## 4 Conclusions  
A new hybrid laminate with sensor functionality was presented. It offers the possibility of combining lightweight construction and functional integration into a component, and producing it in large quantities. For this purpose, it was necessary to develop a continuous joining technology which combines continuous piezoceramic foil and an aluminum sheet, and it guarantees a constant quality. This was achieved through previous research and further investigation.  
A new heating concept and a new tool concept using variothermal tempering were developed for further processing. Both have been integrated into a servo-electric press to minimize cycle time and energy loss caused by transport. By measuring the temperature on a sample plate, the process was verified. Good parts of high quality were produced with appropriate parameters.  
In further investigations, the parts will be scanned by an optical measuring system and compared with the target geometry. The acquired information about thinning and springback will form the basis of adjusting the FE simulation and further improving the process. The polarization behavior of hybrid laminates with modified PZT components, as well as the development of tool concepts for in-line polarization processes, are still part of ongoing research activities.  
In the signal processing part, an electrical circuit was implemented to amplify the low impedance piezoelectric effect signal and to ensure the correct measuring range. On the other hand, a full pipelined FPGA structure was presented, guaranteeing real-time processing. On the basis of the novel SoC architecture, the feature determined in the FPGA can be passed directly to the ARM processor, which classifies the features using an SVM, which had 94% accuracy on the training set and 84% on the testing set. With a power consumption of approximately 1.7 W, the presented solution is also very efficient in terms of energy consumption, enabling usage in mobile devices. However, although the used data set represents a valid basis for ensuring the evidence of feasibility, additional human-specific parameters, such as touch pressure, touch length, and characteristics of human fingers, have to be evaluated in further research before commercial use.  
Figure 10: Comparison between different kernel functions for support vector machine (SVM) training with respect to accuracy on the training data set and test data set.  
In summary, a novel manufacturing process for the production of piezo-based hybrid laminates was described. Further processing of the laminate--forming and in-line polarization--enable multifunctional structures, e. g., automotive center consoles with integrated touch functionality. The input gestures are processed by machine learning methods on an embedded system. The accuracy of the procedure was presented by an energy-efficient and real-time SoC solution, which precisely localized points of touch by human fingers. This demonstrates the practicability and usability of the hybrid laminates and the signal processing.  
Writing--aoriginal draft, R.S., A.G. and R.D.; Writing--review & editing, V.K., W.H., D.L. and L.K.  
Deutsche Forschungsgemeinschaft: EXC 1075; Deutsche Forschungsgemeinschaft: GRK 1780/1; Deutsche Forschungsgemeinschaft: SFB/TR 39.  
We gratefully acknowledge the cooperation of our project partners and the financial support of the DFG (Deutsche Forschungsgemeinschaft) within the Collaborative Research Center/Transregio 39 \"PT-PIESA\", the Federal Cluster of Excellence EXC 1075 \"MERGE\" and GRK 1780/1 CrossWorlds.  
The authors declare no conflict of interest.