Chalmers Open Digital Repository

Välkommen till Chalmers öppna digitala arkiv!

Här hittar du:

Studentarbeten utgivna på lärosätet, såväl kandidatarbeten som examensarbeten på grund- och masternivå
Digitala specialsamlingar, som t ex Chalmers modellkammare
Utvalda projektrapporter

Forskningspublikationer, rapporter och avhandlingar hittar du i research.chalmers.se

Enheter i Chalmers ODR

Välj en enhet för att se alla samlingar.

Visar 1 - 2 av 2

Senast publicerade

Nonlinear Model Predictive Control of Active Air Suspension for Roll Stability in Tractor-Semitrailer Vehicles
(2026) Liao, Fanxiang; Lu, Chaojie
Tractor–semitrailer combinations have a high center of gravity and strong coupling between the two vehicle units. Steering and combined steering-braking maneuvers can therefore produce large body roll and lateral load transfer. Active air suspension can reduce this risk by changing the vertical support force at each side of the tractor. Its control authority is limited by pressure, valve flow, and the pneumatic system’s response speed. This thesis builds on an earlier active air-suspension and NMPC framework. The vehicle configuration considered is a 4x2 two-axle tractor with a three-axle semitrailer. Active air suspension is installed only on the tractor, while the semitrailer keeps its passive suspension. The controller model is reformulated so that air-pressure and mass-flow dynamics are not included among the prediction states. Their physical limits are instead represented by constraints related to force, force rate, pressure, and mass flow. Pitch states and pitch weights are added. This reformulation reduces the order of the prediction model and improves computational efficiency while preserving the key actuator constraints. The model also includes forces and moments transmitted through the fifth wheel, together with a bounded preview correction for the trailer-induced roll moment. The high-fidelity Volvo Transport Model (VTM) is used as the closed-loop simulation plant. A nonlinear two-track model provides the control-oriented vehicle prediction. The upper-layer NMPC calculates increments in tractor suspension force. A lower layer converts these force requests to pressure references and on–off valve commands. The strategy is evaluated under step steering, ramp steering, lane change, and braking-in-a-turn maneuvers. Compared with the passive baseline, the NMPC controller reduces the semitrailer Load Transfer Ratio (LTR) and improves roll response in the main steering scenarios. These results indicate that, within the simulation environment and actuator constraints, the NMPC-based active air suspension strategy improves the roll stability of tractor-semitrailer combinations and provides a useful reference for future active suspension control in heavy-duty vehicles.
Controllable Gaze and Head-Pose Redirection via Latent Disentanglement in Convolutional Autoencoders
(2026) Blohm, Eric; Harari, Nadav
Driver Monitoring Systems (DMS) increasingly rely on gaze and head pose estimation to assess driver attention and detect unsafe states. However, existing datasets are dominated by common driving patterns while rare yet safety-critical behaviors occur irregularly and are difficult to capture systematically. This motivates the use of synthetic and controllable image generation to improve robustness and validation. This thesis investigates whether gaze direction and head pose can be controllably manipulated in image space through autoencoder-based latent disentanglement. A custom data collection procedure is developed to enable dense and geometrically consistent supervision of gaze and head pose, supporting controlled learning of latent factors. Based on this data, convolutional autoencoders are trained using a latent-swapping strategy and explicit label supervision to encode gaze and head pose into interpretable latent dimensions. In addition, a Laplacian-based edge loss is introduced to improve preservation of high-frequency image details. The results demonstrate consistent and interpretable control of gaze and head pose within the training distribution. The model achieves high reconstruction quality and preserves fine-scale features such as corneal reflections, verified through a dedicated detection pipeline. For unseen identities, coherent eye-region structure and meaningful gaze and head pose variations are retained, though distortions in other image regions and lower evaluation scores reveal limited out-of-distribution generalization. The results highlight both the potential and the limitations of deterministic autoencoders, motivating future work on improved realism and generalization.
OMP-Based Target Detection for Pulse-Doppler Radar
(2026) Rimarcuk, Tess; Udén, Adam
