The Lunar Zebro rover is a nano rover designed by student research team Lunar Zebro at the Technical University of Delft. This rover will be sent to the lunar surface to conduct scientific experiments. In order to protect the rover during transit and facilitate successful deployment onto the lunar surface, a rover deployment system was designed.

This thesis describes the design of the sensing and actuation part of the rover deployment control system. The thesis details the design of a system which is able to deploy 4 Non-Explosive Actuators by means of sequentially supplying more than 4A for 50ms to each NEA. This sequence is inhibited by a physical connection to the rover by means of an umbilical cord which can be overridden when the rover and microcontroller send an override signal at the same time. The system contains a heating element and two temperature dependent relaxation oscillators that can be used to regulate the temperature. Thermal regulation can function independently of a digital control system, but can also be managed by the microcontroller. In the case that the microcontroller experiences failure, the NEA activation sequence can be initiated by two control signals from the lander, to which the deployment system is attached.

The system has not been physically tested, but has been verified in simulation. The combination of all these subsystems uses a peak power of 1.1W in simulation.

A test printed circuit board was designed to incorporate the complete rover deployment control system. This board can be used to physically simulate the deployment of the four non-explosive actuators by means of glass fuses. The board also allows any equivalent NEA model to be used in order to verify the limits of the system.

The system meets all functional requirements in simulation. Future work regarding the design entails physical testing of the PCB and the resolution of two major vulnerabilities, namely its reliability on the stability of the lunar lander’s 28V supply as well as its inability to handle excessive thermal energy.

This thesis details the design and development of the Power System for the Rover Deployment System. This power system delivers and manages the necessary power required by the entire Rover Deployment System. The RDS is responsible for ensuring the rover’s survival inside the transportation pod during transit. It also handles releasing the rover, which a mechanical mechanism will lower onto the lunar surface. The goal of Lunar Zebro is to send a nanosatellite to the moon for lunar surface exploration and radiation measurements. The power system was designed to power the MCU and transceivers at 3.3V, to provide power for rover charging at 12V, and to charge a capacitor bank used to provide the necessary actuation power to the NEAs. An electrically triggered umbilical release mechanism, unfortunately, could not be implemented due to a lack of available data. The circuit for this system was created, simulated, and added to the PCB design of the RDS. The simulations of the circuit behaved desirably. Due to the lead time on orders, the PCB has unfortunately not been received yet. Because of this, the entire power system has unfortunately not been tested yet.

The analysis of integrated front ends operated in the high-frequency regimes is addressed in this work. The analysis of these problems has been a critical bottleneck for decades due to the difficulties arising in adopting full-wave techniques. Assuming, as typical at lower frequencies, that the structures are planar leads to the inaccurate representation of some characteristic reactive behaviors. As a case in point, the characteristic impedance of transmission lines, whose thickness is comparable to the width, is not well represented by planar tools. Moreover, existing analytic formulas based on quasi-static approximations for the surrounding fields typically fail when the dynamic components of the fields are also affected by the stratifications. In this thesis, planar stratified media with transmission lines and radiators are considered to be part of the front end, with this latter being integrated (or in package) thanks to the systematic presence of a dielectric lens antenna.

Estimating the transmembrane currents travelling through the epicardium and local activation times based on atrial epicardial electrograms can greatly help in the study of cardiac arrhythmias such as atrial fibrillation. This work focuses on the accurate estimation of the aforementioned signals and features. To do this, two least squares-based regression methods were used to estimate transmembrane currents from electrograms and then find their local activation times by searching for the maximum negative slope. The first least squares optimization method consists of using standard least squares, while the second consists of regularized least squares, by combining both lasso and ridge regression, to deal with signal sparsity and multicollinearity, respectively. Furthermore, to improve estimation results, multiresolution analyses based on wavelet decompositions and principal components analysis were used to filter out parasitic components that were present in the estimated transmembrane currents by separating them from the main activation complex of the decomposed signals.
Using these algorithms on simulated data, it was shown that promising results can be achieved for both transmembrane current estimations and LAT estimations. Several wavelet support sizes were tested on the simulated data to observe performance changes. These were compared to an already existing LAT estimation algorithm. The results mainly confirm the efficiency of the proposed methods on severely diseased tissue corrupted by conduction blocks and noise.

In the context of designing a real-time brain-computer interface for playing a game using the OpenBCI Ultracortex "Mark IV" headset, this paper focuses on the work of the decoding subgroup. The primary responsibility is to analyse EEG data retrieved from the OpenBCI headset and classify the intention of the user. Our objective is to achieve a high-accuracy classification of the EEG signals. The paper is structured into three main sections: preprocessing, feature extraction, and classification. Multiple methods for preprocessing and classification of motor execution EEG signals will be analysed, striving to contribute to the real-time implementation of the project. The results of our work provides valuable insights for future research and development in this field.

