This project addresses the challenge of monitoring large, dynamic classrooms by proposing a privacyoriented multimodal data acquisition system tailored for MMLA. Traditional learning analytics rely on unimodal data and fail to capture complex classroom interactions. In contrast, MMLA leverages multiple data sources to better understand learning behaviors. Current systems lack adaptability, userfriendliness, and privacy considerations, impeding their integration into classrooms. The proposed system comprises static and dynamic nodes, with dynamic nodes worn by individuals and static nodes strategically placed in classrooms. Data features, selected on MMLA relevance, are transmitted wirelessly to the static node for storage and analysis. Privacy is prioritized by avoiding sensitive data collection and adhering to GDPR guidelines. The design ensures adaptability, supporting additional sensors and seamless integration into various educational settings. This foundational system enables future research while addressing ethical and technical challenges in large-scale classrooms.

The goal of this project is to create a power supply for an electrical discharge machine (EDM). This machine can drill holes and create shapes in metal objects by evaporating material using discharges from the electrode to the workpiece. The electrode should be supplied with a high-voltage pulse wave in order to initate sparks. The power supply produces this waveform by turning a DC source on and off using a transistor as a switch. A current-limiting resistor that is placed between the source of the MOSFET and the electrode prevents short circuits during discharges. The circuit was first created with a DC voltage of 15V. A gate driver circuit to drive this MOSFET was designed to reduce power losses and to make the frequency and duty cycle adjustable. Then the design was improved by adding a diode to remove oscillations caused by the parasitic inductance of the power resistor. Afterwards, the circuit was built on a custom PCB to reduce parasitics. A filtering capacitor was added to remove high-frequency noise, after which a stable 15V pulse signal was obtained. A microcontroller is employed to regulate the pulse duration, detect spark occurrences, and relay this information to a speed regulator. This establishes a closed-loop system aimed at optimizing the overall system operation. To achieve this, circuitry is employed to convert the power supply output into a digital format, enabling the utilization of the microcontroller’s specialized hardware for rapid sampling.

This paper presents the design and development of an Electrical Discharge Machining (EDM) device aimed at achieving precise hole creation in diverse metal materials. The EDM device was conceptu- alized and constructed based on specific requirements identified by the group. The design process encompassed four main stages: dielectric fluid selection, electrode design, control system develop- ment and power supply. In the dielectric fluid stage, the importance and criteria for selecting an appropriate fluid were discussed, resulting in the choice of distilled water for its superior dielectric properties. The electrode design stage followed a similar methodology, leading to the selection of a copper rod as the optimal electrode material. The control system stage detailed the development of an open-loop, manual, and closed-loop control system, emphasizing the utilization of Klipper software for precise electrode control. The power supply section outlined three primary circuits: the power source, power amplification circuit, and square wave generator circuit. Detailed schematics, component justifications, and optimization values for key parameters were provided to enhance power supply efficiency. Experimental evaluation demonstrated the capability of the EDM device to effectively create holes in various metals using an open-loop control system. Additional experiments focused on parameter variations within the power supply setup further illustrated their impact on machining performance. The discussion highlights the challenges encountered throughout the project, particularly the constraints imposed by limited time, which prevented the realization of all initially set requirements. Despite these challenges, the EDM device successfully met most of the specified objectives, showcasing promising results for future refinements and applications in precision machining.

This thesis presents the design, implementation, and evaluation of the RF (Radio Frequency) section of an Open-Hardware Vector Network Analyzer (VNA) intended for quantum research applications. The project aims to create a cost-effective, modular VNA system that fulfills the functional requirements necessary for qubit readout and other quantum measurements.
In the initial chapters, the overall architecture of the VNA is outlined, with specific attention to the power budget and system requirements. The RF generation principles are examined, and a range of RF generators are tested to ensure they meet the signal quality standards, such as spurious emissions and harmonic content. The performance of various RF mixers is also evaluated and found to be sufficient for the RF system.
Experimental results demonstrate the system’s capability to measure the S21 parameter of a resonator cavity, comparable to commercial VNAs. This validates that the RF system meets the specified requirements and can be effectively used in quantum research.
Future work suggested includes the measurement of generator frequency/phase stability over time and exploring the feasibility of implementing power sweeps to enhance the system’s functionality. The findings of this thesis contribute to the development of accessible and flexible tools for quantum technology research, promoting further advancements in the field.

