The new coworker has been on the assembly line for three days. He’s familiar with the standard model, but today an order with special features has come in, and the folder with the work instructions is two stations away. Whether the right screw is tightened to the correct torque won’t be clear until the final inspection or when the product reaches the customer. A digital assistance system is designed to close exactly this gap. Whether it does so depends less on the choice of software than on how you implement the assembly assistance system.
THE MOST IMPORTANT POINTS AT A GLANCE
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IN SHORT
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What is an assembly assistance system?
An assembly assistance system is a digital system at the assembly workstation that guides assemblers through each step of the process, verifies the execution, and documents the result. It indicates which part is to be installed next, along with the tool to use and the relevant parameters. It retrieves results from connected tools, such as screwdrivers, and does not authorize the next step until the previous one has been completed correctly.
The terms in this context overlap. The table clarifies their distinctions.
| Term | Focus | Typical Technology |
|---|---|---|
| Operator Guidance | Step-by-step guidance through a work process | Software on a tablet, monitor, or terminal |
| Operator Assistance System | Umbrella term for digital support in the workplace, often including operator guidance | Software plus sensors, tool integration |
| Assembly assistance system | Operator assistance tailored to assembly processes involving parts, tools, and inspection steps | Operator guidance, screwdriver integration, part recognition, traceability |
| Pick-by-Light | Identification of the correct container via a light signal | Light modules on shelf compartments |
| Projection systems | Projection of work instructions directly onto the workpiece | Projector above the workstation |
“Pick by Light” and projection are components that can complement an assembly assistance system. At the core is operator guidance, integrated with tools and documentation. Those who wish to learn more about the fundamentals of operator guidance can find further information in the articles “Operator Guidance: Definition ” and “Digital Operator Guidance: Definition, Benefits, and Roadmap.”
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369,516 jobs for qualified workers that cannot be filled, based on calculations, as an annual average in 2025 Source: KOFA, IW Skilled Workforce Database, 2026 |
33.3% of all open positions for skilled workers could not be filled with suitable candidates in 2025 Source: KOFA 2025 Year in Review |
18,000 Work processes in bogie assembly and overhaul at Stadler Rail are digitally managed and documented Source: CSP Project Report: Stadler Rail on DirectIndustry |
487 Workstations at Stadler Rail are equipped with the PG operator guidance system Source: CSP Project Report on Stadler Rail on DirectIndustry |
When is an assembly assistance system worthwhile?
An assembly assistance system costs money, project time, and attention on the factory floor. It’s worth the investment when written instructions and experience-based knowledge reach their limits. Four situations in particular make it a good choice.
| Situation | Typical Symptom | How the system makes a difference |
|---|---|---|
| High variety of variants | Mix-ups with rare variants, rework due to special equipment | Instructions tailored to the specific order variant |
| Frequent turnover of new employees | Long training period, high error rate in the first few weeks | Guided workflow from day one, less reliance on mentors |
| Safety-critical connections | Requirement to document torque and rotation angle | Tightening results automatically saved with the serial number |
| Customers or standards require traceability | Time-consuming search for documentation in the event of a complaint | Complete documentation of every work step |
The shortage of skilled workers exacerbates these effects. According to the annual review by the Competence Center for Securing Skilled Workers (KOFA) at the German Economic Institute, by 2025, one in three open positions for qualified workers will not be filled with suitable candidates. As a result, more assembly jobs are being filled by semi-skilled or new workers, and process knowledge must be available at the workplace rather than solely in the minds of experienced colleagues. Read more in the article “Quality Despite the Skilled Labor Shortage.”
This applies not only to large corporations, as the article “Worker Leadership Only for Large Companies? An Expensive Mistake” demonstrates. Smaller businesses in particular, with few experienced key personnel, are reliant on documented process knowledge.
What functions does an assembly assistance system need on the assembly line?
