Examensarbeten för kandidatexamen


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    Designing a PCB microstrip antenna array for 5G mm-wave frequencies Designing and testing a dual-polarized aperture-coupled microstrip patch antenna for the (26.5-29.5) GHz band
    (2024) Eriksson, Simon; Kraamer, Johanna; Bujalla, Per Ingmar; Ali Shah, Syed Ahsan; Chalmers tekniska högskola / Institutionen för elektroteknik; Chalmers University of Technology / Department of Electrical Engineering; Ström, Erik; Vilenskiy, Artem
    Abstract This report presents the development and testing of a dual linearly polarized patch antenna array. The designed antenna covers the frequency range of (26.5-29.5) GHz, which also is known as the 5G NR FR2 n257 band. The antenna went through multiple iterations of simulation in Ansys HFSS, starting with the construction of a single element that then served as a building block for a three element array. After completing the array in HFSS it was sent for manufacturing. The project compares the simulated results to the ones from the tested manufactured array. For the antenna to be effective in a communication scenario, targets were set for various performance aspects including the radiation pattern, total efficiency and scattering parameters (S-parameters). Each element in the array is aperture-coupled, cavity-backed and dual-polarized. The results showed that for a single isolated element, the peak broadside gain was 6.88 dBi for the vertical polarized port and 6.58 dBi for the horizontal polarized port. Moreover, the cross-polarization discrimination was > 14.6 dB, which suggest that it could be used for MIMO applications. It should be noted that these values are taken from the HFSS results as only the array and not the single element was manufactured. The manufactured antenna underwent multiple tests. The S-parameters were measured with a VNA, the radiation pattern was measured in an anechoic chamber and lastly the total efficiency was characterized in a reverberation chamber. All measured and simulated S-parameters achieved the target. Beam steering capabilities were also investigated by phase shifting each elements in post-processing from the accumulated data of the radiation pattern. The test results from the manufactured array follow the simulated ones well in its S-parameters and radiation pattern. The measured total efficiency was above > 75%. Finally, beam steering was achieved with a scanning range of ±44◦ for the simulated data and ±46◦ for the measured data.
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    Analyses of EMC- & Grid-connected Filters in an Electric Power-train
    (2024) Eriksson, Andreas; Ekborg, Tobias; Chalmers tekniska högskola / Institutionen för elektroteknik; Chalmers University of Technology / Department of Electrical Engineering; Maaskant, Rob; Andersson, Emil
    Abstract Epiroc have had a need to investigate the EMC and LCL-filters that are currently placed and operating in a lot of their vehicles. They have questioned whether or not their currently used capacitor and inductor-based filters are working adequately in filtering unwanted noise or if there could be a risk of wear to the system with prolonged operation and if any improvements could be made. This thesis has, with the help of Epiroc and extensive research, examined these questions in detail by conducting measurements on a drill rig vehicle at Epiroc’s facilities in Örebro. The thesis dives into areas such as Electromagnetic interference, electrical noise prevention methods and signal processing. The measurements indicated that both of the filters work and do filter unwanted noise, differences can be seen in the overall noise level. There are however some ideas outlined in this thesis that potentially could help increase the noise suppression of the filters.
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    DORA - Dexterous Robot Assistant Autonomous door opening with a mobile manipulator
    (2024) Bramsved, Felix; Gunterberg-Klase, Lukas; Hendriksen, Vincent; Schuchert, Ellen; Chalmers tekniska högskola / Institutionen för elektroteknik; Chalmers University of Technology / Department of Electrical Engineering; Zou, Changfu
    Abstract This thesis has focused on building a ROS based system for autonomous door detection and opening using a mobile manipulator. The mobile manipulator in question, DORA (Dexterous Robot Assistant), is based on the MiR200 mobile platform along with an UR10 robotic arm. The robot is equipped with an Intel realsense D435i depth camera. DORA had a navigation system and motion planning system for the arm already implemented and these systems were used in the process of this project. Object detection was achieved through a YOLO algorithm on the image stream from the depth camera, and pose estimation was done using the depth values obtained. The program was tested and found to be consistent and accurate when the robot was located in front of the door, but becomes unreliable in edge cases when the door is located at the edge of the field of vision or on an angle. The door opening program creates a trajectory for opening a door with unknown kinematics and an uncertain hinge location by utilizing readings from a force/torque sensor that is located between the arm and the end-effector, and the position of said end-effector. By employing the MoveIt framework, DORA was able to follow that trajectory and successfully open the door. Testing has confirmed that the force/torque sensor enables the program to operate successfully even in the presence of a 16% error in the estimation of the placement of the hinge position. In conclusion it has been determined that although further development in safety systems and increased versatility is required for real world use, a solid foundation for further work has still been created in this thesis and the capabilities of DORA to interact with the world has been greatly expanded.
