Cobots or lightweight robots have numerous properties that are advantageous for a wide range of applications and enable new types of applications. This is illustrated in Figure 1 by classifying cobot applications by considering techno-economic factors. It becomes clear that the potential for the use of collaborative robots ranges from manual processes to hybrid or partially automated processes through to full automation. This results from the possibility of using the cobot in coexistence with humans, in cooperative or collaborative applications or independently of humans as a cost-effective entry-level option for full automation. Accordingly, in contrast to traditional industrial robots, cobots can already be used for smaller quantities, a greater number of variants, with greater flexibility and lower investment costs.

Easy entry into automation

A major advantage of cobots is that they allow a low-threshold entry into the automation of processes. The reasons for this are the generally low investment costs. This makes it possible to test applications and introduce the technology in the company at relatively low financial risk. Entry is further facilitated by the fact that many cobot applications can be operated with significantly less safety equipment than conventional industrial robots, which reduces investment costs and the required footprint of the system. This makes it easier to integrate cobots into existing working environments. Overall, this also enables partial automation of processes. Process steps that are easy to automate or particularly monotonous and unergonomic for humans can be considered first. The degree of automation can then be gradually increased in parallel with the development of know-how.

Introduction of cobots in the company

Humans and cobots can work together in hybrid partial automation.

© TQ-Systems GmbH

The introduction and maintenance of cobots can be expected to involve less effort and complexity than for fully automated industrial robots. In comparison, cobots allow for easier modification, expansion and programming. The introduction can be divided into several steps from project preparation to implementation.

Project preparation

Before starting the project, it is important to appoint a cobot manager. This person or group of people involves all stakeholders in the process at an early stage. This includes employees from the relevant specialist department, the works council and those responsible for occupational safety. A resulting project team carries out the introduction process. Advice centers such as the employers' liability insurance association or regional support options should also be consulted at an early stage. Based on an initial rough definition of the task to be implemented and determination of the type of interaction, software tools for quick checks, such as a cobot planner from the Berufsgenossenschaft Holz und Metall (BGHM, https://cobotplaner.de/preambel), can be used to carry out initial feasibility analyses.

The start of the project

At the start of the project, the company should consider which specific strategic goals are worth pursuing. Examples could include maintaining long-term competitiveness and reducing the workload of employees. An initial concrete task is then formulated based on existing optimization potential that can be solved through the use of cobots. The given workplace and process should then be evaluated for their suitability for the project. Further evaluation criteria are, for example, the complexity of the application, the hazard potential, cycle time fulfillment and batch size. Due to their flexibility, cobots are already worthwhile for small and medium batch sizes, for example. These criteria are used to develop an entry-level project that can be implemented without any major hurdles. The project should be easily scalable and expandable for more complex tasks. Examples include non-ergonomic or repetitive handling tasks.

How do you find the right cobot?

The selection of a suitable cobot is largely dependent on the task requirements. In addition to the costs for the cobot system, the robot license, commissioning, training, maintenance and certification must also be taken into account. Depending on the application, the total costs can be almost double the acquisition costs for a robot system including the safety equipment. The amortization period is influenced by the batch size, among other factors. Amortization periods of over two years are possible for small batch sizes. Therefore, a classic ROI analysis may not be suitable. The operator should be aware of this and consider more long-term criteria such as production flexibility or employee satisfaction. When pre-selecting a cobot, application requirements such as payload, reach, repeat accuracy or operating mode must be taken into account. Taking reach as an example, a robot with six degrees of freedom can reach all points in three-dimensional space with any orientation. An additional seventh axis increases flexibility and speed, but also the programming effort. Additional axes are rather unusual and redundant.

Implementation of entry-level projects

Cobots should also undergo safety integration. If possible, the dual control principle should be applied and an occupational safety specialist and the BG should be involved at an early stage to accompany the certification process. The main purpose of the introductory project is to dispel concerns and fears and demonstrate the benefits of the cobot to employees. Acceptance is particularly high when the respective employees are involved in the development process. Nevertheless, it must be communicated to them that the cobot is not a replacement for an employee, but is intended to support and relieve them.

Conclusion and outlook

Cobots - as a tool for cost-effective and practical automation - offer a low-threshold option for automation due to their low investment risk, intuitive programming and suitability for collaborative processes. The application examples shown illustrate that the cobot can decisively strengthen production sites in high-wage countries such as Germany. Cobots can also counteract challenges such as the growing shortage of skilled workers. During implementation, the most important technical requirements for the cobot system must be identified, taking into account the use case in focus. In addition, the aforementioned safety guidelines must be observed during implementation in order to fully exploit the potential.In the future, it is expected that cobots will be used in other industrial and trade applications. Cobots will continue to grow in relevance due to disruptive innovations from research and development on the one hand and the high demand for automation solutions on the other. They are therefore seen as an important building block for overcoming future challenges.

This article is an excerpt from the white paper "Cobot - a tool for cost-effective and practical automation?", which was produced by WZL Aachen GmbH and the Laboratory for Machine Tools and Production Engineering WZL at RWTH Aachen University in collaboration with Conrad Electronic. The white paper is subject to careful scientific research, but nevertheless only provides an overview of the topic. Furthermore, the paper makes no claim to completeness or exact interpretation of the legal provisions.

The authors

Oliver Petrovic, M.Sc. RWTH, Laboratory for Machine Tools and Production Engineering (WZL) at RWTH Aachen University

Minh Trinh, M.Sc. RWTH, Machine Tool Laboratory WZL of RWTH Aachen University

Lukas Gründel, M.Sc. RWTH, Machine Tool Laboratory WZL of RWTH Aachen University

Dr.-Ing. Werner Herfs, MBA, WZL Aachen GmbH