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

IMU-Based Posture Monitoring for Rehabilitation Applications
(2026) Zhou, Yi
Accurate assessment of posture is important in rehabilitation-related applications, where abnormal body alignment may contribute to musculoskeletal discomfort, altered movement patterns, and reduced functional performance. Inertial Measurement Units (IMUs) provide a portable and low-cost alternative to laboratory-based motion capture systems for posture monitoring. This thesis investigated the accuracy and reliability of IMU-based posture estimation using Movella DOT sensors, with a Qualisys optical motion capture (MoCap) system used as the reference measurement. Four sagittal posture variables were evaluated: pelvic tilt, thorax tilt, thorax–pelvis relative alignment, and forward head posture (FHP). The influence of breathing on thorax-mounted IMU measurements was investigated, and the feasibility of IMU-based respiration monitoring was also explored. The results demonstrated good agreement between IMU-based posture estimates and the MoCap reference for pelvic tilt, thorax tilt, and thorax–pelvis alignment, with mean RMSE values of 0.86◦, 1.65◦, and 1.82◦, respectively, and ICC values above 0.96 for all three variables. Forward head posture showed lower agreement and greater inter-subject variability. The comparison between Euler-angle–based and quaternion-based methods revealed only minor differences under the evaluated posture conditions. Deep breathing introduced visible oscillations and increased variability in thorax-mounted IMU signals, although overall IMU–MoCap agreement remained high. IMU-based respiration monitoring demonstrated moderate to strong agreement with a respiratory belt reference during deep breathing, but lower reliability during normal breathing. Overall, the findings indicate that IMU-based sagittal posture estimation is feasible for rehabilitation-related posture monitoring, particularly for pelvic and thoracic measurements.
Säker människa-robot-interaktion i fotorealistisk simuleringsmiljö
(2026) Berg, Eric; Wallerstedt, Calle; Alnervik, Wilhelm; Bengtsson, Tilda; Kristensson, Simon; Forsberg, Sofia
The development of automated industrial environments increases the need for a safe and efficient transition toward fully automated factories where humans and robots can collaborate. One effective approach for enabling this is the creation of a digital twin that can replicate reality within a simulated environment for simulation, testing, and validation before implementation in real production environments. This bachelor’s thesis investigates how 3D Gaussian Splatting (3DGS) can be used to create a realistic digital twin of an industrial robot cell. The model is based on the RITA-cell, a kitting environment containing a collaborative robot arm (cobot), and is implemented in the Unity game engine for simulation and visualization. The project includes the development of a 3DGS-based simulation model integrated into Unity. In addition, an algorithm for generating synthetic training data and a YOLO-based segmentation model were implemented for identifying components within the RITA-cell. Motion planning for the cobot was developed through com munication between Unity and MoveIt using ROS 2, and a simplified sensor fusion solution was implemented to coordinate camera data in a shared coordinate system. These subsystems were primarily developed and tested as separate parts of the project. Furthermore, VR was chosen as the interaction method for visualization and manipulation of the simulated environment. The results show that 3DGS can be used in an efficient and practical way to create visually realistic digital environments, although with certain limitations related to mesh geometry, which resulted in challenges regarding collision handling and physical simulation. The developed environment showed potential as a platform for robotic application development, but the final demonstration should mainly be viewed as a proof-of-concept since motion planning and sensor fusion were not fully integrated into the final simulation environment. The conclusion is that 3DGS is well suited for creating visually realistic digital twins of industrial environments, but that the lack of straightforward mesh geometry integration makes it less suitable as a complete basis for physical simulation. The developed environment demonstrates potential as a platform for the development of robotic applications, provided that the visual model is combined with separate collision geometry and more robust integration of perception, sensor fusion, and robot control.
