A Kalman Filter for Nonlinear Attitude Estimation Using Time Variable Matrices and Quaternions

[Abstract] The nonlinear problem of sensing the attitude of a solid body is solved by a novel implementation of the Kalman Filter. This implementation combines the use of quaternions to represent attitudes, time-varying matrices to model the dynamic behavior of the process and a particular state vector. This vector was explicitly created from measurable physical quantities, which can be estimated from the filter input and output. The specifically designed arrangement of these three elements and the way they are combined allow the proposed attitude estimator to be formulated following a classical Kalman Filter approach. The result is a novel estimator that preserves the simplicity of the original Kalman formulation and avoids the explicit calculation of Jacobian matrices in each iteration or the evaluation of augmented state vectors.Ministerio de Ciencia, Innovación y Universidades; RTI2018-101114-B-I00Xunta de Galicia; ED431C 2017/1

A time-varying Kalman filter for low-acceleration attitude estimation

CC BY-NC-ND 4.0 https://creativecommons.org/licenses/by-nc-nd/4.0/[Abstract]: This work shows an attitude estimator (AE) based on a time-varying Kalman filter (TVKF) and adapted to those cases where a low-acceleration assumption can be applied. This filter is an extended version of a previously published time-varying Kalman filter attitude estimator (TVKAE). A comparative analysis of the accuracies of those two estimators is provided. The efficiencies of both filters are also compared with those of other published AEs. The results show that the new AE achieves the best overall performance, followed by the original one.Xunta de Galicia; EDC431C-2021/39This research has been financed by the Xunta de Galicia and the European Regional Development Funds through grant EDC431C-2021/39, the Spanish Ministry of Education and Science under grants PID2021-126220OB-100 and TED2021-129847B-I0

Potential and Limitations of an Improved Method to Produce Dynamometric Wheels

[Abstract:] A new methodology for the estimation of tyre-contact forces is presented. The new procedure is an evolution of a previous method based on harmonic elimination techniques developed with the aim of producing low cost dynamometric wheels. While the original method required stress measurement in many rim radial lines and the fulfillment of some rigid conditions of symmetry, the new methodology described in this article significantly reduces the number of required measurement points and greatly relaxes symmetry constraints. This can be done without compromising the estimation error level. The reduction of the number of measuring radial lines increases the ripple of demodulated signals due to non-eliminated higher order harmonics. Therefore, it is necessary to adapt the calibration procedure to this new scenario. A new calibration procedure that takes into account angular position of the wheel is completely described. This new methodology is tested on a standard commercial five-spoke car wheel. Obtained results are qualitatively compared to those derived from the application of former methodology leading to the conclusion that the new method is both simpler and more robust due to the reduction in the number of measuring points, while contact forces’ estimation error remains at an acceptable level.Ministerio de Ciencia e Innovación; TRA2012-38826-C02-01Madrid (Comunidad Autónoma); S2013-MIT271

Utilización de hojas de cálculo para la enseñanza de modelos matemáticos en fotogrametría analítica

Se presenta una aplicación sobre hojas de cálculo utilizada en la enseñanza de Fotogrametría Analítica en la Universidad de Jaén en las titulaciones de Ingeniería en Geodesia y Cartografía e Ingeniería Técnica Topográfica. Se han seleccionado 2 ejemplos: orientación externa de un par estereoscópico mediante el método de dos pasos y la calibración de una cámara mediante el método de las líneas rectas. Cabe señalar que pueden ser implementados otros modelos basados en la resolución de sistemas de ecuaciones mediante mínimos cuadrados. La utilización de las hojas de cálculo permite a los alumnos visualizar directamente las ecuaciones empleadas y la forma en la que las mismas son actualizadas en el proceso iterativo durante las sucesivas aproximaciones. Las hojas de cálculo actuales permiten una gran capacidad de cálculo que incluyen herramientas de gran utilidad (p.ej., álgebra matricial), dentro de un entorno gráfico de gran comodidad. Las ecuaciones pueden ser escritas mediante un editor de fórmulas y la resolución se facilita gracias al lenguaje de macros de cualquier hoja convencional

¿Por qué las corrientes sociológicas soslayaron la investigación biográfica?

