Singularity Analysis of a High-Speed Parallel Robot with Schönflies Motion

Author(s):  
Fugui Xie ◽  
Xin-Jun Liu ◽  
Zubing Min
2021 ◽  
Author(s):  
Luquan Li ◽  
Yuefa Fang ◽  
Lin Wang ◽  
Jiaqiang Yao

Abstract Due to the complex structures of multi-limbed parallel robots, conventional parallel robots generally have limited workspace, complex kinematics, and complex dynamics, which increases the application difficulty of parallel robot in industrial engineering. To solve the above problems, this paper proposes a single-loop Schönflies motion parallel robot with full cycle rotation, the robot can generate Schönflies motion by the most simplified structure. The novel Schönflies motion parallel robot is a two-limb parallel mechanism with least links and joints, and each limb is driven by a 2-degree of freedom (DOF) cylindrical driver (C-driver). The full cycle rotation of the output link is achieved by “…R-H…” structure, where the revolute (R) and helical (H) joints are coaxial. Mobility, kinematics, workspace and singularity analysis of novel Schönflies motion parallel robot are analyzed. Then, dynamic model is formulated based on the principle of virtual work. Moreover, a pick-and-place task is implemented by proposed Schönflies motion parallel robot and a serial SCARA robot, respectively. The simulation results verify the correctness of the theoretical model. Furthermore, dynamics performances of Schönflies motion parallel robot and serial SCARA robot are compared, which reveal the performance merits of proposed Schönflies motion parallel robot.


Author(s):  
Mansour Abtahi ◽  
Hodjat Pendar ◽  
Aria Alasty ◽  
Gholamreza Vossoughi

In the past few years, parallel manipulators have become increasingly popular in industry, especially, in the field of machine tools. Hexaglide is a 6 DOF parallel manipulator that can be used as a high speed milling machine. In this paper, the kinematics and singularity of Hexaglide parallel manipulator are studied systematically. At first, this robot has been modeled and its inverse and forward kinematic problems have been solved. Then, formulas for solving inverse velocity are derived and Jacobian matrix is obtained. After that, three different types of singularity for this type of robot have been investigated. Finally a numerical example is presented.


2015 ◽  
Vol 7 (4) ◽  
Author(s):  
Fugui Xie ◽  
Xin-Jun Liu

In this paper, a novel parallel kinematic mechanism (PKM) with Schönflies motion has been proposed under the guidance of a graphical type synthesis method. This PKM is composed of four identical arms and a single platform and has high rotational capability. The single-platform structure used in the proposed PKM can reduce structural complexity, increase dynamic response. In addition, the composite parallelogram structure in each arm brings in better limb stiffness. Based on the proposed concept, optimal design is carried out to make the PKM realize its high rotational potential. In this process, an input transmission index (ITI) and an output transmission index (OTI) (the two indices can be used to numerically evaluate motion and force transmission performance of PKMs, respectively) are taken as the performance evaluation criteria. On this basis, some other indices are defined and the corresponding performance atlases are also plotted to investigate the potential workspace. Consequently, dimensional parameters of the discussed PKM are derived on the precondition that the rotational capability should reach at least ±90 deg, and the workspace has also been identified. Based on these foundations, a parallel robot X4 has been developed which can realize high-speed pick-and-place manipulation in industrial lines.


2012 ◽  
Vol 4 (3) ◽  
Author(s):  
Songtao Liu ◽  
Tian Huang ◽  
Jiangping Mei ◽  
Xueman Zhao ◽  
Panfeng Wang ◽  
...  

This paper deals with the optimal design of a 4-DOF SCARA type (three translations and one rotation) parallel robot using dynamic performance indices and angular constraints within and amongst limbs. The architecture of the robot is briefly addressed with emphasis on the mechanical realization of the articulated traveling plate for achieving a lightweight yet rigid design. On the basis of the kinematic singularity analysis, two types of transmission angle constraints are considered to ensure the kinematic performance. A simplified model of rigid body dynamics is then formulated, with which two global dynamic performance indices are proposed for minimization by taking into account both inertial and centrifugal/Coriolis effects. In addition, the servomotor specifications are estimated using the Extended Adept Cycle. The proposed approach has successfully been employed to develop a prototype machine.


