Orthotopic liver transplantation for urea cycle enzyme deficiency

Hyperammonemia, abnormalities in plasma amino acids and abnormalities of standard liver functions were corrected by orthotopic liver transplantation in a 14‐day‐old boy with carbamyl phosphate synthetase‐I deficiency and in a 35‐yr‐old man with argininosuccinic acid synthetase deficiency. The first patient had high plasma glutamine levels and no measureable citrulline, whereas citrulline values were markedly increased in Patient 2. Enzyme analysis of the original livers showed undetectable activity of carbamyl phosphate synthetase‐I in Patient 1 and arginosuccinic acid synthetase in Patient 2. Both patients were comatose before surgery. Intellectual recovery of patient 1 has been slightly retarded because of a brain abscess caused by Aspergillus infection after surgery. Both patients are well at 34 and 40 mo, respectively, after surgery. Our experience has shown that orthotopic liver transplantation corrects the life‐threatening metabolic abnormalities caused by deficiencies in the urea cycle enzymes carbamyl phosphate synthetase‐I and arginosuccinic acid synthetase. Seven other patients–six with ornithine transcarbamylase deficiency and another with carbamyl phosphate synthetase‐I deficiency–are known to have been treated elsewhere with liver transplantation 1 1/2 yr or longer ago. Four of these seven recipients also are well, with follow‐ups of 1 1/2 to 5 yr. Thus liver transplantation corrects the metabolic abnormalities of three of the six urea cycle enzyme deficiencies, and presumably would correct all. (Hepatology 1992;15:419–422). Copyright © 1992 Wiley Subscription Services, Inc

Real-time FEM based control of soft surgical robots

International audienceIn this paper, we present a new method for the control of soft surgical robots based on the real-time inverse simulation with internal deformation computed through the use of Finite Element Method. We also consider the coupling of this method with a modified version of the same algorithm for parametrization of soft-tissue models, in order to control the navigation of the robot while gathering information on the surrounding organs

Finite element method-based kinematics and closed-loop control of soft, continuum manipulators

International audienceThis paper presents a modeling methodology and experimental validation for soft 1 manipulators to obtain forward and inverse kinematic models under quasistatic conditions. It offers a way to obtain the kinematic characteristics of this type of soft robots that is suitable for offline path planning and position control. The modeling methodology presented relies on continuum mechanics which does not provide analytic solutions in the general case. Our approach proposes a real-time numerical integration strategy based on Finite Element Method (FEM) with a numerical optimization based on Lagrangian Multipliers to obtain forward and inverse models. To reduce the dimension of the problem, at each step, a projection of the model to the constraint space (gathering actuators, sensors and end-effector) is performed to obtain the smallest number possible of mathematical equations to be solved. This methodology is applied to obtain the kinematics of two different manipulators with complex structural geometry. An experimental comparison is also performed in one of the robots, between two other geometric approaches and the approach that is showcased in this paper. A closed-loop controller based on a state estimator is proposed. The controller is experimentally validated and its robustness is evaluated using Lypunov stability method

Nonparametric Online Learning Control for Soft Continuum Robot: An Enabling Technique for Effective Endoscopic Navigation.

Bioinspired robotic structures comprising soft actuation units have attracted increasing research interest. Taking advantage of its inherent compliance, soft robots can assure safe interaction with external environments, provided that precise and effective manipulation could be achieved. Endoscopy is a typical application. However, previous model-based control approaches often require simplified geometric assumptions on the soft manipulator, but which could be very inaccurate in the presence of unmodeled external interaction forces. In this study, we propose a generic control framework based on nonparametric and online, as well as local, training to learn the inverse model directly, without prior knowledge of the robot's structural parameters. Detailed experimental evaluation was conducted on a soft robot prototype with control redundancy, performing trajectory tracking in dynamically constrained environments. Advanced element formulation of finite element analysis is employed to initialize the control policy, hence eliminating the need for random exploration in the robot's workspace. The proposed control framework enabled a soft fluid-driven continuum robot to follow a 3D trajectory precisely, even under dynamic external disturbance. Such enhanced control accuracy and adaptability would facilitate effective endoscopic navigation in complex and changing environments

Software toolkit for modeling, simulation and control of soft robots

International audienceThe technological differences between traditional robotics and soft robotics have an impact on all of the modeling tools generally in use, including direct kinematics and inverse models, Jacobians, and dynamics. Due to the lack of precise modeling and control methods for soft robots, the promising concepts of using such design for complex applications (medicine, assistance, domestic robotics...) cannot be practically implemented. This paper presents a first unified software framework dedicated to modeling, simulation and control of soft robots. The framework relies on continuum mechanics for modeling the robotic parts and boundary conditions like actuators or contacts using a unified representation based on Lagrange multipliers. It enables the digital robot to be simulated in its environment using a direct model. The model can also be inverted online using an optimization-based method which allows to control the physical robots in the task space. To demonstrate the effectiveness of the approach, we present various soft robots scenarios including ones where the robot is interacting with its environment. The software has been built on top of SOFA, an open-source framework for deformable online simulation and is available at https://project.inria.fr/softrobot

Portrait of a Young Nobleman

https://digitalcommons.unf.edu/campus_art/1192/thumbnail.jp