In this article, rigid-body attitude tracking using vector measurements and gyro rate is studied. A gyro-bias observer and an attitude tracking controller are first devised, which in combination ...ensure the exponential stability of the desired equilibrium of the overall system. To address inertia-matrix uncertainties and external disturbances, an adaptive controller relying on a modified gyro-bias observer and a disturbance estimator are then developed. Simulations are included to illustrate the proposed adaptive controller under realistic conditions.
This paper presents a novel Lagrangian approach to attitude tracking for rigid bodies. The 4-DOF Lagrangian dynamics presented in this paper describes the rotational rigid motion on the unit sphere. ...Energy conservation property is explored, which holds on the entire unit quaternion group. This enables one to address the full attitude control problem where the attitude may evolve on the entire rotation group and to design controllers to track any desired attitude by leveraging the rich literature on energy-shaping based control methodology in Euclidean space. Global exponential tracking on the unit quaternion group is achieved using a simple potential function. In addition, the adaptive technique is used to deal with unknown on-orbit torque disturbances and uncertainties of the inertia matrix. Simulations are included to illustrate the theoretical results.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper proposes a new angular velocity observer for attitude tracking of spacecraft based on contraction analysis. The observer is designed in the inertial reference frame via estimating the ...inertial angular momentum to avoid the square term of the angular velocity when the spacecraft dynamics is expressed in the body frame. It employs a continuous angular-velocity dependent innovation term generated by means of a simple first-order linear filter, instead of a discontinuous attitude-dependent innovation term commonly used in angular velocity observer designs, resulting in a smooth behavior. The global exponential convergence is achieved. Moreover, when combined with the exponentially convergent tracking controller devised in this paper, it gives an overall system with exponential stability relying on a separation property. Finally, a switching function with hysteresis is introduced to stabilize the closest equilibrium in the configuration space, achieving the global exponential stability. Numerical simulations are included to illustrate the performance of the proposed observer in the closed loop, comparison with similar results, and robustness verification under inertia parameter uncertainties and noisy measurements.
•A novel angular velocity observer with separation property is designed.•Global exponential convergence is shown for the proposed observer, relaying on contraction analysis.•Two attitude tracking controllers are developed in a controller-observer scheme, resulting in an overall convergent system in view of the contraction of hierarchical systems.•The separation property and robustness of the proposed controller-observer schemes are analyzed and illustrated through numerical simulations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To determine whether time-to-intubation was associated with higher ICU mortality in patients with COVID-19 on mechanical ventilation due to respiratory insufficiency.
We conducted an observational, ...prospective, single-center study of patients with confirmed SARS-CoV-2 infection hospitalized with moderate to severe ARDS, connected to mechanical ventilation in the ICU between March 17 and July 31, 2020. We examined their general and clinical characteristics. Time-to-intubation was the time from hospital admission to endotracheal intubation.
We included 183 consecutive patients; 28% were female, and median age was 62 years old. Eighty-eight patients (48%) were intubated before 48 h (early) and ninety-five (52%) after 48 h (late). Patients intubated early had similar admission PaO2/FiO2 ratio (123 vs 99; p = 0.179) but were younger (59 vs 64; p = 0.013) and had higher body mass index (30 vs 28; p = 0.006) compared to patients intubated late. Mortality was higher in patients intubated late (18% versus 43%), with admission PaO2/FiO2 ratio < 100 mmHg (OR 5.2; p = 0.011), of older age (OR 1.1; p = 0.001), and with previous use of ACE inhibitors (OR 4.8; p = 0.026).
In COVID-19 patients, late intubation, Pafi <100, older age, and previous ACE inhibitors use were associated with increased ICU mortality.