This thesis, conducted as part of the Bachelor Graduation Project at TU Delft, focusses on designing the communication and storage components of a data acquisition system for Multimodal Learning Analytics (MMLA). The goal is to create an adaptable system that improves learning outcomes in large, dynamic classrooms such as Tellegen Hall. Current systems often fail to address issues of privacy and integration, limiting their effectiveness in real-world applications. Theproposeddesignemployswearabledynamicnodesfordatacollection, andutilisesstaticnodesand arootnodeforwirelesscommunication. WirelesscommunicationusestheESP-NOWwirelessprotocol, and data is stored in a time-series database, InfluxDB, running on a Raspberry Pi 5. A Graphical User Interface(GUI) built in Grafana, allows monitoring and visualises the data. The system was tested for reliability and performance, showing a high success rate of 99.93% in data transmission. It enables a network consisting of, theoretically, up to 200 nodes. Future improvements include real-time analytics and data security mechanisms.

The focus of this report is the design and implementation of a universal gate driver for half-bridge circuits. This design includes a programmable dead-time controller and adjustable properties to ensure efficient and reliable switching on a variety of high-voltage applications. Furthermore, this work includes a comparative understanding of all design choices, such as the options considered for the dead-time controller, the gate driver component and the circuit of the output phase. The designed system is expected to receive as input a PWM signal and generate two output signals to drive a halfbridge configuration. The output pulses must be generated with a programmable dead-time and at the input switching frequency. The end product of this design will be used in the TU Delft Power Electronics Lab. The specific requirements are determined in order to meet the lab’s needs and this report further describes the process from acquiring the technical requirements, the circuit design, and finally, the prototype evaluation.

The increase in non-linear loads of modern electronics raises concerns over power quality. Additionally, existing power-quality analyzers are expensive and not intended for household use. This thesis aims to develop a single-phase, user-friendly power-quality analyzer using a Raspberry Pi 4 Model B with an emphasis on low cost and class S specifications. The design was split into modules consisting of analog to digital conversion, voltage sensing, and current sensing. Sub-modules were added for circuit protection and PCB. Various approaches are discussed before circuit design, simulation, and testing occur. A functioning prototype was assembled on a dedicated PCB while not exceeding the set budget of €250.00. However, it could not be determined whether the class S specifications were achieved due to insufficient testing. A variety of improvements have been suggested.

This thesis describes the design of a low-cost class-S power quality analyzer based on a Raspberry Pi 4. Capable of detecting power frequency, magnitude, voltage dips and swells, harmonics, and total harmonic distortion, the project consists of four main components: the communication protocol, the interface, the algorithms for power quality parameters, and the database. Each with its subdivisions. The communication module, which uses the I2C protocol, is chosen for its high sampling rates and built-in acknowledgement system, ensuring robust and fast operation. The interface module features a secure login process with two-step verification, a graphical user interface for real-time monitoring, and integration with algorithms for power quality parameter calculation. The algorithm module includes Fast Fourier Transform for harmonic detection, zero crossing method for power factor and frequency, and peak detection for voltage dips and swells. The database, powered by MariaDB on Raspberry Pi 4, securely manages the received data with restricted access for increased security, allowing remote access only from specified IP addresses.