Radar systems transmit radio-frequency electromagnetic waves and receive the reflected signals from objects within their field of view. A surveillance radar aims to detect and estimate the state of targets in the surveillance volume. Traditional detection algorithms struggle in environments containing closely spaced objects or heavy clutter, resulting in false alarms or missed detections. Greedy compressed sensing algorithms, such as Orthogonal Matching Pursuit (OMP), address this through an iterative process that identifies and subtracts the strongest component in the residual signal, enabling detection of weaker targets masked by stronger ones. In this Master’s thesis, OMP was implemented and evaluated on both real and simulated pulse-Doppler radar data, focusing on scenarios involving closely spaced targets and clutter-rich environments. The performance of the OMP detector was compared to a conventional Cell-Averaging Constant False Alarm Rate (CA-CFAR) detector. A proposed hybrid of the two detectors, denoted CA-OMP, was also evaluated. The results indicate that the OMP detector can resolve closely spaced targets and targets in the presence of strong clutter more effectively than CA-CFAR, particularly in simulated data. However, on real data it is unable to fully suppress detected signal components, resulting in false alarms and degraded detection performance across the surveillance space. The CA-OMP detector exhibited improved detection performance on real data compared to the CA-CFAR detector, while mitigating most of the incorrect detections generated by the OMP algorithm.
Optimization and Analysis of Sector Coupled Flexible Energy System
(2026) Pardo, Anna; Ratka, Julia
Modern civilization is dependent on electricity, often generated from fossil fuels. Meanwhile, the global transition toward renewable energy sources and decarbonization has led to an increased demand for flexible energy systems. Challenges such as power peaks, fluctuating electricity prices, limited grid capacity, and the increasing share of renewable energy sources require buildings to be designed in a way that it becomes capable of controlling, storing, and shifting energy use over time. This report describes a scenario-based study that investigates sector coupling solutions and electrical energy storage methods with the goal to asses their potential to reduce power peaks and enhance local energy flexibility. The scenarios are simulated in Python for Power System Analysis (PyPSA) software. The data was obtained from a literature study as well as from a property project by Bengt Dahlgren AB. This study also evaluates the solutions from economicaland environmental perspectives. The results indicate that there are various storage methods that contribute to a more flexible energy system, particularly when combined with local power production and sector coupling. After simulating the scenarios, the findings in the report suggest that many technologies, such as hydrogen tanks and Vehicle to grid (V2G), are a key component to a transition of industries and heavy vehicles to fossil-free. However, based on analysis of the results, they are technologies that need further development and standardization in order to be a viable alternative. After evaluation from a technical- , environmental- and economical perspective, the results suggest that the accumulator tank in combination with heat pumps is the most optimal alternative for the property area investigated in this study. Furthermore, integration of solar photovoltaic cells seems to contribute to a reduction of power peaks by being a support to the grid, mostly during the days with many sun hours. Overall, the findings suggest that integrated system solutions, such as battery storage systems, thermal tanks, hydrogen tanks, have the potential to reduce peak demand and improve the utilization of renewable energy sources. Thermal tank scenario, that turned out to be the most optimal scenario in the study, offers economic and environmental benefits, while it also reducing power peaks. The heat demand can be met, without using the grid, by using the energy stored in the tank.
Preliminär dimensionering och produktionsplanering av en platsgjuten plattrambro
(2026) Engström, Axel; Isaksson, Victor
Mellan Götene och Mariestad planeras en ny vägsträckning och utbyggnad av E20 där totalt 13 broar planeras uppföras. En av dessa broar ligger till grund för arbetet där en preliminär dimensionering ska göras utifrån en preliminär förslagsskiss och platsens förutsättningar. Syftet med arbetet är att undersöka tre olika tvärsnitt av en överbyggnad och studera hur byggbarheten varierar mellan dessa och vilka målkonflikter som uppstår kopplade till byggbarhet. Dimensioneringen har utförts utifrån Eurokods krav på bärförmåga och beständighet där en längsgående 1 meterstrimla av brobanan studerats. Byggbarheten har beaktats utifrån armeringsinläggningens komplexitet och armeringsmängden. Resultatet visar att slankare tvärsnitt resulterar i en lägre materialdriven klimatpåverkan men ökar även risken för en försämrad byggbarhet då en högre armeringsmängd krävs. På motsvarande sätt skapar ett större tvärsnitt ökade förutsättningar till en bättre armeringsinläggning men även risken för en försämrad klimatpåverkan. Slutsatsen av arbetet är att dimensionering av konstruktioner inte exklusivt bör baseras på krav för bärförmåga och beständighet utan även att klimatpåverkan och byggbarhet bör tas hänsyn till i ett tidigt skede. Studien visar en tydlig målkonflikt mellan klimatpåverkan och byggbarhet. En avvägning måste därför göras kring vilken aspekt som prioriteras i projektet, då val av tvärsnittshöjd påverka utfallet.