•Time to intubation maybe associated with an increase in mortality in hypoxemic COVID-19 patients.•COVID-19 patients > 60 years-old, admitted with PaO2FiO2 ratio < 100 may have higher ICU mortality when intubated after 48 h.•Patients admitted with PaO2FiO2 ratio < 100 intubated > 48 h have worse lung mechanics than similar patients intubated < 48 h.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract The COVID-19 pandemic has intensely affected the quality of life and labor conditions of healthcare workers (HCWs). This study sought to understand the experiences of 16 professionals in ...medicine, nursing and physical therapy who work on the “frontline” of the new Coronavirus. A phenomenological design was used. Results were organized into four axes: (a) the impact of the arrival of the pandemic; (b) participants’ progressive exhaustion; (c) fear and coping; and (d) rethinking life and death. Experiences of anguish, anxiety, depression, and physical and psychological health problems stand out. It was possible to observe that the lack of national coordination, in addition to unscientific political positions, were felt as an aggravating factor for work demands, and that impotence in the face of the disease implicated in rethinking the meaning of life and death. According to the JD-R model, the need to expand resources and emotional support so HCWs can properly manage psychosocial risk factors at work is evident.
Resumen La pandemia ha afectado intensamente la calidad de vida y condiciones laborales de los trabajadores de la salud (TS). Este estudio buscó conocer experiencias de 16 profesionales de medicina, enfermería y fisioterapia que trabajan en la “primera línea” del nuevo coronavirus. Se utilizó diseño fenomenológico. Los resultados se organizaron en: (a) el impacto de la llegada; (b) desgaste progresivo; (c) miedo y confrontación; y (d) repensar la muerte y la vida. Se destacan experiencias de angustia, ansiedad, depresión, problemas de salud física y psicológica. Se observó que la falta de coordinación nacional, sumada a posiciones políticas acientíficas, fue un agravante de demandas laborales y que la impotencia frente a la enfermedad implicaba repensar el sentido de la vida y la muerte. Desde el modelo JD-R, es evidente la necesidad de ampliar recursos y apoyo emocional a los TS para gestionar adecuadamente los Factores de Riesgo Psicosocial en el Trabajo.
Resumo A pandemia vem afetando intensamente a qualidade de vida e condições laborais dos trabalhadores da saúde (TS). Este estudo teve por objetivo compreender as vivências de 16 profissionais da medicina, enfermagem e fisioterapia que atuam na “linha de frente” do novo coronavírus. Empregou-se desenho fenomenológico. Os resultados foram organizados em quatro eixos: (a) o impacto da chegada; (b) desgaste progressivo; (c) medo e enfrentamento e (d) repensando a morte e a vida. Destacam-se vivências de angústia, ansiedade, depressão, agravos à saúde física e psicológica. Foi possível observar que a falta de coordenação nacional somada a posicionamentos políticos anticientíficos foi sentida como agravante das demandas laborais e que a impotência diante da doença implicou repensar o sentido da vida e da morte. Com base no modelo JD-R, fica evidente a necessidade de ampliar recursos e suporte emocional aos TS a fim de administrar adequadamente os Fatores Psicossociais de Risco no Trabalho.
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NUK, ODKLJ, UL, UM, UPUK, VSZLJ
Abstract Attitude tracking on the unit sphere of dimension 3 based on sliding mode is considered in this article. The tangent bundle of Lagrangian dynamics that describes the rotational motion of a ...rigid body is first equipped with the structure of a Lie group, then a sliding subgroup emerged on it is defined. Next, a sliding‐mode controller is designed for attitude tracking that relies on an intrinsic error defined on the Lie group. Almost global asymptotic stability of the closed loop is demonstrated using the Lyapunov analysis. Comparisons of the proposed geometric sliding mode controller designed on the nonlinear manifold with one designed in the Euclidean space showed that under the same working conditions the former is more energy efficient, more robust to measurement noises, and has a shorter and smoother transient response.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
O objetivo deste artigo foi analisar as políticas públicas que garantem os direitos das pessoas com deficiência no Brasil e em Moçambique, a fim de identificar convergências e divergências entre ...elas. O estudo realizado foi de caráter qualitativo, de cunho documental, por meio da seleção e análise das legislações de ambos os países e documentos jurídicos de origem nacional e internacional que regulam os direitos das pessoas com deficiência. Constatou-se que, em Moçambique, não foram identificadas políticas específicas para auxiliar na proteção de determinados grupos de pessoas com deficiência. No Brasil, embora existam políticas específicas, percebeu-se a necessidade de ampliar os estudos no sentido de compreender o alcance das ações propostas em termos legais, isto é, perceber até que ponto os termos legais são efetivamente incorporados.
