Improving visual SLAM accuracy through deliberate camera oscillations

Visual Simultaneous Localization And Mapping, (VSLAM) algorithms exploit the observation of scene naturally-existing distinct features to infer the camera motion and build a map of a static environment. There is an increasing interest towards building efficient VSLAM algorithms mainly from computational perspectives; however, there may be insufficient clues to solve for SLAM parameters efficiently. In this paper, deliberate camera oscillations are superimposed on the camera main motion (robot motion), mostly in a lateral direction to give sufficient physical clues for the solution. Filtering methods exploit correlation to infer the motion parameters, and since oscillation introduces more local changes, it can enhance the estimation by correlation. Simulation results are presented showing the effects of oscillation parameters on visual SLAM performance in different motion scenarios. The results showed significant improvement of accuracy for oscillating camera over the steady camera case, and in several cases errors are reduced to less than half its value. These simulation results can be the basis to design a real experimental system

DYNAMICS BASED CONTROL OF A SKID STEERING MOBILE ROBOT

In this paper, development of a reduced order, augmented dynamics-drive model that combines both the dynamics and drive subsystems of the skid steering mobile robot (SSMR) is presented. A Linear Quadratic Regulator (LQR) control algorithm with feed-forward compensation of the disturbances part included in the reduced order augmented dynamics-drive model is designed. The proposed controller has many advantages such as its simplicity in terms of design and implementation in comparison with complex nonlinear control schemes that are usually designed for this system. Moreover, the good performance is also provided by the controller for the SSMR comparable with a nonlinear controller based on the inverse dynamics which depends on the availability of an accurate model describing the system. Simulation results illustrate the effectiveness and enhancement provided by the proposed controller

Direct Data-Driven State-Feedback Control of Linear Parameter-Varying Systems

We derive novel methods that allow to synthesize LPV state-feedback controllers directly from a single sequence of data and guarantee stability and performance of the closed-loop system, without knowing the model of the plant. We show that if the measured open-loop data from the system satisfies a persistency of excitation condition, then the full open-loop and closed-loop input-scheduling-state behavior can be represented using only the data. With this representation, we formulate synthesis problems that yield controllers that guarantee stability and performance in terms of infinite horizon quadratic cost, generalized $\mathcal{H}_2$-norm and $\mathcal{L}_2$-gain of the closed-loop system. The controllers are synthesized by solving an SDP with a finite set of LMI constraints. Competitive performance of the proposed data-driven synthesis methods is demonstrated w.r.t. model-based synthesis that have complete knowledge of the true system model in multiple simulation studies.Comment: Submitted to IEEE Transactions on Automatic Control, extended version, 14 page

Brain Natriuretic Peptide is a Predictor of Cardiac Thrombus in Critically Ill Acute Ischemic Stroke Patients

CONTEXT: Plasma brain natriuretic peptide (BNP) levels are elevated in patients with acute ischemic stroke, particularly when accompanied by atrial fibrillation (AF). Plasma BNP might be a useful marker of vulnerability to thromboembolism in non-valvular AF patients. AIM: The aim of the present study was to assess whether the BNP level can serve as a biomarker of the left atrial (LA) thrombus in AF patients with acute ischemic stroke. SETTINGS AND DESIGN: This was a multicenter prospective cohort study. PATIENTS AND METHODS: Thirty AF patients with acute ischemic stroke were included in the study. Their transesophageal echocardiography (TEE) and BNP were assessed. RESULTS: There was a positive significant relation between serum BNP levels and LA thrombus detection by TEE. BNP with a cutoff value >498 pg/l can be used as a diagnostic biomarker for the presence of the LA thrombus. A significant positive correlation existed between serum BNP and LA diameter. Furthermore, a statistically significant positive correlation between serum BNP and AF rate and duration was found in all patients. In addition, a statistically significant inverse correlation was detected between serum BNP and direct bilirubin, international normalized ratio, and albumin. A statistically significant positive correlation existed between serum BNP and prothrombin concentration. CONCLUSION: BNP can be a good diagnostic biomarker for the detection of the LA thrombus in chronic AF patients with acute ischemic stroke

