Workspace of Four-Degree-of-Freedom Manipulators

1996 ◽  
Author(s):  
Karim Abdel-Malek ◽  
Harn-Jou Yeh
Keyword(s):  
Perturbation Technique ◽  
Underlying Mechanism ◽  
Degree Of Freedom ◽  
Parametric Surfaces ◽  
Singular Surfaces ◽  
End Effector ◽  
Serial Manipulators ◽  
Constraint Equations ◽  
First Order ◽  
Revolute Joints

Abstract An analytical method is presented to obtain all boundary surfaces to the accessible output set of four degree-of-freedom serial manipulators. The method is applicable to all manipulators that comprise combinations of prismatic and revolute joints. Position constraints of the end-effector of such mechanisms are formulated using the Denavit-Hartenberg representation. Examining the Jacobian of the underlying mechanism using a row-rank deficiency method yields sets of first-order singularities. These sets of singularities are substituted into the position constraint equations yielding parametric surfaces upon which the manipulator looses at least one degree of mobility. Singular curves are determined by intersecting singular surfaces. Due to the complexity of intersecting parametric singular surfaces, the resultant singular curves are numerically computed. Bifurcation points are identified and tangents are computed. Singular surfaces are partitioned into sub-surfaces that are studied for existence inside the accessible output set using a proposed perturbation technique. The result is a number of sub-surfaces that envelop the accessible output set. The theory presented is validated using a four-degree-of-freedom example.

scholarly journals Analysis of Finite Self Motion and Finite Dwell in Closed-Loop Mechanisms and Parallel Manipulators

2001 ◽  
Author(s):  
Sandipan Bandyopadhyay ◽  
Ashitava Ghosal
Keyword(s):  
Parallel Manipulator ◽  
Closed Loop ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Kinematic Constraints ◽  
Constraint Equations ◽  
First Order ◽  
Necessary And Sufficient Criteria ◽  
Necessary And Sufficient ◽  
Self Motion

Abstract In this paper, we present the necessary and sufficient criteria for finite self motion and finite dwell of the passive links of a parallel manipulator or a closed-loop mechanism. We study the first order properties of the constraint equations associated with the kinematic constraints inherent in a closed-loop mechanism or a parallel manipulator, and arrive at the criteria for the mechanism to gain a degree-of-freedom at a singular point of its workspace. By analyzing the second order properties of the constraint equations, we show that the gain of degree-of-freedom may lead to finite self motion of the passive links if certain configurational and architectural criteria are met. Special configurations and architecture may also lead to finite dwell of the passive links, and the criteria for the same has been derived. The results are illustrated with the help of several closed-loop mechanisms.

Finite Twist Mapping and its Application to Planar Serial Manipulators with Revolute Joints

1995 ◽  
Vol 209 (4) ◽  
pp. 263-271 ◽  
Author(s):  
J S Dai ◽  
N Holland ◽  
D R Kerr
Keyword(s):  
Rigid Body ◽  
Image Space ◽  
End Effector ◽  
Serial Manipulators ◽  
Reference Position ◽  
Revolute Joints ◽  
Twist Mapping ◽  
Position And Orientation ◽  
Joint Motions

This paper reviews a method of representing the finite twist motion of a rigid body, and applies this concept to the problem of describing the motion capabilities of planar serial manipulators. In particular, this finite twist representation describes the position and orientation of the end-effector link relative to a defined reference position and orientation. The transformations associated with the joint motions are used to investigate the range of end-effector motion, including the effects of limits of joint travel. The finite twist representations are then extracted from such transformations and presented in an image space so that the motion of the manipulator is fully characterized. Further, the reachable and dexterous workspaces are predicted by the same general means. Examples of planar serial manipulators with two (RR) and three revolute (RRR) joints are given to illustrate the approach.

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.

Force Capabilities of Two-Degree-of-Freedom Serial Robots Equipped With Passive Isotropic Force Limiters

2015 ◽  
Author(s):  
Meiying Zhang ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
Human Robot Interaction ◽  
Contact Forces ◽  
Degree Of Freedom ◽  
Practical Implementation ◽  
Robot Interaction ◽  
End Effector ◽  
Serial Robots ◽  
Serial Robot ◽  
Maximum Contact ◽  
Two Degree Of Freedom

This paper proposes the use of passive force and torque limiting devices to bound the maximum forces that can be applied at the end-effector or along the links of a robot, thereby ensuring the safety of human-robot interaction. Planar isotropic force limiting modules are proposed and used to analyze the force capabilities of a two-degree-of-freedom planar serial robot. The force capabilities at the end-effector are first analyzed. It is shown that, using isotropic force limiting modules, the performance to safety index remains excellent for all configurations of the robot. The maximum contact forces along the links of the robot are then analyzed. Force and torque limiters are distributed along the structure of the robot in order to ensure that the forces applied at any point of contact along the links are bounded. A power analysis is then presented in order to support the results. Finally, examples of mechanical designs of force/torque limiters are shown to illustrate a possible practical implementation of the concept.

