The LPS is currently pursuing a new approach of integrating an assistance robot into an assembly workstation. The robot's tasks focus on logistics, in particular the handling of parts containers. The economic efficiency of the hybrid assembly workstation is to be achieved by allowing the human to concentrate on the haptically demanding tasks while the robot assists with the non-value-adding ancillary activities. The robot takes over the intralogistics at the workstation by transporting the parts containers into the gripping area of the worker, who performs the value-adding activities. This makes it possible to carry out very extensive assembly processes with a large number of parts containers at an assembly workstation, as the worker only has the components for the current and some subsequent work steps in front of him in the ergonomically optimized gripping area. Search times, during which the worker has to select the next components from a large number of parts containers, are therefore eliminated and the focus is more on value-adding assembly.

While many assembly workstations consist of a combination of assembly table and Kanban rack, in the new approach these are separated and connected by a robot area.

The structure of the assembly workstation

The robot knows the assembly sequence and always provides the worker with the required components through a pass-through. Parts for subsequent work steps are also provided so that the worker does not have to wait for the robot. Once the worker has completed a work step, the robot sorts the parts container back onto the shelf. This means that instead of the entire shelf, the worker only has a few boxes in front of him in his ergonomically optimized gripping area. As the worker and the robot have no contact with each other apart from a small monitored pass-through, it is possible to use powerful industrial robots instead of HRC robots. As a result, there should be no waiting times in the parts supply and heavier parts containers are also possible. Furthermore, the rack with the parts containers does not have to be adapted to a human user, but to the robot's gripping space. This makes it possible to use larger shelves that are filled to the floor, for example. By using an additional linear axis for the robot, the gripping space can be extended or the robot can supply additional assembly tables with parts containers. The system is therefore flexible and scalable, as is usual in the field of manual assembly.

First test runs

An initial demonstrator has already been set up at the LPS and is currently being used to test how the new concept works. A small control unit consisting of 22 components serves as an assembly example. The assembly steps range from a few seconds to around 1.5 minutes. In total, the assembly process takes 15 to 20 minutes. A comparison between conventional manual assembly and the new robot-assisted variant shows a time saving of up to 3 minutes in this specific application example. This results from the reduction in search times for the next component, as the worker no longer has to choose from the 22 component containers, but only from five. The particular advantage of this new approach is that the search times do not increase, even for more complex assembly tasks with significantly more individual parts, as the worker is only supplied with the necessary boxes. It was also shown that the robot's speeds are sufficient to ensure that the worker never comes to a standstill. In addition, all test persons involved find the new assembly process very pleasant, as they are not distracted by the search process and can concentrate better on the value-adding assembly. M. Krampe, L. Penczek, B. Kuhlenkötter

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. By demonstrating the results, the LPS promotes the transfer of technology to industry.

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: http://www.wgmhi.de