Mechatronics
Refine
Document Type
- Master's Thesis (25)
Has Fulltext
- yes (25)
Is part of the Bibliography
- no (25)
Keywords
- Machine learning (2)
- Robotik (2)
- 5G (1)
- 6DoF pose estimation (1)
- AI on the Edge (1)
- AWG (1)
- Acceleo (1)
- Blockheizkraftwerk (BHKW) (1)
- Bounding Box (1)
- CFD (1)
This thesis focuses on implementing and testing communication over a private 5G standalone network in an industrial environment, with a specific emphasis on communication between two articulated robots. The main objective is to examine machine-to-machine communication behavior in various test scenarios. Initially, the 5G core and radio access network components are described, along with their associated interfaces, to establish foundational knowledge. Subsequently, a use case involving two articulated robots is implemented, and essential metrics are defined for testing, including round-trip time, packet and inter-packet delay, and packet error rate. The tests investigate the impact of 5G quality of service, packet size, and transmission interval on communication between the robots, focusing on the effects of network traffic. The results highlight the significance of prioritizing network resources based on the assigned quality of service identifier (5QI), demonstrate the influence of packet sizes on communication performance, and underscore the importance of transmission intervals for automation purposes. Additionally, the study examines how network disturbances influence the movements of a robot controlled via 5G, establishing a direct relationship between network metrics and the resulting deviations in the robot’s trajectory. The work concludes that while machine-to-machine communication can be successfully implemented with 5G SA, tradeoffs must be carefully considered, especially concerning packet error rate, and emphasizes the importance of understanding the required resources before implementation to ensure feasibility. Future research directions include investigating network slicing, secure remote control of robots, and exploring the use of higher frequency bands. The study highlights the significance of aligning theoretical standards with practical implementation options in the evolving landscape of 5G Networks.
Medizinische Verpackungen werden in der Industrie häufig mittels thermischen Siegelns verschlossen. Um eine kontinuierliche Qualitätsprüfung zu ermöglichen, soll in dieser Arbeit untersucht werden, ob es möglich ist, mittels Infrarotkamera, anhand der sich ausbildenden Wärmesignatur, fehlerhafte Teile zu erkennen. Dabei teilt sich die Forschungsfrage in zwei Teile. Im ersten Teil wird analysiert was zu beachten ist, um eine ideale Auswertung zu ermöglichen. Der zweite Teil der Forschungsfrage untersucht, welche Wärmesignatur sich bei fehlerhaften Teilen ausbildet. Im ersten Teil der Forschungsfrage wird mittels Modellierung des Siegelprozesses und der nachfolgenden Abkühlung, sowie eines späteren Versuchs analysiert, wie die Kamera am besten positioniert werden muss, um das beste Eingangssignal zu erhalten. Im zweiten Teil werden in verschiedenen Versuchsreihen Fehler provoziert und anschließend die Unter-schiede der Wärmesignatur ausgewertet. Anhand der Modellierung und der Durchführung von Versuchen zeigt sich, dass eine Siegelung am besten 1-2s nach dem Siegelende ausgewertet werden kann. Die weitere Untersuchung zeigt, dass große Fehler zwar gut erkannt, kleinere aber eher nicht mehr zuverlässig erkannt werden können.
The Fast Average Current Mode control methodology is a novel method for the implementation of a current compensator in a switched-mode power supply. It does not require compensation against sub-harmonic instability and is inductor independent. In this work, the digital implementation of this topology is compared against an analog implementation using simulation. Additionally, a hardware prototype is created to validate the digital simulation's results. In a Simulink environment, parameters of the digital implementation, such as the digital-to-analog converter resolutions and the delay counter frequency are varied to research their impact on system performance. The simulations show that a digital current compensator has similar performance as an analog implementation when designed tailored to the application. When evaluating the whole control loop the digital system is inferior due to added delays caused by digital to analog conversion. By operating the Buck converter hardware implementation as a current source, the functionality of the current mode control implementation in a FPGA was proven. Voltage control cannot be validated due to hardware issues. Due to the successful simulation of the source code with a mixed signal model of the converter, it can be assumed that it is functional. Apart from performance, a digital implementation shows many benefits compared to an analog solution, such as configurability of control parameters and easy compensation of component variations and aging.
