The Kinetostatic Conditioning of Two-Limb Schönflies Motion Generators

2008 ◽  
Vol 1 (1) ◽  
Author(s):  
Jean-François Gauthier ◽  
Jorge Angeles ◽  
Scott B. Nokleby ◽  
Alexei Morozov
Keyword(s):  
Characteristic Length ◽  
Kinematic Chain ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Substantial Part ◽  
Robot Arm ◽  
End Effector ◽  
Serial Robots ◽  
Fixed Orientation ◽  
Schönflies Motion

This paper introduces a study on the kinetostatic conditioning of two-limb Schönflies motion generators. These are robots capable of producing the motions undergone by the end-effector of what is known as selective-compliance assembly robot arm (SCARA) systems, which can best be described as the motions of the tray of a waiter: three independent translations plus one rotation about an axis of fixed orientation. SCARA systems are usually understood as four-axis serial robots, Schönflies motion generators being a generalization thereof, that encompass first and foremost parallel architectures. Kinetostatic conditioning is understood here in connection with the condition number of each of the two Jacobian matrices of the parallel robot under study. After a brief introduction on the geometry and the kinematics of two-limb parallel systems, the kinetostatics of this class of robots is discussed; whence, the calculation of the kinetostatic conditioning of these robots is undertaken. The motivation behind this work is the need to understand an unstable behavior of the prototype in a substantial part of its workspace, which is attributed to poor conditioning. A main result of this paper is the correlation between the shortest dimension of the robot kinematic chain and the characteristic length, which hints to the need of specifying the range of the characteristic length when optimizing the dimensions of robots of the class studied here, a result that may equally hold for parallel robots in general.

The Manta and the Kanuk: Novel 4-DOF Parallel Mechanisms for Industrial Handling

1999 ◽  
Author(s):  
Luc H. Rolland
Keyword(s):  
Parallel Mechanism ◽  
Kinematic Chain ◽  
Parallel Robot ◽  
Chain Structure ◽  
Parallel Robots ◽  
Parallel Mechanisms ◽  
End Effector ◽  
Low Mass ◽  
Loading And Unloading ◽  
Very High

Abstract Two novel 4-DOF very fast parallel robots were designed. This paper introduces the new parallel mechanism designs which are named the Manta and the Kanuk. In order to reduce manipulator overall costs, the actuator and encoder numbers are minimized to the exact effective degrees-of-freedoms (DOF) which is usually not the case in most parallel robot designs. The robots allow end-effector displacements along the three Cartesian translations and one platform transversal rotation. The two remaining rotations are blocked by the intrinsic mechanical structure including the rotation along the platform normal which is always limited in range. The main advantages are high stiffness through the multiple kinematic chain structure which allow for low mass designs. Moreover, they feature simple mechanical construction. Thus, it shall be possible to achieve very high throughput since high accelerations are feasible. To circumvent the known workspace limitations, the actuators were selected to be prismatic along linear axes. The applications are automated warehouse manipulation, mediatheque manipulation, machine tool tool changers, loading and unloading.

scholarly journals Kinetostatic Design of an Innovative Schönflies-Motion Generator

2006 ◽  
Vol 220 (7) ◽  
pp. 935-943 ◽  
Author(s):  
J Angeles ◽  
S Caro ◽  
W Khan ◽  
A Morozov
Keyword(s):  
Parallel Robot ◽  
Degree Of Freedom ◽  
Robot Arm ◽  
Serial Robots ◽  
Fixed Base ◽  
Rigid Body Motions ◽  
Schönflies Motion ◽  
Displacement Group ◽  
Serial Chains ◽  
Motion Generator

In this paper, a novel parallel robot is introduced. The robot, a Schönflies-motion generator (SMG), is capable of a special class of motions, namely those produced with serial robots termed SCARA (selective-compliance assembly robot arm). These motions involve three independent translations and one rotation about an axis of fixed direction. Such motions are known to form a subgroup of the displacement group of rigid-body motions, termed the Schönflies subgroup. The SMG is composed of two identical four-degree-of-freedom serial chains in a parallel array, sharing one common base and one common moving platform. The proximal module of each chain is active and has two controlled axes, the motors being installed on the fixed base. The links can thus be made light, thereby allowing for higher operational speeds. The distal module, in turn, is passive and follows the motions of its active counterpart, the whole mechanism giving, as a result, a four-degree-of-freedom motion to its end platform.