El artículo muestra cómo las corrientes sociológicas más importantes, la corriente comprensiva y la corriente crítica, dejaron de lado la investigación biográfica. Aunque la hermenéutica de Schleiermacher permitía la investigación de la generalidad en la particularidad, fue la introducción del ?grado de evidencia? por parte de Weber el que orientó la corriente comprensiva hacia el funcionalismo estructuralista. Los estudios sobre el campesino polaco o los parados de Marienthal apuntaban una superación de esa restricción, que tardó décadas en producirse. En el segundo caso, la corriente crítica, la tesis de la determinación de la conciencia soslayó la metodología biográfica, aunque tal afirmación ni se encuentra en Marx ni se corresponde con su proyecto teórico. Por último, se analiza la excepción de la biografía de Offenbach de Kracauer

Fusión de sensores de bajo coste para la monitorización de dinámica de vehículos

[ES] La caracterización dinámica de vehículos, permitiendo obtener la posición y orientación espacial de un vehículo en cada instante de tiempo, es fundamental no sólo evaluar cómo se comporta dinámicamente el vehículo y de esa forma hacer los ajustes necesarios en sus componentes para conseguir unas prestaciones determinadas, sino que se trata de, junto con otros sistemas, ser capaces de guiar el vehículo y realizar incluso una “conducción inteligente”. La aplicación de sistemas de caracterización dinámica mediante el uso de sensores de bajo coste en vehículos terrestres es relativamente reciente y está en auge en los últimos años por el gran desarrollo de estos sensores. El presente trabajo presenta los desarrollos de una línea de investigación seguida por los autores que tiene como finalidad investigar las distintas posibilidades que ofrece la fusión de sensores para caracterizar dinámicamente un sistema móvil. El objetivo fundamental es conseguir desarrollar un sistema que pueda ser implementado sobre un vehículo y permita estimar la posición y orientación del mismo, proporcionando información del valor de sus estados en cada instante. Con ello, se pretende ser capaz de evaluar el comportamiento dinámico del automóvil. Se estudian diferentes técnicas para lograr la estimación de los estados de un sistema y se analizarán los distintos tipos de sensores que se pueden emplear para la toma de medidas y el proceso de fusión de los mismos. Todo ello, con la intención de desarrollar una herramienta que permita determinar, de la forma más precisa posible y con unos costes reducidos, aquellas variables que definen la dinámica de los vehículos: balanceo, cabeceo, guiñada, velocidades angulares, aceleraciones, etc.Luque Rodríguez, P.; Álvarez Mántaras, D.; García De Jalón, J.; Bueno López, JL.; Cardenal Carro, J.; Deribe Diaz, Á. (2016). Fusión de sensores de bajo coste para la monitorización de dinámica de vehículos. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 2565-2574. https://doi.org/10.4995/CIT2016.2015.3549OCS2565257

Risk factors, clinical features, and outcomes of listeriosis in solid-organ transplant recipients: a matched case-control study