With the development of the fifth generation (5G) technologies and beyond, the requirements for future wireless communication systems become more stringent, which demand novel antenna design at millimetre waves. The most commonly proposed array topology for 5G usage is square 8x8 or 16x16 microstrip patches with the full digital beam-forming method. Such designs result in massive complexity, high power consumption, and heat generation, especially with the full digital beam-forming method. To reduce design complexity and power consumption, the hybrid beam-forming is proposed, in which the linear subarrays are used with a fixed beam pattern in elevation, and combined in an array with digital beam-forming to realize the beam scanning in azimuth. Recent studies in the MS3 group at TU Delft have demonstrated that the series-fed subarray can be used in hybrid beam-forming and can realize any desired pattern by independent control of amplitude and phase on each unit cell. However, the main drawbacks of the series-fed arrays are the radiation beam squint and pattern distortion under different frequencies, which can limit the radiation bandwidth. Therefore, it is necessary to investigate the design of the series-fed antenna arrays to reduce the beam squint and pattern distortion. In this thesis, the performance of series-fed antenna arrays radiating the csc2-shaped beam pattern is investigated in terms of beam squint and pattern distortion. The RMS value is used in this thesis to quantify the pattern distortion in series-fed arrays and is used as a performance metric. Firstly, seven types of edge-fed series-fed subarrays are designed and optimized in CST. Their performance in terms of beam squint and pattern distortion is evaluated with and without considering the mutual coupling effect. Then, the subarray with the most stable radiation pattern over the evaluated frequency band (25 GHz - 27 GHz) is selected. Following this, the center-fed series-fed proximity-coupled subarray is designed aiming to reduce the amount of beam squint while having a stable radiation pattern. The performance of the center-fed subarray is compared with the edge-fed configuration in terms of the beam squint and pattern distortion. The simulation results show that the center-fed configuration can significantly reduce the beam squint but can increase the pattern distortion. Finally, the array of center-fed series-fed proximity-coupled subarrays is designed and simulated in CST. The results show that the array is able to reduce the beam squint (within 1°) while having a reasonable pattern distortion (around 20% difference compared to the synthesized pattern) within the frequency range from 25.8 GHz to 26.5 GHz.

The most common serious heart rhythm disease is atrial fibrillation. It is not fatal on its own but does increase the risk of heart failures and strokes. There is little understanding about the mechanisms behind the disease, so more insight is desired. Using an array of electrodes, measurements are being performed of the electrical atrial activity directly on the heart tissue. These signals are, however, not clean and suffer from far-field interference coming from the ventricles.

During normal sinus rhythm these atrial and ventricular activities are separated in time and easy to distinguish. In case of atrial fibrillation this is not always the case. Luckily, there is a major difference between both signals: the ventricular signal comes from far away and arrives therefore approximately simultaneously at all electrodes. A simple, but effective way to remove this ventricular activity is to use a bipolar electrode. It produces the difference between two normal unipolar electrodes, thus removing the common ventricular signal component.

The bipolar electrode, however, distorts the atrial signal component, which in some orientations can even lead to removing it altogether. This bipolar electrode is known as a differential beamformer from the field of array signal processing. There are more complex beamformers that can keep the atrial component undistorted and therefore produce better results than the bipolar electrode.

This thesis proposes a Fourier-domain signal model for all available electrodes relying on an atrial and ventricular transfer function. It is possible to estimate these transfer functions from the data blindly. Three beamformers are derived utilizing the signal model and the transfer functions. The bipolar electrode is extended to multiple electrodes like the other beamformers as well.

Experiments with simulated data show that the complex beamformers indeed keep the atrial activity undistorted and are still able to remove the ventricular activity effectively when using multiple electrodes, except for very complex data where the signal model is not valid. For low numbers of electrodes the beamformers are not useful, they hardly remove the ventricular activity while keeping the atrial component undistorted, where the bipolar electrode does the opposite.

The electrograms are also used to estimate local activation times of the cells underneath the electrodes which says something about the health of the cardiac tissue. Besides the mentioned filtering, this thesis proposes a method to estimate those moments in time by looking at the time-domain version of the atrial transfer function, called the atrial impulse response. For simple data, it performs well compared to state-of-the-art methods, but for more complicated data, it does not.

In this thesis, a closer look will be taken into the design of a propulsion system of an eVTOL (electric Vertical Take-off and Landing aircraft). The primary goal of the eVTOL is to maximize the payload for a given maximum take-off weight and the eVTOL has to go into service in 2030. To make an as light weight as possible propulsion system, an investigation will be done for the propeller length and the number of rotors, which is present on a given eVTOL design. In addition to this, different drive choices will be discussed and an optimal drive choice will be made. For this drive, a closer look will be taken in efficiency optimisation. From these parameters a design example will be given using the current state-of-the-art drive technology. In addition to this possible future drive, developments will be taken into account. 