This thesis presents the design and development of a UV-C LED-based seed treatment machine aimed at enhancing seed quality by the extermination of pathogens. The research covers design choices, including a round irradiation pattern, consisting of two rings with three and nine LEDs for the inner and outer ring respectively, the use of a quartz plate as a holding plate for seeds for its high UV-C light permeability capabilities, the use of a vibration motor underneath the main operational stack for seed movement, and the use of Ethernet ports for power distribution and communication. The thesis discusses a comparative study between square and circular plate configurations, evaluating their performance using simulation results. Safety considerations were prioritized in the design, and appropriate precautions were implemented throughout the design process. The thesis also highlights the iterative design process for the mechanical system, discussing challenges encountered and improvements made to achieve a functional and robust prototype. Results demonstrate successful integration of components and achievement of objectives. The thesis concludes with discussions on the strengths, limitations, and future enhancements of the UV-C LED-based seed treatment machine. The research presented in this thesis provides valuable insights for further advancements in seed treatment technology, contributing to sustainable agricultural practices. Due to time constraints, conclusive results of testing on seed with this machine could not be obtained yet.

Unmanned underwater vehicles benefit from communication with a high data rate on relatively small distances (under 100 m). Existing communication methods are not able to provide this or present other shortcomings. Therefore, this bachelor end project focuses on a new type of underwater communication, quasi-static electric field communication. The software and modulation techniques in such a communication system are covered in this thesis. This includes a detailed analysis of modulation techniques, and especially of differential methods such as pi/M-DPSK, which can be demodulated non-coherently. Our system implements OFDM and according to simulations, it is able to achieve data rates of up to 1 Mbit/s. Additionally, this research focuses on the effect of error correction coding on the performance of the system. Moreover, an adaptive data rate control system is designed. The efficiency of the system is optimized by a power distribution algorithm. Finally, suggestions are given for a communication protocol.

This report details the design and development of an agar/NaCl gel-like tissue phantom mimicking the electrical properties of wet human skin. The skin phantom provides a reliable, reproducible testing ground for dry-contact polydimethylsiloxane (CNT/PDMS) electrodes, with the aim of recording electroencephalograms (EEGs) and stimulating brain activity in a controlled environment. These electrodes are being designed for the development of an in-ear brain-computer interface (BCI).
The electrical properties of biological tissue are referred to as the conductivity σ and permittivity ε and denote the ability for a material to conduct and trap electric charge respectively. These properties are frequency dependent and particularly for EEGs, a frequency range of 1-1000 Hz is of interest (with some added leeway). Wet skin hereby has a conductivity of around 0.1 Siemens to 0.2 Siemens in the 1-1000 Hz frequency range whereas the permittivity ranges from 5.7 * 10^5 to 5.2 * 10^5. Different agar and agar/NaCl solutions are created to try and obtain solutions with the mentioned electric properties. Specifically, NaCl is added to improve the conductivity and obtain a non-linear frequency response similar to that of human skin. The electrical properties of the phantoms were verified/measured using the parallel plate method. This method is essentially sandwiching a material under test (MUT) (in this case the fabricated gel-like agar and agar/NaCl solutions) between two conducting plates. This method is most suited for measurements in the lower frequency spectrum.
The skin phantom consisting of 3.04 mass fraction weight (wt.%) agar and 0.539 wt.% NaCl shows the closest similarity to the conductivity of wet skin. Namely, a conductivity of ~ 0.1 Siemens to 0.45 Siemens in the frequency range of 1-1000 Hz. A decrease of 0.250 wt.% NaCl will most likely achieve the desired conductivity response of 0.1 Siemens to 0.2 Siemens in the frequency range of 1-1000 Hz. The skin phantom consisting of 3.00 wt.% agar and 1.02 wt.% NaCl showed the permittivity closest to that of wet skin, but might have been a noisy outlier. Its permittivity ranges from 10 * 10^6 and 7.5 * 10^6. This is still a large error margin from the desired 5.7 * 10^5 to 5.2 * 10^5. Additional fillers like glycine or Al powder need to be added to the solutions to obtain a permittivity close to that of wet human skin. Multi-day and difference in applied pressure measurements are performed to check the sensitivity and reproducibility of the phantoms. Applied pressure hereby has little to no influence whereas a longer life-span of the fabricated phantom shows a drastic decrease of the electrical properties of the phantoms after day 1. The changes then seem to settle. Worth mentioning is that the change is only drastic when the solution has a high conductivity. This is generally not the case for solutions with conductivities close to wet skin.

