Fakultät für Elektrotechnik Feinwerktechnik Informationstechnik
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Embedded permanent magnets are widely used for electrical machines with interior-rotor. This provides better protection of the magnets and enables the use of an additional reluctance torque for torque density improvements. For external rotors, the use of surface-mounted permanent magnets is common. The following paper analyses the application of inserted magnets at exterior-rotors with segmentation to achieve an increase in torque density.High pole electrical machines are often designed with a fractional-slot concentrated winding which leads to field harmonics. Therefore, an analytical method for qualitative comparison of different winding configurations for using reluctance torque with consideration of stator field harmonics is applied. Besides rotor saliency, the magnetic flux concentration is a positive effect of interior permanent magnets. Here, the flux leakage along mechanical necessary iron bridges is crucial. With the segmented rotor geometry, these iron bridges can be avoided for interior placed magnets. This allows a flux concentration for electrical machines with a high number of pole-pairs. The paper presents a simplified geometry-based approach to describe these improvements. The method is validated with a finite element analysis (FEA) and a prototype with a segmented rotor is built.
Because of the absence of rare earth magnets, the reluctance synchronous machine has a more favourable sustainability balance compared to the permanent magnet synchronous machine with NdFeB magnets. Additional advantages include the absence of copper in the rotor and the ease of manufacture of the non modified rotor. A clear disadvantage of the reluctance synchronous machine is the relatively high torque ripple if no measures such as skewing are taken. Therefore, the machine is mainly used in applications such as fans where the torque ripple is not critical for the operation. The paper makes a contribution to addressing the problem of torque pulsation. For the reduction of torque harmonics, the usage of various rotor designs as well as asymmetric rotor geometry are presented. In addition, the aspect of torque harmonics, which is predicted by the finite element analysis is discussed and possibilities of torque ripple reduction for further investigations are shown. The description of a reluctance network of the machine is addressed with a semi-analytical approach for this purpose. Finally, the results of the preliminary calculation are validated by finite element analysis (FEA) and the quantities are verified with measurements on a device under test. The deviations between the methods are shown and discussed.
This paper presents a current control approach for permanent magnet synchronous machines (PMSMs) using the deep reinforcement learning algorithm deep deterministic policy gradient (DDPG). The proposed method is designed by examining different training setups regarding the reward function, the observation vector, and the actor neural network. In doing so, the impact of the different design factors on the steady-state and dynamic behavior of the system is assessed, thus facilitating the selection of the setup that results in the most favorable performance. Moreover, to provide the necessary insight into the controller design, the entire path from training the agent in simulation, through testing the control in a controller-in-the-loop (CIL) environment, to deployment on the test bench is described. Subsequently, experimental results are provided, which show the efficacy of the presented algorithm over a wide range of operating points. Finally, in an attempt to promote open science and expedite the use of deep reinforcement learning in power electronic systems, the trained agents, including the CIL model, are rendered openly available and accessible such that reproducibility of the presented approach is possible.
In this paper, the influence of temperatures up to
250 °C on core losses and magnetization demand of electrical
steel sheets is illustrated. Therefore, measurements are made
using an adopted high-temperature Epstein frame and a stator
core as a ring probe. Three different electrical steel sheet grades,
M330-50A, M530-50A and NO20-15, and a stator core are
tested. Magnetic property measurements are performed at
various frequencies from DC to 1.2 kHz with a defined
sinusoidal waveform of magnetic polarization. This covers a
wide range of electric motor applications from industrial drives
to electric vehicle drives. With increasing temperature,
magnetization demand rises significantly in medium
polarization range. For specific core losses, a loss separation is
performed using the Jordan approach, separating specific
hysteresis and specific eddy current losses to determine the
temperature influence on each loss component. The
temperature behavior of the specific electrical resistivity of
electrical steel sheets is measured and used to calculate the
physical specific eddy current losses. After separation, specific
hysteresis losses also show a significant temperature influence.
Control of multi-phase machines is a challenging topic due to the high number of controlled variables. Conventional control methods, such as field-oriented control (FOC), address this issue by introducing more control loops. This, however, increases the controller design complexity, while the tuning process can become cumbersome. To tackle the above, this paper proposes a deep deterministic policy gradient algorithm based controller that fulfills all the control objectives in one computational stage. More specifically, the proposed approach aims to learn a suitable current control policy for six-phase permanent magnet synchronous machines to simplify the commissioning of the drive system. In doing so, physical limitations of the drive system can be accounted for, while the compensation of imbalances between the two three-phase subsystems is rendered possible. After validating the training results in a controller-in-the-loop environment, test bench measurements are provided to demonstrate the effectiveness of the proposed controller. As shown, favorable steady-state and dynamic performance is achieved that is comparable to that of FOC. Therefore, as indicated by the presented results, reinforcement learning-based control approaches for multi-phase machines is a promising research area.
Using Mask R-CNN for Image-Based Wear Classification of Solid Carbide Milling and Drilling Tools
(2020)
In order to ensure high productivity and quality in industrial production, early identification of tool wear is needed. Within the context of Industry 4.0, we integrate wear monitoring of solid carbide milling and drilling cutters automatically into the production process. Therefore, we propose to analyze wear types with image instance segmentation using Mask R-CNN with feature pyramid and bounding box regression. Our approach is able to recognize the five most important wear types: flank wear, crater wear, fracture, built-up edge and plastic deformation. While other methods use image classification and classify only one wear type for each image, our model is able to detect multiple wear types. Over 35 models with different hyperparameter settings were trained on 5,000 labeled images to establish a reliable classifier. The results show up to 82.03% accuracy and benefit for overlapping wear types, which is crucial for using the model in production.
Energy-saving potential for centrifugal pump storage operation using optimized control schemes
(2021)
AbstractIn this paper, we present the energy-saving potential of using optimized control for centrifugal pump–driven water storages. For this purpose, a Simulink pump-pipe-storage model is used. The equations and transfer function for steady-state and transient system behavior are presented and verified. Two different control strategies — optimum constant flow rate and level guided speed control — are compared to an allegedly optimal-driven pump with constant rotational speed. Twelve centrifugal pumps between 1 and 120 kW nominal power are evaluated to analyze the influence of different system parameters. The system characteristics, which are the static head, dynamic head factor, and maximum filling head, are varied 25 times for each pump in consideration of the pump’s best efficiency point. Thus, 300 different systems are optimized for each control strategy and compared to the constant speed control. The results are analyzed and the relevant system’s parameters, which have the most significant impact on energy savings, are shown. This theoretical energy–saving potential is verified with measurements, which show the high impact of the part load losses of the frequency converter and the electric motor. A law for identifying and estimation potential energy savings is developed using this information. Four use cases are analyzed with this law. It is shown that for a cost-minimal operation, not only the savings potential but also the operating time is decisive.
In laboratory practicals (labs), students actively investigate technical and scientific phenomena and thus experience autonomy, competence, and social embedding, factors that promote motivation. However, labs mostly rely on highly structured and instructive concepts and often require costly equipment. Therefore, the research question in this paper is: How can learner-centered teaching methods and learning formats be improved by rethinking the digitization of lab practicals?
The implementation of a reliable vision system for a human-robot environment is a key issue for the collaborative production industry. The core challenge of human-robot collaboration is to ensure safety. Furthermore, a flexible safety system is required for frequently changing applications and work areas. This paper focuses on the development and application of a workspace monitoring system for safeguarding using radar sensors. The human-robot collaboration cell is designed to enable a flexible integration regardless of the work location. This results in higher productivity. Since no separating protective devices are provided for the cell, safety-oriented monitoring and control by suitable safety sensors is required. The methods to minimize the size of the necessary safety distance will be presented. The experimental validation shows that this safety system with radar sensors performs a reliable workspace monitoring system. The high robustness, reactivity and flexibility of the safet y concept makes this system usable for collaborative tasks in a real industrial environment.
