Direct Kinematics of the Exechon Tripod

2016 ◽  
Author(s):  
Cuong Trinh ◽  
Dimiter Zlatanov ◽  
Matteo Zoppi
Keyword(s):  
Linear Equations ◽  
Parallel Manipulators ◽  
Revolute Joints ◽  
Spherical Wrist ◽  
In Series ◽  
Parallel Kinematic ◽  
Numerical Solver ◽  
Three Degree Of Freedom ◽  
Non Linear Equations ◽  
Direct Kinematics

This paper presents a solution to the forward kinematics problem of the Exechon parallel mechanism, a three-legged three-degree-of-freedom spatial mechanism with a complex motion pattern of the platform. In series with a universal or a spherical wrist, it has been used in a number of PKM (parallel kinematic machine) designs, and more recently as a mobile robotic fixture. The inverse kinematics solution has been known for a number of years. However, past publications on the Exechon tripod have not presented a method successfully solving the direct kinematics problem. To achieve this here, we first reduce the forward problem to a system of four non-linear equations and then use a standard numerical solver to obtain all sets of possible real roots. This solution allows the calculation of all joint displacements and from there the transformation matrix describing the pose of the end-effector. The obtained solutions divide into two groups, each for a different assembly mode of the mechanism. The method is easy to implement and can potentially be applied to other types of parallel manipulators with revolute joints at the mobile platform.

On the Direct Kinematics of Spherical Three-Degree-of-Freedom Parallel Manipulators with a Coplanar Platform

1994 ◽  
Vol 116 (2) ◽  
pp. 587-593 ◽  
Author(s):  
C. M. Gosselin ◽  
J. Sefrioui ◽  
M. J. Richard
Keyword(s):  
Parallel Manipulator ◽  
Minimal Polynomial ◽  
Polynomial Solution ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Real Solutions ◽  
Revolute Joints ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator ◽  
Direct Kinematics

This paper presents a polynomial solution to the direct kinematic problem of a class of spherical three-degree-of-freedom parallel manipulators. This class is defined as the set of manipulators for which the axes of the three revolute joints attached to the gripper link are coplanar and symmetrically arranged. It is shown that, for these manipulators, the direct kinematic problem admits a maximum of 8 real solutions. A polynomial of degree 8 is obtained here to support this result and cases for which all the roots of the polynomial lead to real configurations are presented. Finally, the spherical parallel manipulator with collinear actuators, which received some attention in the literature, is also treated and is shown to lead to a minimal polynomial of the same degree. Examples of the application of the method to manipulators of each category are given and solved.

On the Direct Kinematics of a Class of Spherical Three-Degree-of Freedom Parallel Manipulators

1992 ◽  
Author(s):  
Clément M. Gosselin ◽  
Jaouad Sefrioui ◽  
Marc J. Richard
Keyword(s):  
Parallel Manipulator ◽  
Minimal Polynomial ◽  
Polynomial Solution ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Real Solutions ◽  
Revolute Joints ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator ◽  
Direct Kinematics

Abstract This paper presents a polynomial solution to the direct kinematic problem of a class of spherical three-degree-of-freedom parallel manipulators. This class is defined as the set of manipulators for which the axes of the three revolute joints attached to the gripper link are coplanar and symmetrically arranged. It is shown that, for these manipulators, the direct kinematic problem admits a maximum of 8 real solutions. A polynomial of degree 8 is obtained here to support this result and cases for which all the roots of the polynomial lead to real configurations are presented. Finally, the spherical parallel manipulator with collinear actuators, which received some attention in the literature, is also treated and is shown to lead to a minimal polynomial of the same degree. Examples of the application of the method to manipulators of each category are given and solved.

Kinematics Analysis of the Exechon Tripod

2010 ◽  
Author(s):  
Matteo Zoppi ◽  
Dimiter Zlatanov ◽  
Rezia Molfino
Keyword(s):  
Machine Tools ◽  
Inverse Kinematics ◽  
Three Dimensional ◽  
Kinematics Analysis ◽  
Axis Parallel ◽  
Spherical Wrist ◽  
In Series ◽  
Successful Design ◽  
Parallel Kinematic ◽  
Fixture System

The Exechon 5-Axis Parallel Kinematic Machine (PKM) is a successful design created in Sweden and adopted by many producers of machine tools around the world. A new version of the manipulator is being developed as a component of a mobile self-reconfigurable fixture system within an inter-European project. The basic Exechon architecture consists of a 3-degree-of-freedom (dof) parallel mechanism (PM) connected in series with a two- or three-dof spherical wrist. The PM has two UPR (4-dof) legs, constrained to move in a common rotating plane, and an SPR (5-dof) leg. The paper presents the kinematic analysis of both the PM and the hybrid parallel-serial architecture. We describe the complex three-dimensional motion pattern of the PM platform, derive the kinematic equations and provide explicit solutions for the inverse kinematics.