To make open door policies easier in nursing homes, it is important to have a smart system that can check whether access is allowed for the person trying to enter some place or not. This thesis documents how an access control system has been built, for Momo Medical, to be used at a nursing home. It sheds light on hardware considerations made and the software written for the final product. All the knowledge gathered and the time spent has led to a final product that with minor tweaks can be used in the existing infrastructure of Momo Medical but also without the presence of it. There are however still improvements left to be made for the final product to be commercially appealing.

Wireless power transfer has been around for a long time. In 1899 Nikola Tesla demonstrated that it was possible to transfer power using a pair of coils. This technology has advanced to now charge a wide range of portable devices, such as phones. In this thesis, a wireless charging system is designed to be integrated into a power bank with UV-C sterilization to charge phones.

The design focuses on creating a small and highly efficient module to transfer energy from the power bank battery to the phone with as little losses as possible. The design adheres to the Qi standard from the Wireless Power Consortium by following the MP-A2 reference design. The design consists of a voltage regulator to provide a constant voltage, a controlled inverter that manages output power, and a series compensated transmitter coil. LTspice simulations predict the power efficiency to be 74% from the battery to the receiver. A prototype PCB was designed and assembled to demonstrate the performance of the design in practice and transferred 5W at an efficiency of 67%. This shows potential for future integration of the design into the power bank.

To enable the portable use of electronic devices, (rechargeable) batteries need to be used. These batteries require a battery management system in order for them to operate safely and efficiently. This thesis describes such a system for the Wireless Powerlizer: a power bank with wireless charging capabilities and an integrated sterilizer using UV-C light.

The battery management system comprises of a charging circuit, a protection module, and cell balancing features. These features are designed to function with Li-ion batteries, which are chosen for their high volumetric energy density, in a 5S1P configuration. These batteries will be charged via a constant-current, constant-voltage (CC-CV) scheme in order to improve charging speed. This charging scheme will be facilitated by a DC-DC boost converter with current and voltage control.

The mechanism behind the protection module (overcharge, overdischarge, overcurrent, and temperature) and passive cell balancing features are elucidated via flowcharts and also verified by simulation in Simulink. A prototype encompassing the charging circuit is implemented on a PCB and tested. The realized boost converter successfully allows for CC-CV charging: it operates at 263kHz, has a charging current of 1A, a constant voltage boundary of 19.6V, and shows an efficiency of 92—93.6%.

The design, production and testing of the Bluetooth Ultrasimple Gamepad, or BUG for short, is laid out in this report. In the current market, most of the controllers available are multi-button controllers with analogue sticks. These controllers are expensive and can not be used for many web browser games which rely on a keyboard input to work. In order for these controllers to work, a video game or self developed app can be used, but this can be difficult or expensive for many users. In the implementation of the BUG, the controller was made to be used by a single hand, having a clear ”main” button, an intuitive reconfiguration scheme and to have Bluetooth connection which is present in a lot of laptops and PCs currently in use. With this approach, the user can have a cheap, simple and comfortable alternative to existing gamepads. It can be stated
that, although not for everybody, the BUG is a good and fun alternative for users. This can be seen because the general user experience is rated at 5 out of 5 points by 50% of the participants, 4 out of 5 by 46.7% of the participants and only 1, or 3.3% of the participants has given a rating of 2 out of 5.