Introducción. Este artículo presenta los resultados de un estudio sobre la inclusión social de mujeres del ámbito rural a través de la adquisición de la competencia digital básica. Su objetivo ...fundamental es conocer el nivel de habilidad adquirido en las diferentes competencias asociadas al nivel básico según dicho modelo, analizar en qué medida estos aprendizajes han mejorado su nivel de competencia digital, considerando también si existen diferencias a nivel sociodemográfico según variables de edad, nivel académico, situación familiar y laboral. Método. Para ello, se ha aplicado un cuestionario sobre competencia digital básica e inclusión sociolaboral a 240 mujeres de entornos rurales participantes en programas de alfabetización digital para el empleo, con edades comprendidas entre 18 y 65 años. Resultados. Los resultados muestran un nivel de competencia digital adquirida que permite el uso intermedio de manejo de algunas herramientas de procesamiento de texto y el uso de portales de internet y redes sociales como Facebook, encontrando diferencias significativas en las mujeres en función de su edad y situación familiar y laboral. En el caso de recursos de un nivel más avanzado relacionados con la inclusión sociolaboral como las aplicaciones LinkedIn y herramientas en la nube, existe un mayor desconocimiento y una mayor dificultad en su manejo y aplicación práctica. En este sentido, se encuentran similitudes con otras investigaciones realizadas con mujeres del ámbito rural, en cuanto a la brecha digital de género existente y su relación con las dificultades en la inserción de estas personas en el mercado laboral. Discusión. La discusión de resultados presenta algunas implicaciones para la formación de una ciudadanía digital según el modelo DigComp2.1 y la necesidad de programas formativos en esta materia, específicamente orientados a mujeres del ámbito rural.
Relying on contraction analysis, this paper addresses the global attitude tracking problem of a spacecraft when angular velocity measurements are corrupted by bias. A nonlinear observer with ...exponential convergence is designed firstly to estimate the bias in gyro sensors. Then an exponentially convergent attitude tracking controller with gyro bias correction is devised. Next, to remove the topological constraints of unit quaternions for global stability, a switching variable with hysteresis is incorporated in the control loop, enhancing the robustness in the presence of measurement noise and energy efficiency by preventing the unwinding phenomenon. Numeric simulations are shown to illustrate the performance and compare with other similar controllers in terms of tracking error, estimation error and energy efficiency, as well as the robustness to noisy measurements and time-varying bias in gyro sensors.
•A nonlinear gyro bias observer with global exponential convergence is designed based on quaternion kinematics.•An attitude tracking controller with global exponential convergence is devised.•A global exponential unwinding-free version of the previous controller is developed.•Comparison of the proposed controller with three representative controllers reported in the literature is carried out through numerical simulations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This article addresses the problem of designing a nonlinear navigation observer for quadrotor unmanned aerial vehicles (UAVs) using vector measurements and a GPS sensor. The observer has a cascaded ...structure and consists of a rotational state (angular velocity and attitude) observer and a translational state (position and linear velocity) observer. Based on the Lyapunov analysis, it is shown that the angular velocity observer is globally exponentially stable, the attitude observer is almost globally asymptotically stable, and the translational state observer is globally exponentially stable under a mild assumption on the attitude estimation error. The cascaded structure facilitates convergence analysis and observer implementation. The performance of the proposed observer was compared with that of an angular velocity observer reported in the literature in numerical simulations and validated through experiments.
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