In the research project AVerdi the influence of photonic sintering methods on the resulting electrical conductivity, sintering duration and adhesion of digitally printed silver nanoparticle inks was investigated and compared to convective sintering. Conductor paths with film thicknesses below 1 μm were applied on flexible polymer substrates via inkjet printing. Aerosoljet printing was used to generate thicker lines up to 11 μm on injection molded substrates. Photonic sintering was carried out with near infrared emitters or ultraviolet light emitting diodes. For inkjet printed structures on polyimide a conductivity up to 24 % relative to bulk silver was achieved after a sintering duration of 2 s and 5 s for the near infrared and the ultraviolet light source, respectively. Oven sintered samples showed an electrical conductivity of 14 % after 1 h at 200° C. On polyethylene terephthalate a conductivity around 7 % was achieved after irradiation with near infrared light for 1 s, whereas convectively sintered samples showed a conductivity around 4 %. All material combinations sintered by the different methods showed good adhesion. The overall results of long-term behavior after thermal-cycling, regarding electrical conductivity and adhesion, show that the photonically sintered structures achieve similar results compared to the reference. The photonically sintered structures generated with the aerosoljet on polyamide 6 achieved conductivity values up to 19 %, which were comparable to the furnace sintered reference samples. On liquid crystal polymer substrates conductivity values reached up to 35 % after sintering with ultraviolet light emitting diodes for 60 s. Oven sintered samples showed a conductivity around 25 % after 1 h at 150° C. The adhesion of the silver nanoparticle ink on liquid crystal polymer and polyamide 6 substrates is better than with the reference samples. The reliability tests show fewer failures with alternative sintered samples. In this study only the results for inkjet printed structures are presented.
The integration of SMT components is necessary to produce more complex assemblies within the framework of conformable electronics. During High-Pressure-Forming (HPF) and subsequent overmolding electronic components must withstand high amounts of stress. In this study 0402- as well as 0603-sized chip resistors were mounted on different common polymer substrates using conductive adhesive paste followed by electrical and mechanical evaluation. Prior to HPF electronic components were positioned in areas of different local deformation. After HPF the specimen were characterized by shear force testing and electrical resistance measurements. In a similar manner, electronic components were tested to assess the mechanical behavior during injection molding. To examine different melt induced stress scenarios, electronic components were arranged parallel as well as perpendicular to the flow direction of the melt at different positions. Additionally, three different injection speeds were evaluated to assess the influence on the electrical conductivity and functionality of the assemblies. It was found that meandering of conductors is necessary for higher deformations. El. components (without additional nonconductive adhesives) can be placed in areas of up to 15% deformation, smaller package sizes seem to be advantageous for HPF. Regarding overmoulding, it was found that larger components (larger bonding area) is beneficial. Also, placement near the injection point, as well as low injection speeds should be avoided. Overall, el. components should be protected (using globtops / underfills etc.) to withstand consecutive HPF and overmoulding.
In this paper the stress on electronic components for Conformable Electronic applications is evaluated. During High-Pressure-Forming (HPF) and subsequent overmolding (OM) these components have to withstand high amounts of stress. Globtops are used to protect 0402 as well as 0603-sized components mounted on different polymer substrates. The components are placed in different areas of deformation (for HPF) and melt velocities (for OM). The components are afterwards examined by means of electrical resistance measurements and shear force measurements as well as micro-sections. For conductive adhesive, the globtop material positively influenced the resistance change after deformation, soldered assemblies showcased good formability up to 20 %. The shear force drop caused by higher deformations could be mitigated using globtop materials. Soldered components were able to withstand OM when globtops were used. Here, smaller components seem to take less damage from the impacting melt. Components should be placed in areas where the melt has cooled down to prevent damages.
Evaluation of detatchable board-to-board interconnects on screen printed electronic structures
(2021)
Hybrid printed electronics (HPE) combines advantages of conventional electronics manufacturing technologies such as surface mount technology with those of printed electronics in order to realize more complex electronic systems. To realize the final product, such HPE subassemblies have to be connected to higher-level assemblies. So far interconnection techniques for the so-called level 3 interconnection between printed subsystems and standard electronics have not yet been considered adequately in scientific research. In this paper, alternative detachable level 3 interconnection technologies, i.e. spring loaded contact pins, zero insertion force (ZIF) as well as Non-ZIF connectors are investigated systematically regarding their electrical behaviour against the background of printed electronics. Screen-printed silver filled polymer thick film paste is used to realize printed conductor patterns on flexible polymer substrates, which are connected later on with the alternatives mentioned above. Transition resistance is measured using the four wire method as produced, after repeated mating cycles as well as after accelerated aging tests. The various electrical contacts are subjected to thermal stress in temperature cycling testing and during aging at a constant high temperature. As a result it can be stated, that the sping-loaded contact pins used in this investigation show superior behavior compared with the selected connectors in terms of resistance increase after mating cycles. Concerning long-term behavior after thermal cyling and high temperature storage, all investigated alternaives reveal convincing results.
Characterization of Crimp Interconnections for Hybrid Integration of Screen-Printed Electronics
(2021)
In this work, electrical contacts between piercing-crimp terminals and screen-printed silver structures on three different polymeric films are characterized electrically and mechanically before and after accelerated thermal aging tests. Temperature cycling and constant thermal load tests were performed as like as ampacity and resistance measurements and tensile tests. The tensile tests show that the mechanical strength of the crimp connection depends on substrate material, but is independent of the aging state. For all joints, breaking forces of more than 100 N were achieved. Furthermore, some of tested connections can be loaded with more than 2.5 A in unaged state till they heat up by 25 K. Besides that, accelerated thermal aging generally leads to a reduction in electrical resistance in our experiments.
In this work, on different substrate materials thermally cured polymer thick-film (PTF) pastes are connected to surface mount technology resistors using a SnBiAg solder alloy. The effect of substrate pre-treatment with atmospheric plasma and thermal cycling on the shear strength of these interconnections is investigated, and the shear forces obtained are graded using United States Defense Standard / Military Standard (MIL-STD) 883. In particular, the build-up of solder interconnections on conductive structures made of commercially available copper-containing PTF pastes and their mechanical characterization is novel. As well as the mechanical characterization of conductive structures, made of PTF pastes, on plasma-treated substrates and their grading using the MIL-STD 883. In addition, interconnections with silver-containing conductive structures are realized for comparison. Depending on the interconnection system, component mean shear forces of up to 31 N are achieved. While some systems meet the 1.25× criterion of MIL-STD 883, the majority of the systems investigated do not meet the 1.00× criterion. Hereby, the adhesion between the conductive structure and the substrate usually fails. Plasma pre-treatment shows an adhesion-increasing effect only for a proportion of substrate materials used, as does thermal aging. But thermal loads can also impair the adhesive strength.
The vapor pressures of two binary mixtures containing 2-trifluoroethanol (TFE) + 1,3-dimethyl-2-imidazolidinone (DMI) and TFE + 2-pyrrolidone (PYR), were investigated at temperatures T = (274.15 to423.15) K using two different static method installations. Both combinations were modelled using an extended
Clausius-Clapeyron equation with concentration dependent parameters and the NRTL equation with temperature dependent parameters. The best fit was obtained using the NRTL equation.
DIN SPEC 5031-100 and CIE S 026:2018 are regulatory frameworks that are intended to establish health-preserving indoor lighting in Europe. Therefore, they are crucial for the visual environment and its sustainability. The standards are largely congruent. Inconsistencies should now be harmonized with the newly published draft standard DIN/TS 5031-100, for which the objection period ended on 3 June 2020; thus, it can be expected that the standard will soon be put into operation. This publication provides the reader with a detailed technical as well as medical overview of the scope and background information on how the standard came about. Applicable laws, ordinances and standards were compiled across countries, and related studies were reviewed. It is demonstrated that the focus of this new standard, as with previous versions, is on the melanopic sensitivity of ganglion cells. The authors base this on a literature search for projects about ecological lighting design over the past 20 years. However, in practice, the publication of the standard does not yet completely counteract the health effects of inappropriate indoor lighting.
This publication describes an application of a
Truncated Signed Distance Mapping approach for disaster
intervention in underground mine shafts through geometrical
change detection of the shaft walls. The paper describes two
main problems of such an approach (aligning two potentially
huge point clouds and automatic change detection by comparing
the reconstructed volumes) and explains in detail the proposed
solution.