Seven-Position Synthesis of a Spatial Eight-Bar Linkage by Constraining a TRS Serial Chain

2009 ◽  
Author(s):  
Gim Song Soh ◽  
J. Michael McCarthy
Keyword(s):  
Degree Of Freedom ◽  
Upper Arm ◽  
End Effector ◽  
Serial Chain ◽  
Position Synthesis ◽  
Two Degree Of Freedom ◽  
Puma Robot

In this paper, we use seven-position synthesis to add four TS constraints to a TRS serial chain robot and obtain a two degree-of-freedom spatial eight-bar linkage. The TRS chain is an elbow manipulator, similar to a PUMA robot. We synthesize a TS dyad to connect the base of the robot to its forearm, and then we synthesize three TS dyads that connect the upper arm of the robot to its end-effector. The result is a two degree-of-freedom spatial eight-bar linkage that moves through seven prescribed positions. It consists of a TRST loop supporting a 3TS-RS platform, which we denote as a TS-TRS-3TS spatial linkage. We formulate and solve the design equations for the TS dyads, and analyze the resulting eight-bar linkage. An example demonstrates our results.

scholarly journals Increasing ABB FlexPicker Robot’s Degree of Freedom (DOF) using Flexible End Effector

2016 ◽  
Vol 78 ◽  
pp. 01056
Author(s):  
M. H. Nordin ◽  
K. Selvaraju ◽  
M. Fathullah
Keyword(s):  
Degree Of Freedom ◽  
End Effector

Parametric Design of a Spherical Eight-Bar Linkage Based on a Spherical Parallel Manipulator

2008 ◽  
Vol 1 (1) ◽  
Author(s):  
Gim Song Soh ◽  
J. Michael McCarthy
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Parametric Design ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
End Effector ◽  
Arbitrary Base ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator

This paper presents a procedure that determines the dimensions of two constraining links to be added to a three degree-of-freedom spherical parallel manipulator so that it becomes a one degree-of-freedom spherical (8, 10) eight-bar linkage that guides its end-effector through five task poses. The dimensions of the spherical parallel manipulator are unconstrained, which provides the freedom to specify arbitrary base attachment points as well as the opportunity to shape the overall movement of the linkage. Inverse kinematics analysis of the spherical parallel manipulator provides a set of relative poses between all of the links, which are used to formulate the synthesis equations for spherical RR chains connecting any two of these links. The analysis of the resulting spherical eight-bar linkage verifies the movement of the system.

A non-overconstrained variant of the Agile Eye with a special decoupled kinematics

Robotica ◽  
2013 ◽  
Vol 32 (6) ◽  
pp. 889-905 ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Jian S. Dai ◽  
Giovanni Legnani
Keyword(s):  
Angular Displacement ◽  
Universal Joint ◽  
Special Configuration ◽  
End Effector ◽  
Revolute Joint ◽  
Revolute Joints ◽  
Prismatic Joints ◽  
Decoupled Motion ◽  
Orientation Mechanism ◽  
Actuated Joints

SUMMARYA non-overconstrained three-DOF parallel orientation mechanism that is kinematically equivalent to the Agile Eye is presented in this paper. The output link (end-effector) of the mechanism is connected to the base by one spherical joint and by another three identical legs. Each leg comprises of, in turns from base, a revolute joint, a universal joint, and three prismatic joints. The three lower revolute joints are active joints, while all other joints are passive ones. Based on a special configuration, some three projective angles of the end-effector coordinates are fully decoupled with respect to the input actuated joints, that is, by actuating any revolute joint the end-effector rotates in such a way that the corresponding projective angle changes with the same angular displacement. The fully decoupled motion is analyzed geometrically and proved theoretically. Besides, the inverse and direct kinematics solutions of the mechanism are provided based on the geometric reasoning and theoretical proof.

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