Robust damping control of mobile manipulators

A novel robust control technique, robust damping control (RDC), is introduced. An RDC controller is further developed for the motion control of a mobile manipulator subject to kinematic constraints. The knowledge of dynamic parameters of the mobile manipulator is assumed to be completely unknown. The proposed RDC controller is capable of disturbance-rejection in the presence of unknown bounded disturbance, without requiring the knowledge of its bound. The stability of the closed-loop system is guaranteed. The controller has a simple structure and can be easily implemented in applications. Experimental tests on a 2-DOF robotic manipulator illustrate that the proposed control is significantly better than conventional robust control.     

Reduction of renal uptake of monoclonal antibody fragments by amino acid infusion

The renal uptake of radiolabeled antibody fragments and peptides presents a problem in radioimmunodetection and therapy, compromising lesion sensitivity, especially with intracellularly-retained isotopes. Previously, we showed that cationic amino acids and their derivatives are capable of significantly reducing kidney uptake in animals. We report our initial clinical results of successful renal uptake reduction in five patients who underwent cancer radioimmunodetection with 99mTc-anti-CEA Fab' fragments. METHODS: The patients were infused with two liters of a commercially-available nutritive amino acid solution (containing approximately 2.25 g/liter lysine-glutamate and 2.50 g/liter arginine), whereas 75 control patients received the same volume of saline (quantification of organ and tumor kinetics from conjugate whole-body views by ROI technique). RESULTS: The renal uptake in the amino acid group was significantly lower (p<0.05) than in the control group (11.1 +/- 2.0% injected dose versus 17.7 +/- 7.0% injected dose at 24 hr postinjection), whereas the uptake of all other organs remained unaffected. Gel filtration chromatography of the urine taken from amino-acid-treated patients showed that a significantly higher amount of excreted activity was bound to intact Fab' (53% of excreted activity) in contrast to only less than 10% in the control group. CONCLUSION: The renal uptake of monoclonal antibody fragments in patients can be reduced significantly by amino acid infusion, even at considerably lower doses than those that were safe and effective in animals. As was found in animals, the mechanism seems to rely on an inhibition of the re-absorption of tubularly-filtered proteins by the proximal tubule cells. These results encourage further clinical trials to lower the renal uptake experienced in radioimmunodetection, as well as in therapeutic trials with antibody fragments and peptides.     

Dynamic control and motion planning technique for a class of nonlinear systems with drift

The paper addresses the synthesis of a smooth dynamic feedback for a class of nonholonomic systems (nonlinear systems with drift). The proposed technique provides asymptotic stability and convergence to a desired equilibrium manifold. The manifold is a (task) function of the generalized co-ordinates. Applications of the proposed technique to control of two classes of nonholonomic systems are presented.     

Effect of hydrogen on fracture of U-notched bend specimens of spheroidized AISI 1095 steel

The effect of hydrogen on fracture was studied in U-notch bend specimens of 1095 steel with three different notch acuities. The hydrogen was introduced by cathodic charging through the notch surfaces. Both precharging and dynamic charging effects on void initiation and growth, crack initiation and fracture were investigated. In prechargea specimens voids were initiated at lower strains and the void population increased more rapidly than in the uncharged case. The role of hydrogen is to promote plastic instability along characteristic slip lines and therefore accelerate void formation. In the dynamically charged specimens, cracks initiated at lower strains than for the other cases and propagated rapidly without accompanying void formation. The results are compared to those for the uncharged case and to previous theoretical and experimental results. formerly with Ohio State University, is now Metallurgist with Korea Institute of Science and Technology, Seoul, Korea, and formerly with Ohio State University, is now Metallurgist with Bell Telephone Laboratories, Allentown, PA 18103.     

