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# Plataforma de desenvolvimento

## Apresentação em tema: "Plataforma de desenvolvimento"— Transcrição da apresentação:

Plataforma de desenvolvimento
Foi escolhida a Plataforma de simulação MatLab/Simulink <---> FlighGear (X-Plane se encontra em processo de teste) Flight Gear Simulator UDP 5500 Barometric Altimeter and Inertial Navigation System & GPS

Unidade Barometrica Recomendação do filtro pasabaixa análógico 650Hz.
Recomendação de filtro Butterworth 2do orden fc= 10Hz? Programação do filtro digital interno do TI ADS1255. O filtro digital interno TI trabalha até 32KSPS A resposta do MPXA4115 = 1ms. Filtro Butterworth maximally flat magnitude Advantages: Maximally flat magnitude response in the pass-band. Good all-around performance. Pulse response better than Chebyshev. Rate of attenuation better than Bessel. Diavantages: Some overshoot and ringing in step response. This filter has the flattest possible pass-band magnitude response. Attenuation is -3dB at the design cutoff frequency. Attenuation beyond the cutoff frequency is a moderately steep -20dB/decade/pole.The pulse response of the Butterworth filter has moderate overshoot and ringing Inertial Navigation System & GPS

Unidade Barometrica No modelo foi considerada a função de transferencia do datasheet. FIR Filters = Finite Impulsional Response Filters y(n)= SIGMA(bk*x(n-k)) It only depends on the input coefficients IIR Filters = Infinite Impulsional Response Filters y(n)= SIGMA(ak*y(n-k)) + SIGMA(bk*x(n-k)) It depends on the input coefficients and the ouput coefficients of the filter IIR Filters are the only one used (Am I right?) because of the advantages described then, but I wonder if they are very good to use because of their disadvantages: Advatages and disadvantages of using IIR filters: + Advantages : They need an order less important than FIR filters to make the same filter (with approximately a factor 10, even if it depends a lot of the characteristics of the filter) - Disadvantages : -They can introduce an instability, so it results in a high frequency sound, because of the recursivity of the filter -You can have an instability of the poles in the z-transform if the poles are to close to the instability circle (it has a link with the previous point, doesn't it?), so by using IIR Filters, you need to take care of that when concatening the coefficients of the filter, when using fixed point technology. -They don't have a linear phase, contrary to the FIR Filters. FIR filters have the same behavior than analog filters in phase. So a teacher told me that audiophilics would prefer to hear FIR filters, because it sounds more comfortable. It's surprising because I had always heard that ears were only sensible to frequency, not to phase. I would like to have your opinion and/or articles about that point if you know about it. If using IIR filters really doesn't sound good, one of a solution by keeping the advantage of low cost of IIR filters (order of filter less important) could be to use a FIR "dephaser" filter, which have the opposite phase of the IIR filter and a unity gain, in order to cancel the non-linear variations of the global phase. So IIR filter + FIR dephaser filter = FIR Filter, and it reduces the global order. I worked on it during my courses, so if someone wants the matlab source code, tell me. Inertial Navigation System & GPS

Altimetro Barometrico
Teste da US Standard Atmosphere 1976 Logo de verificar os limites da função no Wolfram Mathematica para achar os coeficientes da equação: Unidades SI; TROPOSPHERE Km; dTH= ; R= ; g= ; T0=288.15; P0=101325; a=T0/-dTH b=-dTH*R/g h[p_]=a (1- (p/P0)b) ` ( ` p `) ( p ) h[0] h[101325] 0. Inertial Navigation System & GPS

RoC Rate of Climb As dificuldades na derivação da altitude para achar a RoC fazerm necessário a escolha de um filtro. Foi escolhido o filtro Wahsout Roc[s]=s/((1+T1s)(1+T2s)) fa <1/T1 e 1/T2 < N (largura de banda do ruido do sensor) Inertial Navigation System & GPS

IAS (Indicated Airspeed)
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GPS/INS complementary characteristics
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Descentralized GPS/INS integration Inertial navigation systems with geodetic applications Por Christopher Jekeli Inertial Navigation System & GPS

Difference between INS and GPS Descentralized processing
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Centralized GPS/INS integration Inertial navigation systems with geodetic applications Por Christopher Jekeli Inertial Navigation System & GPS

Cycle Ambiguaty Detection INS/GPS Centralized Integartion
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Dificuldades Definir os passos de propagação e atualização.(asíncrono ou síncrono) Exemplo 85Hz propagação e 20Hz atualização. O algoritmo de inversão de matrizes (erros por determinantes muito pequenos, precisão) Exemplo: Gauss Jordan Desempenho esperado: Attitude , Latitude, Longitude e Altura. Requisito para pouso e decolagem automatico, erro: 0.2 m e 0.5° 1997 Joseph Brown (Covariance modification) 1999 Koifman Inserção do modelo dinâmico da plataforma. Inertial Navigation System & GPS

Dificuldades Erros de integração fixed-step, fazem diverger rapidamente o INS sem KF. Definição da arquitetura do filtro (centralizado, desacoplado). Definição do vetor de estados. Definição do tipo de filtro: KF Linear, EKF, UKF, CKF. No caso de usar um EKF, avaliar o metodo Bierman-Thornton. Inertial Navigation System & GPS

Dificuldades 2008 Jay A. Farrell AIDEDNAVIGATION GPS with High Rate Sensors
Specification of the initial error covariance matrix P is often a cause of difficulties. Being careless in the definition of P, especially the portions of P related to the attitude errors, can have serious detrimental effects on the performance of the system. It is often best to use the sensor readings during a short period at the start of operation to initialize the state vector. Based on the statistics of the sensor measurements and the initialization period duration, the error covariance matrix P can be specified reasonably. Inertial Navigation System & GPS

Cascata Tress-Stage INS/GPS Eldredge Thesis IMPROVED STATE ESTIMATION FOR MINIATURE AIR VEHICLES Inertial Navigation System & GPS

Tree-Stage 2004 DESIGN AND DEVELOPMENT OF DSP BASED GPS-INS INTEGRATED SYSTEM Bhaktavatsala S
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Integration of INS and GPS System Using Kalman Filtering 2004 Vikas Kumar
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