Not every feature is necessary at every workstation. The following overview helps you prioritize requirements for your own assembly process before comparing vendors.
| Function | Benefits in Assembly | Priority |
|---|---|---|
| Step-by-step instructions with images, videos, or 3D models | Correct sequence and execution without paper | Required |
| Variant control based on the order | Only the steps that apply to this variant | Required for variant manufacturing |
| Integration of screwdrivers and measuring equipment | Result is accepted; step is released only if the result is OK | Required for safety-critical connections |
| Part identification via scan or camera | Incorrect part is detected before installation | High |
| Inspection steps and acknowledgment | Visual inspections are enforced and documented | High |
| Traceability to serial number | Evidence for audits and complaints | Mandatory in regulated industries |
| Gradual guidance based on experience | New employees see more guidance, experienced employees less | Medium to high |
| Interface to MES and ERP | Orders and variants are generated automatically; results are fed back | High for mass production |
The integration with higher-level systems determines whether the assembly assistance system remains a standalone system or becomes part of the production data. The technical details are explained in the article “Worker Assistance Systems with MES Integration.”
Which end devices are suitable for the assembly workstation?
The choice of end device depends on the workstation. At fixed stations with a consistent line of sight, permanently mounted monitors or industrial terminals are common because they are always in the same location and do not obstruct the user’s hand. For large assemblies where assemblers move around the product, mobile devices such as tablets offer advantages. At Stadler Rail, according to a user report, the work steps in bogie assembly are guided via tablet computers. In both cases, ensure that the devices are easy to operate while wearing gloves, provide sufficient brightness under factory lighting, and have a mount that does not interfere with the workflow. Test the devices in a pilot program under real-world conditions before placing an order for all production lines.
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CHECKLIST 7 Principles of Safe Worker Guidance Before comparing vendors, you should have a clear understanding of the principles that should guide your assembly assistance system. This checklist summarizes seven principles you can use to evaluate requirements for the pilot line. |
What prerequisites must be met before implementation?
Many issues that could later hold up a project can be resolved before the first workstation is set up. Four requirements are among them.
Work Instructions and Master Data
An assistance system is only as effective as the content it displays. Check whether work instructions are up-to-date, complete, and unambiguous for each variant. Outdated instructions remain outdated even in digital form; they’re just distributed more quickly. Also, determine who will maintain and approve content in the future.
Tools and Equipment
For each pilot workstation, document the screwdrivers, measuring equipment, and scanners in use, including the manufacturer, control system, and interface. Manufacturer independence is an important selection criterion here, because established assembly lines rarely use tools from just one manufacturer.
IT and OT Infrastructure
Clarify the network configuration at the workstation, end devices, user login procedures, and whether the system will be operated in your own data center or as a cloud solution. For interfaces with MES and ERP systems, it is essential to involve IT contacts early on.
Co-determination by the Works Council
An assembly assistance system records who performed which work step and when. According to Section 87(1)(6) of the Works Constitution Act (BetrVG), the works council has the right to participate in decisions regarding the introduction and use of technical equipment intended to monitor employees’ behavior or performance. According to established case law of the Federal Labor Court, it is sufficient for this purpose that a system is objectively capable of monitoring employee behavior or performance, even if the employer does not intend to do so. You should therefore plan to establish a works agreement that governs the purpose, scope of data, access rights, and data analysis. This information does not constitute legal advice.
How do you implement an assembly assistance system in seven steps?
The following seven steps take you from the target vision to the rollout. Each step concludes with an outcome that informs the decision for the next step.
| Step | Content | Result |
|---|---|---|
| 1. Define the target scenario | Identify the problem: types of errors, variants, training, documentation requirements | Goals with measurable metrics |
| 2. Measure baseline values | Record first-pass yield, rework rate, and training time on the pilot line | Benchmark values prior to launch |
| 3. Select a pilot line | A line with a high number of variants or known error hotspots, but of a manageable scope | Pilot scope, including workstations and tools |
| 4. Involve the works council and the team | Provide information in accordance with the Works Constitution Act (BetrVG); involve technicians in the development of the instructions | Draft the works agreement; designate key users |
| 5. Implement content and integration | Digitize work instructions, integrate screwdrivers and scanners, test interfaces | Operational workstations in test mode |
| 6. Run and evaluate the pilot | Several weeks of live operation; collect feedback from technicians; compare key metrics | Evaluation against baseline values |
| 7. Plan the rollout | Incorporate findings, prioritize lines, establish a content maintenance process | Rollout plan and operating agreement |
Step 2 is easily skipped when under time pressure. However, without baseline metrics, it is impossible to demonstrate what has improved after the pilot, and the decision regarding the rollout lacks a solid foundation.
