Control strategy for cooperating disparate manipulators

To manipulate large payloads typical of space construction, the concept of a small arm mounted on the end of a large arm is introduced. The main purposes of such a configuration are to increase the structural stiffness of the robot by bracing against or locking to a stationary frame, and to maintain a firm position constraint between the robot's base and workpieces by grasping them. Possible topologies for a combination of disparate large and small arms are discussed, and kinematics, dynamics, controls, and coordination of the two arms, especially when they brace at the tip of the small arm, are developed. The feasibility and improvement in performance are verified, not only with analytical work and simulation results but also with experiments on the existing arrangement Robotic Arm Large and Flexible and Small Articulated Manipulator

A Case of Pseudo-Duane's Retraction Syndrome With Old Medial Orbital Wall Fracture

We report a case of pseudo-Duane's retraction syndrome with entrapment of the medial rectus muscle in an old medial orbital wall fracture presenting identical clinical symptoms as Duane's retraction syndrome. A 15-year-old boy presented with persistent limited right eye movement since a young age. Examination showed marked limited abduction, mildly limited adduction, and globe retraction accompanied by narrowing of the palpebral fissure during attempted adduction in the right eye. He showed a right esotropia of 16 prism diopters and his head turned slightly to the right. A slight enophthalmos was noted in his right eye. A computed tomography scan demonstrated entrapment of the medial rectus muscle and surrounding tissues in an old medial orbital wall fracture. A forced duction test revealed a marked restriction of abduction in the right eye. A 5 mm recession of the right medial rectus muscle was performed. Postoperatively, the patient's head turn and esotropia in the primary position were successfully corrected, but there was still some limitations to his ocular movement. The importance of several tests such as the forced duction test and an imaging study should be emphasized in making a diagnosis for limitation of eye movement

Mycobacterium kansasii Pulmonary Diseases in Korea

Mycobacterium kansasii is one of the most common cause of pulmonary diseases due to nontuberculous mycobacteria. We investigated the changing in the number of isolation of M. kansasii and the clinical characteristics of M. kansasii pulmonary disease in Korea. Through searching the database of the Korean Institute of Tuberculosis, we identified the cases of isolated M. kansasii from 1992 to 2002. The number of M. kansasii isolation had increased from once in 1992 to 62 in 2002. Fifteen patients with M. kansasii pulmonary disease were identified during the period January 1997 to December 2002. Twelve patients (80%) were male and fourteen (93%) were from highly industrialized areas. The most common symptom was a cough. Seven patients (47%) had a cavitary lesion and right upper lobe was most commonly involved. Patients responded well to isoniazid and rifampicin based regimens both bacteriologically and radiographically. In conclusion, M. kansasii isolation has increased, especially in highly industrialized areas, as well as other nontuberculous mycobacteria in Korea

Coinfection of Viral Agents in Korean Children with Acute Watery Diarrhea

Currently, there are a few reports on viral coinfection that causes an acute watery diarrhea in Korean children. So, to evaluate the features of coinfectious viral agents in children with acute watery diarrhea, we enrolled 155 children with acute watery diarrhea from July 2005 to June 2006. Fecal samples were collected and evaluated for various viral infections such as rotavirus, norovirus, adenovirus and astrovirus. The mean (±standard deviation) age of the children was 2.71±2.37 yr. The detection rate of viral agents was most common in children between the ages of 1 and 3 yr. Rotavirus was detected in 63 children (41.3%), norovirus in 56 (36.2%), adenovirus in 11 (7.1%), and astrovirus in 1 (0.6%). Regarding rotavirus, there were 38 (60.3%) cases with monoinfection and 25 (39.7%) with coinfection. For norovirus, there were 33 (58.9%) cases with monoinfection and 23 (41.1%) with coinfection. Coinfection with rotavirus and norovirus was most common, and occurred in 20/155 cases (12.9%) including coinfection with adenovirus. So, rotavirus and norovirus were the most common coinfectious viral agents in our study population with acute watery diarrhea

Comparison of Higher-Order Aberration and Contrast Sensitivity in Monofocal and Multifocal Intraocular Lenses

PURPOSE: The visual performance of pseudophakic eyes depends on the type of intraocular lenses (IOLs) that are implanted. Aspherical and multifocal IOLs have recently been developed to improve visual quality after cataract surgery, but multifocal IOLs can be associated with decreased contrast sensitivity (CS), halos, and glare. This study compares the visual performance of monofocal and multifocal IOLs by measurement of higher-order aberrations (HOAs) and CS values. MATERIALS AND METHODS: HOAs and CS values of 42 eyes with implanted monofocal IOLs and 40 eyes with implanted multifocal IOLs were measured preoperatively and more than 6 months after surgery. In the multifocal IOL group, HOAs and CS values were also measured with addition of a trial lens of -0.5 diopter (D) to evaluate the compensatory effect on spherical aberration. RESULTS: CS values of the multifocal IOL group were significantly lower than those of the monofocal IOL group for all spatial frequencies tested (p<0.01), and the spherical aberration was significantly higher in the multifocal IOL group than in the monofocal IOL group (p<0.001). Addition of a -0.5 D lens to the multifocal IOL group decreased the difference in CS between the two groups (p=0.003). CONCLUSION: Increased spherical aberration may contribute to lower CS in the multifocal IOL group. In such cases, CS can be improved by addition of a -0.5 D lens to compensate for the spherical aberration.ope

Control of bracing micro/macro manipulators

Ph.D.Wayne J. Boo

Control for Two Cooperative Disparate Manipulators

Proceedings of the American Nuclear Society 4th Topical Meeting on Robotics and Remote Systems, February 24-28, 1991, Albuquerque, NM.The concept of a small arm mounted on the end of a large arm has been introduced to provide precise motion as well as a large workspace. However, the performance of such a serial configuration lacks payload capacity which is a crucial factor for handling a massive object. Also, this configuration induces more flexibility on the structure. To overcome these problems, the topology of bracing the tip of the small arm (not the large arm) and having an end effector in the middle of the chain is proposed in this paper. Also, simulation results are presented to show the possibility that the proposed control scheme provides the disparate manipulators with better accuracy than the large arm and more payload capacity than the small arm. In the near future, experimental studies on the existing arrangement (RALF and SAM) are scheduled to verify the feasibility of the proposed concepts

Dynamics of Two Serially Connected Manipulators

© American Society of Mechanical EngineersThe objective of this paper is to generate a closed form of the equations of motion for two serially connected manipulators. Instead of computing the coupled dynamics directly, this work constructs overall dynamic equations from previously known equations of each manipulator and coupling terms derived in this paper. This approach will reduce the number of computations significantly and show the structure of the coupling dynamics between two arms. The proposed technique has been coded in Mathematica for symbolic computation. As a case study, the proposed approach is applied to two examples: micro/macro manipulators and a mobile manipulator. Each case shows not only simplicity of derivation but also a reduction in computation time of at least one-third compared to the conventional direct derivation