Research

Subproject: Development of modular 3D textile structures for sensor elements and connection structures

BMBF 16ES0915

Abstract

The Manta and Dachs robot platforms can find their way around in the respective environment with the innovative, flexible bionic 3D sensor skin (“Bionic RoboSkinden”) and independently carry out exploration and service tasks. A three-dimensional textile serves as an integration platform for components for data analysis and communication. The modular structure of the textile system enables easy adaptation for different robotic application.

Aufgabenstellung

The "Bionic RoboSkin" is a flexible technology solution that can be used for navigation and exploration regardless of the nature of the environment. The new semi-autonomous robotic solutions "Manta" and "Dachs" are being developed especially for areas that are difficult to reach or too dangerous for humans, or in areas with harsh environmental conditions where previous technologies can only be used to a limited extent. These developments are specifically designed for use under water and on land. The sub-project of the TITV Greiz focuses on the development and production of 3D textiles, the integration of conductive structures and sensor modules into the textile fabrics as well as on tests for the use and reliability of the textile-integrated electronics and sensor technology. All electrical connections and contacts are designed by encapsulation so that they work reliably for at least two years in seawater use.

The application of the sensor skin is demonstrated by means of two service robotics applications. The autonomously operating underwater unit "Manta" is equipped with a skin that can detect and map metallic structures by means of magnetic field measurements. At the same time, communication with the divers involved is possible through textile-technologically integrated touch sensors. The semi-autonomous unit "Dachs" is used to survey ground structures by measuring static magnetic fields and high-frequency electromagnetic pulses.

Lösungsweg

One main area of research in the sub-project of the TITV Greiz deals with the development and production of the textile sensor skin and the integration of conductive structures and sensors as well as their contacting.

Based on the area of application and the defined tasks of the textile sensor skin, requirements for the textile 3D basic structure, the conductive material used and the textile-technological processing parameters are defined together with the project partners. These are, for example:

• Multi-directional elastic/stretchable,
• Long-term stability against environmental influences such as UV radiation and seawater,
• Low water absorption capacity,
• Partial impermeability to allow pressure equalisation under water,
• Processability of the conductive materials on textile machines.

Spacer fabrics are used to produce the textile 3D structures. This allows textile structures with a defined thickness and elasticity to be produced. Electronic cables and components are integrated mechanically securely and permanently. With the choice of material, the requirements for durability and stability are also met.
To functionalise the 3D structure, conductive structures and sensor elements are applied using embroidery technology. This enables free, shape-independent placement of the conductive structures and electronic components.
The consortium has decided on a multi-layer structure for the robotic skin. An outer textile layer (without electrical function) serves as a mechanical protective layer. Underneath this, the bus system for communication and the textile sensor elements are integrated in a separate functional layer. The special advantage of these new flat sensors is that they increase the sensitivity of the system and guarantee a large field of view, which enables efficient measurement of large areas.
The project is accompanied by textile-physical investigations for the specification of the threads and the textile surfaces. Within the scope of the thread selection, e.g. thread strength and thread fineness according to DIN EN ISO 2062, maximum tensile strength elongation and fineness-related maximum tensile strength according to DIN 53834 are tested.

The various layouts of the 3D warp knitted fabrics, which are produced on a pilot scale and on an industrial scale, are tested both as unfinished goods and as finished goods with regard to, among other things:

• Mass per unit area according to DIN EN 12127;
• Mesh density according to DIN EN 14971;
• Thickness according to DIN EN ISO 5084;
• Elasticity according to DIN EN 14704-1.

On the one hand, this is important to ensure the specified requirements for the bionic skin and, on the other hand, the test results provide important specifications for the transfer of subsequent processes, such as finishing, from pilot scale to industrial scale.

The tests of the functional elements, which include textile conductors and textile-based sensors and their connection, are carried out in the Smart Textiles test laboratory at TITV Greiz.
In addition to reliability testing for individual electrical supply lines, combined tests of a load and the associated function monitoring are carried out. In the case of the robot skin, these are primarily mechanical loads, i.e. the cyclical movement of the skin, and the monitoring of the electrical resistance of the conductor paths, the signal quality (reduced by e.g. artefacts), the stability of contact points and the influence of cross-sensitivities to the ambient conditions (e.g. seawater).

Fig. 1: Function test robotic unit "Manta

with sensored sub-skin in water basin, with outer skin after use, function test - touch sensor

Results and Applications

The TITV Greiz has further expanded its expertise in the production of functionalised 3D textiles and the integration of textile-based sensor technology for use under extreme conditions in the project.

Both systems have been tested in a practical trial. The functional 3D sensor skin developed fulfils the possibilities for the two application areas of Manta and Dachs outlined in the task. Due to the modular design, the results/assemblies can also be transferred to other systems.

Fig. 2: Function test in the field

Robotic unit "Dachs", graphic from test drive "metal detection" in the terrain, raw data with signal increases in the event of a find

Projectpartners:        EvoLogics GmbH, Berlin

                                    Fraunhofer IZM, Berlin

                                    Sensorik Bayern GmbH (SBG), Regensburg

                                    GEO-DV GmbH, Stendal

                                    BalticTaucher GmbH, Rostock

Many thanks to all project partners for the constructive and good cooperation.

We would like to thank the Federal Ministry of Education and Research for the financial support of the Bionic RoboSkin project, which was provided as a grant from the federal budget, and the project management organisation VDI/VDE Innovation + Technik GmbH for its support.