At the Fraunhofer IST, a piezo-resistive thin-film system was developed which is deposited directly onto the complex shape of the so-called kingpin which connects the tractor unit and the trailer. The interaction of the force-measurement sensors, the electric powertrain module, the traction battery and the battery management system is ensured through intelligent control algorithms.
The task of the Fraunhofer IST within the project was the integration of the thin-film sensors for measuring the load and temperature distribution in the main load zone of the kingpin, which weighs 6 kg. For this, the film system presented in the adjacent lower figure is deposited and structured on the manually polished surface of the kingpin in such a manner that the measurement areas are located in the upper part. The conductive paths to the contact areas must be routed over several edges, in order for them to be arranged in the lower screw-connection area.
The results of the local tensile force measurement of the sensory kingpin are used for control purposes in order to compensate for any tensile or shear force occurring in the trailer coupling. Energy from the braking power, which is recovered via the electric motors during downhill driving and then stored in batteries, can be made available to the vehicle again as drive power when required, i.e. during uphill driving or acceleration phases. The load on the towing vehicle is reduced, thereby minimizing energy consumption and CO2 emissions.