This document describes the design process the prototype of a measurement light bulb which is able to project spherical harmonics of orders 0-1-2. Photographs of these projections can be combined to represent many light distributions. The measurement light bulb can be used in the field of research focused on the computation of the illumination impact of lighting, more specifically, simulating different light sources. Our prototype consists of a laser beam rotating over two axes, which allows the device to project onto a sphere around itself. The device can be controlled wirelessly using Bluetooth. The lamp can project spherical harmonics in a resolution of 4 degree and 256 monochrome light levels. The time one projection takes is about one second, which allows for quick measurements. The dimensions and the weight of the lamp are such that it is portable. At this stage, the prototype can only operate in a dark environment, due to the use of a low powered laser. In this document, the focus will be on the design of control, communication and the PCB.

At virtually every public venue, announcements for visitors are made via a public addressing system. It is important that announcements transmitted by means of a public addressing system are not only audible, but also well understood by the general public. This thesis covers one of three subsystems required to make
a product that is capable of improving intelligibility of speech based on noise statistics in a room. Moreover, these statistics allow for an automatic volume control in order for listeners to experience an improved audio level. Therefore, this thesis aims at estimating the noise statistics in real time, while prior knowledge on the distorting announcement signal is available. Consequently, the concept of adaptive filtering deems suiting and is extensively studied. In order to meet the real time processing constraint, members of least mean squares algorithms are examined. Therefore, the method of steepest decent is covered, leading to the expounding of the traditional least mean squares (LMS) algorithm and the normalized LMS (NLMS) algorithm.
By assessment of the algorithms regarding different step sizes and filter lengths, the NLMS algorithm is shown to be superior in terms of faster convergence speed and better stability characteristics considering similar conditions for both algorithms. Subsequently, the results show that the NLMS is able to estimate the
noise in noise-to-signal ratio’s higher than -15dB. Also, its low complexity allows it to be suitable for real time applications, hence meeting the requirements.

In order to make offshore working conditions safer, Ampelmann B.V. builds platforms that stay stable by compensating for a ship’s motion. These platforms are controlled via motion reference units (MRUs). In order to test the performances of these MRUs, a linear motion MRU test setup was developed. The system was divided into three parts: hardware, software and MRU assessment. This thesis focuses on the design and implementation of the MRU assessment part and on testing MRUs with the complete prototype setup.
Ampelmann supplied the MRU with which the test were conducted. Validation tests have been done with a simulator and with the setup itself. Included in the assessment of the MRUs was the latency, signal-tonoise ratio and low-frequency behaviour, compared to a ground truth. Concluded from the tests was that the designed test setup has potential to accurately assess the performance of MRUs. There are some minor improvements to be made, but the overall system works as intended.

The Motion Reference Unit (MRU) is an important component in the Ampelmann Operation B.V. systems. In order to assess the performance of different MRUs a test system is developed. By using a one Degree of Freedom rail, wave motions can be simulated in the sway, surge and heave direction of a ship. The test system is divided in three parts: hardware, software and MRU assessment. This thesis focuses on the software design and implementation of the system. It turned out that the software performed well enough for the test system. However, due to limited project time, not all designed functionality could be implemented.

This report discusses one part of a project consisting of three parts. The goal of the project is to design a battery less sensor powered by RF energy fields present in an office environment. The sensor is able to measure the temperature and is able to communicate wirelessly using a low power communication protocol.In this report the energy conversion and storage of the system will be discussed. A high-frequency signal coming from an antenna must be converted to an output signal which is functional for the communication module. Therefore a steady 3.3 V DC output needed to be created with a rectifier circuit. In order to achieve maximum power transfer to the load, a matching circuit with the RF energy harvesting antenna needed to be designed. The main challenges were to achieve a high enough input voltage to reach the threshold voltage of the diodes of the rectifier and to rectify the AC input as efficient as possible. To tackle these challenges a design with a Greinacher rectifier with low-threshold Schottky diodes and a DC/DC booster is presented.