On Performance Enhancement of Parallel Kinematic Machine

2005 ◽  
Author(s):  
Dan Zhang ◽  
Lihui Wang
Keyword(s):  
Remote Control ◽  
Degrees Of Freedom ◽  
Geometric Model ◽  
Kinematic Model ◽  
Parallel Kinematic Machine ◽  
Web Based ◽  
Remote Manipulation ◽  
Parallel Kinematic ◽  
Moving Platform ◽  
Three Degrees Of Freedom

This paper proposes a spatial three degrees of freedom parallel kinematic machine enhanced by a passive leg and a web-based remote control system. First, the geometric model of the three degrees of freedom parallel kinematic machine is addressed; in the mechanism, a fourth kinematic link — a passive link connecting the base center to the moving platform center — is introduced. This last link is used to constrain the motion of the tool (located in the moving platform) to only three degrees of freedom, as well as to enhance the global stiffness of the structure and distribute the torque from machining. With the kinematic model, a web-based remote control approach is then applied. The concept of the web-based remote manipulation approach is introduced and the principles behind the method are explored in detail. Finally, an example of remote manipulation is demonstrated to the proposed 3-DOF structure using web-based remote control concept before conclusions.

scholarly journals Kinematic Analysis and Trajectory Planning of the Orthoglide 5-Axis

2015 ◽  
Author(s):  
S. Caro ◽  
D. Chablat ◽  
P. Lemoine ◽  
P. Wenger
Keyword(s):  
Trajectory Planning ◽  
Kinematic Analysis ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Inverse Kinematic ◽  
Hybrid Architecture ◽  
Parallel Kinematic Machine ◽  
Control Loop ◽  
Parallel Kinematic

The subject of this paper is about the kinematic analysis and the trajectory planning of the Orthoglide 5-axis. The Orthoglide 5-axis a five degrees of freedom parallel kinematic machine developed at IRCCyN and is made up of a hybrid architecture, namely, a three degrees of freedom translational parallel manipulator mounted in series with a two degrees of freedom parallel spherical wrist. The simpler the kinematic modeling of the Orthoglide 5-axis, the higher the maximum frequency of its control loop. Indeed, the control loop of a parallel kinematic machine should be computed with a high frequency, i.e., higher than 1.5 MHz, in order the manipulator to be able to reach high speed motions with a good accuracy. Accordingly, the direct and inverse kinematic models of the Orthoglide 5-axis, its inverse kinematic Jacobian matrix and the first derivative of the latter with respect to time are expressed in this paper. It appears that the kinematic model of the manipulator under study can be written in a quadratic form due to the hybrid architecture of the Orthoglide 5-axis. As illustrative examples, the profiles of the actuated joint angles (lengths), velocities and accelerations that are used in the control loop of the robot are traced for two test trajectories.

Design and Experimental Investigation of a New 2R1T Overconstrained Parallel Kinematic Machine With Actuation Redundancy

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Lingmin Xu ◽  
Xinxue Chai ◽  
Qinchuan Li ◽  
Liangan Zhang ◽  
Wei Ye
Keyword(s):  
Inverse Kinematics ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Curved Surfaces ◽  
Parallel Kinematic Machine ◽  
Actuation Redundancy ◽  
Dimensional Parameters ◽  
Force Transmissibility ◽  
Parallel Kinematic

Two rotations and one translation (2R1T) parallel kinematic machines (PKMs) are suitable for the machining of complex curved surfaces, which requires high speed and precision. To further improve rigidity, precision, and avoid singularity, actuation redundancy, and overconstrained PKMs with fixed actuators and limited-degrees of freedom (DOF) limbs are preferred. However, there are few 2R1T PKMs with these features. This paper introduces a new 2R1T overconstrained PKM with actuation redundancy, which is called Tex4. The Tex4 PKM consists of four limited-DOF limbs; that is, two PUR limbs and two 2PRU limbs (where P denotes an actuated prismatic joint, U denotes a universal joint, and R denotes a revolute joint). The kinematic model of the proposed 2PUR-2PRU machine is presented along with the results of mobility, inverse kinematics, and velocity analysis. By considering the motion/force transmissibility, the dimensional parameters of the Tex4 PKM were optimized to obtain an improved satisfactory transmission workspace without singular configurations. Finally, a prototype based on the optimized parameters was fabricated, and its feasibility and accuracy were validated by motion and position error experiments. The Tex4 PKM has the advantages of high rigidity, simple kinematic model, and zero singularity in the workspace, which suggests that it has potential for use in the high-speed machining of curved surfaces.

