Dimensional synthesis is a type of inverse problem in linkage kinematics where the objective is to calculate the linkage dimensions required to achieve prescribed linkage output motion. It includes...

Developments in quantitative dimensional synthesis (1970–present): four-bar path and function generation

In this work, a family of two degrees of freedom (2-DOF) rotational parallel manipulators (RPMs) with an equal-diameter spherical pure rotation (ESPR) is presented and discussed systematically. The theoretical models of both kinematics and constraints inherited in the manipulators are analyzed through a graphical approach. Based on the established constraint model, these 2-DOF ESPR RPMs are classified into three types according to their compositions of constraint spaces and several novel parallel manipulators are illustrated correspondingly. Finally, two common necessary geometric conditions satisfied for these manipulators are discussed in details with examples. The two conditions will be helpful for engineers with designing ESPR RPMs. Moreover, as one characteristic existing in the ESPR RPMs, two cases of self-rotations accompanying revolutions around fixed axes are revealed. As a result, the corresponding loci of points in the moving platform are proved to be compositions of two subrotations, which are spatial curves and surfaces rather than spherical curves and surfaces. [DOI: 10.1115/1.4025860]

A Family of Rotational Parallel Manipulators With Equal-Diameter Spherical Pure Rotation

In this work, a systematic approach is presented to obtain the input-output equations of a single loop 4-bar spatial mechanisms. The dialytic method along with Denavit-Hartenberg parameters can be used to obtain these equations efficiently. A genetic algorithm (GA) has been used to solve the problem of spatial mechanisms synthesis. Two types of mechanisms, e.g., RSCR and RSPC (R: revolute; S: spherical; C: cylindrical; P: prismatic), have illustrated the application of the GA to solve the problem of function generation and path generation. In some cases, the GA method becomes trapped in a local minimum. A combined GA-fuzzy logic (GA-FL) method is then used to improve the final result. The results show that GAs, combined with an adequate description of the mechanism, are well suited for spatial mechanism synthesis problems and have neither difficulties inherent to the choice of the initial feasible guess, nor a problem of convergence, as it is the case for deterministic methods.

Analysis and optimal synthesis of single loop spatialmechanisms

Les techniques classiques de synthese des mecanismes sont encore limitees de point de vue application et performances. L'experience du c oncepteur est encore l'atout essentiel pour resoudre ce genre de probleme. Dans ce but, on se propose de developper des outils de synthese de mecanismes plans et spatiaux et de robots paralleles par une methode evolutionnaire. La premiere partie s'interesse a la synthese des mecanismes plans et spatiaux. La nouvelle modelisation proposee utilise le parametrage de Denavit-Hartenberg. Ce parametrage permet facilement d'etudier, les quatre familles de mecanismes que nous avons identifie. Ils sont resolus par une technique d'optimisation basee sur un couplage entre un algorithme genetique et un controleur de logique floue. On developpe egalem ent une application d'un mecanisme spatial, que nous avons propose, comme dispositif anti-escarres. La deuxieme partie est dediee a l'analyse et a la synthese dimensionnelle du robot DELTA pour un espace de travail prescrit. On introduit la notion de puissance d'un point par rapport a une surface, utilisee dans la formulation du probleme de synthese. En fait, cette approche repose sur un processus d'optimis ation genetique s'adaptant aux differents criteres de synthese.

https://tel.archives-ouvertes.fr/tel-00706309/document

M.N. Siddhanty

Papers

Higher-order synthesis of an RSSR mechanism with application