2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicholas Baron ◽  
Andrew Philippides ◽  
Nicolas Rojas

This paper presents a novel kinematically redundant planar parallel robot manipulator, which has full rotatability. The proposed robot manipulator has an architecture that corresponds to a fundamental truss, meaning that it does not contain internal rigid structures when the actuators are locked. This also implies that its rigidity is not inherited from more general architectures or resulting from the combination of other fundamental structures. The introduced topology is a departure from the standard 3-RPR (or 3-RRR) mechanism on which most kinematically redundant planar parallel robot manipulators are based. The robot manipulator consists of a moving platform that is connected to the base via two RRR legs and connected to a ternary link, which is joined to the base by a passive revolute joint, via two other RRR legs. The resulting robot mechanism is kinematically redundant, being able to avoid the production of singularities and having unlimited rotational capability. The inverse and forward kinematics analyses of this novel robot manipulator are derived using distance-based techniques, and the singularity analysis is performed using a geometric method based on the properties of instantaneous centers of rotation. An example robot mechanism is analyzed numerically and physically tested; and a test trajectory where the end effector completes a full cycle rotation is reported. A link to an online video recording of such a capability, along with the avoidance of singularities and a potential application, is also provided.


Author(s):  
Bogdan Gherman ◽  
Iosif Birlescu ◽  
Paul Tucan ◽  
Calin Vaida ◽  
Adrian Pisla ◽  
...  

As the life span increases and the availability of physicians becomes more and more scarce, robotic rehabilitation for post-stroke patients becomes more and more demanding, especially due to the repeatability character of the rehabilitation exercises. Both lower and upper limb rehabilitation using robotic systems have proved to be very successful in different stages of the rehabilitation process, but only a few address the immediate (critical) post-stroke phase, especially when the patient is hemiplegic and is unable to stand. The paper presents the kinematic modelling, singularity analysis and gait simulation for a new 4-DOF parallel robot named RECOVER used for lower limb rehabilitation for bedridden patients. The robotic system has been designed for the mobilization of the lower limb, namely the following motions: the hip and knee flexion and the plantar adduction/abduction and flexion/dorsiflexion. The kinematics has been studied and the singularity configurations have been determined to achieve a failsafe rehabilitation robot. Numerical simulations prove that the system can be used for gait training exercises in safe conditions.


2010 ◽  
Vol 166-167 ◽  
pp. 457-462
Author(s):  
Dan Verdes ◽  
Radu Balan ◽  
Máthé Koppány

Parallel robots find many applications in human-systems interaction, medical robots, rehabilitation, exoskeletons, to name a few. These applications are characterized by many imperatives, with robust precision and dynamic workspace computation as the two ultimate ones. This paper presents kinematic analysis, workspace, design and control to 3 degrees of freedom (DOF) parallel robots. Parallel robots have received considerable attention from both researchers and manufacturers over the past years because of their potential for high stiffness, low inertia and high speed capability. Therefore, the 3 DOF translation parallel robots provide high potential and good prospects for their practical implementation in human-systems interaction.


Author(s):  
S.V. Palochkin ◽  
Y.V. Sinitsyna ◽  
K.G. Erastova

The increased accuracy in high-speed positioning of the parallel robot effector in comparison with that of serial robots with a sequential structure is often the main reason for their use in various modern industries, such as the manufacture of printed circuit boards for microelectronics. However, despite the higher theoretical positioning accuracy, due to the kinematic structure of the parallel robot, in practice this characteristic largely depends on the accuracy of manufacturing individual elements of this mechanism, the most important of which are the gearboxes of the drives of its input pairs. A solution to the urgent problem of determining the effect of the manufacturing accuracy of planetary pinion gearboxes included in the drive of a five-link parallel robot on the positioning accuracy of its output link is proposed. A specific relationship has been determined between the grade of accuracy number of the gear part dimensions and the robot positioning accuracy. The unevenness of the positioning accuracy along the coordinate axes of its working area is revealed. It was found that near the area of certain robot positions the accuracy of its positioning drops sharply.


Author(s):  
Coralie Germain ◽  
Se´bastien Briot ◽  
Victor Glazunov ◽  
Ste´phane Caro ◽  
Philippe Wenger

This paper presents a novel two-degree-of-freedom (DOF) translational parallel robot for high-speed applications named the IRSBot-2 (acronym for IRCCyN Spatial Robot with 2 DOF). Unlike most two-DOF robots dedicated to planar translational motions, this robot has two spatial kinematic chains which confers a very good intrinsic stiffness. First, the robot architecture is described. Then, its actuation and constraint singularities are analyzed. Finally, the IRSBot-2 is compared to its two-DOF counterparts based on elastostatic performances.


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