Chalmers Open Digital Repository

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Student theses and papers
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Selected project reports

Research publications, reports and dissertations can be found in research.chalmers.se

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Now showing 1 - 2 of 2

Recent Submissions

Beyond the Legend
(2026) Ström, Eddie
The digitization of industrial diagrams has seen increasing attention across many engineering domains due to these documents often being the backbone for downstream applications such as maintenance, revision work and validation. But working with these drawings can often times be expensive, time-consuming and repetitive. While related work has explored automated symbol detection in domains such as piping and instrumentation diagrams (P&IDs), electrical housing diagrams are less studied even though they have many of the same challenges. This thesis investigates symbol localization and reference-guided classification in electrical housing diagrams, focusing on the use of diagram legends as references. The work compares two methodologies, a more traditional template matching approach and a two-stage approach, where symbol regions are detected, by a generic symbol region of interest detector, and then classified using legend-based references. The two-stage method is tested using both template matching and Siamese-networkbased classification. By relying on legend symbols, the proposed methods reduces the dependence on annotated training datasets reflecting realistic scenarios where data, more often than not, is very limited. The generic regions of interest detector was able to localize a large portion of the relevant symbols, reaching a maximum recall of 95.42%. Classification on the proposed regions showed promising performance, with results comparable to the traditional template matching approach. The reference-guided two-stage method also offers a more flexible structure by separating localization from classification as well as incorporating deep-learning models, providing stronger potential for scalability, speed, refinement and versatility.
Electric vehicle charging strategies among private users
(2926) Gustafsson, Amanda
Estimation of driver control limitations and adaptation of intervention strategies based on crash data
(2026) Lundmark, Thea; Milevski, Simone
Sweden’s Vision Zero initiative aims to eliminate fatalities and serious injuries in road transportation. A key component is the development of Advanced Driver Assistance Systems (ADAS), supporting drivers in crash-imminent situations. However, determining the optimal timing and magnitude of system interventions remains challenging, as interventions should support rather than conflict with the driver’s intended maneuver. One proposed approach is to define driver control limitations, such as maximum braking and steering inputs, and use these limitations to support ADAS intervention design. This thesis analyzes real-world crash data to evaluate driver control limitations using four metrics: Steering Wheel Angle (SWA), Steering Wheel Angle Velocity (SWAV), Driver Deceleration Request (DDR), and Actual Time-to-Collision (ATTC). Actual vehicle deceleration was also considered relevant to distinguish between driverrelated braking demand and the resulting vehicle response. The metrics were examined across varying driving contexts, including vehicle speeds, vehicle actions, crash types, road and lighting conditions, and ADAS activation. The results showed that SWA varied slightly with maneuver type, while SWAV remained more consistent and may represent a more stable upper limit of steering behavior. Most drivers reached maximum deceleration request; however, the ATTC results showed that braking was often initiated too late to prevent a collision. DDR alone was insufficient in low-friction conditions, highlighting the importance of considering actual vehicle deceleration. ADAS activation generally had limited influence. Simulation results indicate that refined steering thresholds may allow drivers to avoid obstacles where current ADAS would intervene prematurely. These findings support incorporating driver control limitations into future ADAS development.
Analysis and performance of three-mode qutrit rotationally symmetric bosonic codes
(2026) Fredrik, Ljungström
Encoding information in bosonic quantum states has an advantage over traditional two level systems since they inhabit Hilbert spaces of infinite dimensions. This makes bosonic codes into very resourceful carriers of quantum information which can be exploited in error correcting codes. Thus, making bosonic codes a viable option in the realisation of fault tolerant quantum computers. In this report we begin by adapting a general formulation of multi-mode d-dimensional Rotational symmetrical bosonic (RSB) codes from Ref. [1] and by setting the dimension to d = 3 results in a general qutrit code space in three modes. Before the code is further specified, the operations of beam splitters, describing linear passive optical system, is analysed from definitions in Ref. [1] and solutions for how excitations transforms under such evolutions are found analytically from an algebraic structure. We then specify the coefficients of a code in two separate methods. First, the single mode RSB basis states are projected onto a state characterized by a binomial distribution. The result is rejected from a preliminary analysis of the symmetries in the resulting single-mode states. Another method is then carried out by arbitrary truncating the sums of general RSB states and enforcing conditions of orthonormality and equal mean photon number ⟨ˆn⟩ of each single-mode basis state. The result is considered to be a good candidate as an error correctable code. The code, denoted as "the arbitrary code" is further analysed with a theorem which defines error correctable codes known as the KL-conditions. From this analytical study, we find that the code is correctable for single photon loss errors but not for dephasing errors. An analytical study of the "arbitrary code", in terms of the KL conditions, is followed by a numerical estimation of its performance against noise in the form of photon loss and dephasing, individually. The performance is estimated in terms of near-optimal entanglement fidelity. Inspired by the analysis of symmetries in the single-mode basis states and the KL conditions for the full code, we find a third approach experimentally, leading to a new framework for the construction and classification of d-nomial RSB codes. The new frame work also makes it clear that the qutrit codes that has been studied, are in fact char acterized by states from trinomial distributions and are therefore denoted as trinomial codes.
Coded pilot synchronization in wide band sub-THz communication systems
(2026) Vijayasri Kristaparapu
Future wireless communication systems operating in the sub-terahertz (sub-THz) frequency range (100–300 GHz) offer extremely large bandwidths, enabling ultra high data rates for next-generation applications such as wireless backhaul, chip-to chip communication, and sensing. However, carrier synchronization (CS) in such systems remains a major challenge due to large carrier frequency offsets (CFO), se vere phase noise, and the impracticality of using ultra-high-speed analog-to-digital converters (ADCs) for wideband signal processing. This thesis proposes a low cost analog-digital hybrid synchronization method us ing a low-power pseudo-noise (PN) coded pilot that can be detected even at very low power levels using matched filtering. A PN-coded pilot is embedded within the transmitted signal (a single wideband signal) at power levels up to 30-50 dB below the data signal. At the receiver, the pilot is extracted using a narrowband filter and processed with a PN-based matched filter to achieve significant processing gain, enabling reliable detection using low-speed ADCs. A hybrid analog–digital phase-locked loop (PLL) architecture is proposed, where carrier frequency and phase estimates obtained from PN correlation are used to control the local oscillator. The system is first validated through MATLAB sim ulations under realistic impairments, including large CFO and strong phase noise. Results demonstrate successful carrier recovery and reliable detection of pilot sig nals buried down to 30 dB below the data signal. The proposed approach is further implemented on an FPGA platform to evaluate real-time performance and hardware feasibility. The results show that PN-coded pilot synchronization is a promising solution for en abling practical, low-complexity carrier recovery in ultra-wideband sub-THz systems without requiring high-speed data converters.