Intuitive touchscreen with high electromagnetic noise immunity

Orbital welders, such as those supplied by Orbitalum Tools, use several thousand volts to ignite a TIG arc, which can cause electromagnetic phenomena that endanger the functional safety of the welding machines. This places high demands on intuitive touch panel PCs, which Orbitalum Tools now uses in its latest orbital welders. A panel PC with enhanced noise immunity prevents operational anomalies.

Orbitalum Tools is a pioneer of automated orbital welding of stainless steel tubes – a technology that produces high-quality, seamless welds. Compared to manual TIG welding, orbital welding ensures continuous welds with a smooth weld root to create highly durable joints, and a flat, homogeneous surface – even on the inside of tubes. Such a high standard of reproducible and documented quality is particularly important in the food and pharmaceutical industries. This is also required in semiconductor manufacturing and the aerospace industry.

For the food and pharmaceutical industries, the smooth surface of the inner tube is crucial. After all, residues and germs can collect around rough weld joints and contaminate the food or drug – something that must be prevented at all costs. A continuous weld root is also important, because areas that are not welded continuously are both prone to corrosion and attracting germs. For the semiconductor industry, on the other hand, high weld impermeability and surface quality are essential. Here, tubes convey manufacturing process liquids such as ultra-pure water and critical gases such as toxic selenium. Fuel pipes in the aerospace industry require similar standards, as the joints must be particularly robust to withstand high mechanical loads.

Handling complexity easily and intuitively

Achieving such high-quality welds requires more than delivering electric currents as in TIG welding. For optimum results, tubes must be divided into several sectors to allow different welding speeds, pulse times, and currents. For quality assurance purposes, the stability of the weld process must also be measured in real time, readjusted as necessary and documented. Orbital welding is therefore not just a simple job but a high-precision industrial technology, complicated further by different stainless steel grades, tube diameters and wall thicknesses, and surface finishes. For each welding job, numerous parameters must be set to optimally adjust the power source and welding process to the specific task.

Incorporation of a touch panel PC, also called a human-machine interface (HMI), into welding machines makes their operation easier and more intuitive, and enhances productivity. As is typical, introduction of new technology often requires the resolution of technical challenges.

Designing an appropriate HMI for such orbital welders is challenging. Orbitalum Tools provides auto-programming software that automatically determines the required welding parameters based on the general parameters of the workpiece. The resulting weld program can then be saved in the machine’s program manager software, allowing individual settings to be reused whenever necessary without needing to redefine all the parameters. Making the numerous weld programs easy to parameterize, store, and access puts high demands on the man-machine interface. After all, it is cumbersome if you must connect an external keyboard and mouse to the otherwise easy-to-operate machine for this purpose. The use of rotary controls and soft keys, as found in central consoles in the automotive industry, has also become obsolete because these methods are not intuitive when used on their own. These days, no one wants to click through endless menu items and then laboriously enter the name of the welding program by selecting and clicking on individual letters. That’s why Orbitalum Tools decided to introduce a touch panel-based user interface for the fourth generation of its orbital welders, thereby adding valuable new functions to the previously used rotary controls. This has significantly improved the ways in which data can be entered and changed.

Touch operation complements rotary controls and soft keys

Today, the tube workpiece is depicted on the screen in its individual sector segments, and the operator can directly select a specific sector segment with a simple touch. In the selected segment, the operator next touches an individual parameter field to select and set the desired parameter, using either touch or haptic rotary control. Previously, operators had to click their way from the raw workpiece to the sector segment and then to the parameter field using a rotary control. Having saved the parameter, they had to return to the sector segment selection point to start the next process – all the time remembering which parameters had already been set. Touch is also extremely convenient for entering text – for example, comments in log files – because it eliminates the need to connect an external keyboard, which would otherwise be required as no one wants to enter text using a rotary control. Now, a soft keyboard can be used for this purpose.

However, designing functionally safe touch controls for orbital welding is challenging. After all, igniting the arc requires voltages of several thousand volts, and this can generate electromagnetic phenomena that trigger ghost operations on the touchscreen. Without appropriate protection, when the power source is ignited, the welder’s display may even briefly turn off and on again under high electromagnetic interference (EMI). HMIs for arc welding machines must therefore meet the high electromagnetic compatibility (EMC) requirements of IEC 60974-10, as well as DIN EN 61000 for the functional safety of electrical and electronic systems, including electromagnetic phenomena. Such HMIs cannot typically be bought and used off the shelf. Instead, they must be custom-designed for the specific application.

EMI resistive touch depends on many parameters

Selecting and parameterizing the touch control to match the demands of the specific operating conditions is particularly important here. For example, operation off welding machines is typically performed using gloved hands. Adapting capacitive touchscreens for gloved operation is a juggling act between high sensitivity and high interference immunity. For gloved operation, high sensitivity is useful, but this makes the touch more susceptible to electromagnetic interference. Thickness and type of touchscreen glass, as well as the method used to bond the underlying display to the glass also affect the design and programming of the touch control. A touch sensor designed for a glass thickness of 1.8 mm, for example, will produce inadequate touch results with 5 mm glass.

