Partially-flagged parallel manipulators: singularity charting and avoidance

There are only three 6-SPS parallel manipulators with triangular base and platform: the octahedral, the flagged, and the partially-flagged studied in this paper. The forward kinematics of the octahedral manipulator is algebraically intricate, while those of the other two can be solved by three trila...

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Detalles Bibliográficos
Autores: Alberich-Carramiñana, Maria, Garolera, Marçal, Thomas, Federico, Torras, Carme
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2009
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/30499
Acceso en línea:http://hdl.handle.net/10261/30499
Access Level:acceso abierto
Palabra clave:Redundant manipulators
Robot design
Descripción
Sumario:There are only three 6-SPS parallel manipulators with triangular base and platform: the octahedral, the flagged, and the partially-flagged studied in this paper. The forward kinematics of the octahedral manipulator is algebraically intricate, while those of the other two can be solved by three trilaterations. As an additional nice feature, the flagged manipulator is the only parallel platform for which a cell decomposition of its singularity locus has been derived. Here we prove that the partially-flagged manipulator admits also a well-behaved decomposition, technically called a stratification, some of whose strata are not topological cells, though. Remarkably, the adjacency diagram of the 5 and 6 dimensional strata (which shows what 5 dimensional strata are contained in the closure of a 6 dimensional one) is the same as for the flagged manipulator. The availability of such a decomposition permits devising a redundant 7-SPS manipulator, combining two partially-flagged ones, which admits a control strategy that completely avoids singularities. Simulation results support these claims.