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Performance evaluation of a sensor concept for solving the direct kinematics problem of general planar 3-RPR parallel mechanisms by using solely the linear actuators’ orientations
Citation Link: https://doi.org/10.15480/882.2381
Publikationstyp
Journal Article
Date Issued
2019-08-16
Sprache
English
Author(s)
Institut
TORE-DOI
TORE-URI
Journal
Volume
8
Issue
3
Article Number
72
Citation
Robotics 8 (3): 72 (2019)
Publisher DOI
Scopus ID
Publisher
Multidisciplinary Digital Publishing Institute
In this paper, we experimentally evaluate the performance of a sensor concept for solving the direct kinematics problem of a general planar 3-RPR parallel mechanism by using solely the linear actuators’ orientations. At first, we review classical methods for solving the direct kinematics problem of parallel mechanisms and discuss their disadvantages on the example of the general planar 3-RPR parallel mechanism, a planar parallel robot with two translational and one rotational degrees of freedom, where P denotes active prismatic joints and R denotes passive revolute joints. In order to avoid these disadvantages, we present a sensor concept together with an analytical formulation for solving the direct kinematics problem of a general planar 3-RPR parallel mechanism where the number of possible assembly modes can be significantly reduced when the linear actuators’ orientations are used instead of their lengths. By measuring the orientations of the linear actuators, provided, for example, by inertial measurement units, only two assembly modes exist. Finally, we investigate the accuracy of our direct kinematics solution under static as well as dynamic conditions by performing experiments on a specially designed prototype. We also investigate the solution formulation’s amplification of measurement noise on the calculated pose and show that the Cramér-Rao lower bound can be used to estimate the lower bound of the expected variances for a specific pose based exclusively on the variances of the linear actuators’ orientations.
Subjects
direct kinematics problem
parallel robots
linear actuators’ orientations
assembly modes
general planar 3-RPR parallel mechanism
inertial measurement units
Cramér-Rao lower bound
static and dynamic experiments
DDC Class
600: Technik
620: Ingenieurwissenschaften
More Funding Information
Deutsche Forschungsgemeinschaft (DFG)
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robotics-08-00072.pdf
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