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Target Position (target + position)
Selected AbstractsActive target particle swarm optimizationCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 1 2008Ying-Nan Zhang Abstract We propose an active target particle swarm optimization (APSO). APSO uses a new three-target velocity updating formula, i.e. the best previous position, the global best position and a new target position (called active target). In this study, we distinguish APSO from EPSO (extended PSO)/PSOPC (PSO with passive congregation) by the different methods of getting the active target. Note that here EPSO and PSOPC are the two existing methods for using three-target velocity updating formula, and getting the third (active) target from the obtained positions by the swarm. The proposed APSO gets the active (third) target using complex method, where the active target does not belong to the existing positions. We find that the APSO has the advantages of jumping out of the local optimum and keeping diversity; however, it also has the disadvantages of adding some extra computation expenses. The experimental results show the competitive performance of APSO when compared with PSO, EPSO, and PSOPC. Copyright © 2007 John Wiley & Sons, Ltd. [source] Long-span seek control system for hard disk drive without mode-switchingELECTRICAL ENGINEERING IN JAPAN, Issue 3 2010Shinji Takakura Abstract In hard disk drives (HDD) there are two control modes: the head positioning control mode and the other is the seek control mode. In the head positioning control mode, a feedback controller is optimally designed to suppress disturbances. In the long-span seek mode, a velocity feedback control system is applied in order to move the heads fast. Thus, an HDD has multiple control systems, and the head is moved to the target position while changing from one control system to the other. However, changing the control system causes a discontinuous control signal, which activates the resonant mode of an actuator. Past methods can only decrease discontinuous control, and therefore a single control system that can be used for both a seek control mode and a head positioning control mode is necessary for a narrow track pitch. In the proposed method, the feedback controller is decomposed into an integrator and a phase compensator. The VCM model is updated by the output of the phase compensator, and the integrator and the output of the velocity feedback controller control the VCM. The validity of the proposed method was confirmed by numerical and experimental results using a miniature 2.5-inch hard disk drive. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 51,60, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20935 [source] A natural redundancy-resolution for 3-D multi-joint reaching under the gravity effectJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 11 2005Masahiro Sekimoto A simple control method for 3-dimensional multi-joint reaching movements under redundancy of degrees of freedom (DOF) is proposed, which need neither introduce any performance index to solve inverse kinematics uniquely nor calculate pseudo-inverse of the Jacobian matrix of task coordinates with respect to joint coordinates. The proposed control signal is composed of linear superposition of three terms: (1) angular-velocity feedback for damping shaping, (2) task-space position error feedback with a single stiffness parameter, and (3) compensation for gravity force on the basis of estimates for uncertain parameters of the potential energy without calculation any inverse joint position to the target in task space. Through a theoretical analysis of the closed-loop dynamics and a variety of computer simulations by using a whole arm model with five DOFs, the importance of synergistic adjustments of damping factors as well as its relation to selection of the stiffness parameter is pointed out. It is shown that if damping factors are chosen synergistically corresponding to the inertia matrix at the initial time and the stiffness parameter then the endpoint converges asymptotically to the target position and reaches it smoothly without incurring any self-motion. © 2005 Wiley Periodicals, Inc. [source] Manual transport in Parkinson's diseaseMOVEMENT DISORDERS, Issue 5 2003Blanka Hejduková MD Abstract We analyze hand dexterity in Parkinson's disease patients (PD) and control subjects using a natural manual transport task (moving an object from one place to another). Eight PD patients and 10 control subjects carried out the task repeatedly at maximum speed both in off and on medicated status. The movement parameters and the grip and load forces were recorded. Using the force and velocity signals, 10 subsequent phases of the transport movement were defined and their durations were measured. The difference between the control group and the test group in off and on was established statistically using non-parametric methods. There was slowed reaching and a striking disturbance of establishing the precision grip in PD. The transport capabilities were impaired differentially. Although acceleration and reaching sufficient height of the lift were disturbed in PD subjects, transport of the object toward the target position was almost normal. A partial disturbance was observed when cancelling the grip. Dopaminergic medication improved only specific hand skills, especially establishment of the precision grip and one of the four transport phases. A long movement path was more sensitive for movement disturbance in Parkinson's disease than a short one.