On the Direct Kinematics of Spherical Three-Degree-of-Freedom Parallel Manipulators of General Architecture

1994 ◽  
Vol 116 (2) ◽  
pp. 594-598 ◽  
Author(s):  
C. M. Gosselin ◽  
J. Sefrioui ◽  
M. J. Richard
Keyword(s):  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Real Solutions ◽  
Three Degree Of Freedom ◽  
General Architecture ◽  
Direct Kinematics

In this paper, the direct kinematics of general spherical parallel three-degree-of-freedom manipulators is investigated. A polynomial of degree 8 is obtained to describe this problem and it is shown that this polynomial is minimal since 8 real solutions corresponding to actual configurations have been found for a given set of actuator coordinates and a given architecture. This result completes the study on the direct kinematics of spherical three-degree-of-freedom parallel manipulators undertaken by the authors in a previous paper. An example of an architecture and a set of actuator coordinates which lead to 8 real solutions is presented to illustrate the results.

A method for the solution of the forward position problems of planar mechanisms with prismatic and revolute joints

2001 ◽  
Vol 216 (4) ◽  
pp. 395-407 ◽  
Author(s):  
A Hernández ◽  
V Petuya ◽  
E Amezua
Keyword(s):  
Iterative Method ◽  
Degrees Of Freedom ◽  
Linear Equations ◽  
Simulation Program ◽  
Planar Mechanisms ◽  
Revolute Joints ◽  
Iteration Sequence ◽  
Geometrical Concepts ◽  
Planar Linkages ◽  
Non Linear Equations

In this paper, a method to solve the forward position problems of planar linkages with prismatic and revolute joints is presented. These linkages can have any number of degrees of freedom. This method has been named the geometrical iterative method and is based on geometrical concepts. An iteration sequence that corresponds to the system of non-linear equations describing closure of the mechanism loops is defined. This sequence is applied in successive iterations to obtain the position of the mechanism. In order to achieve convergence, the iteration sequence must fulfil two fundamental conditions. A searching algorithm has been developed to obtain a useful iteration sequence. It is based on the use of hierarchical rules and criteria. The method has been implemented in a simulation program developed by the authors. Several illustrative examples are presented using representative linkages.

The Synthesis of Planar Parallel Manipulators with a Genetic Algorithm

1999 ◽  
Vol 121 (4) ◽  
pp. 533-537 ◽  
Author(s):  
R. Boudreau ◽  
C. M. Gosselin
Keyword(s):  
Genetic Algorithm ◽  
Parallel Manipulators ◽  
Optimization Method ◽  
Degree Of Freedom ◽  
Natural Evolution ◽  
Revolute Joints ◽  
Prismatic Joints ◽  
Genetic Algorithm Approach ◽  
Three Degree Of Freedom ◽  
Planar Parallel Manipulators

This paper presents a genetic algorithm approach for the synthesis of planar three-degree-of-freedom parallel manipulators. A genetic algorithm is an optimization method inspired by natural evolution. As in nature, the fittest members of a population are given better chances of reproducing and transmitting part of their genetic heritage to the next generation. This leads to stronger and stronger generations which evolve towards the solution of the problem. For the applications studied here, the individuals in the population consist of the architectural parameters of the manipulators. The algorithm optimizes these parameters to obtain a workspace as close as possible to a prescribed working area. For each individual of the population, the geometric description of the workspace can be obtained. The algorithm then determines the intersection between the prescribed workspace and the actual workspace, and minimizes the area of the regions that do not intersect. The method is applied to two planar three-degree-of-freedom parallel manipulators, one with prismatic joints and one with revolute joints.

On the Direct Kinematics of General Spherical Three-Degree-of-Freedom Parallel Manipulators

1992 ◽  
Author(s):  
Clément M. Gosselin ◽  
Jaouad Sefrioui ◽  
Marc J. Richard
Keyword(s):  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Real Solutions ◽  
Three Degree Of Freedom ◽  
Direct Kinematics

Abstract In this paper, the direct kinematics of general spherical parallel three-degree-of-freedom manipulators is investigated. A polynomial of degree 8 is obtained to describe this problem and it is shown that this polynomial is minimal since 8 real solutions corresponding to actual configurations have been found for a given set of actuator coordinates and a given architecture. This result completes the study on the direct kinematics of spherical three-degre-of-freedom parallel manipulators undertaken by the authors in a previous paper. An example of an architecture and a set of actuator coordinates which lead to 8 real solutions is presented to illustrate the results.

The Synthesis of Planar Parallel Manipulators With a Genetic Algorithm

1998 ◽  
Author(s):  
Roger Boudreau ◽  
Clément M. Gosselin
Keyword(s):  
Genetic Algorithm ◽  
Parallel Manipulators ◽  
Optimization Method ◽  
Degree Of Freedom ◽  
Natural Evolution ◽  
Revolute Joints ◽  
Prismatic Joints ◽  
Genetic Algorithm Approach ◽  
Three Degree Of Freedom ◽  
Planar Parallel Manipulators

Abstract This paper presents a genetic algorithm approach for the synthesis of planar three-degree-of-freedom parallel manipulators. A genetic algorithm is an optimization method inspired by natural evolution. As in nature, the fittest members of a population are given better chances of reproducing and transmitting part of their genetic heritage to the next generation. This leads to stronger and stronger generations which evolve towards the solution of the problem. For the applications studied here, the individuals in the population consist of the thirteen architectural parameters of the manipulators. The algorithm optimizes these parameters to obtain a workspace as close as possible to a prescribed working area. For each individual of the population, the geometric description of the workspace can be obtained. The algorithm then determines the intersection between the prescribed workspace and the actual workspace, and minimizes the area of the regions that do not intersect. The method is applied to two planar three-degree-of-freedom parallel manipulators, one with prismatic joints and one with revolute joints.

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