Vagus nerve stimulation (VNS) has been proven to be an effective treatment for patients suffering from drug­-resistant epilepsy. Current vagus nerve stimulators are either implantable devices or bulky, handheld devices. The implant consists of a pulse generator beneath the skin of the chest, connected to electrodes that are wired to the cervical vagus nerve. While capable of delivering localized electrical impulses, the implantation is highly invasive. Handheld devices do not ask for a risky surgery, but their imprecise targeting of the neck reduces efficiency and provokes additional side effects.

Ultrasound has been widely used in clinical applications ranging from focused ultrasound (FUS) tissue ablation to medical imaging. Much research is being carried out on the use of FUS neuromodulation as a low-­cost, non-invasive alternative to electrical VNS. The combination of using ultrasound for neuromodulation as well as imaging allows for image-­guided FUS where automated tracking of the nerve location improves the targeting of the vagus nerve.

In this thesis, the design of an ultrasound vagus nerve stimulator with combined imaging capabilities is presented. The novel architecture combines FUS for vagus nerve neuromodulation and plane wave imaging (PWI) with optimized sparse receive sub­arrays to obtain the location of the nerve within the neck.

A 2D array of piezoelectric transducers with λ/2-pitch poses a strict constraint on the pixel area. The goal of the system design is to minimize the area consumption of the on­-pixel electronics by making use of already present circuit blocks. A shared delay­-locked loop generates the required continuous phases for FUS neuromodation, while a row-­column pulse control block generates a single pulse from the available phases for use in PWI. This way the on-­pixel transmit hardware is reduced to a multiplexer and high­-voltage driver.

The receiver consists of an analog front­-end and analog-­to­-digital converter and is shared among a sub-­array of receive elements. Different degrees of random sparsity are explored for the optimal implementation of the receive sub-­arrays within the full array. Synthetic aperture imaging allows the multiplexing of multiple receive elements to the shared front-­end and reduces the time spent on imaging using dynamic beamforming on a single data set.

The full system­-level architecture of a complementary metal­-oxide­-semiconductor (CMOS) interface is proposed and the receiver front-end has been designed and simulated.

In this thesis, a design of a passive radar for use on a drone used in inhospitable areas where air traffic control is not available due to circumstances. The thesis focusses on the receiver chain and angle of arrival algorithm.

This thesis presents the development of circuits and systems for fast wireline transceiver links that will enable a move towards highly integrable RF digital-to-analog converters. A new perspective on the analysis of bit error rates in wireline links leads to the PAM spectral design space chart: a novel, visual system design analysis tool for PAM wireline circuit designers. Moreover, a <2 mW/Gbps/lane, 10 Gbps wireline transmitter has been designed and taped-out in 40 nm CMOS. The proposed inherently pipelined 16:1 multiplexer and current mode logic driver design procedure are the key enablers for this performance. Finally, for development of a 10 Gbps wireline receiver, a novel self-synchronized receiver design is proposed that removes the need of a classical clock and data recovery loop. At its core, this receiver comprises the design of a high-speed two-tail comparator and an asynchronous metastability detection loop.

Wings for Aid is a company which develops an airborne aid-delivery system in emergency-struck areas and wants to use the radar system of Selfly to make an autonomously flying system. The goal of this project is to optimise the current ground-based radar system of Selfly for this application. This is done through the design of a Bi-static radar system, which can be mounted on, and used for drones to detect and avoid other obstacles in the airspace.\\
This thesis describes the design process and results of a sub-system of the Bi-static Sense and Avoid System for Drones (BiSAD). This a Bi-static radar system, consisting of three sub-systems that together form the base of the radar system. There will be one transmitter drone and several smaller receiver drones which are designed. Also, an optimal waveform is created for this purpose.\\
The report gives a proof of concept and will focus on a proof of concept for the transmitter chain as well as highlight some total system design choices and results.

Nowadays, localization of cars is mostly done using GPS. Some major disadvantages of this method are that it is not very accurate and that it cannot be used indoors. These disadvantages do not form a major problem when an active human driver is controlling the car, but will become more critical when the autonomy of vehicles increases. The goal of this project is to use Synthetic Aperture Radar techniques to overcome the problems of GPS. To achieve this, different imaging algorithms have been implemented, and a single method has been extended to directly accommodate the road-mapping application. Different measurements were done to test the algorithms and the results were promising. It is hoped that the use of this technology will become wide-spread and that it can help with creating a safer and more efficient world of traffic, where increased self-driving capabilities are facilitated.

A system has been developed that utilises the techniques of Ultra Wideband and Synthetic Aperture Radar to produce top view images of a scene using measurements from the side. The system consists of the PulsON P410 radar module, a set of antennas, a moving platform and an imaging algorithm. This thesis will cover all the aspects of the data acquisition part of the system with additionally an analysis on antennas.