Last but not least, to meet all real-world environmental conditions, the touch control firmware must be programmed to precisely match the requirements of the installed system. Standard touch controls are defined by 90 to 200 parameters. Managing the parameter chain from the analog front end, to back end digital filters, to evaluation filters makes programming touch controllers highly complex. Orbitalum Tools was therefore looking for an HMI manufacturer that is familiar with the challenges of touch control programming and offers systems that feature high electromagnetic compatibility by design. Another important criterion was that the complete HMI system comes from a single source, so that there would be just one supplier and contact for ordering and resolving all potential issues. A high level of vertical integration, including component development, was also critical. After all, this gives the supplier greatest flexibility to respond to customer needs and to act independently of other suppliers. Ideally, Orbitalum Tools was also hoping to find a system that offers native CAN bus support within the HMI as Orbitalum's in-house controller board provides this interface for HMI communication with the power supply and weld head motor control. On the software side, Orbitalum Tools wanted support for Yocto Linux and the integrated development environment (IDE) QT. This would allow them to seamlessly harmonize the application and platform layers, thereby minimizing the software customization effort.

High electromagnetic compliance by design

Today, Orbitalum Tools uses HMI systems of SECO’s Santino series of products. This developer and manufacturer of cutting-edge technological solutions offers Santino HMIs with a choice of NXP i.MX 6 and i.MX 8 processors, each with 15-year availability. The Santino family also supports upcoming generations microprocessors, supporting OEM customer product roadmaps long-term.

For stationary variants, the open-frame HMI features a touch panel with a custom-designed front glass that extends across the entire width of the housing and is rounded at the top edge. This design gives the system a high-end appearance commensurate with its performance. As the system was already highly EMI resistant by design, only the touch controller software and minor package tweaks were required.

For mobile variants, Orbitalum Tools has recently started to deploy the standard design of this HMI series. In this case, only the touch controller software had to be adapted, but not the mechanical design. Incidentally, the remote control that the company is currently developing for their orbital welders, and which will be connected via Ethernet with power over Ethernet (PoE) support, will use the same system. The aim of this development is to make welding operation more independent from the welding location. There are also plans to integrate wireless connectivity in the future. However, a high level of electromagnetic interference immunity must be guaranteed before this can be realized. The potential for innovation in orbital welding is therefore far from exhausted.

What comes next?

The project to incorporate touch panels into orbital welders started back in 2016. In the first instance, SECO delivered a production prototype for the stationary system. Next, SECO designed the touch panel glass according to Orbitalum’s specifications, followed by EMC pre-testing and then preparations for volume production. As part of this process, SECO also developed special packaging for the customized product that makes deployment into the assembly of the Orbitalum Tools welder highly ergonomic and efficient. At this point, the decision was made to deliver the HMI with a pre-assembled seal so that installation would require just a few simple steps. For SECO, such value-added service is common, reflecting a high level of client orientation. SECO provides solutions for all phases of product development and delivery ¬– from requirements specification to design and validation through to volume manufacturing. Moreover, for SECO, the quality of a product naturally extends from its internal electronics and software to the packaging. The solution for Orbitalum Tools’ stationary systems has now been in production since the end of 2018.

Scaling the system to the mobile design, which followed the introduction of the stationary system, was primarily an in-house task for Orbitalum Tools. The user interface had to be adapted from a 12.4-inch display in 3:4 format to a 7-inch display in 16:9 format, which necessitated scaling of the graphic user interface. On the hardware side, no migration effort was needed since both systems come from the same SECO Santino product series. The Santino family fully supports both Yocto and QT, which meant that the application software could be ported smoothly, without any problems. Going beyond the HMI, SECO helped Orbitalum Tools develop the injection mold tool of the orbital welder enclosure, providing precision flush mounting for the HMI. Close cooperation between suppliers is imperative here, because later adjustments to optimize an injection mold are costly. SECO delivered the correct specifications, enabling Orbitalum Tools to procure the injection mold tooling without the need for any iterations.

Orbitalum Tools is currently integrating PDF-based documents such as operating instructions and documentation into their welding machines. To make it easy for operators to work with such documents, a multi-touch panel is the next development step for Orbitalum Tools. The goal is to be able to easily zoom documents with two-finger gestures. With single-touch, operation is a bit more complicated, as a plus and minus magnifier must be placed over the document and the zoom function requires multiple touches. So the next potential development task for SECO has already been specified.

Quality and service excellence

Asked about the cooperation with SECO so far, Christoph Dämmig, Product Manager Orbital Welding at Orbitalum Tools, is full of praise. “What I really like about SECO besides the high product quality and vertical range of manufacturing capability is the support. SECO has put together a highly professional project team that is available to support us throughout the entire development process up to volume production. The team includes specialists for hardware and firmware, Linux, Yocto and QT, as well as mechanics, testing, and documentation. Every question that came up during the integration of the flush-mount systems was answered promptly and competently.” He is therefore confident that SECO will also deliver the next development steps in providing the best quality product within the scope of what is technically feasible and cost effective.

News release from SECO Northern Europe, 23/05/2023

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