<div class="section abstract"><div class="htmlview paragraph">Aircraft traffic causes a significant amount of greenhouse gas emissions. Since modern aircrafts are highly electrified, the total weight is affected by cables within the components. Piezoelectric energy harvesting appears to be a reasonable option for reducing cables in certain parts of the aircraft and hence reducing fuel consumption. The proposed work covers energy harvesting in lightweight design with transmission mechanisms using so-called ferroelectrets. The energy harvester (EH) design is motivated by a strain-excitation in an aircraft wing caused by a quasi-stationary dynamic pressure. Ferroelectrets are piezoelectric polymers that show a higher ecological compatibility and a much higher structural flexibility than piezoceramics. Furthermore they provide charge constants in the same order of magnitude as piezoceramics. As a novelty compared to previous studies the energy harvesters are arranged in a cluster in the concept presented herein to increase the power output within a certain area. A central research question is, if and to what extent energy harvesting is possible using a cluster of ferroelectret EHs without and with additional seismic masses to increase the power output and the power output per total cluster mass. This question is answered with the help of a numerical simulation of a modally reduced finite element beam structure subject to a force excitation. The applied cluster is simulated using simplified, yet validated EH models. They are coupled to the structure using only a set of node numbers. In this way the suitability of the ferroelectret transmission mechanisms as vibroacoustic metamaterials for energy harvesting in aircrafts is estimated as the final result of the work.</div></div>

In this work, a concept for strain-bending energy harvesting with lightweight ferroelectrets subject to metallic host structures is proposed. The energy harvester (EH) works with the ferroelectret irradiation cross-linked polypropylene (IXPP) and uses the piezoelectric δ33-mod by transferring in-plane strain energy of a host structure to a compression of an IXPP stack. This is achieved with a simple and lightweight transmission made of structural steel. In this way, a high ratio of generated power per used EH mass can be achieved. To demonstrate this, miniature EHs as unit cells for larger EH systems are investigated. The strain magnitude of the excitation in an aircraft wing of 4.5*10^-5 m/m at 1.5 Hz from previous work is partly taken into account for calculations. In an analytical modeling approach, the energy conversion abilities of the presented concept is compared to concepts using PZT ceramics to stress the usefulness in cases where strain energy is the prominent source of vibration energy. Further, an optimization algorithm is presented for a static and a dynamic case without a host structure and for a dynamic case with an aluminum host structure. The optimized power output and power output per total EH mass for the three cases is calculated to 1.52µW and 271µW/kg, 0.7mW and 80mW/kg as well as 6.53µW (at 1N excitation magnitude) and 10.8mW/kg (at 1N excitation magnitude) respectively. Finally, experimental results for case three are presented to validate the model of the proposed and optimized EH topology up to 500Hz. The results further show a good mechanical reproducibility of the measured transfer behaviour and a fairly good reproducibility of the mechanical-electrical results due to deviations in material properties. A comparison of the model with the experimental results shows a good agreement. Therefore a linear ferroelectret model appears to be suitable to predict the system behaviour in lower and higher frequency ranges as well as for high ferroelectret material strains. The optimized EH provides a comparably high ratio of power output per mass when added to a structure like an aircraft which is shown in a comparison to other research works. The performance in a real application can be further improved to 52 mW within a 1m² area using a clustering approach, discussed in the paper. Large deformations of of lightweight structures like aircraft wings at low and high frequencies can thus be exploited to provide enough electrical power decentrally for low-power consumers.

In this work, a simulation framework for virtual testing of autonomous driving functions under the influence of a fault occurring in a component is presented. The models consist of trajectory planning, motion control, models of actuator management, actuators and vehicle dynamics. Fault-handling tests in a right-turn maneuver are described, subject to an injected fault in the steering system. Different scenarios are discussed without and with a fault and without and with counteractions against the fault. The results of five scenarios for different criticality metrics are discussed. In the case of a fault without a counteraction, a pronounced lateral position deviation of the ego vehicle from the reference curve is observed. Furthermore, the minimal and hence most critical time-to-collision (TTC) and post-encroachment time (PET) values are calculated for each scenario together with a parameter variation of the initial position of a traffic agent. The minimum TTC values are lowest in the case of a fault without counteraction. For the lateral position deviation and the TTC, the counteractions cause reduced criticality that can become even lower than in the case without a fault, corresponding to a decrease in the dynamic behavior of the vehicle. For the PET, only in the case of a fault without counteraction, a non-zero value can be calculated. With the implemented testing toolchain, the automated vehicle and the reaction of the HAD function in non-standard conditions with reduced performance can be investigated. This can be used to test the influence of component faults on automated driving functions and help increase acceptance of implemented counteractions as part of the HAD function. The assessment of the situation using a combination of metrics is shown to be useful, as the different metrics can become critical in different situations.

Automated driving functions are expected to increase both the safety and ride comfort of future vehicles. Ensuring their functional safety and optimizing their performance requires thorough testing. Costs and duration of tests can be reduced if more tests can be performed numerically in a feasible simulation framework. This simulation setup must include all subsystems of the autonomous vehicle, which significantly interact with the system under test. In this paper, a modular model chain is presented, which is developed for testing systems with an impact on vehicle motion. It includes trajectory planning, motion control, and a model of the vehicle dynamics in a closed loop. Each subsystem can easily be exchanged to adapt the model chain with respect to the simulation objectives. As a use case, the testing of an active suspension control system is discussed. It is designed directly for use in autonomous cars and uses inputs from the vehicle motion planning subsystem for planning the suspension actuator motion. Using the presented closed-loop model chain, the effect of different actuator control strategies on ride comfort is compared, such as curve tilting. Furthermore, the impact of the active suspension system on lateral vehicle motion is shown.

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