numerical problems in the calculation of electric field and charge density profiles for mass impregnated non-draining hvdc cables subjected to fast polarity reversals

The goal of this simulation thesis is to present a tool for studying and eliminating various numerical problems observed while analyzing the behavior of the MIND cable during fast voltage polarity reversal. The tool is built on the MATLAB environment, where several simulations were run to achieve oscillation-free results. This thesis will add to earlier research on HVDC cables subjected to polarity reversals. Initially, the code does numerical simulations to analyze the electric field and charge density behavior of a MIND cable for certain scenarios such as before, during, and after polarity reversal. However, the primary goal is to reduce numerical oscillations from the charge density profile. The generated code is notable for its usage of the Arithmetic Mean Approach and the Non-Uniform Field Approach for filtering and minimizing oscillations even under time and temperature variations.

Motion Control of an Advanced Electric Implement for Agricultural Autonomous Vehicles

Nowadays, the development of intelligent and autonomous vehicles used to perform agricultural activities is essential to improve quantity and quality of agricultural productions. Moreover, with automation techniques it is possible to reduce the usage of agrochemicals and minimize the pollution. The University of Bologna is developing an innovative system for orchard management called ORTO (Orchard Rapid Transportation System). This system involves an autonomous electric vehicle capable to perform agricultural activities inside an orchard structure. The vehicle is equipped with an implement capable to perform different tasks. The purpose of this thesis project is to control the vehicle and the implement to perform an inter-row grass mowing. This kind of task requires a synchronized motion between the traction motors and the implement motors. A motion control system has been developed to generate trajectories and manage their synchronization. Two main trajectories type have been used: a five order polynomial trajectory and a trapezoidal trajectory. These two kinds of trajectories have been chosen in order to perform a uniform grass mowing, paying a particular attention to the constrains of the system. To synchronize the motions, the electronic cams approach has been adopted. A master profile has been generated and all the trajectories have been linked to the master motion. Moreover, a safety system has been developed. The aim of this system is firstly to improve the safety during the motion, furthermore it allows to manage obstacle detection and avoidance. Using some particular techniques obstacles can be detected and recovery action can be performed to overcome the problem. Once the measured force reaches the predefined force threshold, then the vehicle stops immediately its motion. The whole project has been developed by employing Matlab and Simulink. Eventually, the software has been translated into C code and executed on the TI Lauchpad XL board.