© 2003 Movement Disorder Society [source] Planning of rapid aiming movements and the contingent negative variation: Are movement duration and extent specified independently?PSYCHOPHYSIOLOGY, Issue 3 2009Hartmut Leuthold Abstract In the present study we investigated motor programming constraints implied by the Generalized Motor Program (GMP) view. A response precuing task was used in which participants performed aiming movements of either short or long duration to either a near or a far target position. Precues provided either no advance information or partial information about extent or duration or fully specified the aiming movement. Reaction time (RT) decreased and late Contingent Negative Variation (CNV) amplitude increased with the amount of advance information. In contrast to predictions of the GMP view, the extent precue led to faster responses and larger CNV amplitude than the duration precue. We conclude that late CNV amplitude reflects independent parameter specification processes at an abstract level at which GMP's motor programming constraints do not apply. [source] The n -back as a dual-task: P300 morphology under divided attentionPSYCHOPHYSIOLOGY, Issue 6 2001Scott Watter The n -back task was hypothesized to be a dual task, permitting the imposition of parametrically increasing attentional and working memory demands, while keeping constant the demands of an embedded matching subtask. Visual targets were presented for 200 ms every 2.2 s at pseudorandomly varying positions on a computer screen. Participants were required to remember the most recent 0, 1, 2, or 3 positions and responded with a choice button push to whether the current target position matched the position presented n items previously. P300 peak latency was constant across n -back tasks, reflecting constant perceptual and cognitive demands of the matching subtask. P300 peak amplitude decreased with increasing memory load, reflecting reallocation of attention and processing capacity away from the matching subtask to working memory activity. These data support a dual-task nature of the n -back, which should be considered when employing this paradigm. [source] Site-Specific Functionalization of Proteins by Organopalladium Reactions,CHEMBIOCHEM, Issue 2 2007Koichiro Kodama Abstract A new carbon,carbon bond has been regioselectively introduced into a target position (position 32 or 174) of the Ras protein by two types of organopalladium reactions (Mizoroki,Heck and Sonogashira reactions). Reaction conditions were screened by using a model peptide, and the stability of the Ras protein under the reaction conditions was examined by using the wild-type Ras protein. Finally, the iF,Ras proteins containing a 4-iodo- L -phenylalanine residue were subjected to organopalladium reactions with vinylated or propargylated biotin. Site-specific biotinylations of the Ras protein were confirmed by Western blot and LC-MS/MS. [source] A New Protein Engineering Approach Combining Chemistry and Biology, Part I; Site-Specific Incorporation of 4-Iodo- L -phenylalanine in vitro by Using Misacylated Suppressor tRNAPheCHEMBIOCHEM, Issue 10 2006Koichiro Kodama Abstract An Escherichia coli suppressor tRNAPhe (tRNAPheCUA) was misacylated with 4-iodo- L -phenylalanine by using the A294G phenylalanyl,tRNA synthetase mutant (G294-PheRS) from E. coli at a high magnesium-ion concentration. The preacylated tRNA was added to an E. coli cell-free system and a Ras protein that contained the 4-iodo- L -phenylalanine residue at a specific target position was synthesized. Site-specific incorporation of 4-iodo- L -phenylalanine was confirmed by using LC,MS/MS. Free tRNAPheCUA was not aminoacylated by aminoacyl,tRNA synthetases (aaRSs) present in the E. coli cell-free system. Our approach will find wide application in protein engineering since an aryl iodide tag on proteins can be used for site-specific functionalization of proteins. [source] Cervicocephalic kinaesthesia: reliability of a new test approachPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 4 2001Eythor Kristjansson Faculty of Medicine Abstract Background and Purpose Relocating either the natural head posture (NHP) or predetermined points in range are clinical tests of impaired neck proprioception but memory might influence these tests. Three new tests, reasoned to be more challenging for the proprioceptive system, were developed. The objectives were to assess the reliability of all tests and whether the three new tests were more challenging for the proprioceptive system. Method A test,retest design was used to assess the reproducibility and errors of all five tests. Twenty asymptomatic volunteers were assessed a week apart, using an electromagnetic movement sensor system, the 3-Space Fastrak. A measure of error magnitude was used to detect kinaesthetic sensibility. Comparison of the means and their corresponding dispersion were analysed descriptively. The between-day intraclass correlation coefficients (ICCs) were calculated and plots of mean differences between days 1 and 2 were conducted to estimate test reliability. Multivariate analysis of variance (MANOVA) and least significant difference (LSD) pairwise comparisons were performed to compare the test accuracy between different target positions. Results ICCs were between 0.35 and 0.9, but plotting the data modified the interpretation in some tests. Relocating a NHP was easier when the trunk was in a neutral position than when pre-rotated (error 2.46° (±0.2°) versus 5.95° (±0.7°). Relocating a 30° rotation position (error 5.8° (±0.6°) and repeatedly moving through a target (error 4.82° (±0.7°) was also difficult. Conclusions The new tests were more challenging than relocating the NHP but the reliability of tests relocating uncommon positions was questionable. Copyright © 2001 Whurr Publishers Ltd. [source] | |||||||||||||