Three-Degree-of-Freedom Parallel Robot Arm

2006 ◽  
Author(s):  
Martin Hosek ◽  
Michael Valasek ◽  
Jairo Moura
Keyword(s):  
Parallel Robot ◽  
Degree Of Freedom ◽  
Motion Path ◽  
Angular Orientation ◽  
Robot Arm ◽  
Flat Panel Display ◽  
End Effector ◽  
Cluster Tools ◽  
Manufacturing Applications ◽  
Three Degree Of Freedom

This paper presents single- and dual-end-effector configurations of a planar three-degree of freedom parallel robot arm designed for automated pick-place operations in vacuum cluster tools for semiconductor and flat-panel-display manufacturing applications. The basic single end-effector configuration of the arm consists of a pivoting base platform, two elbow platforms and a wrist platform, which are connected through two symmetric pairs of parallelogram mechanisms. The wrist platform carries an end-effector, the position and angular orientation of which can be controlled independently by three motors located at the base of the robot. The joints and links of the mechanism are arranged in a unique geometric configuration which provides a sufficient range of motion for typical vacuum cluster tools. The geometric properties of the mechanism are further optimized for a given motion path of the robot. In addition to the basic symmetric single end-effector configuration, an asymmetric costeffective version of the mechanism is derived, and two dual-end-effector alternatives for improved throughput performance are described. In contrast to prior attempts to control angular orientation of the end-effector(s) of the conventional arms employed currently in vacuum cluster tools, all of the motors that drive the arm can be located at the stationary base of the robot with no need for joint actuators carried by the arm or complicated belt arrangements running through the arm. As a result, the motors do not contribute to the mass and inertia properties of the moving parts of the arm, no power and signal wires through the arm are necessary, the reliability and maintenance aspects of operation are improved, and the level of undesirable particle generation is reduced. This is particularly beneficial for high-throughput applications in vacuum and particlesensitive environments.

On Force and Motion Control of Serial-Parallel Robots

1996 ◽  
Author(s):  
Shih-Liang Wang
Keyword(s):  
Control Algorithm ◽  
Virtual Work ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Joint Torque ◽  
Compact Structure ◽  
Serial Robots ◽  
S Matrix ◽  
Serial Robot ◽  
Rate Control Algorithm

Abstract A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.

Simultaneous base and tool calibration for self-calibrated parallel robots

Robotica ◽  
2002 ◽  
Vol 20 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Guilin Yang ◽  
I-Ming Chen ◽  
Song Huat Yeo ◽  
Wee Kiat Lim
Keyword(s):  
Parallel Robot ◽  
Parallel Robots ◽  
Sufficient Accuracy ◽  
Least Square ◽  
Mobile Platform ◽  
Calibration Model ◽  
End Effector ◽  
The World ◽  
Kinematic Transformation ◽  
Kinematic Errors

In this paper, we focus on the base and tool calibration of a self-calibrated parallel robot. After the self-calibration of a parellel robot by using the built-in sensors in the passive joints, its kinematic transformation from the robot base to the mobile platform frame can be computed with sufficient accuracy. The base and tool calibration, hence, is to identify the kinematic errors in the fixed transformations from the world frame to the robot base frame and from the mobile platform frame to the tool (end-effector) frame in order to improve the absolute positioning accuracy of the robot. Using the mathematical tools from group theory and differential geometry, a simultaneous base and tool calibration model is formulated. Since the kinematic errors in a kinematic transformation can be represented by a twist, i.e. an element of se(3), the resultant calibration model is simple, explicit and geometrically meaningful. A least-square algorithm is employed to iteratively identify the error parameters. The simulation example shows that all the preset kinematic errors can be fully recovered within three to four iterations.

Finite element method stiffness analysis of a novel telemanipulator for minimally invasive surgery

SIMULATION ◽  
2019 ◽  
Vol 95 (11) ◽  
pp. 1015-1025 ◽  
Author(s):  
Roman Trochimczuk ◽  
Andrzej Łukaszewicz ◽  
Tadeusz Mikołajczyk ◽  
Francesco Aggogeri ◽  
Alberto Borboni
Keyword(s):  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Invasive Surgery ◽  
Numerical Study ◽  
Kinematic Chain ◽  
Robot Arm ◽  
End Effector ◽  
Stiffness Analysis ◽  
Position Accuracy ◽  
Main Factors

This paper presents the concept of a novel telemanipulator for minimally invasive surgery, along with numerical analysis to validate the main system performance. The proposed kinematic structure consists of a passive and an active module. The passive module is similar to the Selective Compliance Assembly Robot Arm - SCARA robot. The active module is based on a parallelogram mechanism. The results of the numerical study are discussed, focusing on the influence of geometry parameters of the kinematic chain on the displacement accuracy of the end-effector. In particular, the paper deals with the identification of the main factors that impact the position accuracy of the robot.