In order to allow robust obstacle detection for autonomous freight traffic using freight trains or shunting locomotives, several different sensors are required. Humans and other objects must be detected so that the vehicle can stop in time. Laser scanners deliver distance information and are popular in robotics and automation. Cameras deliver further pieces of information on the environment and are especially useful for the classification of objects, but do not deliver distance measurements. Thermal cameras are ideal for the detection of humans based on their body temperature if the surrounding temperature is not too similar. It is only the combination of these different sensors which delivers enough robustness. Therefore a sensor fusion and an extrinsic calibration has to take place. This article presents an approach fusing a 2D and an 8-layer 3D laser scanner with a thermal and a Red-Green-Blue (RGB) camera, using a triangular calibration target taking all six degrees of freedom into account. The calibration was tested and the results validated during reference measurements and autonomous and manually controlled field tests. This sensor fusion approach was used for the obstacle detection of an autonomous shunting locomotive.
The decentralized feed-ins from distributed energy resources (DER) represent a significant change in the manner in which the power grid is used. If this leads to high loads on electrical equipment, its aging can be accelerated. This applies in particular with regard to the thermal aging of older generations of power cables, namely paper insulated lead covered (PILC) cables. This type of power cable can still be found frequently in medium voltage (MV) networks. If aging of these cables is significantly accelerated in the presence of DER, distribution system operators (DSO) could face unplanned premature cable failures and a high replacement demand and costs. Therefore, this paper investigates the thermal aging of PILC cables in a MV distribution network benchmark for different load scenarios, using standardized load profiles and representative expansion scenarios for wind power and photovoltaics plants in particularly affected network areas in Germany. A main objective of this paper is to present a methodology for estimating the thermal degradation of PILC cables. An approach is used to draw simplified conclusions from the loading of cables to their conductor or insulation temperature. For this purpose, mainly Joule losses are considered. In addition, thermal time constants are used for the heating and cooling processes. Based on the insulation temperature, thermal aging is determined using the Arrhenius law or the Montsinger rule. However, it is important to note that there is an urgent need for research on reference data in this area. For this reason, the results of the lifetime estimation presented in this paper should only be considered as an approximation if the selected reference data from the literature for the aging model are actually applicable. The lifetime assessment is performed for a highly utilized line segment of the network benchmark. Accordingly, extreme values are examined. Different operational control strategies of DSO to limit cable utilization are investigated. The results show that the expansion of DER can lead to a short but high cable utilization, although the average utilization does not increase or increases only slightly. This can lead to significantly lower cable lifetimes. The possible influence of these temporarily high loads is shown by comparing the resulting cable lifetime with previous situations without DER. It is also shown that DSO could already reduce excessive aging of PILC cables by preventing overloads in a few hours of a year. In addition to these specific results, general findings on the network load due to the influence of DER are obtained, which are of interest for congestion management.
In this paper, a novel approach is introduced
which utilizes a Rapidly-exploring Random Graph to improve
sampling-based autonomous exploration of unknown environments with unmanned ground vehicles compared to the current
state of the art. Its intended usage is in rescue scenarios
in large indoor and underground environments with limited
teleoperation ability. Local and global sampling are used to
improve the exploration efficiency for large environments.
Nodes are selected as the next exploration goal based on a
gain-cost ratio derived from the assumed 3D map coverage
at the particular node and the distance to it. The proposed
approach features a continuously-built graph with a decoupled
calculation of node gains using a computationally efficient ray
tracing method. The Next-Best View is evaluated while the robot
is pursuing a goal, which eliminates the need to wait for gain
calculation after reaching the previous goal and significantly
speeds up the exploration. Furthermore, a grid map is used to
determine the traversability between the nodes in the graph
while also providing a global plan for navigating towards
selected goals. Simulations compare the proposed approach
to state-of-the-art exploration algorithms and demonstrate its
superior performance.
This publication describes a novel approach to
generic robot navigation using elevation maps based on pointregion-Quadtrees. The described approach plans optimized trajectories in dependency of the robot’s morphology by detecting and rating obstacles. This is achieved by tailoring the tree based
elevation map to the robot’s design. The approach and the related
work, it is based on, is described in detail, experiments are
provided, which verify the results.
In this paper, a novel state machine for mobile robots is described that enables a direct use for exploration and inspection tasks. It offers a graphical user interface (GUI) to supervise the process and to issue commands if necessary. The state machine was developed for the open-source framework Robot Operating System (ROS) and can interface arbitrary algorithms for navigation and exploration. Interfaces to the commonly used ROS navigation stack and the explore_lite package are already included and can be utilized. In addition, routines for mapping and inspection can be added freely to adapt to the area of application. The state machine features a teleoperation mode to which it changes as soon as a respective command was issued. It also implements a software emergency stop and multiplexes all movement commands to the motor controller. To show the state machine's capabilities several simulations and real-world experiments are described in which it was used.
Sensitive robots are an innovative technology of tomorrow ´s production. The Human–Robot-Collaboration (HRC) with its variable combination of unique skills represents a future-oriented form of work. Yet, there is a lack of experience in process realization, safety requirements are often not given and economic efficiency is still missing. There are a lot of innovative process solutions in research but industrial conditions are less considered. In this work, the approaches for the realization of standardizable HRCs for assembly operations in the automotive sector will be outlined. The aim is to present simple ways from the idea to series production by considering permitted limits. Based on an industrial application, innovative collaborations are realized with only few hardware and software components. In this context, standard compliant safety is ensured through internal system features and adjusted component designs. Additionally, an approach for HRC safety through real-time monitoring of the endeffector area is presented. As an
outlook there is a guideline for HRC realization.
The concept of the digital twin (DT), which accompanies a plant or machine throughout its entire life cycle, has further reinforced the role of Virtual Commissioning (VC). Of decisive importance for the economically and technically sensible use of the DT is its creation as early as possible in the life cycle. In the field of mechanical engineering, therefore, the first digital artifacts of the DT should ideally already be created in parallel with the mechanical design phase. The first step is the kinematization of the CAD model. This paper presents a new method for the semi-automated kinematization of 3D CAD models. The method uses a verbal description of the motion sequence desired by the designer, based on DIN EN 60848 (GRAFCET) [2] and using elements from VDI Guideline 2860 (handling functions) [8]. The presented method is easy to use and self-describing to a large extent. It enables designers to define in their own domain, in parallel to their mechanical designs, the desired motion sequence of the machine they have designed in machine-readable form. The actual kinematization of the CAD model is performed automatically. At the end, the kinematized design is available in COLLADA format and can be imported via the import interfaces of common simulation tools and can therefore be used for the DT.
The magnitude of current harmonics depends on the design of an electrical machine. By suppressing these harmonics noise can be reduced and efficiency improved. Iterative Learning Control (ILC) has proven effective in reducing harmonics. One of the challenges of working with ILC is operation at varying speeds. Variable speeds are particularly important for applications like automotive drives. The ILC period length changes during the learning process at varying speeds. Due to fixed sample rates, the number of values processed by the ILC varies with motor speed.This paper proposes a method to solve this problem and uses ILC at varying speeds. The ILC used to eliminate the harmonics is based on the inverse system. The usage of a two-dimensional memory array is proposed. This data structure holds rows for specific speeds between which interpolation is performed, enabling the elimination of errors which are periodically cyclic to one electrical rotation. This includes the reduction of the motor current harmonics. To verify the presented method a permanent magnet synchronous motor with distinctive 5th and 7th harmonics is used. In real-time implementations, limitations of memory and computational capacity occur.
B8.3 Influence of Temperature on Distributed Strain Sensing with OTDR in Polymer Optical Fibers
(2021)
Strain in ground and earthworks can be measured by polymer optical fibers (POF) applied to geotextiles. We measure the increase of backscatter (IOB) in the fiber under strain using optical time domain reflectometry (OTDR). The effect of temperature on this measurement principle is investigated. The local backscatter changes by 0.003 dB/K for common ambient temperature. In addition it is shown, that temperature depended viscoelastic properties of the polymer does affect IOB.
