23 research outputs found
Compensation of compliance errors in parallel manipulators composed of non-perfect kinematic chains
The paper is devoted to the compliance errors compensation for parallel
manipulators under external loading. Proposed approach is based on the
non-linear stiffness modeling and reduces to a proper adjusting of a target
trajectory. In contrast to previous works, in addition to compliance errors
caused by machining forces, the problem of assembling errors caused by
inaccuracy in the kinematic chains is considered. The advantages and practical
significance of the proposed approach are illustrated by examples that deal
with groove milling with Orthoglide manipulator.Comment: Advances in Robot Kinematics, France (2012
Stiffness modelling of parallelogram-based parallel manipulators
International audienceThe paper presents a methodology to enhance the stiffness analysis of parallel manipulators with parallelogram-based linkage. It directly takes into account the influence of the external loading and allows computing both the non-linear ``load-deflection" relation and relevant rank-deficient stiffness matrix. An equivalent bar-type pseudo-rigid model is also proposed to describe the parallelogram stiffness by means of five mutually coupled virtual springs. The contributions of this paper are highlighted with a parallelogram-type linkage used in a manipulator from the Orthoglide family
Performance evaluation of parallel manipulators for milling application
This paper focuses on the performance evaluation of the parallel manipulators
for milling of composite materials. For this application the most significant
performance measurements, which denote the ability of the manipulator for the
machining are defined. In this case, optimal synthesis task is solved as a
multicriterion optimization problem with respect to the geometric, kinematic,
kinetostatic, elastostostatic, dynamic properties. It is shown that stiffness
is an important performance factor. Previous models operate with links
approximation and calculate stiffness matrix in the neighborhood of initial
point. This is a reason why a new way for stiffness matrix calculation is
proposed. This method is illustrated in a concrete industrial problem
Funções de pedotransferência para estimativa da retenção de água em alguns solos do Rio Grande do Sul
Comparação de dispersantes quÃmicos na análise granulométrica de solos do Estado de Pernambuco
Pedotransfer functions to predict water retention for soils of the humid tropics: a review
An Interval ANalysis Based Study for the Design and the Comparison of Three-Degrees-of-Freedom . . .
This paper addresses an interval analysis based study that is applied to the design and the comparison of three-degrees-of-freedom (3-DoF) parallel kinematic machines. Two design criteria are used: (i) a regular workspace shape and (ii) a kinetostatic performance index that needs to be as homogeneous as possible throughout the workspace. The interval analysis based method takes these two criteria into account; on the basis of prescribed kinetostatic performances, the workspace is analyzed to find the largest regular dextrous workspace enclosed in the Cartesian workspace. An algorithm describing this method is introduced. Two 3-DoF translational parallel mechanisms designed for machining applications are compared using this method. The first machine features three fixed linear joints which are mounted orthogonally and the second features three linear joints which are mounted in parallel. In both cases, the mobile platform moves in the Cartesian x--y--z space with fixed orientation