Motion Plan of a Parallel Kinematic Machine Based on Stiffness Control

2010 ◽  
Author(s):  
Zhongzhe Chi ◽  
Dan Zhang ◽  
Qiaokang Liang
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Tool Path ◽  
Parallel Kinematic Machine ◽  
Tool Path Planning ◽  
Parallel Kinematic ◽  
Stiffness Control ◽  
Three Degrees Of Freedom

This paper proposes a design for a machine tool based on a parallel kinematic manipulator with three degrees of freedom, including rotations about x and y axis and translation along z axe. Based on the investigated displacement and inverse kinematics, the system stiffness of the parallel manipulator is conducted. Then in order to observe the highest system stiffness single and multi objective optimizations are performed in terms of rotation angles about x and y axis and translation displacement along z axe. Finally, a case study of tool path planning is presented to demonstrate the application of stiffness mapping.

A Model of the Human Spine: Forward and Inverse Kinematics

1992 ◽  
Author(s):  
Sunil Kumar Agrawal ◽  
Siyan Li ◽  
Glen Desmier
Keyword(s):  
Range Of Motion ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Joint Angles ◽  
Human Spine ◽  
Forward And Inverse Kinematics ◽  
Position And Orientation ◽  
Three Degrees Of Freedom ◽  
Adjacent Vertebra

Abstract The human spine is a sophisticated mechanism consisting of 24 vertebrae which are arranged in a series-chain between the pelvis and the skull. By careful articulation of these vertebrae, a human being achieves fine motion of the skull. The spine can be modeled as a series-chain with 24 rigid links, the vertebrae, where each vertebra has three degrees-of-freedom relative to an adjacent vertebra. From the studies in the literature, the vertebral geometry and the range of motion between adjacent vertebrae are well-known. The objectives of this paper are to present a kinematic model of the spine using the available data in the literature and an algorithm to compute the inter vertebral joint angles given the position and orientation of the skull. This algorithm is based on the observation that the backbone can be described analytically by a space curve which is used to find the joint solutions..

Some Implications for Parallel Kinematic Machine Design Based on Kinetostatic Model

2000 ◽  
Author(s):  
Clément M. Gosselin ◽  
Dan Zhang
Keyword(s):  
Material Properties ◽  
Geometric Model ◽  
Design Guidelines ◽  
Machine Design ◽  
Parallel Kinematic Machine ◽  
System Behavior ◽  
New Type ◽  
Link Flexibility ◽  
Parallel Kinematic ◽  
Kinetostatic Model

Abstract In this paper, a new method — named lumped kinetostatic modeling — to analyze the effect of the link flexibility on the mechanism’s stiffness is provided. A new type of mechanism whose degree of freedom (dof) is dependent on a passive constraining leg connecting the base and the platform is introduced and analyzed. With the proposed kinetostatic model, a significant effect of the link flexibility on the mechanism’s precision has been demonstrated. The influence of the changement of structure parameters, including material properties, on the system behavior is discussed. In the paper, the geometric model of this kind of mechanism is first introduced. Then, a lumped kinetostatic model is proposed in order to account for joint and link compliances; some results and design guidelines are obtained. Finally, the optimization of the precision is addressed using a genetic algorithm.

Analysis and simulation of a new Cartesian cable-suspended robot

2009 ◽  
Vol 224 (8) ◽  
pp. 1717-1726 ◽  
Author(s):  
G Castelli ◽  
E Ottaviano ◽  
A González
Keyword(s):  
Numerical Simulation ◽  
Degrees Of Freedom ◽  
Robot Arm ◽  
Fixed Frame ◽  
Cartesian Space ◽  
Compliant Assembly ◽  
Moving Platform ◽  
Geometry Analysis ◽  
Three Degrees Of Freedom

In this article, a manipulator is presented belonging to the class of cable-suspended robots, for which the cable length variations are related by suitable functions in order to achieve specific kinematic characteristics. In particular, in this article, a Cartesian cable-suspended robot is proposed that has eight cables to have three degrees of freedom (DOF) in Cartesian space. The eight cables of the robot are arranged in parallel by pairs with identical length, with the aim of constraining the moving platform to keep a constant orientation with respect to the fixed frame. The robot can be used for selective compliant assembly robot arm (SCARA) motions (when an additional revolute actuated joint is placed on the moving platform) for a variety of applications in which a large workspace is required. In this article, a geometry analysis of the robot is presented together with a numerical simulation of the kinetostatics and dynamics to investigate the robot's performances in several operative conditions. Furthermore, a characterization of the position workspace regions is reported for this cable-suspended robot.

