Increasing Efficiency and Quality Despite Growing Demands

Due to the trend toward customization and increasing variety, manual processes in assembly and post-processing are becoming increasingly complex. Digital worker guidance plays an important role in making work easier for employees: It provides workers with information and instructions – for example, indicating which work step to perform next. Dynamic laser or video projection is recommended wherever a direct spatial reference to the workpiece is important for worker guidance – whether for precise dimensioning or simply to identify specific elements accurately and without confusion. This allows companies not only to increase efficiency and quality but also to create a bidirectional bridge between the analog and digital worlds.

In the past, worker guidance was mostly done analogously, for example with a manual or laminated information boards posted at the station. A basic distinction is made between free-order worker guidance, where the order of work steps is arbitrary, and fixed-order processes with a fixed sequence. The latter becomes more challenging the more tasks the worker has to perform one after the other in exactly a specific sequence. In conditions of high complexity, a large variety of variants, and short cycle times, analog methods of worker guidance are hardly practical. Not only does the worker lose valuable time searching for the right information board, but the risk of confusion and errors also increases. Added to this is the effort required to repeatedly design and install new information boards.

Many companies have therefore already established digital worker guidance. There are various options for this. Simple solutions include screens at the assembly station that display instructions, or so-called pick-by-light systems that support the assembly process with optical signals. Lights on the storage bins then show the worker which workpiece they should assemble next. Such systems are cost-effective and are well suited to displaying a simple, two-dimensional step-by-step sequence. However, the worker receives no additional information or instructions on exactly where to attach the workpiece.

Dynamic laser projection comes into play for applications where spatial context is important: It displays work instructions, CAD data, or other important information directly on the workpiece, accurately positioned and, if necessary, with an accuracy of up to 0.1 mm – even while the workpiece is moving. This allows even more complex workflows to be mapped out in the worker guidance system and ensures high precision. Furthermore, 3D data can be evaluated in the context of a workpiece. Even fully automated projection based on data processes is possible.

BMW uses dynamic laser projection, for example, for quality assurance in the paint shop. First, a vision system, supported by AI, identifies potential rework areas in the primer or topcoat. A laser projection for worker guidance is then automatically generated from this data. A green triangle appears on the body where the employee needs to manually rework.

The digital worker guidance system with dynamic laser and video projection can be quickly adapted to new variants at any time, allowing maximum flexibility. It offers high precision of up to 0.1 mm. The worker is optimally supported in their work without having to wear distracting VR glasses or look something up on a tablet. This leaves their hands free, allows them to work smoothly, and saves a lot of time. For example, Audi was able to increase the efficiency of bolt marking in prototype construction by 75 percent using this method. Workers no longer have to laboriously mark the marking points with the column measuring machine. Instead, the laser projects the exact position.

Convenient, digital worker guidance reduces the risk of errors and increases quality. It ensures that no work step is missed. The better the worker guidance system supports the assembler, the less prior knowledge they require. Even employees without specific training can get up to speed quickly, especially since the intuitive visual instructions overcome language barriers. This enables companies to better manage the shortage of skilled workers and cushion the high fluctuation that often occurs in assembly.

Digital worker guidance with laser or video projection is generally recommended for short cycle times, large product variants, high levels of complexity, or high employee turnover. It also supports particularly tiring tasks. For example, if a worker has to manually count which hole to insert the next plug into, there is a high risk of errors. Digital assistance ensures greater safety here.

Even if only a few variants need to be manufactured, the complexity can be high, for example because many add-on parts or manual work steps are required. A striking example is the ITER fusion energy research project: countless sensors and connecting cables have to be mounted on the reactor chamber, with a total of 150,000 weld points having to be placed – and all with a precision that allows a maximum deviation of 2 mm. Thanks to dynamic laser projection, the assembly team can overcome these challenges. The workers use the system not only to indicate the starting points for the welding device, but also to visualize the position of workpieces that need to be attached with spot welds. The laser also projects additional instructions, such as the part number and weld number. Although the ITER project has a duration of five years, it is so complex that it would be impossible to manage without digital worker guidance.

Conversely, dynamic laser or video projection is also worthwhile for low-complexity projects when cycle times are very short. Then, the application pays for itself with just three to five variants or as few as ten manual steps. A Japanese automobile manufacturer, for example, uses this innovative worker guidance for the assembly of wiring harnesses on the roof lining. While this work is simple in itself, the worker is under extreme time pressure: They must immediately recognize which model they are dealing with and where they need to fix the wiring harness. The projection supports them and prevents errors.

Due to increasing customization, manufacturers are increasingly having to fulfill special customer requests. Dynamic laser and video projection is ideal for scenarios where workpieces are taken off the line for manual processing and transported to the assembly island by AGV (Autonomous Guided Vehicle). This is usually the case for complex tasks that require more time from the worker. At the assembly island, the worker can process the workpiece individually and without being tied to a specific cycle. The AGV then returns the workpiece to the line. In addition to individual adaptations, the technology is already being used in the automotive industry, where, for example, combustion engines and electric vehicles run on the same production line. Special, time-consuming, and high-precision tasks for electric cars, such as the assembly of battery cells, are then delegated to an assembly island. Worker guidance with dynamic laser or video projection helps the assembler work more quickly, adhere to correct sequences, and monitor and document critical steps. The workpiece can ultimately be returned to the line more quickly.

