Signal Processing of MEMS Gyroscope Arrays to Improve Accuracy Using a 1st Order Markov for Rate Signal Modeling

This paper presents a signal processing technique to improve angular rate accuracy of the gyroscope by combining the outputs of an array of MEMS gyroscope. A mathematical model for the accuracy improvement was described and a Kalman filter (KF) was designed to obtain optimal rate estimates. Especially, the rate signal was modeled by a first-order Markov process instead of a random walk to improve overall performance. The accuracy of the combined rate signal and affecting factors were analyzed using a steady-state covariance. A system comprising a six-gyroscope array was developed to test the presented KF. Experimental tests proved that the presented model was effective at improving the gyroscope accuracy. The experimental results indicated that six identical gyroscopes with an ARW noise of 6.2 °/√h and a bias drift of 54.14 °/h could be combined into a rate signal with an ARW noise of 1.8 °/√h and a bias drift of 16.3 °/h, while the estimated rate signal by the random walk model has an ARW noise of 2.4 °/√h and a bias drift of 20.6 °/h. It revealed that both models could improve the angular rate accuracy and have a similar performance in static condition. In dynamic condition, the test results showed that the first-order Markov process model could reduce the dynamic errors 20% more than the random walk model

Error budget for geolocation of spectroradiometer point observations from an unmanned aircraft system

We investigate footprint geolocation uncertainties of a spectroradiometer mounted on an unmanned aircraft system (UAS). Two microelectromechanical systems-based inertial measurement units (IMUs) and global navigation satellite system (GNSS) receivers were used to determine the footprint location and extent of the spectroradiometer. Errors originating from the on-board GNSS/IMU sensors were propagated through an aerial data georeferencing model, taking into account a range of values for the spectroradiometer field of view (FOV), integration time, UAS flight speed, above ground level (AGL) flying height, and IMU grade. The spectroradiometer under nominal operating conditions (8° FOV, 10 m AGL height, 0.6 s integration time, and 3 m/s flying speed) resulted in footprint extent of 140 cm across-track and 320 cm along-track, and a geolocation uncertainty of 11 cm. Flying height and orientation measurement accuracy had the largest influence on the geolocation uncertainty, whereas the FOV, integration time, and flying speed had the biggest impact on the size of the footprint. Furthermore, with an increase in flying height, the rate of increase in geolocation uncertainty was found highest for a low-grade IMU. To increase the footprint geolocation accuracy, we recommend reducing flying height while increasing the FOV which compensates the footprint area loss and increases the signal strength. The disadvantage of a lower flying height and a larger FOV is a higher sensitivity of the footprint size to changing distance from the target. To assist in matching the footprint size to uncertainty ratio with an appropriate spatial scale, we list the expected ratio for a range of IMU grades, FOVs and AGL heights.Deepak Gautam, Christopher Watson, Arko Lucieer and Zbynĕk Malenovsk

Low-cost solution for assessing performance in football teaching

Ao longo dos anos, a evolução da tecnologia a nível do desporto, neste caso particular no futebol, tem vindo a ser uma constante com implementações a nível do treino e jogo, com dispositivos de acompanhamento baseados em tecnologia GPS e ainda outros tipos de tecnologia que auxiliam a decisão dos árbitros durante os jogos como o recente vídeo arbitro. Apesar da tecnologia estar cada vez mais acessível hoje em dia, apenas clubes com maior poderio financeiro têm acesso à mesma, fazendo com que a diferença entre estes clubes e os restantes aumente. Acaba por ser um investimento relativamente avultado, tendo em conta que normalmente este tipo de dispositivos apenas consegue acompanhar um atleta de cada vez. Esta dissertação tem como objetivo propor um dispositivo de baixo custo baseado em sensores inerciais, que seja acessível à maioria dos clubes para fazer acompanhamento individual dos atletas em exercícios típicos durante a sua preparação física com foco na postura. O Pikku (nome do sistema) poderá auxiliar os treinadores para que os atletas tenham um melhor desempenho e melhor postura, que poderá ajudar no seu desenvolvimento e prevenção de lesões. Como demonstração de conceito sobre a validade do sistema, este foi avaliado em exercícios simples (abdominais) e em exercícios mais específicos do futebol (remate). Da análise dos resultados obtidos, apesar de algumas lacunas identificadas, foi possível identificar algumas características que poderão ser úteis aos atletas sem comprometer a aplicabilidade (preço e utilização) no seu acompanhamento.Over the years, the evolution of technology in sports, and in this particular case football, has been developing in a steady pace, with constant implementations training wise, thanks to devices powered by GPS technology and in an official game type context with the latest addition of the video assistant referee. Although the technology is nowadays more accessible, only the powerful clubs, the ones with the bigger financial power have access to it, increasing the gap between these bigger clubs and the clubs with fewer means. Making a purchase of such equipment ends up being a big investment because usually only one device can be used by a player at a time. This dissertation has the goal of closing this gap contributing with a low-cost device in order to be accessible to most of the clubs and to accompany players individually in typical exercises during their physical preparation with insight in their posture. Pikku(name of the system) can contribute to managers help players to achieve better performances and better postures that might help in their development and the prevention of injuries. In order to demonstrate the concept about the validity of the system some exercises were arranged, these range from simple exercises (abdominals) to football-specific exercises (shooting). From the results obtained, regardless of some deficiencies identified, it was possible to identify characteristics that might be useful to the players without compromising the applicability (price and usage) in their monitoring.Mestrado em Engenharia Eletrónica e Telecomunicaçõe