Stadler Rail is an example of a phased implementation. According to the project report, the company opted for the vendor-neutral PG worker guidance system in 2015 and implemented it in a modular fashion. Today, over 18,000 work processes in bogie assembly and overhaul are digitally managed and documented there, across 487 equipped workstations. More information on the project can be found in the article “Mobile Quality Assurance in Rail Vehicle Manufacturing.”
How do you get fitters and the works council on board with the system?
An assembly assistance system changes the way people who use it every day work. Whether they perceive it as a help or as a form of monitoring depends heavily on how the project involves them.
- Bring experienced assembly workers into the project as key users. They know exactly where instructions are actually needed and where they get in the way.
- Have the instructions reviewed by the people who will be following them. Wording and images from the shop floor are better understood than texts from the planning department.
- Use step-by-step instructions. Experienced workers need fewer details than new ones, and a system that explains every single step is quickly perceived as patronizing.
- Clearly define in the company agreement what the data will and will not be used for. A clear commitment to quality and traceability builds trust.
- Make results visible. When the team sees that rework and follow-up questions are decreasing, acceptance increases.
Related to the topic of usability is the article “Boosting Worker Motivation Through Intuitive Software Solutions.”
“An assembly assistance system is truly adopted when the assemblers would use it even if no one were watching.”
Key point on acceptance
How do you measure the success of the implementation?
The success of a rollout is reflected in metrics that were measured before the launch. The following metrics are suitable for comparing the baseline with the pilot.
| Key Metric | What it indicates | Measurement |
|---|---|---|
| First-Pass Yield | Percentage of parts that are in good condition on the first pass | Per station and variant |
| Rework Rate | Percentage of parts that require rework | Per station by defect type |
| Defects by variant | Whether rare variants continue to stand out | Number of defects per variant |
| Training time | How quickly new employees can work independently | Days until clearance for the workstation |
| Assembly-related complaints | Whether defective products continue to leave the plant | Number per period |
| Time spent searching for documentation | Effort required for audits and complaints | Time to provide complete documentation |
Compare the values over the same time period and with the same mix of variants. A pilot that happens to coincide with a phase of simple orders will show better results, even though the system is not responsible for this. Also, document the feedback provided by the technicians during the pilot and which of those suggestions were implemented. This qualitative evaluation shows whether the system holds up in day-to-day use and provides arguments for discussions with the works council prior to the rollout. The article “KPI Design for Quality Managers” provides guidance on developing reliable metrics.
What mistakes could jeopardize the implementation?
Any of the following mistakes can delay a rollout or reduce its benefits.
- Paper instructions are digitized exactly as they are. Unclear or outdated content remains unclear—only now it’s on the screen.
- The works council is informed too late. This delays the pilot program, and the system launches amid mistrust.
- The importance of tool integration is underestimated. Without connected screwdrivers, the system remains merely a set of instructions without verification.
- Baseline data is missing. After the pilot, the benefits cannot be demonstrated.
- No one is responsible for maintaining the content. After the first design change, the instructions no longer match the product.
- The system is marketed as a monitoring tool. Technicians bypass it whenever they can.
- The rollout begins before the pilot evaluation is complete. Errors from the pilot are carried over to all production lines.
Two additional articles explore the quality aspect in greater depth: “Operator Assistance Systems and Quality Standards ” and “Operator Assistance Systems: Systematically Avoiding Quality Defects.”
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NEXT STEP Prepare the pilot line Use the checklist to verify that your requirements are complete. If you’d like to see how PG guides workers at an assembly station, you’ll find all the features and instructions for accessing the demo on the product page. |
How does PG support the assembly rollout?
PG is the operator guidance feature in CSP’s Manufacturing OS. It guides assembly workers step by step through the assembly process according to the specific variant, links tools regardless of manufacturer, and documents every step.
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What PG Brings to the Table When Implementing an Assembly Assistance System
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Details on tool integration are provided in the article “PG Integration with ITH High-Torque Screwdrivers,” while the camera module is introduced in the article “PG: New Module for Camera Integration.” Practical examples are available from rail vehicle manufacturing at Stadler Rail and from engine assembly in the article “PG Operator Guidance at the Hatz Engine Plant.” The page “PG Operator Guidance” provides an overview of all functions.
Frequently Asked Questions
What is a parking assist system?