Real-time control of robots: Strategies for hardware and software development

A review of various strategies for hardware and software development of real-time controllers for commercial robots is presented. These developments, all depending on state-of-the-art hardware and software, are designed to correspond to specific research objectives. The Robotics and Automation Laboratory (RAL) TUNIS multiptocessor system, used to control a PUMA without VAL, is presented. The proposed scheme is suitable for implementing the computed torque technique, the feedback linearization technique, and various modern control methods applied to both joint and task space variables.     

Articulated hybrid mobile robot mechanism with compounded mobility and manipulation and on-board wireless sensor/actuator control interfaces

This paper presents the development of a remotely operated mobile robot system with a hybrid mechanism whereby the locomotion platform and manipulator arm are designed as one entity to support both locomotion and manipulation interchangeably. The mechanical design is briefly described as well as the dynamic simulations used to analyze the robot mobility and functionality. As part of the development, this paper mainly focuses on a new generalized control hardware architecture based on embedded on-board wireless communication network between the robot’s subsystems. This approach results in a modular control hardware architecture since no wire connections are used between the actuators and sensors in each of the mobile robot subsystems and also provides operational fault-tolerance. The effectiveness of this approach is experimentally demonstrated and validated by implementing it in the hybrid mobile robot system. The new control hardware architecture and mechanical design demonstrate the qualitative and quantitative performance improvements of the mobile robot in terms of the new locomotion and manipulation capabilities it provides. Experimental results are presented to demonstrate new operative tasks that the robot was able to accomplish, such as traversing challenging obstacles, and manipulating objects of various capacities; functions often required in various challenging applications, such as search and rescue missions, hazardous site inspections, and planetary explorations.     

In vivo degradation of semi-rigid polymeric films made of alginate and polyethylene glycol

Alginate-based biomaterials can form naturally derived polymeric hydrogels with sufficient structural integrity to readily be used in many clinical applications. However, ionically cross-linked alginate gels do not always possess structural properties suitable for application as erodable polymeric films for controlled release of drugs and growth factors. In this study, semi-rigid polymeric films were constructed of sodium alginate and polyethylene glycol (PEG) by means of a rehydration cross-linking technique. The films were assembled by dehydrating a solution of alginate and PEG and cross-linking the alginate during its rehydration with a solution of calcium chloride. The product is a highly dense polymeric network that prevents in vivo cellular infiltration and disassembles primarily by surface erosion. By implanting the PEG-alginate films into the subcutis of rats, the mechanism of polymer degradation was demonstrated to occur via inflammation-mediated erosion of the material rather than by means of cellular infiltration. There were extensive areas of foamy macrophages at the site of the implant, indicating a likely mechanism of removal and disposal of the disassembled PEG and alginate polymer. The eroded fragments of the film that remained after six weeks did not exhibit signs of a cellular infiltrate but rather stayed intact, appearing as small, dense fragments of polymer. Our observations that nearly all the PEG-alginate material was cleared from the implantation site by the sixth postoperative week highlight the potential exploitation of these films as bioresorbable wound dressings with prospective utilization as a drug delivery device. Moreover, the employment of polymeric films made of functionalized PEG, which enables covalent attachment of biological molecules, potentiates their use for growth factor delivery applications.     

Severe laryngeal injury caused by blunt trauma to the neck: a case report

Acute blunt laryngeal trauma can be a life-threatening event and often poses a difficult airway management problem. Patients may be unable to supply important anemnestic facts because of aphonia or intubation as a result of their injury. Therefore the immediate recognition and appropriate initial assessment and treatment are vital for a successful outcome. The first step is assuring an appropriate airway, either by careful intubation or temporary tracheotomy. An assessment of potential vascular and oesophageal injuries must be undertaken. The use of computerized tomography (CT) with contrast material is especially useful in identifying and localizing the damage caused by blunt neck injuries. Laryngeal fractures, air in the soft tissues and the extravasation of contrast material in the neck are all helpful in assessing the injuries before surgical intervention. Immediate initial surgery is aimed at stabilizing the cartilaginous framework and repairing the mucosa. We present a case of severe laryngeal injury caused by blunt trauma to the neck; our evaluation, treatment and the outcome.