Observer-based controller for VTOL-UAVs tracking using direct Vision-Aided Inertial Navigation measurements.

This paper proposes a novel observer-based controller for Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicle (UAV) designed to directly receive measurements from a Vision-Aided Inertial Navigation System (VA-INS) and produce the required thrust and rotational torque inputs. The VA-INS is composed of a vision unit (monocular or stereo camera) and a typical low-cost 6-axis Inertial Measurement Unit (IMU) equipped with an accelerometer and a gyroscope. A major benefit of this approach is its applicability for environments where the Global Positioning System (GPS) is inaccessible. The proposed VTOL-UAV observer utilizes IMU and feature measurements to accurately estimate attitude (orientation), gyroscope bias, position, and linear velocity. Ability to use VA-INS measurements directly makes the proposed observer design more computationally efficient as it obviates the need for attitude and position reconstruction. Once the motion components are estimated, the observer-based controller is used to control the VTOL-UAV attitude, angular velocity, position, and linear velocity guiding the vehicle along the desired trajectory in six degrees of freedom (6 DoF). The closed-loop estimation and the control errors of the observer-based controller are proven to be exponentially stable starting from almost any initial condition. To achieve global and unique VTOL-UAV representation in 6 DoF, the proposed approach is posed on the Lie Group and the design in unit-quaternion is presented. Although the proposed approach is described in a continuous form, the discrete version is provided and tested.

Adaptive Neural Network Stochastic-Filter-Based Controller for Attitude Tracking With Disturbance Rejection.

This article proposes a real-time neural network (NN) stochastic filter-based controller on the Lie group of the special orthogonal group [Formula: see text] as a novel approach to the attitude tracking problem. The introduced solution consists of two parts: a filter and a controller. First, an adaptive NN-based stochastic filter is proposed, which estimates attitude components and dynamics using measurements supplied by onboard sensors directly. The filter design accounts for measurement uncertainties inherent to the attitude dynamics, namely, unknown bias and noise corrupting angular velocity measurements. The closed-loop signals of the proposed NN-based stochastic filter have been shown to be semiglobally uniformly ultimately bounded (SGUUB). Second, a novel control law on [Formula: see text] coupled with the proposed estimator is presented. The control law addresses unknown disturbances. In addition, the closed-loop signals of the proposed filter-based controller have been shown to be SGUUB. The proposed approach offers robust tracking performance by supplying the required control signal given data extracted from low-cost inertial measurement units. While the filter-based controller is presented in continuous form, the discrete implementation is also presented. In addition, the unit-quaternion form of the proposed approach is given. The effectiveness and robustness of the proposed filter-based controller are demonstrated using its discrete form and considering low sampling rate, high initialization error, high level of measurement uncertainties, and unknown disturbances.

The therapeutic potential of convalescent plasma therapy on treating critically-ill COVID-19 patients residing in respiratory care units in hospitals in Baghdad, Iraq.

The current COVID-19 pandemic needs unconventional therapies to tackle the resulted high morbidity and mortality. Convalescent plasma is one of the therapeutic approaches that might be of benefit. Forty nine early-stage critically-ill COVID-19 patients residing in Respiratory Care Units (RCU) of three hospitals in Baghdad, Iraq, were included: 21 received convalescent plasma while 28, namely control group, did not receive it. Recovery or death, length of stay in hospital, and improvement in the clinical course of the disease were monitored clinically along with laboratory monitoring through SARS-CoV-2 RNA detection via PCR, and SARS-CoV-2 IgG and IgM serological monitoring. Patients who received convalescent plasma showed reduced duration of infection in about 4 days and showed less death rate [1/21 versus 8/28 in control group]. In addition, all the patients who were given convalescent plasma showed high levels of SARS-CoV-2 IgG and IgM three days after plasma transfusion. Plasma from donors with high levels of SARS-CoV-2 IgG and donors with positive SRAS-CoV-2 IgM showed better therapeutic results than other donors. Convalescent plasma therapy is an effective therapy if donors with high level of SARS-Cov2 antibodies are selected and if recipients are at their early stage of critical illness, being no more than three days in RCUs.

Brightness Mode and Color Doppler Ultrasound in Differential Diagnosis of Breast Lesions in Saudi Females.

OBJECTIVE: The aim of the study was to identify the pathological characteristics of benign and malignant breast lesions among Saudi females using brightness mode (B-mode) and color Doppler ultrasound (US). MATERIALS AND METHODS: This study was retrospectively carried out in a single center in the Radiology and Medical Imaging Department, King Fahad Medical City, Riyadh, Saudi Arabia. A convenient method of sampling was used to include all patients referred for different diagnosis during the period of January 2016 and December 2018. A sample size of 100 cases was selected with 50% of the cases being benign breast lesions, while the rest were malignant. The data collection instruments comprised data collection sheets, while a Philips US system with a 9 MHz linear probe was used to give the differential results. The results were considered significant when P < 0.05. The statistical diagnostic test was used to detect sensitivity, specificity, and accuracy of US in the differential diagnosis of breast lesions in Saudi females. RESULTS: B-mode and color Doppler US findings of breast mass measurements, shape, echotexture, and the presence and absence of vascularity present a sensitivity, specificity, and accuracy of 97.09%, 80.65%, and 93.28% in the diagnosis of benign and malignant breast masses. CONCLUSION: In Saudi females with dense breasts, the risk of breast cancer development is increased. Moreover, B-mode in combination with color Doppler US was highly determined the results of differential diagnosis for any breast lesions.