Fotorealistisk simulering av mobila robotar i fabriksmiljöer
(2026) Ekström, Sigrid; Sunnar, Adam; Wallin, Hugo; Håkansson, Filip; Kazlauskaite, Valerija; Edvinsson Björkman, Jonathan
Modern factories handle more components than ever before, creating major logistical challenges. As a solution, autonomous mobile robots (AMRs) are now being used. Training the behavior of these robots in real-world environments is expensive and time-consuming. For this reason, the possibility of using simulated environments built with 3D Gaussian Splatting (3DGS) is being investigated as an alternative to real-world training. This bachelor’s thesis evaluates whether the simulation environment can be used to collect synthetic data for a segmentation model for object localization, which in turn can enable the control of AMRs. The method involved filming industrial environments which could then be used to create a digital twin using a 3DGS model. From the 3D model, a simulation environment was created through synthetic dynamic and static objects that replicate the real industrial environment. Synthetic data was then collected from the simulation environment which could be used to train a segmentation model. The fine-tuned model could be used for object localization and identification, which was utilized for the control of AMRs. The results showed that it is possible to produce photorealistic simulation environments of industrial environments, from which it is possible to produce large quantities of high-quality annotated data automatically. The instance segmentation model YOLOv8-Seg Nano was able to localize objects in the simulation environment in real time. Consequently, AMRs could be controlled using the segmented instances. The conclusion is that although perfect photorealism was not achived in this project, 3DGS proves to be a viable tool in towards complete realism. The resulting environment is however good enough to create synthetic training data that results in a segmentation model capable of predicting objects in real world photos.
Planering och styrning av en flotta autonoma mobila robotar med centraliserad rörelsespårning
(2026) von Brömsen, Julia; Edofsson, Elsa; Leffler, Tim; Lindblom, Oscar; Rajabi, Altaf; Strandberg, Debora
Autonomous mobile robots are increasingly utilized in logistical workflows and material flow management. The process of automating heavy transportations leads to increased efficiency of material handling while simultaneously decreasing manual labour. This study investigates the coordination of a scalable fleet of autonomous mobile robots (AMR) as they transition from logistical patterns to dynamic scenarios. External real time data about the location of a moving target is obtained from a drone based surveillance system whereas the fleet is traced in real time by a motion capture system with high precision localization. The realisation of the system is achieved through a strategy of efficient path planning and collision avoidance. An A* path planning strategy A* is implemeted which utilizes euclidean distance heuristics to minimize the cost between start and goal positions. This determines the optimal trajectory from inital, to designated position. As the fleet scales, the increasing number of agents leads to collisions and conflicts such as deadlocks. This issue is addressed through a multi agent path finding (MAPF) strategy evaluating a local collision resolver A* (LCRA*). LCRA* is based on the model lifelong priority based search (LPBS) and the benefit of using LCRA* is that it significantly improves computational performance as it does not require global time optimization to handle collisions locally. This results in a smooth transition between a logistical pattern mode or an intruder mode in order to collectively encircle the moving target.
Looking Beyond Marginal Pricing of Electricity Reimagining Market Design for a Near-Zero Marginal Cost Electricity System
(2026) Brechter, Erik; Eliasson, Adam
The Nordic power market is organized around an energy-only design in which marginal pricing of electricity and the merit order coordinate dispatch and, in principle, remunerate investment. As the generation mix shifts toward near-zero marginal cost sources, primarily variable renewables, hydropower and nuclear, the price signal that this design relies on becomes structurally weaker, while capitalintensive technologies depend on revenue predictability scarcity rents alone do not provide. This thesis examines how the transition toward near-zero marginal cost generation of electricity affects price formation, investment incentives and system adequacy in the Nordic context. It evaluates structurally distinct market design alternatives against the stated challenges. The study adopts a qualitative, abductive research design combining an integrative literature review with two rounds of semi-structured expert interviews. Four market designs are constructed and positioned along a spectrum of intervention: the energy-only status quo, a Mosaic model that layers complementary mechanisms onto the existing architecture, a Broadband model that anchors revenue in contracted capacity rather than delivered electricity, and a Command model based on centralized state planning. Each design is assessed against a five-criterion framework covering price formation efficiency, investment adequacy, system adequacy and flexibility incentives, regulatory and political feasibility, and stakeholder acceptance. The analysis finds that the Nordic clearing price currently remains functional largely due to hydropower’s water value mechanism and European market coupling rather than marginal pricing, and that scarcity rents tend towards becoming insufficient in order to incentivize long-term investment. No design dominates across all criteria, but the Mosaic model emerges as the most empirically supported and institutionally feasible direction. The Broadband and Command models address the underlying coordination problem, but at costs the Nordic and EU context cannot currently absorb. The central contribution of the thesis is to reframe the design question, rather than choosing between distinct market architectures. The more productive framing is which combination of complementary mechanisms best addresses the specific structural challenges the Nordic system faces at each stage of the transition.