（节选）外文翻译---新型二自由度平动并联机器人的结构和运动学分析

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1、附录（一）英文文献   Structure and kinematic analysis of  a novel 2-DOF translational parallel robot Chen Tao1 Wu Chao2 and Liu xiujun2* ( 1. School of Application Science and Technology HarbinUniversity of Science And Technology ， Harbin l50080,China ； 2. Department of Precision Instruments Tsingh

2、uaUniversity, Beijing 100084, China) Accepted on February 13, 2007 Abstract This paper addresses the analysis of a novel parallel robot with 2 translational degrees of freedom (DOFs). The robot can position a rigid body in a plane with constant orientation. The kinematic structure of the robot is fi

3、rst described in detail, Some kinematic problems, such as the inverse and forward kinematics, velocity, and singularity are then analyzed. The working and assembly modes are discussed. Since it is the most important index to design a robot , the workspace of the robot is studied systematically in th

4、is paper. Based on the analysis of reachable workspace and singularity, a kind of workspace concept characterizing the region that the end-effector of the robot can reach in practice is defined. The results of this paper will be very useful for the design and application of the robot. Keywords： &nbs

5、p;parallel robot, degree of freedom, kinematics workspace.   The conceptual design of parallel robots can be dated back to the time when Gough established the basic principles of a device with a closed-loop kinematic structure that can generate specified position and orientation of a moving pla

6、tform so as to test tire wear and. tear. Based on this principle, Stewart designed a platform used as an aircraft simulator in 1965. In 1978, Hunt made a systematic study of robots with parallel kinematics, in which the spatial 3-RPS (R-revolute joint， P-prismatic joint, and S- spherical joint) para

7、llel robot is a typical one. Since then, parallel robots have   been studied extensively by numerous researchers. The parallel robots with 6 DOFs possess the ad-vantages of high stiffness, low inertia, and large payload capacity. However, they suffer the problems of relatively small useful work

8、space and design difficulties .Their direct kinematics possess a very difficult problem. The same problem of parallel robots with 2 and 3 DOFs can be described in a closed form . As is well known, there are three kinds of singularities in parallel robots. Generally, not all singularities of a 6- DOF

9、 parallel robot can be found easily. For a parallel robot with 2 or 3 DOFs, the singularities can always be identified readily. For such reasons, parallel robots with less than 6 DOFs, especially 2 and 3 DOFs, have increasingly attracted more and more researchers  attention with respect to indu

10、strial applications. In these designs, parallel robots with three translational CKDFs have been playing important roles in the industrial applications. For example, the design of the DELTA robot is covered by a family of 36 patents. Tsais robot， in which each of the three legs consists of a parallel

11、ogram, is the first de, sign to solve the problem of UU chain. Such parallel robots have wide applications in the industrial world, e. g., pick-and-place application, parallel kinematic machines, and medical devices. The most famous planar 2-DOF parallel robots are the well-known five-bar mechanism

12、with prismatic actuators or revolute actuators. In the case of the robot with revolute actuators, the mechanism consists of five re volute pairs and the two joints fixed to the base are actuated, while in the case of the robot with prismatic actuators, the mechanism consists of three revolute pairs

13、and two prismatic joints, in which the prismatic joints are usually actuated. The output of the robot is the translational motion of a point on the end-effector. This means the orientation of the end- effector is also changed at any moment. Accordingly, some versions of the 2-DOF translational paral

14、lel robot (TPR) have been disclosed. One of them has been applied in precise pick & place operations at high speed at SFB in German, In 2001, another 2-DOF TPR has been proposed for the conceptual design of a 5-axis machine tool, The structure, kinematics and dynamics of the TPR were discussed i

15、n de- tail, Recently, a 2-DOF TPR with revolute actuators was introduced. The TPR presented in Ref. 4 has been used in the design of a planer machine tool with a gantry structure instead of a traditional one with serial chains to improve its stiffness and inertia characteristics. However* all of the

16、se TPRs consist of at least of one parallelogram, which increases the difficulty of manufacturing and affects the accuracy. This paper introduces a novel planar translational parallel robot with simple   kinematic structure. The robot can position an objective with constant orientation. Some ki

17、nematic problems, such as inverse and forward kinematics, workspace and singularity are discussed. 1 Description of the 2-DOF TPR and its topological architectures 1.1 Architecture description The novel 2-DOF translational parallel robot and its schematic are shown in Fig. 1. The end-effector of the

18、 robot is connected to the base by two kinematic legs 1 and 2. Leg 1 consists of three revolute joints and leg 2 two revolute joints and one cylinder joint, or three re volute joints and one prismatic joint- In each leg, the re volute joints are parallel to each other. The axes of the revolute joint

19、s in leg 1 are normal to those of the joints in leg 2. The two joints attached to the end-effector are put in the adjacent sides of a square. The kinematic chain of the robot is denoted as RRR-RRC (C-cylinder joint) or RRR-RRRP, One may see that, if the P joint is fixed, the robot is actually the fa

20、mous Sarrus mechanism. As introduced previously， other TPRs have at least one parallelogram in their structures. The TPR proposed here has no parallelogram. This makes the manufacturing easier. However, compared with the TPRs presented in Refs. 9,10，the TPR studied here has some disadvantages. For e

21、xample, the performance of the new TPR is not symmetric in its workspace. Additionally, the new TPR is likely to need more occupying space. (a) the CAD model                  (b) the schematic Fig.1 The 2-DOF translational parallel robot 1.2 Capability Here, an expression like , , ； , ,jx x y z x y zis used to describe the capability of