Sentinel | Sensor integration in CFRP structures for exoskeletons

The aim of the research project "Sentinel" is to improve the understanding of human-machine interaction (HMI) by integrating sensor technology in active-assistive exoskeletons from the company German Bionic Systems (GBS). In cooperation with Fraunhofer IGCV, a sensor network is being developed on the basis of a functional demonstrator that provides the basis for self-adaptation of the system. SGL Carbon is developing a process that is suitable for large-scale production and enables cost-effective integration of sensors in structures made of carbon fiber-reinforced plastic (CFRP).

This creates a knowledge base that enables data-driven adaptation of the CFRP structure and control of the exoskeleton based on real-world operating conditions. The systems can be adapted to the individual requirements of the human wearer through the use-specific adjustment of the operating parameters. These innovations lead to an improvement of the wearing and operating comfort as well as to an improved efficiency of the system.

The use of CFRP structures for support systems such as exoskeletons, but also in medical applications (e.g. prostheses and orthoses), offers significant advantages in terms of lightweight construction and load-bearing capacity due to the superior material properties compared with conventional materials such as aluminum or steel. By integrating sensor technology into the layer structure, data can be collected independently of the situation. This data basis can be used subsequently to better design components in line with the application and thus increase component performance. It can also be used to adaptively regulate the support provided by the system without the wearer having to intervene.

In order to make optimum use of the lightweight construction potential, the "Sentinel" project is also looking at novel manufacturing processes for fiber-reinforced components. One of these technologies is Fiber Patch Placement (FPP) from Cevotec GmbH. In this process, small blanks (patches) of fiber-reinforced plastic strips are placed on a tool by two collaborating robots. By using small and flexibly adaptable patches, a high variety of fiber orientations can be realized in the component to optimally absorb and redirect forces. Likewise, this technology can be used to integrate patches equipped with sensors in the process. This makes the FPP construction method ideal for the production of sensor-integrated components such as the carrier structure of the Cray X exoskeleton from German Bionic.

After the end of the first project year and numerous tests, the first field tests of a sensor-integrated exoskeleton are on the horizon. Together with SGL Carbon, Fraunhofer IGCV has equipped a CFRP carrier structure of the Cray X exoskeleton with sensors, which has successfully passed all manufacturing steps. German Bionic Systems creates the connection to human wearers through the use of textile sensor technology. Together, the functionality of the system is then tested in various application scenarios and methods are developed through which the many different sensor data can be digitized and evaluated. The goal is to build a network of sensors around the exoskeleton that will enable the system to be used in the Internet of Things (IoT) by accurately determining the state of its wearer and interacting with the environment in the best possible way.