A model-free terminal sliding mode control for robots: Achieving fixed-time prescribed performance and convergence.

This paper introduces a new control strategy for robot manipulators, specifically designed to tackle the challenges associated with traditional model-based sliding mode (SM) controller design. These challenges include the need for accurately computed system models, knowledge of disturbance upper bounds, fixed-time convergence, prescribed performance, and the generation of chattering. To overcome these obstacles, we propose the incorporation of a neural network (NN) that effectively addresses these issues by removing the constraint of a precise system model.

Endovascular treatment for life-threatening hemoptysis due to rupture of descending thoracic aortic aneurysm: A case series.

Introduction And Importance: Aortic aneurysm is an uncommon but life-threatening cause of hemoptysis. Treatments include surgery and/or endovascular intervention, each with its own advantages and disadvantages. Endovascular intervention is associated with good early and medium-term outcomes.

Real-Time Implementation of the Prescribed Performance Tracking Control for Magnetic Levitation Systems.

For magnetic levitation systems subject to dynamical uncertainty and exterior perturbations, we implement a real-time Prescribed Performance Control (PPC). A modified function of Global Fast Terminal Sliding Mode Manifold (GFTSMM) based on the transformed error of the novel PPC is introduced; hence, the error variable quickly converges to the equilibrium point with the prescribed performance, which means that maximum overshoot and steady-state of the controlled errors will be in a knowledge-defined boundary. To enhance the performance of Global Fast Terminal Sliding Mode Control (GFTSMC) and to reduce chattering in the control input, a modified third-order sliding mode observer (MTOSMO) is proposed to estimate the whole uncertainty and external disturbance.

An Adaptive Prescribed Performance Tracking Motion Control Methodology for Robotic Manipulators with Global Finite-Time Stability.

In this paper, the problem of an APPTMC for manipulators is investigated. During the robot's operation, the error states should be kept within an outlined range to ensure a steady-state and dynamic attitude. Firstly, we propose the modified PPFs.

A Novel Prescribed-Performance-Tracking Control System with Finite-Time Convergence Stability for Uncertain Robotic Manipulators.

Through this article, we present an advanced prescribed performance-tracking control system with finite-time convergence stability for uncertain robotic manipulators. It is therefore necessary to define a suitable performance function and error transformation to guarantee a prescribed performance within a finite time. Following the definitions mentioned, a modified integral nonlinear sliding-mode hyperplane is constructed from the transformed errors.

A Novel Active Fault-Tolerant Tracking Control for Robot Manipulators with Finite-Time Stability.

Many terminal sliding mode controllers (TSMCs) have been suggested to obtain exact tracking control of robotic manipulators in finite time. The ordinary method is based on TSMCs that secure trajectory tracking under the assumptions such as the known robot dynamic model and the determined upper boundary of uncertain components. Despite tracking errors that tend to zero in finite time, the weakness of TSMCs is chattering, slow convergence speed, and the need for the exact robot dynamic model.

A Robust Observer-Based Control Strategy for n-DOF Uncertain Robot Manipulators with Fixed-Time Stability.

In this paper, a robust observer-based control strategy for n-DOF uncertain robot manipulators with fixed-time stability was developed. The novel fixed-time nonsingular sliding mode surface enables control errors to converge to the equilibrium point quickly within fixed time without singularity. The development of the novel fixed-time disturbance observer based on a uniform robust exact differentiator also allows uncertain terms and exterior disturbances to be proactively addressed.

Aortic prosthetic size predictor in aortic valve replacement.

Background: Patient-prosthesis mismatch (PPM) is a major concern in aortic valve replacement (AVR) and leads to perioperative morbidity and rehospitalization. Predicting aortic annulus diameter pre-procedurally is crucial to managing patients with high-risk of PPM.

Objectives: To compare preoperative measurements of aortic annulus from echocardiography and CT scan with surgical sizing and develop an imaging-based algorithm to predict PPM.

Conservative Treatment of Postinfarction Left Ventricular Free Wall Rupture.

Left ventricular free wall rupture is a fatal complication of acute myocardial infarction. Emergency surgical repair is usually indicated to treat this condition. However, in very high surgical risk cohort, conservative treatment can also be considered.

Anomalous left coronary artery from the pulmonary artery (ALCAPA) as a concealed cause of severe mitral regurgitation in children and adults: Case reports.

Introduction: Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital coronary artery anomaly and is a concealed cause of mitral regurgitation.

Presentation Of Case: We reported two cases of severe mitral regurgitation in whom the presence of ALCAPA was overlooked in the first cardiac surgery. In the first case, ALCAPA was diagnosed one year after the mitral annuloplasty and the surgical reimplantation was successfully performed.

Long-Term Outcome of Thrombolytic Therapy for Massive Pulmonary Embolism in Pregnancy.

A 25-year-old pregnant woman presented at 12 weeks of gestation with syncope and shortness of breath caused by massive pulmonary embolism. Due to persistent shock, fibrinolytic therapy with rtPA was administered. After fibrinolysis, clinical and hemodynamic response was excellent.

Learning curve in minimally invasive mitral valve surgery: a single-center experience.

Background: Minimally invasive mitral valve surgery is becoming a gold standard and provides many advantages for patients. A learning curve is required for a surgeon to become proficient, and the exact number to overcome this curve is controversial. Our study aimed to define this number for mitral valve surgery in general, for replacement and repair separately.

Minimally Invasive Mitral Valve Surgery for Rheumatic Valve Disease.

Background: The development of minimally invasive mitral valve surgery has created the motivation for using this approach in young patients with chronic rheumatic valve disease. We report our recent experience with patients undergoing minimally mitral valve surgery in this group of patients.

Methods: Between July 2014 and June 2018, 142 patients with rheumatic mitral valve dysfunction underwent minimally invasive surgery through a right thoracotomy approach at the University Medical Center of Ho Chi Minh City in Vietnam.

Ministernotomy for correction of ventricular septal defect.

Background: The development of minimally invasive surgery in the adult has created motivation for similar approaches in the congenital heart domain. Over the past 20 years, this type of surgery has been advocated in an effort to reduce costs related to hospital stay, and to improve the cosmetic results. We report our experience with ventricular septal defect repair utilizing a ministernotomy incision.

Left isomerism syndrome with total anomalous systemic connection.

We present a case of left isomerism with total anomalous systemic venous connection where the inferior vena cava was absent and all other systemic veins connected abnormally to the left atrium. The right atrium was hypoplastic with an intact atrial septum. Blood flow to the lungs was through a large ventricular septal defect.