BACKGROUND: Solid-organ transplant (SOT) recipients are classically considered to be at increased risk for listeriosis. However, risk factors for this infection have not been assessed. METHODS: We carried out a multicenter, matched case-control study (1:2 ratio) from January 1995 through December 2007. Control subjects were matched for center, transplant type, and timing. Conditional logistic regression was performed to identify independent risk factors. Clinical features and outcomes for all case patients were reviewed. RESULTS: Thirty patients (0.12%) with cases of listeriosis were identified among 25,997 SOT recipients at 15 Spanish transplant centers. In a comparison of case patients with 60 matched control subjects, the following independent risk factors for listeriosis were identified: diabetes mellitus (odds ratio [OR], 5.6; 95% confidence interval [CI], 1.6-19.6; ), P = .007 history of cytomegalovirus infection or disease within the preceding 6 months (OR, 35.9; 95% CI, 2.1-620; P = .014), receipt of high-dose prednisone within the preceding 6 months (OR, 6.2; 95% CI, 1.8-21.1; P = .003), and trimethoprim-sulfamethoxazole (TMP-SMZ) prophylaxis (OR, 0.07; 95% CI, 0.006-0.76; P = .029). Twenty-six patients (86.7%) had bacteremia, and 7 had shock at presentation. Other manifestations included meningoencephalitis (10 cases), spontaneous peritonitis (2), pleural empyema (1), brain abscesses (1), and liver abscesses (1). The 30-day mortality rate was 26.7% (8 of 30 patients died). CONCLUSIONS: Listeriosis in SOT recipients is uncommon but causes high mortality. Diabetes mellitus, cytomegalovirus infection or disease, and receipt of high-dose steroids are independent risk factors for this infection, whereas TMP-SMZ prophylaxis is a protective factor

Executive summary: Guidelines for thediagnosis and treatment of septic arthritis in adults and children, developed bythe GEIO (SEIMC), SEIP and SECOT.

Infection of a native joint, commonly referred to as septic arthritis, is a medical emergency because of the risk of joint destruction and subsequent sequelae. Its diagnosis requires a high level of suspicion. These guidelines for the diagnosis and treatment of septic arthritis in children and adults are intended for use by any physician caring for patients with suspected or confirmed septic arthritis. They have been developed by a multidisciplinary panel with representatives from the Bone and Joint Infections Study Group (GEIO) belonging to the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), the Spanish Society of Paediatric Infections (SEIP) and the Spanish Society of Orthopaedic Surgery and Traumatology (SECOT), and two rheumatologists. The recommendations are based on evidence derived from a systematic literature review and, failing that, on the opinion of the experts who prepared these guidelines. A detailed description of the background, methods, summary of evidence, the rationale supporting each recommendation, and gaps in knowledge can be found online in the complete document

The Different Microbial Etiology of Prosthetic Joint Infections According to Route of Acquisition and Time After Prosthesis Implantation, Including the Role of Multidrug-Resistant Organisms

The aim of our study was to characterize the etiology of prosthetic joint infections (PJIs)-including multidrug-resistant organisms (MDRO)-by category of infection. A multicenter study of 2544 patients with PJIs was performed. We analyzed the causative microorganisms according to the Tsukayama's scheme (early postoperative, late chronic, and acute hematogenous infections (EPI, LCI, AHI) and "positive intraoperative cultures" (PIC)). Non-hematogenous PJIs were also evaluated according to time since surgery: 12 months. AHIs were mostly caused by Staphylococcus aureus (39.2%) and streptococci (30.2%). EPIs were characterized by a preponderance of virulent microorganisms (S. aureus, Gram-negative bacilli (GNB), enterococci), MDROs (24%) and polymicrobial infections (27.4%). Conversely, coagulase-negative staphylococci (CoNS) and Cutibacterium species were predominant in LCIs (54.5% and 6.1%, respectively) and PICs (57.1% and 15.1%). The percentage of MDROs isolated in EPIs was more than three times the percentage isolated in LCIs (7.8%) and more than twice the proportion found in AHI (10.9%). There was a significant decreasing linear trend over the four time intervals post-surgery for virulent microorganisms, MDROs, and polymicrobial infections, and a rising trend for CoNS, streptococci and Cutibacterium spp. The observed differences have important implications for the empirical antimicrobial treatment of PJIs.Acknowledgments: This work was supported by the Instituto de Salud Carlos III, Spanish Ministry of Economy and Competitiveness (grant number PI15/1026) (Co-funded by European Regional Development Fund/European Social Fund "Investing in your future"). REIPI (Spanish Network for Research in Infectious Disease) is supported by the Instituto de Salud Carlos III, Spanish Ministry of Economy and Competitiveness, and by the European Development Regional Fund “A way to achieve Europe”