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Senast publicerade

Improvement of Carry-back Problem on Dumper Body
(2026) Sapre, Saket Sharad
Carry-back in hauler dumper bodies can reduce unloading efficiency and result in material being transported back to the loading area. This thesis investigates potential methods for reducing carry-back, with particular focus on solutions applicable to battery-electric haulers. The work began with an investigation of the carry-back problem and its influencing factors, followed by the development and screening of several solution concepts. Two approaches were selected for further study: a material-based approach involving UHMW-PE liners and geometric modifications, and an energy-based approach involving the heating of selected dumperbody surfaces. The material-based approach was investigated using Discrete Element Method simulations in Altair EDEM, while the energy-based approach was examined through engineering calculations of the required heating energy. The study considers the influence of surface properties, dumper-body geometry, operating conditions, and energy requirements on carry-back reduction. Field observations from an UHMW-PE liner application were also included to provide practical context for the material-based approach. In addition, the energy-based approach was assessed for different heating scenarios, including the potential use of the traction battery in a battery-electric hauler as the energy source. The findings provide a basis for comparing material-based and energy-based concepts and for identifying requirements for their continued development and validation.
Kv. Varianten
(2026) Ölme, Frida
Active Yaw Rate Stabilization for Steer-by-Wire Cars
(2026) Faddawi, Mohammad; Janmark, Elmer
The automotive industry is transitioning toward Steer-by-Wire (SbW) technology, which eliminates the traditional mechanical connection between the steering wheel and the road wheels. While a baseline SbW system actively controls the steering rack position based on driver input, the vehicle’s overall lateral dynamics can lack sufficient damping to naturally reject macroscopic body disturbances, such as crosswinds or trailer sway. This thesis develops and physically validates a closed-loop active lateral stabilization system that utilizes the SbW actuator as a continuous yaw rate correction channel. An ideal, undisturbed vehicle response is established using a linear single-track reference model. Against strict hardware constraints specifically a 50 ms actuation delay. A model-free Proportional (P) controller proved superior to model-based alternatives, guaranteeing absolute stability and preventing the delay-induced oscillations that arose with more complex algorithms. Dynamic track testing in the prototype vehicle, including lane changes, trailer towing and subjective evaluation. The tests both objectively and subjectively confirmed that the active controller significantly improved disturbance attenuation without corrupting the driver’s intended trajectory by reducing the yaw rate error, increasing responsiveness and improving stabilization compared to the unassisted vehicle. The feedback controller also demonstrated robust reference tracking despite unmodeled physical parameter variations, such as changes in tires and shifts in mass distribution, without requiring real-time system recalibration.
Digital Predistortion for Power Amplifier Linearization in Radar-Communication Shared Apertures
(2026) Müntzing, Måns
Shared radar and communication apertures are commonly optimized with radar performance as the primary design objective. As a result, transmitter operating conditions such as output power and amplifier efficiency are often chosen in a way that is sub-optimal for communication performance. In particular, operating a power amplifier close to compression improves efficiency and radar signal-to-noise ratio, but introduces nonlinear distortion that degrades communication metrics. This thesis investigates the use of digital predistortion as a software-based linearization technique for communication signals transmitted through commonly utilized radar power amplifiers. Two amplifier models are considered: a memoryless Saleh model representing a traveling-wave tube amplifier (TWTA), and a generalized memory polynomial (GMP) model representing a solid-state power amplifier (SSPA) with nonlinear memory effects. Four communication waveforms are evaluated: two single carrier waveforms and two orthogonal frequency-division multiplexing (OFDM) waveforms. Digital predistortion models are trained using an indirect learning architecture and assessed in terms of linearization performance, model complexity, robustness to noise, and sensitivity to amplifier mismatch. The results show that digital predistortion can significantly reduce nonlinear distortion without requiring changes to the radio frequency hardware. For the memoryless TWTA model, a low-complexity memoryless polynomial predistorter provides sufficient linearization performance. For the memory-dependent SSPA model, memory depth is the dominant factor affecting performance, especially for OFDM-based waveforms. Polynomial order and cross terms provide additional improvements, but with diminishing returns. Further analysis also shows that the predistortion models are robust to moderate noise and amplifier variations, although the SSPA model case is more sensitive to nonlinear memory mismatch. Overall, the thesis demonstrates that digital predistortion is a promising approach for improving communication performance in shared radar-communication transmitter systems.
Vehicle Level EMC Performance Prediction from Component Test Results
(2026) Li, Wenda; Fang, Shinuo
This thesis investigates the feasibility of predicting vehicle-level Electromagnetic Compatibility (EMC) performance from component-level testing and simulation. Using an automotive wiper drive system as the case study, the work aims to reduce dependence on costly and time-consuming whole-vehicle EMC tests by establishing an integrated methodology combining empirical measurement and numerical modeling. Component-level conducted and radiated emission tests were performed in accordance with Comité International Spécial des Perturbations Radioélectriques (CISPR) 25, and the measured common-mode currents were used as excitation sources in Computer Simulation Technology (CST) Studio Suite simulations. The correlation between measured and simulated electric fields in the 150 kHz–30 MHz range showed close agreement, confirming that measurement-driven source modeling can accurately reproduce radiated emission behavior. The validated component model was then extended to a full-vehicle electromagnetic simulation, where near-field coupling and grounding effects were analyzed. Results indicate that component-based models can qualitatively predict vehicle-level trends, offering engineers an early-stage diagnostic tool for identifying potential EMC risks. Although full substitution of physical vehicle testing remains challenging due to modeling and computational limitations, the proposed hybrid workflow demonstrates a practical pathway toward simulation-supported EMC development, aligning with the automotive industry’s goals for faster, more efficient, and cost-effective design validation.