scholarly journals Evaluation of a Cable-Driven Parallel Robot: Accuracy, Repeatability and Long-Term Running

2021 ◽  
pp. 375-388
Author(s):  
Marceau Métillon ◽  
Nicolò Pedemonte ◽  
Stéphane Caro
Keyword(s):  
Parallel Robot ◽  
Robot Accuracy

Accuracy calibration of a 3-CRU translational parallel robot based on the subset of error measurements

2020 ◽  
pp. 095440622096769
Author(s):  
Tie Zhang ◽  
Guangcai Ma ◽  
Yachao Cao ◽  
Yingwu He
Keyword(s):  
Linear Combination ◽  
Error Compensation ◽  
Calibration Method ◽  
Parallel Robot ◽  
Laser Tracker ◽  
End Effector ◽  
Structural Error ◽  
Robot Accuracy ◽  
Calibration Methods ◽  
Complete Set

Robot accuracy calibration is an effective method to improve its kinematic accuracy. However, most of the existing calibration methods need to measure the complete set of 6-dimensional pose errors of the end-effector, which makes the calibration process especially complicated. In this paper, an accuracy calibration method for a 3-CRU translational parallel robot is proposed based on the subset of error measurements. The process is implemented by four steps: 1) the error model is established based on matrix method. Then the structural errors to be identified are separated. 2) part of pose errors of the end-effector are measured by laser tracker and used to form the subset of error measurements. 3) the minimum structural error linear combination affecting robot accuracy is determined according to the minimum parameter error linear combination theorem. After that, the structural errors can be identified based on the subset of error measurements. 4) error compensation based on the identification results. This method can not only ensure the identifiability of the structural errors, but also can realize error identification based on the subset of error measurements, which will significantly reduce the calibration workload and improve the calibration efficiency. Experiments are carried out to prove the effectiveness of the calibration method.

scholarly journals Parametric Study for Nonlinear Dynamic Behaviors using Integrated Cable Elongation Model of Cable Driven Parallel Robot

2018 ◽  
Vol 192 ◽  
pp. 02010
Author(s):  
Sung-Hyun Choi ◽  
Kyoung-Su Park
Keyword(s):  
Cyclic Load ◽  
Parallel Robot ◽  
High Accuracy ◽  
Elastic Model ◽  
Light Weight ◽  
Dynamics Model ◽  
Cable Length ◽  
Dynamic Creep ◽  
Parametric Studies

Polymer is one of the most widely used cable materials in the CDPR system due to its light weight and low inertia. However, it is not easily to achieve high accuracy because of the complicated response of polymer cable while CDPR is operated. In our previous study, the integrated dynamics model of cable was derived with the visco-elastic model. With the integrated dynamics model of cable, the parametric studies were carried out for the cable length, the applied force and the tensile rate for various nonlinear cable elongation behaviors. At first, dynamic creep behavior was defined and investigated in CDPR system. Dynamic creep was saturated with one value as the cyclic load/unload is continuously carried out. The saturation number was inversely proportional to the cable length because of the residual stress. And as the tensile rate was increased, the dynamic creep was decreased linearly. In long-term recovery, the long-term recovery is finished more quickly for the case of a shorter cable.

Therapy and prevention for mental health: What if mental diseases are mostly not brain disorders?

2019 ◽  
Vol 42 ◽  
Author(s):  
John P. A. Ioannidis
Keyword(s):  
Mental Health ◽  
Mental Disease ◽  
Brain Disorders ◽  
Social Stressors ◽  
Labor Education ◽  
Mental Diseases ◽  
Long Term Follow Up ◽  
Political Decisions

AbstractNeurobiology-based interventions for mental diseases and searches for useful biomarkers of treatment response have largely failed. Clinical trials should assess interventions related to environmental and social stressors, with long-term follow-up; social rather than biological endpoints; personalized outcomes; and suitable cluster, adaptive, and n-of-1 designs. Labor, education, financial, and other social/political decisions should be evaluated for their impacts on mental disease.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Brief summary of Kleť photographic search programme for minor planets

1999 ◽  
Vol 173 ◽  
pp. 189-192
Author(s):  
J. Tichá ◽  
M. Tichý ◽  
Z. Moravec
Keyword(s):  
Ccd Camera ◽  
Minor Planet ◽  
Minor Planets ◽  
Main Belt

AbstractA long-term photographic search programme for minor planets was begun at the Kleť Observatory at the end of seventies using a 0.63-m Maksutov telescope, but with insufficient respect for long-arc follow-up astrometry. More than two thousand provisional designations were given to new Kleť discoveries. Since 1993 targeted follow-up astrometry of Kleť candidates has been performed with a 0.57-m reflector equipped with a CCD camera, and reliable orbits for many previous Kleť discoveries have been determined. The photographic programme results in more than 350 numbered minor planets credited to Kleť, one of the world's most prolific discovery sites. Nearly 50 per cent of them were numbered as a consequence of CCD follow-up observations since 1994.This brief summary describes the results of this Kleť photographic minor planet survey between 1977 and 1996. The majority of the Kleť photographic discoveries are main belt asteroids, but two Amor type asteroids and one Trojan have been found.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

2000 ◽  
Vol 179 ◽  
pp. 201-204
Author(s):  
Vojtech Rušin ◽  
Milan Minarovjech ◽  
Milan Rybanský
Keyword(s):  
Emission Lines ◽  
High Latitudes ◽  
Green Line ◽  
Solar Cycles ◽  
The South ◽  
Coronal Emission ◽  
Local Maxima ◽  
The North ◽  
Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

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