The advent of autonomous and self-driving cranes represents a significant advancement in industrial automation. One critical prerequisites for achieving this long-term goal is the accurate and reliable detection of tools guided by ropes in real-world environments. Since the tool is suspended by ropes, the tool pose cannot be controlled directly. This master’s thesis addresses the challenges of pose estimation for rope-guided tools using point cloud measurements. The proposed algorithm utilizes constraints imposed by the crane kinematics and information extracted during the segmentation process to efficiently infer the pose of the hook, therefore enabling the use of the pose for decision making in real-time critical applications. RANSAC (Random Sample and Consensus) is deployed in the segmentation process to extract geometric primitives from the point cloud which represent the ropes and distinctive parts of the tool. Since the point cloud is often to sparse for feature matching a bounding box is used to estimate the initial position of the tool. Two different methods are presented to improve the initial pose. A computationally expensive method with a high level of confidence, integrating the ICP (Iterative Closest Point) algorithm is used as a benchmark. A linear Kalman filter is used in the second method which is real-time capable. The benchmark is then used to evaluate the real-time capable approach. The core contributions of this research lie in the innovative utilization of bounding boxes for pose estimation. The findings and methodologies presented herein constitute an advancement towards the realization of autonomous and self-driving cranes.
IEC 61499 ist ein Standard für die verteilte Automatisierung. Damit lassen sich Systeme designen, die eine Vielzahl von Knoten vernetzen können. Dadurch lassen sich komplexe Aufgaben in der Industrie leichter bewältigen. Um dies zu ermöglichen, müssen alle Systembestandteile miteinander kommunizieren können. Ein solches Kommunikationsnetzwerk kann dann schnell sehr komplex werden und damit schwer zu verwalten sein. Wenn es darum geht, an viele Teilnehmer Daten zu verteilen, hat sich das Publish-Subscribe Kommunikationsmuster bewährt.
ZeroMQ ist eine Bibliothek, mit der über Sockets unter anderem solche Publish-Subscribe Kommunikationsnetzwerke realisiert werden können. Sie baut auf dem ZeroMQ Message Transport Protocol (ZMTP) auf. Dabei ist die Verwendung unwesentlich komplexer als mit Berkeley Sockets.
4DIAC/Forte bietet ein Framework um Applikationen nach IEC 61499 zu erstellen. In dieser Thesis wird 4DIAC/Forte und ZeroMQ vorgestellt. Es wird die Struktur einer Kopplungsschicht zwischen Forte und ZeroMQ präsentiert und implementiert. Anschließend werden Messungen von Latenz und Throughput durchgeführt, um die Performance zu evaluieren.
In Forte sind traditionelle Sockets für die Kommunikation bereits implementiert. Sie unterstützen das Client-Server Muster und Publish-Subscribe mittels UDP Multicast. Mit diesen Lösungen werden die Messungen ebenfalls durchgeführt um einen Vergleich mit ZeroMQ aufzustellen. Es werden auch vorhandene Daten für DDS herangezogen. Die Ergebnisse zeigen, dass sich ZeroMQ für die Kommunikation in Forte eignet und dabei hilft, die Komplexität zu reduzieren und die Handhabung zu vereinfachen.