Finite control set model predictive control (FCS-MPC) is a promising method for the control of multi-phase machines, due to its capability to directly account for nonlinearities and multiple controlled variables. To overcome the drawback of high current ripples and excitation of harmonic currents in the so-called xy-subsystem, several methods have been proposed in the literature so far. This paper proposes an MPC-based method that achieves high granularity of switching by not only switching at the discrete time steps, but also within the sampling interval. In doing so, the discussed algorithm, referred to as variable switching point current control (VSP 2 CC), produces low current distortions, while still keeping the advantages of conventional FCS-MPC, such as fast dynamic behavior during transients. To highlight the above, VSP 2 CC is applied to a six-phase permanent magnet synchronous machine (PMSM) and compared with conventional FCS-MPC and MPC that employs virtual voltage vectors (VV-MPC).
Absolute spectral backscatter measurements of large-core multimode PMMA polymer optical fibers
(2021)
To our knowledge, we are the first to measure the absolute value of the backscattering coefficient of a standard 1 mm core-diameter, multimode (MM) step-index (SI) polymethylmethacrylate (PMMA) polymer optical fiber (POF) for the spectral range of 450 nm to 700 nm. Our optical time domain reflectometer (OTDR) setup consists of a femtosecond supercontinuum laser with an acousto-optical filter as a tunable light source with short pulses and a time-correlated single-photon counting system as a receiver with a high dynamic range. The backscattering coefficient is calculated from the ratio between the energy within the fiber end reflex and the distributed backscattering level. We also measured the spectral attenuation with our OTDR setup and compared it with a standardized measurement method. At the attenuation minima within the measured spectral range the backscattering level of a 1 ns pulse is about −46 dB at 520 nm, −48 dB at 570 nm, and −51 dB at 650 nm. We were also able to show by the observed wavelength dependence that Rayleigh scattering causes a majority of the scattering.
Depending on the application range, there are various recommendations in the literature which converter topology should be used. These are mostly based on experience or more or less deeper considerations. For DC/DC converters, which are operated over a wide input voltage range, such recommendations rarely exist. Therefore, this contribution shows the evolution of two input voltage dependent selection matrices, which should facilitate the selection of future topologies based on known publications and basic considerations. The focus here lies on converters for λ = V i_max /V i_min ≥ 3 with galvanic isolation. First, the data set is introduced, where a distinction is made between flyback converters, forward converters and other 1stage or 2stage converters before the evolution of the novel input voltage dependent matrices is carried out. These two matrices support the selection of a suitable topology and whether the energy transfer should be done by one or two stages.
This paper presents a comparative simulation analysis of an Interior Permanent Magnet Synchronous Machine (IPMSM) performance once fed by a traditional three-phase two-level inverter and then using a three-phase five-level Cascaded H-Bridges Multilevel Inverter (CHBMI). For this purpose, an enhanced mathematical model of the IPMSM, that take into account simultaneously saturation, cross-coupling, spatial harmonics and iron loss effects, has been employed. Furthermore, two different PWM modulation strategies have been considered. The study was conducted for several working conditions, evaluating the impact of CHBMI adoption on the IPMSM performance in terms of improved efficiency and torque ripple reduction.
This paper presents the design, construction and measurements on a transverse flux machine. The lamination concept is designed for easy fabrication and low iron losses. For a good flux guidance and a high magnetic field, electrical sheet is used for the soft magnetic circuit. The design of the machine is performed with a fast semi-analytical calculation and validated by 3D finite element analysis. The calculated quantities are compared with measurements on a prototype. Despite certain deviations, the measurements show good agreement with the calculations for the induced voltage and torque. In terms of efficiency, however, the measurement deviates significantly from the simulation. This is due to the iron losses being calculated much too small, which is evident from the separation of the measured losses.
To guaranty a safe load transfer through adhesively bonded joints, Structural Health Monitoring (SHM) methods that allow for permanent monitoring of the structural bond condition, are becoming more and more important. To meet this increasing demand, a novel approach for SHM of adhesively bonded joints by use of integrated Polymer Optical Fibers (POF) has been demonstrated in previous work. The sensor operating principle is based on strain transfer from the structural adhesive to the integrated POF. This strain transfer leads to a deformation of the POF cross-sectional shape and in that way affects the optical light propagation in the POF.
In the current work, numerical and experimental results are presented into the mechanical behavior of embedded POF in adhesive bulk specimens subjected to tensile loading. Local deformations of both the POF (Asahi Kasei DB 500) and the structural adhesive (3 M Scotch Weld DP410) are evaluated using Digital Image Correlation (DIC). In the loading direction, a linear correlation is shown between strain inside the POF core and strain of the surrounding adhesive. Tests results, as well as fracture analysis, show a highly ductile behavior and failure of the POF cladding material and the interface between the POF core and annular cladding.
We present a robust concept for quasi distributed strain measurement using optical time domain reflectometry (OTDR) in polymer optical fibers (POF). The spatial shifts of discrete reflective events in the OTDR trace are evaluated as reference points. It is shown how such reference reflections can be prepared and which properties can be expected.
In this paper, a flux linkage-based direct model predictive current control approach is presented for small permanent magnet synchronous motor (PMSM) drives. The method aims to minimize the current ripples at steady state by deciding on the optimal switching instant, while exhibiting fast dynamic behavior during transients. To this end, the future trajectory of the stator current is not computed based on the machine inductances or inductance look-up tables, but on the changes of the magnetic flux linkage by utilizing flux linkage maps. As shown, the proposed method can be particularly advantageous for electric drives with a noticeable nonlinearity in terms of saturation and/or cross-coupling effects since it allows for a significantly increased prediction accuracy, which leads to an improved steady-state performance as indicated by the reduced current distortions.
A transformer with variable primary windings for wide input voltage range DC/DC converters is presented. This transformer structure allows three states of the primary winding to be converted by only two individual windings. Based on the evaluations of a two-switch flyback converter, the potential of DC/DC converters with variable structures, the implementation of such a transformer and the advantages and disadvantages are shown and discussed. Real measurement results demonstrate the noticeable increase in efficiency and the reduction in component stress, having a positive influence on the operation of the converter and the component selection during the design process.
According to the current state of the art, adhesively bonded joints cannot be tested completely non-destructively. This is the main motivation to permanently monitor adhesively bonded joints in order to record their structural integrity and - as a result - to ensure safe load transmission. By the use of permanent non-destructive Structural Health Monitoring (SHM) methods, structural damages in the adhesive bond can be detected at an early stage. This paper presents a new method for monitoring the structural integrity of adhesively bonded joints by integrating a Polymer Optical Fiber (POF) into the adhesive layer. The sensor concept is based on a deformation transfer from the adhesive to the POF, which results in a change in the cross-sectional shape of the POF. The cross-sectional shape influences the optical light propagation in the POF, which can be detected by simple optical measuring devices. The paper describes the general principle and first results of investigations on a structural adhesive (3M Scotch-Weld DP 609). The sensor signal is in a good relation to the stress state of the adhesive layer.
Machine learning algorithms are increasingly used in industrial applications for a multitude of use-cases. However, using them in control tasks is a challenge due to real-time requirements and limited resources. In this paper, an implementation scheme for real-time inference of multilayer perceptron (MLP) neural networks on FPGAs is proposed. Design constraints for using MLPs in reinforcement learning agents for motor control applications are derived and accounted for in the implementation. Two MLP architectures are evaluated on an FPGA, and the timing and resource-usage data are reported. The real-time capability of the implementation for motor control applications is investigated for standard control frequencies. It is shown by experimental validation that real-time interference with an area-efficient implementation for motor control applications is achievable. Therefore, the proposed implementation scheme can be applied to deep reinforcement learning controllers with hard real-time requirements.
PMMA polymer optical fibers embedded in semi-structural polyurethane adhesive bonds serve as economical load sensor for structural health monitoring by evaluating load-dependent optical transmission as well as modal distribution measured by a far-field camera. Scaling of sensor quantities by the sensitive fiber length is shown.