A New 4-DOF Fully Parallel Robot With Decoupled Rotation for Five-Axis Micromachining Applications

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Oleksandr Stepanenko ◽  
Ilian A. Bonev ◽  
Dimiter Zlatanov
Keyword(s):  
Degrees Of Freedom ◽  
Mechanical Design ◽  
Parallel Robot ◽  
Parallel Kinematic Machine ◽  
Constant Length ◽  
End Effector ◽  
Kinematic Models ◽  
Parallel Kinematic ◽  
Linear Actuators ◽  
Five Axis

We present a novel 4-DOF (degrees of freedom) parallel robot designed for five-axis micromachining applications. Two of its five telescoping legs operate simultaneously, thus acting as an extensible parallelogram linkage, and in conjunction with two other legs control the position of the tooltip. The fifth leg controls the tilt of the end-effector (a spindle), while a turntable fixed at the base of the robot controls the swivel of the workpiece. The robot is capable of tilting its end-effector up to 90 deg, for any tooltip position. In this paper, we study the mobility of the new parallel kinematic machine (PKM), describe its inverse and direct kinematic models, then study its singularities, and analyze its workspace. Finally, we propose a potential mechanical design for this PKM utilizing telescopic actuators as well as the procedure for optimizing it. In addition, we discuss the possibility of using constant-length legs and base-mounted linear actuators in order to increase the volume of the workspace.

Accuracy estimation of a stretch-retractable single section continuum manipulator based on inverse kinematics

2019 ◽  
Vol 46 (5) ◽  
pp. 573-580
Author(s):  
Hao Wang ◽  
GuoHua Gao ◽  
Qixiao Xia ◽  
Han Ren ◽  
LianShi Li ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Content Type ◽  
Kinematics Model ◽  
Six Degrees Of Freedom ◽  
Single Section ◽  
Motion Range ◽  
Continuum Manipulator ◽  
Three Degrees Of Freedom

Purpose The purpose of this paper is to present a novel stretch-retractable single section (SRSS) continuum manipulator which owns three degrees of freedom and higher motion range in three-dimension workspace than regular single continuum manipulator. Moreover, the motion accuracy was analyzed based on the kinematic model. In addition, the experiments were carried out for validation of the theory. Design/methodology/approach A kinematics model of the SRSS continuum manipulator is presented for analysis on bending, rotating and retracting in its workspace. To discuss the motion accuracy of the SRSS continuum manipulator, the dexterity theory was introduced based on the decomposing of the Jacobian matrix. In addition, the accuracy of motion is estimated based on the inverse kinematics and dexterity theory. To verify the presented theory, the motion of free end was tracked by an electromagnetic positioning system. According to the comparison of experimental value and theoretical analysis, the free end error of SRSS continuum manipulator is less than 6.24 per cent in the region with favorable dexterity. Findings This paper presents a new stretch-retractable continuum manipulator that the structure was composed of several springs as the backbone. Thus, the SRSS continuum manipulator could own wide motion range depending on its retractable structure. Then, the motion accuracy character of the SRSS continuum manipulator in the different regions of its workspace was obtained both theoretically and experimentally. The results show that the high accuracy region distributes in the vicinity of the outer boundary of the workspace. The motion accuracy gradually decreases with the motion position approaching to the center of its workspace. Research limitations/implications The presented SRSS continuum manipulator owns three degrees of freedom. The future work would be focused on the two-section structure which will own six degrees of freedom. Practical implications In this study, the SRSS continuum manipulator could be extended to six degrees of freedom continuum robot with two sections that is less one section than regular six degrees of freedom with three single section continuum manipulator. Originality/value The value of this study is to propose a SRSS continuum manipulator which owns three degrees of freedom and could stretch and retract to expend workspace, for which the accuracy in different regions of the workspace was analyzed and validated based on the kinematics model and experiments. The results could be feasible to plan the motion space of the SRSS continuum manipulator for keeping in suitable accuracy region.

Fabrication and Analysis of a Novel 3 DOF Parallel Wrist Mechanism

1995 ◽  
Vol 117 (2A) ◽  
pp. 343-345 ◽  
Author(s):  
S. K. Agrawal ◽  
Glen Desmier ◽  
Siyan Li
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Ohio University ◽  
Three Degrees Of Freedom ◽  
Nominal Position

This paper describes a three-degrees-of-freedom parallel-actuated wrist mechanism developed at Ohio University. This mechanism is capable of pointing an axis within a cone from the nominal position. The mechanism allows unlimited rotation about the pointing axis. Experiments were conducted to validate the kinematic model of the designed wrist.

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