Real-time simulation and virtual commissioning in aviation

The automation offensive is in full swing in the aviation industry. Modular and versatile robot systems are increasingly replacing costly stationary systems and machines in aircraft construction. The big advantage is that mobile robots can be used universally and quickly adapted to new tasks.

The MFlex project (Mobile Robot Units for Flexible and Resource-Efficient Aircraft Production 2025) made an important contribution to intelligent automation in aircraft construction. The aim of the project was to develop concepts and technologies for the robotic automation of processes in aircraft production in order to reduce costs and increase production capacity. A modular, mobile robot platform was developed and a solution for robot-based drilling on a vertical tail was realized as a use case. All modules were orchestrated from a central controller using the OPC UA communication standard. The MFlex project involved Airbus, ESPACE 2001, 3D.aero, FFT, Fraunhofer IFAM, Fraunhofer IFF and the Institute of System Dynamics and Control (SR).

Visualization of the overall simulation with the modules mobile platform, robot, navigation, drilling module, precision module as well as the vertical stabilizer (Credits: DLR)

Overall system simulation

SR was responsible for the simulation and virtual commissioning. Simulation models for all modules of the system were developed at the institute (mobile platform, navigation, robot, drilling module, precision module). The basis was the object-oriented, cross-domain modeling language Modelica, which was combined with real-time robot simulation, real-time visualization, contact dynamics and model-integrated OPC UA technology. For the modeling, existing Modelica libraries from SR could be used. In addition, new libraries were created within the project. The solution developed at the institute enables the simulation of the system on multiple levels of detail, from the kinematics of the mobile platform to the programming of the robot with G-code up to the forces of the drill process in detail.

A custom-developed Modelica OPC UA library enabled the integration of OPC UA servers into the simulation model, mapping the behavior of the real OPC UA servers of the hardware modules. Since the interface of the virtual and real OPC UA servers is identical, it makes no difference from the point of view of the central controller whether it controls a real module or a virtual module in the simulation. In the project, the central controller was able to successfully control the entire system in the simulation before it is used to control the real system. This virtual commissioning allows errors to be detected at an early stage.

Virtual camera data

One focus was the modeling of the precision module. This is a stereo camera developed by 3D.aero that uses image recognition to detect the position of the vertical stabilizer, thereby increasing the positioning accuracy of the drill module.

Images from the real precision module (Credits: 3D.aero)

Virtual images from the simulation including light effects and textures with recognized features (Credits: DLR)

In the commercial "DLR Visualization 2 Library" developed at SR, virtual camera images can be generated in the simulation visualization. This allows the entire image processing pipeline to be tested before the real system is built.

The MFlex project was funded by the German Federal Ministry for Economic Affairs and Climate Action under the code 20X1720B.

Project duration: 03/2019 to 02/2022

Contact

Dr. Tobias Bellmann
German Aerospace Center
Institute of System Dynamics and Control, Space Systems Dynamics
Oberpfaffenhofen-Wessling
Tel.: +49 8153 28-1833
Fax: +49 8153 28-44-3883