Design of a Wide Input Voltage Range Current-Fed DC/DC Converter Within a Reduced Duty-Cycle Range
(2020)
A design of a current-fed push-pull converter for wide input voltage ranges within a reduced duty-cycle range is presented. Based on the converter conversion ratios of three different clamping configurations, the potential of the input clamping is shown analytical, simulative and by measurements. A differentiation is made between the four possible operating modes, which can be distinguished in the control of the semiconductors and the magnetomotive force in the reactor. By optimizing the turn ratios of both transformers, the wide input voltage range capability of the input clamped current-fed push-pull converter was improved, which has been proved by measurements on a real prototype.
According to the current state of the art, adhesively bonded joints cannot be tested completely non-destructively. This is the main motivation to permanently monitor adhesively bonded joints in order to record their structural integrity and - as a result - to ensure safe load transmission. By the us e of permanent non-destructive Structural Health Monitoring (SHM) methods, structural damages in the adhesive bond can be detected at an early stage. This paper presents a new method for monitoring the structural integrity of adhesively bonded joints by integrating a Polymer Optical Fiber (POF) into the adhesive layer. The sensor concept is based on a deformation transfer from the adhesive to the POF, which results in a change in the cross-sectional shape of the POF. The cross-sectional shape influences the optical light propagation in the POF, which can be detected by simple optical measuring devices. The paper describes the general principle and first results of investigations on a structural adhesive (3M Scotch-Weld DP 609). The sensor signal is in a good relation to the stress state of the adhesive layer.
Design Concept of a Wound Field Transverse Flux Machine using Soft Magnetic Composite Claw-Poles
(2020)
This paper presents the machine concept of a wound field transverse flux machine (WFTFM). In contrast to permanent magnet transverse flux machines (PMTFM), here the magneto motive force (mmf) of the rotor is generated by a current. The magnetic circuit of the WFTFM is made of soft magnetic composite (SMC) and is designed as claw-poles. Thus the magnetic circuit consists of only a few components. Together with the simple ring coils in stator and rotor, the WFTFM offers advantages in the production of electrical machines. The basic structure of the machine and a first design is described here. The results generated by numerical three-dimensional finite element analysis (FEA) are compared with those of conventional machines.
This article presents a flux linkage-based direct model predictive current control approach that achieves favorable performance both during steady-state and transient operation. The former is achieved by computing the optimal time instants at which a new switch position is applied to the converter. To this end, the future current behavior is not computed based on the machine inductances or inductance look-up tables; instead, flux linkage maps are utilized to predict the trajectory of the magnetic flux linkage, and subsequently of the current. This is advantageous for electric drives with noticeable magnetic nonlinearity in terms of saturation and/or cross-coupling effects. Hence, by using flux linkage maps in the prediction process, the evolution of the stator current can be calculated more accurately, enabling the controller to make better switching decisions. Moreover, the discussed predictive controller exhibits excellent dynamic performance owing to its direct control nature, i.e., the control and modulation tasks are performed in one computational stage rendering a dedicated modulation stage redundant. Three different drive systems based on permanent magnet synchronous motors are examined to demonstrate the effectiveness of the presented control approach.
n this paper a semi-analytical calculation of a transverse flux machine is presented. First the design of the machine is explained, then the semi-analytical calculation, which is finally compared with a numerical 3D finite element analysis (FEA). The semi-analytical approach is based on a magnetic equivalent circuit, which is solved by nodal analysis and the Broyden-Method. The air gap of the machine is transformed into the magnetic equivalent circuit by conformal mapping using the Schwarz-Christoffel transformation. The comparison to numerical simulation shows that the approach gives good results and is sufficiently accurate for a rough design of the machine.
Results from field measurement campaigns for structural health monitoring (SHM) at giant mine heaps by optical time domain reflectometry (OTDR) in polymer optical fibers (POF) are presented. Polymer geogrids built for soil reinforcement are fitted with POF for strain sensing as part of a geosynthetic sealing system designed to protect the heap from infiltration of surface water. Strain is detected by a local increase of backscatter. Measurements on eight sensor lines have been performed over a time period of six months to monitor the system behavior and potential development of or cracks within the underlying base of a sealing system. Results show the usability of this technology for strain sensing and SHM in such a harsh environment. Challenges still exist in the quantitative evaluation of the fiber sensor data due to cross sensitivity to fiber bending and lateral pressure.
Enhanced Flexible Algorithm for the Optimization of Slot Filling Factors in Electrical Machines
(2020)
The continuous development in the field of industrial automation and electric mobility has led to the need for more efficient electrical machines with a high power density. The improvement of electrical machines’ slot filling factors is one of the measures to satisfy these requirements. In recent years, this topic has aroused greater interest in the industrial sector, since the evolution of the winding technological manufacturing processes allows an economically sustainable realization of ordered winding arrangements, rather than random ones. Moreover, the manufacture of electrical machines’ windings must be preceded by an accurate design phase in which it is possible to evaluate the maximum slot filling factor obtainable for a given wire shape and for its dimensions. For this purpose, this paper presents an algorithmic approach for the evaluation of maximum slot filling factors in electrical machines under an ideal geometric premise. In particular, this algorithm has a greater degree of flexibility with respect to the algorithm approaches found in the literature, since the study has been extended to round, rectangular and hexagonal wire sections. Furthermore, the slot filling factor calculation was carried out both for standard and non-standard slots. The algorithmic approach proposed can be considered as an additional useful tool for the fast design of electrical machine windings.
This paper presents two rapid control prototyping (RCP) use cases facilitated by the open-source platform UltraZohm. The openly available UltraZohm development frame-
work eases the transition from simulation to the test bench. The framework offers the integration of automatic code generation for field-programmable gate arrays (FPGAs), either by using Simulink models based on the HDL Coder, or by synthesizing C++ code into VHDL via the Vivado high-level synthesis tool. The first use case focuses on the implementation details of an on-chip controller-in-the-loop setup, where a permanent magnetsynchronous machine is emulated in the FPGA with a sampling frequency of 2 MHz. The second use case presents an efficient real-time implemen-tation of the sphere decoding algorithm employed to solve the long-horizon finite control set model predictive control problem for a three-level neutral point clamped inverter driving an induction machine. Experimental results based on a small-scale prototype confirm that the algorithm can be executed in real time on the FPGA, with an execution time of a few tens of microseconds. Both use cases highlight the benefits of using a high-performance RCP platform for research in power electronics and their control.
In recent decades, adhesive bonding technology has become increasingly important in all industrial sectors, for example in the aerospace industry, the automotive industry or the construction industry. This is accompanied by an increased need for monitoring of adhesive bonds, especially for load-bearing, structural joints. In order to detect a possible failure at an early stage, this work is investigating a cost-effective sensor principle based on embedding of a polymer optical fiber (POF) into the adhesive layer. The strain and stress behavior of the adhesive bond are transferred to the POF and change its light-guiding properties. In the presented work, different light coupling conditions into the fiber (full excitation and angle-selective excitation) and different measurable quantities of the transmitted light decoupled from the fiber (photocurrent and far-field) are studied, to find an optimum sensor performance. The combination of a structural polyurethane adhesive with commercially available POF is investigated. The results show a high potential of the method for simple photocurrent measurement (transmission loss of 8% by half of maximum load) and an even more sensitive sensor effect for mode-dependent light power measurement.
This paper provides an accurate and high-bandwidth current measurement method, using a differential, PCB integrated Rogowski coil. This measurement is ideal for
switching characterization of wide-bandgap semiconductors, which are progressively improving switching speeds of power electronic circuits and require a PCB design with low parasitic inductance. A design workflow for system integration of a differential Rogowski coil, including the necessary signal processing circuits onto a printed circuit board is provided. Different parasitic effects have been analyzed, and an amplifier topology for high bandwidth and superior Common Mode rejection is presented. The calculations are verified by simulation and measurements.
An optical wavelength tuning range up to 12 nm has been achieved within 10 μs, using VCSELs operating in the near infrared. The range has been measured with an interferometric setup and an optical spectrum analyzer respectively. Potentially, low-cost sensor systems based on tunable diode laser absorption spectroscopy or coherent optical frequency domain reflectometry could be realized, achieving sub-mm two-point range resolution or even better single-point range precision within a few microseconds for a single measurement.