DELTA: a simple and efficient parallel robot

Robotica ◽  
1990 ◽  
Vol 8 (2) ◽  
pp. 105-109 ◽  
Author(s):  
F. Pierrot ◽  
C. Reynaud ◽  
A. Fournier
Keyword(s):  
Inverse Kinematics ◽  
Research Team ◽  
Dynamic Models ◽  
Inverse Dynamics ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Kinematic Parameters ◽  
Mechanical Structure ◽  
Serial Robots ◽  
École Polytechnique

SummaryThe DELTA parallel robot, designed by an EPFL (Ecole Polytechnique Fédérale de Lausanne) research team, is a mechanical structure which has the advantage of parallel robots and ease of serial robots modeling. This paper presents solutions for a complete modeling of the DELTA parallel robot (direct and inverse kinematics, inverse statics, inverse dynamics), with few arithmetic and trigonometric operations. Our method is based on a satisfactory choice of kinematic parameters and on a few restricting hypotheses for the static and dynamic models. We give some details of each model, we present some computation results and we put the emphasis on some particular points, showing the capabilities of this mechanical structure.

Stiffness estimation of a parallel manipulator using image analysis and camera calibration techniques

Robotica ◽  
2012 ◽  
Vol 31 (4) ◽  
pp. 657-667 ◽  
Author(s):  
Abraham Gonzalez-Hernandez ◽  
Eduardo Castillo-Castaneda
Keyword(s):  
Image Analysis ◽  
Camera Calibration ◽  
Parallel Manipulator ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Mobile Platform ◽  
End Effector ◽  
Simple Implementation ◽  
Specific Position ◽  
Calibration Techniques

SUMMARYThis work presents a methodology using image analysis to estimate the experimental stiffness of a parallel robot, Parallix LKF-2040, a 3-degree-of-freedom manipulator. The proposed methodology has a simple implementation and can be applied to different architectures of parallel robots. This methodology uses image analysis and camera calibration techniques to estimate compliant displacements of mobile platform produced by several loads at the end effector level, and calculate stiffness in a specific position of mobile platform. Experimental results are presented for different positions within the workspace.

Kinematics and Stiffness Modeling of a 4-DOF Parallel Robot for Schönflies Motion Generation

2014 ◽  
Author(s):  
Shaoping Bai ◽  
Lasse Køgs Andersen ◽  
Carsten Rebbe Mølgaard
Keyword(s):  
Dynamic Performance ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Motion Generation ◽  
Stiffness Modeling ◽  
Pick And Place ◽  
Fea Simulation ◽  
Schönflies Motion ◽  
Pick And Place Operation ◽  
Good Agreement

This work deals with the design of parallel robots for the generation of pick-and-place operation, or Schönflies motion. The aim is to develop a robot with workspace optimized for fast pick-and-place operations, namely, a robot with a superellipsoidal reachable volume, which suits best for the pick-and-place operations on conveyers, where robots’ working areas are nearly rectangular. In this paper, the kinematics and stiffness modeling of the new robot are presented. A method of stiffness modeling by means of Castigliano’s Theorem is developed. Using the new method, the stiffness of the robot is analyzed. The results are compared with FEA simulation, which shows a good agreement between the results. The method is finally applied to the engineering design of the new robot for enhanced static and dynamic performance.

scholarly journals Design and Analysis of a Novel Schönflies Motion Parallel Robot with Full Cycle Rotation

2021 ◽  
Author(s):  
Luquan Li ◽  
Yuefa Fang ◽  
Lin Wang ◽  
Jiaqiang Yao
Keyword(s):  
Complex Dynamics ◽  
Virtual Work ◽  
Parallel Robot ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
The Novel ◽  
Scara Robot ◽  
Pick And Place ◽  
Place Task ◽  
Schönflies Motion

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.

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