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In this paper is presented the design, construction and evaluation of an autonomous mobile robot, designed to outdoor competitions. The category of outdoor competition, in Brazil named Trekking Pro, is based on a mobile robot in an open field, which must pass through preset coordinates. A commercial (at first remote controlled) robot was adapted for autonomous operation. The perception of the robot consists of 9-axis Absolute Orientation Sensor and an encoder. At fist, the system was simulated in a ROS (Robotic Operation System) environment integrated with a scene V-REP (Virtual Robot Experimentation Platform). PID controllers, were used in implementation. Afterwards, a prototype was built, that participated in a competition with success, winning the first place. Both simulation and real-world experimental results of the constructed prototype are shown in detail. The robot described in this paper was the champion of the Winter Challenge 2018 (Robocore - Brazil) in the Trekking Pro category.

The need for models that represent the behaviour of transformers operating in steady state or submitted to transient events is of great importance in studies involving power systems. In this context, this study presents a model used to represent the impedance frequency response of transformers at no load and under nominal conditions. In the model, networks of parameters with RLC cells are employed to reproduce the resonances present in the frequency responses and also RL network sections are used to represent the frequency-dependent effects in the core, which aid in the current damping during transient events. The parameter values of these networks are determined with the least-squares numerical method. To evaluate the model as well as the methodology to determine the parameter values, data originating from measurements of the frequency responses with frequency range from 10 Hz to 2 MHz of two single-phase transformers (16 kVA and 55 MVA) are used. Validations of the model are carried out in the frequency and time domains. The model can be used to simulate transformer operation under nominal conditions of voltage and frequency and also for a broad frequency spectrum.

Considering the importance of modeling the electri- cal power system behavior under high frequency transients, this paper aims to present a practical methodology to obtain a RL lumped parameters model of an air-cored reactor. Firstly, the RL frequency responses are obtained using the Finite Element Method (FEM). Thus, the frequency response is converted into a RL circuit in accordance with the classical series Foster model and its parameters values are calculated through Least Square (LS) fitting algorithm. Finally, the lumped parameters circuit is converted to an ATP network model. For validation purposes a well-known air-cored reactor is modeled for a frequency range from 10 Hz to 100 kHz and the frequency responses obtained with FEM, LS fitting and ATP are compared. Index Terms—Frequency response, Finite Element Method, Least Square, ATP, Air-cored reactor

This work presents the performance of the well-known program ATP-Alternative Transient Program applied to the simulation of continuous windings of transformer under the incidence of a voltage surge. The motivation for this analysis lies in the fact that once ATP is widely applied for circuit simulation in several conditions, it is expected that it can also be applicable to this problem that is of significant importance for transformer designer. If so, thanks to wide ATP availability designers will have available an easy and user friendly tool for helping in their designs. Basis of analysis is in new experimental data obtained by the authors as well as some other data presented in previously published paper, in which experimental data have also validated applicability of the TLM- Transmission Line Modeling Method for the same problem, known as a classical one for concerns of voltage insulation for transformer designers.