable mounting could have presented a challenge. But thanks to the integrated cable routing, an elegant and safe DENSO Robotics solution, this is not an issue.“
The communications flange, patented by DENSO Robotics, features an Ethernet connection and an additional 17 signal links, all fully embedded inside the robot arm, all the way from the robot base into the 6th axis. As a result, cameras can be mounted easily and safely without risking any cable breaches.
“In addition, we were convinced by the DENSO Robotics support, primarily in the kick-off phase and beyond,“ says Udo Krüger. “The fact that the basic training only requires two days and can also be implemented on-site, has turned out to be another advantage as it’s also of great interest to our customers.“
Coming from around the world, TechnoTeam customers are mostly display manufacturers and companies using displays in their products; they also can use the system on site, while also operating it using one or several different lenses and special lenses.
The LMK Position System is controlled by C++ with the LMK itself relying on its internal libraries and camera interfaces and – for the robot controlling – ORiN2 SDK. This allows for handling and transforming the LMK coordinate system with the optics used as well as the DUT coordinates’ system, i.e. a display. For the robot, the zero-point lies on the display’s surface; and relative to this point, one can shift or rotate (for example in relation to one of its corners) – this can even be implemented for the whole DUT surface. This is particularly important when measuring the complex geometries of display surfaces in cars, as their angular alignments have to be double-checked.
Taken together, these features make the system easy to operate for customers, also because the potential complexity of standard tasks has been deliberately limited in order to guarantee user-friendliness; as a result, each measuring task is packaged into one easy-to-access GUI. In addition, the LMK Position System is designed as an SDK, so customers can also program their very own measuring processes while using the alignment function, as the system is communicating with the SDK camera.
It’s the robot facilitating the combination of machine vision, photometry and movement, which, in turn, enables fully automated, flexible and highly repeatable measuring solutions. As the system is aligning itself relative to the display, the much faster setup time is the decisive advantage; if compared to the manual measuring of the past, the setup time now is shortened by a factor of 20, while also making the measuring as such must less prone to errors. This is particularly true for the pre-development of products when, for example, a new system including different components, has to undergo testing.
Using this one system only, both an integrated, standing display or a (i. e. horizontally positioned) prototype (without all its layers already being fixed) can be measured. The traditional, manual re-adjusting of each single camera orientation has now become but a faint memory: Using the LMK Position System, the adjustment is carried out in just a few seconds, saving both time and costs.
The system’s flexibility makes it a perfect fit for the future, also because it can be combined with various special lenses. Lately, it has also been used in another application checking the illumination of license plates. In the future, the application could also be employed in the areas of AR/VR glasses and head-up displays, where movements in space in general and in angular spaces in particular are relevant.