The projection for digital worker guidance can be created either manually or automatically. For manual teaching, an employee loads the 3D model of a workpiece into the projection solution's software and, with a mouse click, specifies what should be projected. With a manageable number of variants (maximum 50 to 100), the effort required for this manual preparatory work is not significant. Each workpiece can then be taught manually once. This may eliminate the need for software interfaces, such as those to an ERP system. Connecting a simple barcode scanner or similar is sufficient, and the application logic can be implemented more or less using the built-in tools of the worker assistance software.

However, when so many workpiece variants occur that manual teaching is no longer possible, automation becomes indispensable. This is especially true for customer-specific manufacturing with a high degree of customization, where hardly any two products are exactly alike and the variants are unknown in advance. Data interfaces to the ERP/MES system and the conveyor system are essential for automation. The projections are then generated from existing 3D data. Suitable data sources include common CAD and network data formats, as well as 3D data from CSV interfaces.

To enable fully automated data processes, the data must be 100% complete and reliably structured in a consistent manner. Only then can the algorithm automatically identify the relevant locations, such as holes and weld points, as well as the attachments, such as plugs and holders. For complex workpieces, the question also arises as to what the projection should display. Is it better to visualize the contact surface on the base body? Or should something distinctive be projected onto the top side of the attachment facing the user to facilitate positioning? And how can the system distinguish the surface of the workpiece from the support surface? The best way to overcome these challenges is to work together with the projection solution provider, who has specialized expertise and experience from numerous customer projects.

Dynamic laser and video projection brings digital information into the analog world. By combining digital worker guidance with tool tracking or optical workpiece recognition, data from manual processing can be transferred back into the digital model. This creates a bidirectional bridge that enables the entire manufacturing process to be digitally mapped. Tool tracking records precisely which tool the employee is currently using and how long it remains in a position. In addition, other process parameters can be transmitted, such as contact pressure, speed, or other individual data. This allows companies to not only accurately document that a worker has performed all work steps correctly, but also to correlate the collected data with other data sources, analyze them using AI, or integrate them into a digital twin.

BMW, for example, uses this option in its quality assurance process in the paint shop, combining tool tracking with worker guidance. As soon as an employee has sanded an area that requires rework, the laser projection changes from a green triangle to a green circle. The worker now knows that polishing is still required. Once this step is completed, the projection disappears completely. Digital tool tracking also documents process parameters such as the contact pressure during sanding and polishing. The automaker collects and analyzes the data to further optimize production.

In some cases, however, no tools are used or they are not suitable for tool tracking. If attachments can be easily captured using 2D or 3D camera images, traditional or AI-based image processing can be an alternative – for example, when attaching clips and plugs, or when positioning or inserting attachments.

The starting point for a digital worker guidance project is usually a specific problem that the customer approaches the provider with. The provider then develops a solution concept. To do this, they first gather all relevant information, such as the appearance of the workpieces or the challenges of the work environment. If color projection is required, a video projector is more suitable; for a dirty or dusty environment and higher precision is required, a laser is more suitable. In a live on-site demonstration, the customer can then get an impression of how the projection will look on their own workpiece under the ambient conditions in terms of precision, sharpness, contrast, and perceptibility.

Before a contract is awarded, detailed planning is necessary. How should the technology be integrated, and which interfaces are required? Are mobile, standalone systems suitable, or does the solution need to be permanently installed in the environment? How many projectors are necessary to optimally support the process? Which referencing method is recommended? These are all questions that the partner will clarify together with the customer.

The implementation of an integrated projection solution typically takes place over two dates: First, the project team installs the hardware. This work is usually scheduled for weekends or during production downtime, as permanent installation requires stopping the line. The software is then commissioned later, while production is running, so the project team can test the interfaces and tracking. The provider supports the implementation with training, which is usually held on-site. Mobile solutions can often be put into operation without any project planning and with minimal training.

To ensure that digital worker guidance is scalable with future developments and requirements, companies should choose a reliable partner who maintains its software over the long term and continuously develops it further. This way, the solution grows as the production environment changes. Maintenance contracts for software and hardware are important. Among other things, they guarantee that the manufacturer adapts the projection solution accordingly when interface updates are made. For example, some systems may need to be migrated to a newer version of Windows or a different CAD format. As part of the software maintenance, the partner then ensures that the digital worker guidance continues to run stably. At the same time, they ensure backward compatibility so that the solution continues to work with older systems. The hardware should also be reliable. To achieve this, wearing parts must be replaced in a timely manner during maintenance, and spare parts must be available over the long term. An extensive network that enables fast on-site service is also advantageous. Laser projectors, which require high precision, must also be recalibrated and certified from time to time in the manufacturer's measurement laboratory. Due to the sometimes sensitive optical workpieces, the recommended interval for frequently moved mobile systems is one year; permanently installed systems can run maintenance-free for up to eight years, depending on the shift model, before a pit stop is required to replace wearing parts and subsequently calibrate.

Digital worker guidance will become increasingly important for manufacturing companies in the future to ensure competitiveness. It helps increase the efficiency and quality of manual processes despite growing challenges. With digital support, workers can work quickly and precisely, even with high variant diversity, complex sequences, and short cycle times. New employees can start immediately without extensive training, thus ensuring operations are secure despite skilled labor shortages and high turnover rates. The combination of digital worker guidance with digital tool tracking is also particularly attractive. In this way, companies establish a feedback channel from the analog to the digital world. They gain valuable data that can be correlated with other sources and evaluated using AI to further optimize production.