The Interior Permanent Magnet Synchronous machine (IPMSM) conventional mathematical model is generally employed to investigate and simulate the IPMSM
control and drive system behaviour. However, magnetic nonlinearities and spatial harmonics have a substantial influence on the IPMSM electromagnetic behaviour and
performances. In order to simulate the IPMSM real electromagnetic behaviour, this paper describes an enhanced mathematical model that takes into account the
saturation, cross-coupling and spatial harmonics effects. This model has been implemented in Matlab®/Simulink environment where the electric and magnetic parameters are derived from FEA investigations and implemented by the use of lookup tables. The high fidelity of the proposed IPMSM Simulink model is validated by the results of the FEA investigations carried out.
Abstract. A wavelength tuning range up to 12 nm has been achieved
over 12 µs pump current pulses within a usable time of 10 µs applied to VCSELs operating in the near infrared around 1550 nm. The instantaneous optical frequency shift has been measured with an interferometric setup; the overall tuning range has then been verified with an optical spectrum analyzer. The repetition rate of the current pulses can
be as high as 20 kHz with almost no influence on the sweep parameters. These
results can be used for fast spectroscopic gas analysis or for rapid interferometric swept-source distance sensors.
Development of a Two In One Motor System as a new Vehicle Energy Concept for Next Generation Car
(2020)
The illumination of registration plates poses challenges for lighting technology. To achieve the wide and steep angles required for homogeneous illumination of the license plate, optics are needed to refract and reflect light. In this work, registration plate lamps with different components are designed. After the construction, the concepts are tested for their limits in terms of position and manufacturability. The
entire work is carried out at the company CREAT GmbH in Ingolstadt. All developments in the field of registration plate lighting are subject to the UNECE and country-specific regulations, which must be considered in the development of the lights.[1] Some vehicles currently available on the automotive market are measured to classify and compare the different lamp systems. From the average values, the lamps are designed. Adjustments are repeatedly made to the lighting device to achieve the most
homogeneous illumination of the registration plate. As soon as the lights meet the legal requirements, the geometric limits of the lighting device are defined in relation to the plate. As there are different polymers to produce optics, these are simulated with their refractive indices and tested for their effects on the light image.
The objective of this study was to develop an experimental framework that allows research on whether the combined use of a virtual reality (VR) driving simulator, electroencephalography signals collected during driving tests and designed attentional paradigms could be applied to assess the performance of affective warning sounds for re-channelling driver’s attention in certain driving situations. Three VR driving scenarios with different stimuli and two driving tasks were designed and implemented. Acquisition of driver’s physiological data and behavioural metrics were integrated to be gathered synchronously. In addition, an experimental protocol was designed for the assessment of the impact of affective warning sounds. The technical feasibility of the framework was evaluated with the results showing that the proposed framework enables the data acquisition and analysis for a variety of warning stimuli. After successful technical deployment, a study with experimental subjects will follow to evaluate the effectiveness of affective warning sounds.
This study aims to compare two different implementations of speech emotion recognition models.The emphasis is directed towards evaluating their efficacy in capturing and characterizing dialogues
portrayed by actors within a film scene to create suitable musical intervals. The goal of the overarching research intends to derive indications to enhance the compositional process of film scores by recognizing the emotion in a particular scene. Based on established deep learning models, the study delves into the exploration of two distinct emotion classification metrics: The Six Emotion Prediction and the Valence/Arousal/Dominance Prediction. To facilitate a comparative analysis, a preliminary study an a following survey is deployed. The preliminary study confirms a significant difference in the generated MIDI data. For this reason, a survey is essential to detect the better fitting algorithm. Participants are tasked to rate the affective suitability of eight generated interval sequences to the corresponding film scenes. The Suitability is verified quantitatively using a bidirectional rating system. Both model assessments are conducted within a uniform sound design, thus ensuring unbiased conditions for evaluation. Upon a thorough examination of our extensive analysis, a preference for method A becomes increasingly evident.
Infradar-Localization: single-chip infrared- and radar-based Monte Carlo localization. This paper proposes a novel approach for indoor robot localization that leverages a fusion of information from single-chip infrared (Time-of-Flight) and radar sensors. The aim of our research is the development of a cost-effective and lightweight system that can achieve high-precision robot localization. Unlike traditional localization methods based on LiDARs or cameras, our proposed system uses single-chip infrared and radar sensors to overcome the limitations of high cost and bulky hardware. Specifically, we employ a Doppler radar-based velocity motion model for the estimation of the robot's ego-motion, eliminating the need for additional sensors such as IMU or wheel encoders. Next, we describe a hybrid sensor model for single-chip infrared and radar sensors that provides robust and accurate environmental perception with dynamic outlier removal. Finally, we integrate these components into a Monte Carlo localization framework to generate accurate real-time estimation of the robot's position and orientation. This is the first time a single-chip infrared and radar fusion based framework has been applied to robot localization, to the best of our knowledge. Through a comprehensive experimental evaluation, we demonstrate the system's high accuracy and efficiency, achieving an average localization error of 9 cm in diverse indoor environments. This remarkable performance, combined with the low-cost and lightweight nature of our proposed solution, positions it as a highly promising alternative for a wide range of applications, including robotics, smart homes, and autonomous vehicles. The significant advancements of this novel approach offer vast potential to revolutionize the field of localization, enabling more precise and cost-effective navigation systems.
Das Ziel der vorliegenden Bachelorarbeit ist die Entwicklung eines Lehrsystems, bestehend aus einer Lasteinheit. Dabei setzt sich die Lasteinheit aus einer Motor-Frequenzumrichter-Kombination zusammen.Es ist sind Steuerprogramme zu entwickeln, die Funktionen, wie eine Lastsimulation, bieten. Zudem ist die Entwicklung einer GUI vorgesehen, die zur Beobachtung und Steuerung dient. Die Programmentwicklung findet im TIA-Portal, in STARTER und in LabVIEW statt. Neben der Programmentwicklung ist eine abschließende Antriebsauslegung durchzuführen. Für die erfolgreiche Programmentwicklung wurde im ersten Schritt ein Programm im TIA-Portal implementiert, wobei dies nur grobe Züge des Endprogramms enthielt und für erste Tests zuständig war. Eine Reglerparametrierung wurde mithilfe des TIA-Programms und des Programms STARTER durchgeführt. Im Anschluss wurden die Programm-teile nach LabVIEW portiert und das Hauptprogramm bis zur endgültigen Funktionsfähigkeit erweitert. Die Antriebsauslegung wurde mithilfe von entsprechend großen Lasten und Temperaturaufnahmen durchgeführt. Das Ergebnis ist ein lauffähiges LabVIEW-Programm mit GUI, das Lasten simulieren und Bremsungen von gekoppelten Motoren durch-führen kann. Die Bremsung wurde schließlich für die größtmögliche Leistungsentnahme und Antriebsauslegung eingesetzt. Der Antrieb kam bisher nicht zum Einsatz.
Deep Learning basierte Segmentierung und Transformation von Spike-Rauschen in der MR-Bildgebung
(2023)
Die Magnetresonanztomographie (MRT) ist ein bildgebendes Diagnoseverfahren, das auf starken Magnetfeldern und sensiblen Detektoren basiert. Es kann zu Spike-Rauschen kommen, das die Bildqualität negativ beeinflusst. In dieser Arbeit wird untersucht, ob neuronale Netzwerke das Spike-Rauschen reduzieren können, um die Bildqualität zu verbessern. Dazu wird eine Bildverarbeitungspipeline entworfen, bestehend aus den Teilbereichen Detektion, Segmentierung und Transformation. Verschiedene neuronale Netzarchitekturen werden für jeden Teilbereich ausgewählt und auf Basis verschiedener Daten trainiert. Die Ergebnisse zeigen, dass die Detektion und Segmentierung basierend auf der L1-Norm die besten Ergebnisse liefern. Es werden bestimmte Netzwerkarchitekturen ausgewählt, um die Transformation durchzuführen. Die gesamte Pipeline reduziert das Rauschen erheblich, aber weitere Tests sind erforderlich, um die Robustheit der Implementierung sicherzustellen.