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    Skärmning av benledare B250 vid hörselundersökningar - En utvärdering av passiva och aktiva skärmningsmetoder för möjliggörandet av pålitliga mätningar vid benledd hjärnstamsaudiometri för 250 Hz.
    (2024) Bengtsson, Alicia; Bursell Palm, Hugo; Emteborg Dabrio,, David; Steen, Victoria; Tomasson, Moa; Westerkull, Saga; Chalmers tekniska högskola / Institutionen för elektroteknik; Chalmers University of Technology / Department of Electrical Engineering; Reindeldt, Sabine; Fredén Jansson, Karl-Johan
    Abstract Auditory Brainstem Response (ABR) utilizes EEG to study the auditory system. When using bone-conducted sound, magnetic fields generated by the bone conductor interfere with the electrode measurements, and therefore air-conducted sound is primarily used. The purpose of this study is to present a method for shielding these aforementioned magnetic fields, particularly those generated by the bone conductor B250 during an ABR examination at 250 Hz. To achieve this objective, the interference was characterized by performing measurements on a watermelon with the following bone conductors: Radioear B71, Radioear B81, and Transducer B250. The watermelon was stimulated at 250 Hz for various sound levels. The results indicated that the interference is repeatable and that its amplitude increases with the stimulation level for all bone conductors. The tests also indicated that the interference generated by B250 is less significant than the interference generated by the other two bone conductors. Three passive shielding methods were then investigated: a wound copper coil, a copper tube without a lid, and a copper tube with a lid. The B250 conductor was positioned in the center of the different configurations, and measurements were taken at various stimulation levels. While all passive methods showed limited effectiveness, the copper coil yielded the best results. Additionally, an active shielding approach was investigated, involving two copper coils: a measuring coil monitoring B250’s interference and an anti-interference coil reducing the impact of the interference on the electrodes. To prevent the magnetic field generated by the anti-interference coil from affecting the measuring coil, a configuration where there is no mutual inductance was required. To find such a configuration, the coils were placed on top of each other with a partial overlap. The configuration was tested by monitoring the generated voltage. The measurement suggested the existence of such a position, and the same study was subsequently conducted in COMSOL multiphysics to determine a more precise theoretical positioning. The COMSOL study resulted in a position where the mutual inductance is zero, indicating that the shielding method is possible.
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    Intelligent Armbågsortos - Intelligent Elbow Orthosis
    (2024) Silfveroxel, Oliver; Silberberg, David; Bardun, Gustav; Chalmers tekniska högskola / Institutionen för elektroteknik; Chalmers University of Technology / Department of Electrical Engineering; Dean, Emmanuel; Laezza, Rita
    Abstract Physiotherapy is crucial for patients with pain or reduced function of muscles and joints. While mechatronic solutions exist to aid care, they are costly, complex, and lack portability. The goal of this project was to construct a smart elbow orthosis to enhance physiotherapy, allowing more accessible and personalized care. This project does not make any claims regarding the clinical efficacy or potential use of the system. The project has consisted of developing multiple different systems from the ground up, including an exoskeleton, tactile sensors, data communication system, and control system. Most of these systems were merged successfully and their functions evaluated. The primary issues encountered concern the communication between devices, and the integration of the controlling algorithms, both of which seem solvable. This limits the current use of the system in following pre-determined trajectories. Data from the tactile sensors can still be collected, though at its current stage, cannot be used to adapt the motion of the orthosis. Although the implementation is not complete, the core idea shows promise, meaning mechatronic solutions might be a valuable step in reducing barriers of entry, and improving care in physiotherapy.