An assembly assistance system is a digital system at the assembly workstation that guides assemblers step by step through the assembly process. It records the results from connected tools such as screwdrivers, only allows the next step to proceed after the current one has been completed correctly, and documents each work step by serial number.
What is the difference between operator guidance and an assembly assistance system?
Operator guidance refers to step-by-step instructions through a work process. An assembly assistance system uses operator guidance as its core and supplements it for the assembly process with tool integration, part recognition, inspection steps, and traceability.
How long does it take to implement an assembly assistance system?
The duration depends primarily on the condition of the work instructions, the number of tools to be integrated, and the interfaces to MES and ERP systems. A pilot project on a single line can be implemented much more quickly than a rollout across multiple plants. Reliable time estimates can only be provided after an analysis of the specific pilot line.
Does the works council have to approve an assembly assistance system?
In companies with a works council, it is generally assumed that a right of co-determination applies under Section 87(1)(6) of the Works Constitution Act (BetrVG), because such a system stores data on the work steps of individual employees and may therefore objectively be suitable for monitoring. It is customary to establish a company agreement that governs the purpose, scope of data, and access rights. In individual cases, labor law advice should be sought.
Which workplaces are suitable for implementation?
Workstations with a high degree of variability, known error-prone areas, or safety-critical bolting operations are suitable for the pilot. The scope should be chosen so that results can be measured within a few weeks.
Which metrics indicate whether an assembly assistance system is worthwhile?
Suitable metrics include first-pass yield, rework rate, defects per variant, training time for new employees, and assembly-related complaints. It is crucial to measure these values before the pilot begins so that the comparison after the pilot is meaningful.
Can an assembly assistance system utilize existing assembly workers?
That depends on the interfaces and the vendor. Vendor-neutral systems integrate screwdrivers and measuring equipment from various manufacturers. Before making a selection, document all tools on the pilot line, including their controls and interfaces.
Does an assembly assistance system replace training?
No. It shortens the period during which new employees rely on constant supervision and ensures that processes run smoothly. Technical instruction on safety, tools, and the product remains the responsibility of the onboarding process.
Sources
- Works Constitution Act, Section 87(1)(6) (explanation in the Works Council Lexicon): https://www.betriebsrat.de/betriebsratslexikon/br/technische-kontrolleinrichtungen
- ADVANT Beiten: Technical Equipment in Everyday Workplace Life (Nov. 25, 2024): https://www.advant-beiten.com/aktuelles/die-technische-einrichtung-im-betrieblichen-alltag
- Noerr: The Works Council as an Entrepreneur, BAG Case Law on Section 87(1)(6) of the Works Constitution Act (BetrVG): https://www.noerr.com/de/insights/der-betriebsrat-als-unternehmer
- Nuremberg Regional Labor Court, 7 Sa 441/16, on the concept of monitoring: https://lag.bayern.de/imperia/md/content/stmas/lag/nuernberg/entscheidungen/2017/7_sa_441_16.pdf
- KOFA: Country Report on Germany, Annual Average Skills Shortage in 2025: https://www.kofa.de/media/Publikationen/Laendersteckbriefe/Deutschland.pdf
- IHK Pfalz: KOFA 2025 Year in Review: https://www.ihk.de/pfalz/produktmarken/fachkraeftesicherung/fachkraeftesicherung-fuer-unternehmen/newsletter-archiv/newsletter-5-26-jahresrueckblick-kofa-7032222
- DirectIndustry: Project Report on PG Operator Guidance at Stadler Rail: https://trends.directindustry.com/csp-gmbh-co-kg/project-4599583-1178785.html
- DirectIndustry: User Report on PG at Stadler Winterthur AG: https://pdf.directindustry.com/pdf/csp-intelligence-gmbh/pg-worker-guidance-secures-assembly-processes-stadler-winterthur-ag/4599583-1076133.html
- IW Cologne: KOFA Study on the Skilled Labor Situation in Metal and Electrical Trades: https://www.iwkoeln.de/studien/lydia-malin-anika-jansen-die-fachkraeftesituation-in-metall-und-elektroberufen.html
- KOFA: Skilled Labor Report Q3 2025: https://www.kofa.de/media/Publikationen/KOFA_Kompakt/Fachkraeftereport_Q3.25.pdf