Weiterentwicklung eines gasbetriebenen Wirbelschicht-Sinterreaktor für kleinste Keramikbauteile
(2023)
Diese Arbeit optimiert einen gasbetriebenen Wirbelschicht-Sinterreaktor für kleinste Keramikbauteile. Der Reaktor nutzt das Prinzip der Wirbelschicht, um die zu sinternden keramischen Bauteile in der Schwebe zu halten und ermöglicht so eine erhebliche Beschleunigung der Prozesszeit im Vergleich zu konventionellen Brennöfen. Ziel dieser Arbeit war es, den bestehenden Forschungs-reaktor zu optimieren, indem der Brenner neu ausgerichtet, ein neues konisches Brennrohr konstruiert und eine neue Vorrichtung zur Probenentnahme entwickelt wurde. Die Anlage wurde erfolgreich verbessert und ermöglicht nun den Schwebezustand der Bauteile sowie eine schnellere Aufheizung. Es wurde auch eine Vorrichtung zur Probenentnahme konstruiert und die Bauteile auf Maßhaltigkeit und Bildung von Agglomeraten untersucht. Allerdings muss das Material des Brennrohrs ersetzt werden. Insgesamt konnte gezeigt werden, dass die Anlage erfolgreich verbessert wurde und das Sintern der Bauteile nun möglich ist.
Capability of scheduled maintenance to detect electromagnetic and lightning protection degradation
(2022)
Due to the growing use of low-conductivity composite materials for airframes and skin, the shielding effectiveness of aircraft has been weakened within recent years. As a result, the importance of electromagnetic hazards and associated effects on flight safety have increased dramatically. Especially high intensity electromagnetic fields are likely to interfere with sensitive avionic systems, while lightning strikes produce high-energetic charges and currents which might cause physical damages and induced transients on onboard wirings and equipment-internal circuits. To ensure safe flight and landing conditions, additional protection measures are required to be introduced in aircraft design. However, aging and degradation effects of mentioned electromagnetic and lightning protection features can't be avoided, thus, specific scheduled maintenance actions within appropriate intervals must be defined during certification process to retain every single aircraft in a serviceable condition. As there's a lack of database to validate expected preliminary degradation and aging behavior until the first scheduled inspection, most maintenance definitions just rely on in-service and maintenance experience of similar aicraft.
Hence, within this thesis, current regulations and practical implementations of lightning and electromagnetic protection on Airbus rotorcraft shall be investigated in order to perform 3D simulations for determination of the correlation of electromagnetic protection failure and wiring-induced transients. As a final aim, maintenance improvements for minimization of adverse degradation impact on helicopter safety can be achieved.
The company Plusoptix GmbH develops and sells medical devices to measure the refraction of infants. For the implementation of these functionalities, the necessary hardware and software is integrated in the apparatus. In addition, an individual OS was developed to perform specific tasks efficiently and quickly. In order to continuously close security gaps and meet requirements, the operating system must constantly be up to date. This activity is realized by the construction of the embedded Linux with the help of the internal NBS. Nightly building of the OS enables testing of changed software code or integrated modules. However, due to the steadily growing project tree of Plusoptix GmbH, the system increasingly shows problem areas. This includes aspects of administration and information overview. In addition, new functionalities such as continuous integration are desired to ensure the greatest possible SQA. Based on these features, the master thesis includes the development of a CIS to address the emerging requirements. Additionally, all previous process cycles of the old system should be integrable. For this purpose, a catalog of requirements for the new system must first be designed and specified. With the framework conditions defined, a targeted search can then be made for software to solve the existing problems. These must be evaluated in order to find the most efficient solution approach. In the end, a system is to be established that replaces the NBS andmeets current and future requirements.
The time available to bring a new product to market is getting shorter and shorter. To keep up, virtual prototypes have become an essential part in the product development cycle. We wanted to create a configuration interface to allow for a fast and easy configuration of said prototypes. We want to evaluate how the created interface performs when used with valid or invalid data and how accurately the requirements for the software were met. As a basis for this analysis we have created an approach to develop a user interface (UI) based on the existing Vivifly application and have extended it with some functionality. We used the approach to perform a set of software tests to evaluate its functionality. The tests focus on the behaviour of the UI and its output, when the user interacts with it. This is done by either testing the UI as it was intended or with inputs, that usually would not be entered. The results of the software tests show that although a large part of the requirements have been implemented, some special cases have not yet been considered and need additional information. Out of the 22 test cases seven did encounter a problem while performing them.
Ziel dieser Bachelorarbeit ist ein ganzes Teilprojekt in sich selbst abzuwickeln, um Datensicherung zur Daten- und Programmsicherung aller Steuerungen der Anlagen bei Firma KOSH durchzuführen. Die verschiedenen Arten von Steuerungen und HMIs, die in Betrieb sind, sind zu analysieren und dazu erforderliche Software und Hardware, die zur Durchführung der Datensicherheit notwendig ist, muss festgelegt und für den Einsatz organisiert werden. Die Datensicherungen sollen zuerst lokal auf einem Laptop und später im Cloud-System von Version Dog für eine spätere Verwendung im Falle von Schäden oder Ausfall an der SPS gespeichert werden. Die Entwicklung und Umsetzung des Projektes soll mit verschiedenen internen und externen Kollegen geplant werden. Die Möglichkeit von Ersatzteilen als Backup oder eine zukünftige Umstellung auf moderne Steuerungen, wie neue Generation von Siemens oder Bosch Steuerungen anstelle der alten Bosch Rexroth-Steuerungen ist zu berücksichtigen. Daher ist eine Kostenabschätzung für die Möglichkeiten und Herstelleroptionen für einen Umstieg auf neue Modelle oder das Vorhalten von Ersatzteilen als Backup zu recherchieren und zu analysieren.
Within the scope of this dissertation a program shall be developed to automatically retrace a given operational cycle of a train set. The program shall be programmed with „Python“. At least two rail vehicles are linked together. The profile contains the setpoint values of the speed as well as the setpoint values of the traction force of both rail vehicles. The last ones are transferred into the control units of both vehicles. A controller shall be implemented to regulate the real value of the speed of the train set when there is a difference to the setpoint value. The real values of speed and traction force of both vehicles as well as the setpoint values shall be saved in a file.
Furthermore, a mode shall be implemented to continuously settle an operating point for the train set. This operating point is defined by a setpoint value of the traction force of the first vehicle and a setpoint value of the speed of the train set. The results of the executed operational cycles show that an automatical retracing is well possible. The accuracy of the operational cycle depends much on the accuracy of the calculated given profile of the setpoint values of the traction force of both vehicles. Interferences are quickly and safely compensated. It is possible to steadly settle any operating point for the train set. Therefore this mode is suitible for approaching all possible operating points in a simple and cost effective way.
The aim of this bachelor thesis is the analysis of the performance of motion algorithms to increase the productivity of industrial robots.
The robot which is therefor used is the COMAU NJ60-2.2 robot, which is controlled by the SINUMERIK 840D sl machine tool control. The Laser Tracker Hexagon Leica Absolute Tracker AT960-SR is used as the measuring instrument. To assess the performance, motion programs are programmed, each of which is executed comparatively with the CC_ROCO compensation cycle activated and deactivated. The test strategy is based on the ISO 9283 standard. Measurements are made of the path characteristics and of the settling performance. Special attention is paid to the differences that result from the use of the compensation cycle. The measurements are initially carried out on the digital twin of the SINUMERIK ONE controller and following on the real robot.
The results of the measurements show that the use of the extension function does not have any negative decisive consequences on the path accuracy or the transient response, but it positively influences the duration of time.
