Maximal Singularity-Free Total Orientation Workspace of the Gough–Stewart Platform

2009 ◽  
Vol 1 (3) ◽  
Author(s):  
Qimi Jiang ◽  
Clément M. Gosselin
Keyword(s):  
Parallel Robot ◽  
Stewart Platform ◽  
Parallel Robots ◽  
Maximal Singularity ◽  
Orientation Workspace

The maximal singularity-free total orientation workspace is highly desirable in a context of design of parallel robots. In practice, this type of workspace is interesting because a parallel robot often works in a given range of orientations. In this work, an algorithm is presented to compute the maximal singularity-free total orientation workspace of the Gough–Stewart platform. In order to demonstrate the presented algorithm, an example is provided.

The Maximal Singularity-Free Workspace of the Gough–Stewart Platform for a Given Orientation

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Qimi Jiang ◽  
Clément M. Gosselin
Keyword(s):  
Case Studies ◽  
Parallel Mechanism ◽  
Stewart Platform ◽  
Parallel Robots ◽  
Analytic Method ◽  
Robot Design ◽  
Parallel Mechanisms ◽  
Leg Length ◽  
Maximal Singularity ◽  
The Relationship

The maximal singularity-free workspace of parallel mechanisms is a desirable criterion in robot design. However, for a 6DOF parallel mechanism, it is very difficult to find an analytic method to determine the maximal singularity-free workspace around a prescribed point for a given orientation. Hence, a numerical algorithm is presented in this paper to compute the maximal singularity-free workspace as well as the corresponding leg length ranges of the Gough–Stewart platform. This algorithm is based on the relationship between the maximal singularity-free workspace and the singularity surface. Case studies with different orientations are performed to demonstrate the presented algorithm. The obtained results can be applied to the geometric design or parameter (leg length) setup of this type of parallel robots.

Optimal wrench-closure configuration of spatial reconfigurable cable-driven parallel robots

2020 ◽  
pp. 095440622097616
Author(s):  
Ghasem Abbasnejad ◽  
Mehdi Tale-Masouleh
Keyword(s):  
Particle Swarm Optimization ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Swarm Optimization ◽  
Closure Condition ◽  
End Effector ◽  
And Performance ◽  
The One ◽  
Orientation Workspace ◽  
Optimization And Performance

In this paper, a method for computing the optimal actuation of reconfigurable cable-driven parallel robots is presented. By using this method, the imperfect ability in exerting torque and limited orientation workspace of these robots may be improved. In a cable-driven parallel robot with reconfigurability, the attachment points of cables on the base are adjusted with regard to the movement of the end-effector on a trajectory. In such a design the redundant degree-of-freedom of the robot is increased accordingly. For an arbitrary pose of the end-effector, a spherical zone is defined in which the called wrench-closure condition is satisfied for a prescribed range of orientation. Taking the volume of such zone into consideration the optimal configuration of the robot may be determined. This configuration is found by appropriately changing the position of the moving attachment points on the base of the robot. By repeating this computation for a number of points on a specified trajectory, appropriate actuation plans are achieved. The computed optimal actuation guarantees balance of any external wrench by tension force of cables when the end-effector moves close to its trajectory. For a case of spatial reconfigurable cable-driven parallel robot, the optimal actuation is found based on Particle Swarm Optimization and performance of the robot is compared to the one with fixed cable attachment points on base. The result shows significant improvement of the performance of reconfigurable spatial cable-driven parallel robot.

scholarly journals Rotational Workspace Expansion of a Planar CDPR with a Circular End-Effector Mechanism Allowing Passive Reconfiguration

Robotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 57 ◽  
Author(s):  
Marco Carpio Alemán ◽  
Roque Saltaren ◽  
Alejandro Rodriguez ◽  
Gerardo Portilla ◽  
Juan Placencia
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Parallel Robots ◽  
End Effector ◽  
Effector Mechanism ◽  
Circular Structure ◽  
Adams Software ◽  
Anchor Points ◽  
Orientation Workspace ◽  
Three Degrees Of Freedom

Cable-Driven Parallel Robots (CDPR) operate over a large positional workspace and a relatively large orientation workspace. In the present work, the expansion of the orientation Wrench Feasible Workspace (WFW) in a planar four-cable passive reconfigurable parallel robot with three degrees of freedom was determined. To this end, we proposed a circular-geometry effector mechanism, whose structure allows automatic mobility of the two anchor points of the cables supporting the End Effector (EE). The WFW of the proposed circular structure robot was compared with that of a traditional robot with a rectangular geometry and fixed anchor points. Considering the feasible geometric and tension forces on the cables, the generated workspace volume of the robot was demonstrated in an analysis-by-intervals. The results were validated by simulating the orientation movements of the robot in ADAMS software and a real experimental test was developed for a hypothetical case. The proposed design significantly expanded the orientation workspace of the robot. The remaining limitation is the segment of the travel space in which the mobile connection points can slide. Overcoming this limitation would enable the maximum rotation of the EE.

