外文翻译-一种合成型法求解复合机器人结构.doc

1、Available online at Mechanism and Machine Theory 43 (2008) 984995Mechanism andMachine TheoryA type synthesis method for hybrid robot structuresAlexandre Campos *, Christoph Budde, Ju rgen HesselbachInstitute of Machine Tools and Production Technology, Technical University of Braunschweig, Langer Kam

2、p 19 B, D-38106 Braunschweig, GermanyReceived 11 May 2006; received in revised form 30 April 2007; accepted 11 July 2007Available online 24 October 2007AbstractIn this paper a new methodology to synthesize hybrid robots as a whole structure is presented. The method is based on Assur groups as the si

3、mplest basic blocks to build kinematic chains. Criterions like symmetry and low inertia are consid- ered in the design process. The method results in hybrid robots whose structures are as simple as possible. The closed chains of some of them are known parallel structures, however one of them is a ne

4、w hybrid structure. 2007 Published by Elsevier Ltd.Keywords: Hybrid robot; Synthesis method; Assur groups1. IntroductionHybrid structures combine the advantages of parallel and serial chains, e.g. stiffness and manipulability 16. Most robots designed are either built up of serial or in-parallel conn

5、ected kinematic chains. Serial robotsconsist of a series of active joints connecting the base to the end effector and feature large workspaces and highdexterity but they suffer from lack of stiffness and from relatively large positioning errors due to their canti-lever type of kinematic arrangement.

6、 On the other hand, parallel manipulators consist of a set of parallel legseach with active and passive joints required to maintain the system mobility and controllability. They connectthe base to the moving platform resulting in structures able to achieve high stiffness and high force-to-weightrati

7、o. However, parallel manipulators are known for a restricted workspace and low dexterity.Aiming to merge the advantages of serial and parallel robots, the basic principle of hybrid kinematic structures is to divide the task of manipulation 1. This task is divided into a position task (position mecha

8、nism)and an orientation task (orientation mechanism), respectively. The position mechanism controls the positionwhereas the orientation mechanism manipulates the orientation of the end effector. Then, these mechanismsmay be connected in series, called conventional hybrid structure, or in parallel, i

9、.e. cooperative structure 1,8.Additionally, the serial combinations of serial and parallel structures can be sub-divided into 3: parallelparallel type 6, parallelserial type 7 and serialserial type, i.e. a conventional serial manipulator. In this* Corresponding author.E-mail addresses: a.camposiwf.i

10、ng.tu-bs.de (A. Campos), ch.buddetu-bs.de (C. Budde).0094-114X/$ - see front matter 2007 Published by Elsevier Ltd. doi:10.1016/j.mechmachtheory.2007.07.006A. Campos et al. / Mechanism and Machine Theory 43 (2008) 984995985work, we focus on the conventional hybrid structure of parallelserial type, n

11、amed hybrid structure for short. Therefore, by using hybrid structures it is intended to retain the merits of serial structures, i.e. large workspace and high dexterity, and parallel structures, i.e. high stiffness and high force-to-weight ratio, while their disad- vantages are minimized.Analysis an

12、d modeling have been the main research field in hybrid robots 1,3,912, additionally some researches have dealt with the design of hybrid robots 46. In spite of the cited advantages of hybrid robots, there is no systematic method to design or synthesize hybrid robots as a whole structure instead of a

13、 separated synthesis for the parallel and the serial structure.This paper proposes a synthesis method for hybrid robots as a whole, built up of sets of Assur groups. It is based on a method for finger synthesis which guarantees the simplest structures, i.e. the least number of bodies and one degree

14、of freedom (dof) joints 13, however the presented method does not use computer algorithms which may result in chain isomorphisms.Section 2 presents a brief introduction to Assur groups, then the hybrid kinematic design and some require-ments for a suitable hybrid robot are introduced. To illustrate

15、the method, all simplest possible chains for sixdegrees of freedom (DOF) of the end effector with 3, 4 and 5 fixed drives are presented. Based on the method asymmetrical hybrid robot is found whose closed structure topology is new according to the knowledge of theauthors. Finally, the joints are allocated into the hybrid chain and for the new robot an embodiment is pro-posed based on legs for fully isotropic translational parallel robots 14.2. Assur groupsOne of the main approaches employed in the literature for carrying out the structural synth