Human-robot interaction (HRI) with the interaction forms of coexistence, synchronization, cooperation and collaboration offers potential for optimizing assembly processes by increasing productivity and quality as well as improving ergonomics. For companies with predominantly manual assembly processes, however, there is uncertainty when implementing MRI applications, as these potentials can only be insufficiently determined and secured in advance using digital planning tools. The Chair of Production Systems (LPS) at the Ruhr University Bochum is researching new ways to investigate and evaluate MRI applications at an early stage in the planning process using simulation.

New simulation approaches for MRI
As part of the joint research project KoMPI (funded by the Federal Ministry of Education and Research), new simulation options for MRI are being researched together with the project partners. The integration of automation functionalities based on the open framework Robot Operating System (ROS) into the existing proprietary software tool Editor of Human Work (EMA) from imk automotive is being researched. Particular attention is paid to realistic path planning, integrated gripping and sensor simulation, collision-free simulation of human-robot movements and the synchronization of various sub-processes. A realistic simulation of the MRI with collision-free path planning provides reliable information during the planning phase and well before the actual commissioning of the application, for example on the cycle time and technical feasibility, which can be used for process and layout design.

Augmented reality as a supplement
In addition to the pure simulation environment, augmented reality (AR) is a useful addition to work system design with MRI. The assembly systems and processes modeled in the simulation environment are transferred to a corresponding AR application. Mobile end devices or AR glasses can now be used to view the future MRI workstation in the existing real work system by operational employees and those responsible for planning. The movement behavior of the robot can also be precisely reproduced, processes in the interaction between humans and robots can be tested and the room layout in the newly designed work system can be experienced.

The visualization of virtual safety fences provides valuable information for the safety design of the application. One advantage that should not be underestimated is that the employees in assembly can get to know the future assistant "lightweight robot" (LBR) themselves and influence it during the planning phase. For example, a joint decision can be made on where the robot should be positioned so that it is perceived as a support for the employees. Ultimately, employee acceptance is one of the factors that determine the success of an implemented MRI application.

Robot-assisted placement of terminal blocks
The LPS operates an assembly system for terminal blocks in its learning and research factory. An MRI potential analysis for the use of collaborative LBR has identified the assembly of end clamp terminal blocks as a suitable application scenario for the MRI. The LBR first places all the end clamps on the top-hat rail. The employee then takes over and completes the pre-assembled module while the LBR prepares the next terminal strip. Placing end clamps requires a force of over 200 Newtons, so the robot relieves the employee considerably. In addition, the end clamps are fitted by the robot without the measuring errors that can occur in the manual process. This eliminates the need to measure initial and intermediate dimensions, which significantly speeds up the assembly process.

The MRI application was first modelled and optimized in a simulation. This allowed the application to be examined and adapted in terms of cycle times, possible collisions and assembly sequences. In the next step, the application was transferred to an AR view in order to observe the interaction between humans and robots in the real environment. Finally, a demonstrator was created to test the feasibility of the safety concept on sample products. In the next step, the application will be transferred to the real operation of the assembly system at the LPS and compared with the results determined in the simulation in order to draw conclusions for further improvements to the digital tools at the LPS.

Previous LPS research activities have shown that the success of an MRI application is closely linked to the early planning and validation of the newly designed workplace system. Simulation systems make a decisive contribution to recognizing potential, evaluating safety concepts and avoiding errors even before investments in new systems have to be made. Augmented reality is a useful addition, especially if employees are to be involved in the planning process, in order to significantly increase the acceptance of MRI. These systems are still mainly found in the research environment, but their high relevance for applications in industry can already be seen today.

M. Linsinger, K. Lemmerz, B. Kuhlenkötter/as

Chair of Production Systems (LPS) © LPS

Briefly explained: The LPS
The Chair of Production Systems (LPS) is headed by Prof. Dr. Bernd Kuhlenkötter. The scientific focus of the LPS covers the fields of production management, production automation and industrial robotics. The LPS operates a learning and research factory (LFF) in which the theoretical concepts are implemented and evaluated. Through these demonstrations of the results, the LPS promotes the transfer of technology to industry.

Scientific Society for Assembly, Handling and Industrial Robotics (MHI e.V.) © MHI e.V.

Briefly explained: The MHI e.V.
The Wissenschaftliche Gesellschaft für Montage, Handhabung und Industrierobotik e.V. (MHI e.V.) is a network of renowned university professors - institute directors and chair holders - from German-speaking countries. The members conduct both fundamental and application-oriented research on a wide range of current topics in the fields of assembly, handling and industrial robotics. Further information on the society, its members and activities: www.wgmhi.de.