Peripartum hysterectomy for cesarean section with morbidly adherent placenta: case series of 25 patients

Background: The current paper reports the outcome of case series of patients presented with placenta accreta confirmed histopathologicaly after management by peripartum hysterectomy.Methods: The study was set in Women’s Health Hospital, Assiut University, Egypt. This was a case series of 25 women presented with placenta accreta between May 2017 and April 2018. We included all pregnant women with placenta previa as diagnosed by ultrasound with suspicion of abnormal placentation by Doppler, confirmed intra-operatively undergoing either emergent or elective CS. All cases were performed by an expert team of obstetricians and anesthetists. Cesarean delivery was done under general anesthesia through pfannensteil incision. The primary outcome was the estimated intra-operative blood loss through assessment of amount of blood in the suction by ml, difference between the weight of surgical drapes and towels before and after operation.Results: Pre-operative Hb was 10.64±1.01 gm/dL and there was significant decline in the postoperative Hb reaching 8.36±1.21 gm/dL (p<0.001). The mean drop in Hb was 2.28±1.43gm/dL. Estimated intra-operative blood loss was 974.4±398.05 ml in the towels and 847.6±362.56 ml in the suction apparatus. The total blood loss was 1822±653.73 ml. The mean number of units of whole blood transfused was 2160.0±825.6 ml and fresh frozen plasma was 1010.0±349.7 ml. Regarding intra-operative complications, bladder injury was the most common one in 14 cases (56%), followed by ureteric injury in two cases (8%). Postoperative ICU admission was in 6 cases (24%) and the mean duration of hospital stay 12.44 ± 4.07 days. No cases of maternal mortality.Conclusions: In conclusion, peripartum hysterectomy is considered life-saving surgery in patients with placenta accreta

A Linear Parameter-Varying Approach to Data Predictive Control

By means of the linear parameter-varying (LPV) Fundamental Lemma, we derive novel data-driven predictive control (DPC) methods for LPV systems. In particular, we present output-feedback and state-feedback-based LPV-DPC methods with terminal ingredients, which guarantee exponential stability and recursive feasibility. We provide methods for the data-based computation of these terminal ingredients. Furthermore, an in-depth analysis of the properties and implementation aspects of the LPV-DPC schemes is given, including alternative recursive formulations, application for nonlinear systems and handling noise-disturbed data. We demonstrate the performance of the proposed methods on a simulation example involving a nonlinear unbalanced disc system.Comment: Submitted to IEEE-TAC. Extended version. 17 page

Effect of global postural correction exercises on stress urinary incontinence during pregnancy: A randomized controlled trial

Background: One of the many consequences of pregnancy that may negatively affect a woman’s quality of life is stress urinary incontinence caused by activities of daily living especially those associated with increased intraabdominal pressure. Objective: This research aimed to explore the impact of global postural correction exercises on stress urinary incontinence among pregnant women. Participants and Methodology: Forty primigravida female at their third trimester (aged between 26–36 years), with a single fetus, diagnosed with stress urinary incontinence take part in the research. Participants were assigned randomly into two groups: Study group (group A; n = 20) and control group (group B; n = 20). The participants were tested twice, before and after a 12-week period, during which group A received global postural correction exercises in addition to Kegel exercises, while group B performed only Kegel exercises. A perineometer was used to evaluate the change in vaginal squeeze pressure both before and after conducting the study. UDI-6 was utilized to assess changes in incontinence severity symptoms. Results: Findings revealed a significant increase in the mean value of vaginal squeeze pressure (p < .05) in the post-test condition in comparison to the pre-test in both groups A and B. Additionally, there was a main decrease (p < .05) in the mean value of UDI-6 in both groups. Moreover, findings showed a significant negative (inverse) correlation (p < .05) between the difference in vaginal squeeze pressure and the UDI-6 in all patients. Conclusions: Postural correction exercises in addition to Kegel exercises are effective in reducing urine leakage in women with stress urinary incontinence and should be an integral part of the management of such condition