Um auch zukünftig die steigenden Datenraten und die damit verbundene Kanalbandbreite in optischen Systemen der Telekommunikationsbranche zur Verfügung zu stellen, sind neue Ansätze bei der Datenübertragung notwendig. In dieser Arbeit wird ein Verfahren untersucht, dass die breitbandige, digitale Datenübertragung über einen solchen neuen Ansatz, den substratintegrierten Wellenleiter (SIW), ermöglicht.
Zur Untersuchung war es zunächst notwendig, die Anforderungen an das Verfahren, anhand der gegebenen Rahmenbedingungen, festzustellen. Für das anschließend erstellte Konzept wurde eine Marktrecherche zu den zur Umsetzung notwendigen Komponenten durchgeführt. Anhand dieser Auswahl konnte mittels einer Transientensimulation die allgemeine Tauglichkeit des Verfahrens nachgewiesen werden, noch bevor es in einen Schaltplan überführt wurde. Das aus dem Schaltplan erzeugte Layout wurde zur Beseitigung etwaiger Störstellen mit einem 3D Feldsimulator untersucht und steht zur Freigabe für eine Leiterplattenproduktion bereit. Das Ergebnis dieser Arbeit ist ein untersuchtes und in die Praxis umsetzbares Verfahren, mit dem ein breitbandiges, digitales Signal über einen substratintegrierten Wellenleiter übertragen werden kann. Jedoch eignet sich die Implementierung des Verfahrens nicht für die direkte Umsetzung in zukünftigen Projekten. Dies liegt zum einen am erhöhten Schaltungs-aufwand gegenüber den aktuell verwendeten Verfahren und zum anderen am Mangel geeigneter, momentan auf dem Markt verfügbarer Komponenten, die die benötigte Bandbreite zur Verfügung stellen.
Ziel der Bachelorarbeit war es, die zwei Videokompressionsverfahren JPEG und H.264 miteinander zu vergleichen. Dazu wurden diese Verfahren unter den Betrachtungspunkten der Latenz, der Bildqualität und der Datenübertragungsrate analysiert und die Ergebnisse gegenübergestellt. Dabei wurden zunächst die Messergebnisse untereinander bewertet und eine weiterführende Abwägung im Hinblick des Einsatzgebietes in einem Embedded-System für den Bahnbetrieb durchgeführt. Als Ergebnis konnte sich die H.264 Codierung in den Vergleichspunkten gegenüber JPEG durchsetzen. Weitergehend wurden die gewonnenen Ergebnisse auf ein bahntechnisches Hard- und Softwaresystem angewendet und dort ein Prototyp zur Darstellung von IP-Streams entwickelt. Zur Entwicklung wurden die Programmiersprache C++ sowie das GStreamer Framework eingesetzt.
In der folgenden Bachelorthesis werden Warn- und Hinweistöne erstellt, welche auf Basis von natürlichen Klängen aufgenommen und in weiteren Schritten bearbeitet werden. Dazu wird vor allem eine Studie analysiert, die sich mit den affektiven Klangwahrnehmungen des menschlichen Bewusstseins auseinandergesetzt hat. Die natürlichen Klänge, die dazu aufgenommen werden, sind in dieser Studie in einem
zweidimensionalen Koordinatensystem verteilt und in vier Quadranten aufgeteilt. Die Bearbeitung der Töne zeigt einen tiefen Einblick in die Audio Produktion. So werden unter anderem Praktiken erläutert, wie Audio Signale qualitativ hochwertig klingen können, ohne den Charakter zu verfremden. Außerdem werden Methoden der West Coast Synthese genutzt, um ein umfangreiches Sound Design anzuwenden. Die West Coast
Synthese ist ebenfalls ein Schwerpunkt dieser Arbeit. Es werden grundlegende Charakterzüge des Buchla 208c Synthesizers erläutert, in dem die einzelnen Module umfangreich erklärt werden. Ebenso wird die digitale Reaktor 6 Variante des Soft- und Hardware Herstellers Native Instruments mit dem analogen Vorbild verglichen.
Damit ein Elektromotor exakt geregelt werden kann, muss die aktuelle Rotorlage erfasst werden. Hierzu werden oftmals Reluktanzresolver eingesetzt. Gegenstand der Arbeit ist die Konzepterstellung, Detailauslegung und Konstruktion eines Prüfstands, mit dem die Auswertung solcher Resolver optimiert werden kann. Dazu sollen die Resolver in den Prüfstand eingesetzt und per Software gesteuert in Rotation versetzt werden können. Ein, in den Prüfstand integrierter, optischer Drehgeber liefert ein Referenzsignal, mit dem die berechnete Winkellage kontrolliert werden kann. Zur Planung werden ein vorhandener Prüfstand und daraus hervorgehendes Wissen aus der Abteilung herangezogen. Daraus wird im Anschluss die Anforderungsliste abgeleitet. Um effizienter Lösungskonzepte aufstellen zu können, wird der Prüfstand in zwei Funktionsgruppen aufgeteilt. Nach der technisch-wirtschaftlichen Bewertung werden beide Funktionsgruppen wieder zu einem Gesamtkonzept zusammengefügt. In der Entwurfsphase werden nach dem Gesamtkonzept und der Anforderungsliste Zukaufteile ausgewählt. Einzelteile werden in der CAD-Software SolidWorks konstruiert. Zeitgleich werden nötige Nachweise über und für diese Teile erbracht. Somit wird sichergestellt, dass die Zukaufteile den Montagevorgaben der Hersteller, aber auch der Anforderungsliste, entsprechen. Einzelteilübergreifende Nachweise werden mit den erstellten Baugruppen zusammen erbracht. Zum Ende dieser Arbeit wird überprüft, ob alle Anforderungen vollständig und korrekt umgesetzt sind. In diesem Zusammenhang werden die Anforderungen mit Nachweisen zur Umsetzung oder der entsprechenden Verifikationen verknüpft.
In dieser Arbeit wird die Rezyklierbarkeit des Kunststoffpulvers Polyamid 12 für den SLS-Druck untersucht. Durch den hohen Pulververbrauch und den geringen Anteil an wiederverwendbarem Pulver ist der SLS-Druck teuer und nicht nachhaltig. Daher soll der Anteil an wiederverwendbarem Pulver erhöht und die Auswirkungen auf das Material betrachtet werden. Hierfür werden Prüfkörper mit verschiedenen Pulvermischungsverhältnissen hergestellt, Zugversuche und Härtemessungen durchgeführt und die Ergebnisse verglichen. Anschließend werden Kennlinien erstellt, welche einen Zusammenhang zwischen dem Neupulveranteil und den Materialkennwerten aufzeigen. Ziel hierbei ist es für jede Anwendung ein spezifisches Mischungsverhältnis bestimmen zu können, bei dem die Materialkennwerte die Anforderungen der Anwendung erfüllen und gleichzeitig möglichst wenig Neupulver verwendet wird.
Ziel dieser Arbeit war die Entwicklung der Steuerung für ein Thorax-Phantom zur Nachbildung der menschlichen Atembewegung. Die Aktorikkomponenten des Phantoms bestanden dabei ausschließlich aus Formgedächtnisdrähten. Mit dem Phantom sollte es möglich sein, neu entwickelte und bestehende Gating-Systeme in einem Atemfrequenzbereich von 0,2 Hz bis 1,2 Hz miteinander zu vergleichen. Hierfür wurde zur Nachbildung der Atemhilfsmuskulatur im Rücken ein künstlicher Muskel
entwickelt, der mit einer Temperatur- und Winkelmessung auf sein temperaturabhängiges Kontraktionsverhalten untersucht wurde. Dadurch konnte der optimale Arbeitspunkt für die Steuerung des künstlichen Muskels ermittelt werden. Für die Steuerung der Atembewegung von Brust
und Bauch wurden Tests an einem bestehenden Gating-System durchgeführt. Es zeigte sich, dass das Thorax-Phantom die Atem-bewegungen im unteren Atemfrequenzbereich erfolgreich nachbilden kann. Bei höheren Atemfrequenzen nahm die Qualität des Atemsignals
bei den durchgeführten Tests, abhängig vom Gating-System, deutlich ab. Ein abschließender Test durchgeführt mit einem bestehenden Gating-System an einem Computertomographen war erfolgreich.