Solving 3-6 Parallel Robots by Dixon Resultant

2012 ◽  
Vol 235 ◽  
pp. 158-163 ◽  
Author(s):  
Wei Kun Sun
Keyword(s):  
Original System ◽  
Parallel Robot ◽  
Stewart Platform ◽  
Parallel Robots ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
System Equations ◽  
Forward Kinematic Problem ◽  
Forward Kinematic ◽  
Necessary And Sufficient

In this paper, we investigated the forward kinematic problem of the 3-6 parallel robots (Stewart platform) via a symbolic computation tool called Dixon resultant. 3-6 parallel robot is a variation of the classic 6-6 Stewart platform. First we constructed the system equations of 3-6 parallel robots with a certain coordinate system, and then gave the necessary and sufficient condition for the existence of roots of this system by resultant. With the expression of resultant, we could find the solution of the original system and determined the position of mobile platform. We also discussed how to deal with the extraneous roots.

Maximal singularity-free orientation workspace over a position region of Gough–Stewart platform

2015 ◽  
Vol 29 (22) ◽  
pp. 1427-1436 ◽  
Author(s):  
Qimi Jiang ◽  
Clément M. Gosselin ◽  
Yujun Wang ◽  
Can Fang
Keyword(s):  
Stewart Platform ◽  
Maximal Singularity ◽  
Orientation Workspace

scholarly journals A Cable-Driven Parallel Robot With Full-Circle End-Effector Rotations

2020 ◽  
Author(s):  
Marceau Métillon ◽  
Saman Lessanibahri ◽  
Philippe Cardou ◽  
Kévin Subrin ◽  
Stéphane Caro
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Rigid Base ◽  
Six Degrees Of Freedom ◽  
Spherical Wrist ◽  
In Series ◽  
Dynamic Performances ◽  
Moving Platform ◽  
Orientation Workspace

Abstract Cable-Driven Parallel Robots (CDPRs) offer high payload capacities, large translational workspace and high dynamic performances. The rigid base frame of the CDPR is connected in parallel to the moving platform using cables. However, their orientation workspace is usually limited due to cable/cable and cable/moving platform collisions. This paper deals with the designing, modelling and prototyping of a hybrid robot. This robot, which is composed of a CDPR mounted in series with a Parallel Spherical Wrist (PSW), has both a large translational workspace and an unlimited orientation workspace. It should be noted that the six degrees of freedom (DOFs) motions of the moving platform of the CDPR, namely, the base of the PSW, and the three-DOFs motion of the PSW are actuated by means of eight actuators fixed to the base. As a consequence, the overall system is underactuated and its total mass and inertia in motion is reduced.

scholarly journals A Cable-Driven Parallel Robot with Full-Circle End-Effector Rotations

2021 ◽  
pp. 1-11 ◽  
Author(s):  
Marceau Metillon ◽  
Philippe Cardou ◽  
Kevin Subrin ◽  
Camilo Charron ◽  
Stéphane Caro
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Rigid Base ◽  
Six Degrees Of Freedom ◽  
Spherical Wrist ◽  
In Series ◽  
Dynamic Performances ◽  
Moving Platform ◽  
Orientation Workspace

Abstract Cable-Driven Parallel Robots (CDPRs) offer high payload capacities, large translational workspace and high dynamic performances. The rigid base frame of the CDPR is connected in parallel to the moving platform using cables. However, their orientation workspace is usually limited due to cable/cable and cable/moving platform collisions. This paper deals with the design, modelling and prototyping of a hybrid robot. This robot, which is composed of a CDPR mounted in series with a Parallel Spherical Wrist (PSW), has both a large translational workspace and an unlimited orientation workspace. It should be noted that the six degrees of freedom (DOF) motions of the moving platform of the CDPR, namely, the base of the PSW, and the three-DOF motion of the PSW are actuated by means of eight actuators fixed to the base. As a consequence, the overall system is underactuated and its total mass and inertia in motion is reduced.

Evaluation and Representation of the Theoretical Orientation Workspace of the Gough–Stewart Platform

2009 ◽  
Vol 1 (2) ◽  
Author(s):  
Qimi Jiang ◽  
Clément M. Gosselin
Keyword(s):  
Theoretical Orientation ◽  
Robotic Manipulators ◽  
Stewart Platform ◽  
Closed Region ◽  
Leg Length ◽  
Fixed Frame ◽  
Cartesian Space ◽  
Orientation Workspace

The evaluation and representation of the orientation workspace of robotic manipulators is a challenging task. This work focuses on the determination of the theoretical orientation workspace of the Gough–Stewart platform with given leg length ranges [ρimin,ρimax]. By use of the roll-pitch-yaw angles (ϕ,θ,ψ), the theoretical orientation workspace at a prescribed position P0 can be defined by up to 12 workspace surfaces. The defined orientation workspace is a closed region in the 3D orientation Cartesian space Oϕθψ. As all rotations R(x,ϕ), R(y,θ), and R(z,ψ) take place with respect to the fixed frame, any point of the defined orientation workspace provides a clear measure for the platform to, respectively, rotate in order around the (x,y,z) axes of the fixed frame. An algorithm is presented to compute the size (volume) of the theoretical orientation workspace and intersectional curves of the workspace surfaces. The defined theoretical orientation workspace can be applied to determine a singularity-free orientation workspace.

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.

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