The detection of glucose is an essential part of diabetes management and can help to prevent secondary diseases, that can occur as a result of diabetes. For this reason, it is important to improve the current glucose monitoring by developing novel sensors with high efficiency, low cost and compact design. The use of microelectrodes with interdigitated array (IDA) structures reduces the total detector size while providing benefits such as large currents, high sensitivity, and fast response. The aim of this thesis is to develop a novel sensor based on platinum interdigitated array (IDA) electrodes and to investigate which method is most effective for the detection of glucose. This work is divided into two parts. The first part is focused on the design and the fabrication of the sensor chips. The second part is concerned with the electrochemical characterisation of the sensors. Two distinct sensor designs are created, each consisting of a four-electrode system arranged as an interdigitated array. For the fabrication of the sensors, two different manufacturing processes are used. A lift-off process is used to fabricate the 2 μm-Gap sensor chips, whereas a lift-off free process is applied to produce the nanogap sensor chips. The electrochemical characterisation of both sensor chips is achieved by the immobilisation of the enzyme glucose oxidase (GOx) on the electrode surface. This thesis investigates the immobilisation of GOx by reduction of diazonium salts and the direct immobilisation of GOx by cyclic voltammetry. As a result of this work, it has been demonstrated that glucose detection by reduction of diazonium salts is error-prone due to modification with a multi-step procedure and is not suitable for our sensors based on platinum IDA electrodes. The direct immobilisation of GOx by cyclic voltammetry, by contrast, demonstrates the successful detection of glucose. In glucose solutions ranging from 5 mM to 20 mM, a direct correlation between the glucose concentration and the measured current is obtained. The reproducibility of direct immobilization is demonstrated by repeated performance with various sensors.
Power cables play an important role in power grids. Insulation faults in cables can have adverse effects on the operating behaviour. These effects can be assessed through an AC withstand test by using a very-low frequency high voltage generator. This generator produces a sinusoidal voltage waveform at 0.1Hz with high voltage levels up to 65kV peak. During the quality assessment, the power cable is repeatedly charged and discharged. The discharging process is done by a discharging circuit where the energy is dissipated thermally. But to reuse the dissipated energy a novel extension in form of an energy storage system is presented. This thesis, therefore, describes the design process of an energy storage system that allows the temporary storage of the discharge energy. The developed system is composed of a bidirectional DC/DC converter and an aluminium electrolytic capacitor as storage type. Based on the maximum VLF system ratings the energy storage unit is dimensioned and sized. The effective power flow control between the storage system and the available discharge energy is done by a synchronous buck-boost converter. This bidirectional converter works in continuous conduction mode over the complete charging phase. Together with a theoretical analysis of the underlying problem and the use of converter analysis methods the selected synchronous buck-boost converter is dimensioned and sized. In addition, a state space AC modeling of the converter with its electrical uncertainties is conducted. With the converters AC model, the controller is designed. A closed-loop input converter current control scheme based on a proportional-integral controller is implemented. The system assessment is done by a model-based hardware implementation in Matlab Simulink and Plecs Blockset. The system is rated to store discharge energies up to 4.3kJ in a short charging period of 2.5s. The maximum peak power during the charging phase is 2.7kW. The digital proportional-integral controller is implemented through an emulation process of the designed analog controller. Based on a C-code implementation of the digital controller the gap between the real hardware is reduced. During the design process theoretical calculations are made and reveal that designing a capacitor storage unit has a direct impact on the peak system currents and also impose also limitations on permissible DC voltage ranges on electrical components. The developed energy storage system and its power flow control strategy were investigated through simulation studies. The results show proper charging of the energy storage medium. In addition, also a statement of the final technical feasibility is made. In total, this work summarizes a detailed design process of the energy storage system. This proof of concept is intended to further advance the system integration.
