Instrumentação e análise do consumo energético baseado na pose de um veículo elétrico de competição

Este trabalho tem como objetivo instrumentar um protótipo de veículo elétrico desenvolvido para competições universitárias de eficiência energética e testar o impacto de diferentes estratégias de pilotagem sobre o consumo de energia do mesmo. As estratégias adotadas para a análise e comparação de resultados se referem ao controle da velocidade de condução e a execução de dois traçados diferentes: minimizando a distância percorrida no circuito e outro suavizando a execução das curvas. O algoritmo que gera o traçado da rota de suavização de curvas foi desenvolvido neste trabalho, tendo como base a aplicação de conceitos de geometria analítica sobre as dimensões da pista e do protótipo. A instrumentação desenvolvida visou mensurar e coletar dados a respeito da posição e orientação do veículo, bem como as grandezas elétricas de tensão e corrente pertinentes a suas medidas de consumo. Os dados coletados a respeito da pose do veículo, inclinação lateral, inclinação frontal e orientação em relação ao norte geográfico da terra, tiveram por objetivo identificar comportamentos do piloto e características de relevo da pista que pudessem estar relacionados a características do consumo do veículo. Registros em vídeo dos ensaios por meio de uma câmera embarcada também complementaram a análise por meio da identificação de padrões de condução e adversidades nos percursos. O algoritmo de traçado de pista que visa suavizar as curvas foi ensaiado em circuitos similares aos circuitos de prova do protótipo, e a influência deste traçado sobre a eficiência energética do veículo foi relacionada com o traçado de menor distância usualmente executado durante as competições de eficiência.The objective of this work is to instrument an electric vehicle prototype developed for energy efficiency competitions, it also aims to test the impact of different driving strategies on energy consumption. The strategies adopted for the analysis and comparison of results will explore different vehicle speeds and the execution of two different traces: minimizing the traveled distance in the circuit and smoothing the execution of the curves. The algorithm that generates the smoothed curves route was developed in this work based on the application of analytic geometry concepts on the track and prototype dimensions. The instrumentation developed is capable to measure and collect data regarding the position and orientation of the vehicle, as well as the consumption values, based on voltage and current measurements. The data collected on vehicle pose, lateral inclination, frontal inclination and orientation in relation to geographic north of the earth, had the objective to identify pilot behaviors and characteristics of relief of the track that could influence consumption of the vehicle. Video footage of the trials was taken using an onboard camera that was used to improve the analysis by identifying driving patterns and adversities on the routes. The track layout algorithm developed to smooth the curves was tested in circuits similar to circuits of the prototype competition. The energy efficiency of this tracing was compared to the energy efficiency of the smaller distance trace usually executed during the efficiency competitions

Effects of Turning Radius on Skid-Steered Wheeled Robot Power Consumption on Loose Soil

This research highlights the need for a new power model for skid-steered wheeled robots driving on loose soil and lays the groundwork to develop such a model. State-of-the-art power modeling assumes hard ground; under typical assumptions this predicts constant power consumption over a range of small turning radii where the inner wheels are rotating backwards. However, experimental results performed both in the field and in a controlled laboratory sandbox show that, on sand, power is not in fact constant with respect to turning radius. Power peaks by 20% in a newly identified range of turns where the inner wheels rotate backwards but are being dragged forward. This range of turning radii spans from half the rover width to R', the radius at which the inner wheel is not commanded to turn. Data shows higher motor torque and wheel sinkage in this range. To progress toward predicting the required power for a skid-steered wheeled robot to maneuver on loose soil, a preliminary version of a two-dimensional slip-sinkage model is proposed, along with a model of the force required to bulldoze the pile of sand that accumulates next to the wheels as it they are skidding. However, this is shown to be a less important factor contributing to the increased power in small-radius turns than the added inner wheel torque induced by dragging these wheels through the piles of sand they excavate by counter-rotation (in the identified range of turns). Finally, since a direct application of a power model is to design energy-efficient paths, time dependency of power consumption is also examined. Experiments show reduced rover angular velocity in sand around turning radii where the inner wheels are not rotated and this leads to the introduction to a new parameter to consider in path planning: angular slip