Development of a low pressure syringe pump for detecting cannabinoids through liquid chromatography
(2022)
The following thesis covers the miniaturization and characterization of a pneumatic syringe pump, which is used for applications in low-pressure liquid chromatography. For this purpose, the components of the prototype are dealt with in the first section. These include the membrane pump and the cylinder for pressure and force generation, the syringe used for sample preparation and the construction of the test column. Furthermore, the pressure preparation on the cylinder, the friction losses of the syringe and then the behavior of the syringe in various application scenarios are considered. In the second section, the focus is on the different behaviors when using water and ethanol as a solvent. Tests in normal applications, as well as with air pockets or leaking seals, show the different behavior and the resulting deviations in the test pressure of the column. In addition, the maximum forces that can be applied to the syringe are worked out in several tests and the different maximum pressures, which depend on the solvent contained, are evaluated. These different maximum pressures, which are due to the different sealing behavior in connection with the surface tension of the liquid, will be discussed in conclusion. An outlook follows, up to which test pressures the system can be used and how these can be achieved.
Die vorliegende Arbeit beschäftigt sich mit der Positionsbestimmung in Innenräumen mittels der Ultra Breitband Technologie, deren Genauigkeit sowie der Positionierung solcher Systeme in relevanten Beleuchtungsmodulen. Im ersten Teil der Arbeit wird die Ultrabreitband Technologie beschrieben, die sich für Ortbarkeit in Innenräumen durch die große Bandbreite, relativ gut eignet. Hierbei wird auf das UWB-Signal, die Regulierung bezüglich Frequenznutzung für Europa und USA sowie auf die UWB-Standards eingegangen. Im weiteren Verlauf der Arbeit werden die gegenwärtigen Positionsbestimmungs Verfahren beschrieben. Beispiele hierfür sind das Time of Flight (ToF), das Time of Arrival sowie nicht funkbasierte Methoden wie z. B. die Inertial Measurement Unit (IMU). Die Positionsbestimmung in der UWB-Technologie wird häufig mittels ToF und ToA bewerkstelligt. Im darauffolgenden Kapitel werden die gegenwärtigen Lokalisierungssysteme erklärt. Real Time Locating Systems (RTLS) kommen in vielen Lebensbereichen zum Einsatz, von Krankenhäusern bis zum Sport. Der zweite Teil der Arbeit besteht aus der Ausarbeitung von verschiedenen Konzepten zur Realisierung eines Demonstrators sowie der Ausarbeitung eines Simulationsmodells für die Positionsbestimmung, mit dem eine Ortungsgenauigkeit von 30 bis 50 cm erreicht werden kann.
Die Mensch-Roboter-Kollaboration verspricht, die Leistungsfähigkeit eines Roboters und die Stärken eines Menschen zu kombinieren. Das junge Thema bringt nicht nur Vorteile, sondern auch neue Sicherheitsbestimmungen und aufwändige Validierungsverfahren mit sich, was den Zeitbedarf für die Entwicklung neuer MRK-Applikationen erhöht. Oft ergibt sich erst bei der Validierung, dass die Sicherheitsbestimmungen (meist die biomechanischen Grenzwerte) nicht eingehalten werden können und dadurch Änderungen an der Applikation durchgeführt werden müssen. So bildet sich ein Kreislauf aus „Validieren“ und „Änderungen vornehmen“, der erst nach mehreren Zyklen beendet werden kann. Ziel der vorliegenden Masterarbeit ist es, Empfehlungen zu konzipieren, mit welchen dieser Kreislauf frühzeitig durchbrochen werden kann. Die Arbeit beschränkt sich dabei auf das Leistungs- und Kraftbegrenzungsschutzprinzip. Um den Einfluss unterschiedlicher Parameter, wie beispielsweise die maximale TCP-Geschwindigkeit oder die Greifergeometrie, auf die Kollisionskräfte und Drücke zu erforschen, wurde ein biofideles Messsystem und ein Roboter vom Typ ABB GoFa™ verwendet. Diese Untersuchungen dienen zusammen mit den Sicherheitsbestimmungen als Grundlage der Gestaltungsempfehlungen. Um eine Anwendung der Empfehlungen vorzuzeigen, wird in der vorliegenden Arbeit exemplarisch eine MRK-Applikation gestaltet und validiert