REDUCED MOTION OF PARALLEL ROBOT MANIPULATORS DUE TO ACTIVE JOINT JAM

2004 ◽  
Vol 28 (2A) ◽  
pp. 165-184 ◽  
Author(s):  
Mahir Hassan ◽  
Leila Notash
Keyword(s):  
Robot Manipulators ◽  
Parallel Robot ◽  
Active Joint

Analysis of Active Joint Failure in Parallel Robot Manipulators

2004 ◽  
Vol 126 (6) ◽  
pp. 959-968 ◽  
Author(s):  
Mahir Hassan ◽  
Leila Notash
Keyword(s):  
Jacobian Matrix ◽  
Null Space ◽  
Robot Manipulators ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Task Space ◽  
Active Joint ◽  
Joint Failure ◽  
Space Vectors ◽  
Six Degree Of Freedom

In this study, the effect of active joint failure on the mobility, velocity, and static force of parallel robot manipulators is investigated. Two catastrophic active joint failure types are considered: joint jam and actuator force loss. To investigate the effect of failure on mobility, the Gru¨bler’s mobility equation is modified to take into account the kinematic constraints imposed by various branches in the manipulator. In the case of joint jam, the manipulator loses the ability to move and apply force in a specific portion of its task space; while in the case of actuator force loss, the manipulator gains an unconstrained motion in a specific portion of the task space in which an externally applied force cannot be resisted by the actuator forces. The effect of joint jam and actuator force loss on the velocity and on the force capabilities of parallel manipulators is investigated by examining the change in the Jacobian matrix, its inverse, and transposes. It is shown that the reduced velocity and force capabilities after joint jam and loss of actuator force could be determined using the null space vectors of the transpose of the Jacobian matrix and its inverse. Computer simulation is conducted to demonstrate the application of the developed methodology in determining the post-failure trajectory of a 3-3 six-degree-of-freedom Stewart-Gough manipulator, when encountering active joint jam and actuator force loss.

A Direct Determination of the Instantaneous Kinematics of Fully Parallel Robot Manipulators

1985 ◽  
Vol 107 (2) ◽  
pp. 226-229 ◽  
Author(s):  
M. G. Mohamed ◽  
J. Duffy
Keyword(s):  
Screw Theory ◽  
Robot Manipulators ◽  
Direct Determination ◽  
Parallel Robot ◽  
End Effector ◽  
Actuated Joints ◽  
Parallel Type

Screw theory is applied to the study of the instantaneous kinematics of the end-effector platform of fully parallel robot type devices. The instantaneous motion of the end-effector is expressed directly in terms of the twists of the input-actuated joints and it is demonstrated that the twist representing the instantaneous motion of the end-effector platform is equal to the sum of its partial twists. A partial twist is defined as the twist representing the instantaneous motion of the end-effector when all but one of the input actuators are locked. The analysis presented forms a proper basis for the study of special configurations of parallel type devices.

Actuation Redundancy as a Way to Improve the Acceleration Capabilities of 3T and 3T1R Pick-and-Place Parallel Manipulators

2010 ◽  
Vol 2 (4) ◽  
Author(s):  
David Corbel ◽  
Marc Gouttefarde ◽  
Olivier Company ◽  
François Pierrot
Keyword(s):  
Dynamic Model ◽  
Dynamic Capabilities ◽  
Robot Manipulators ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Actuation Redundancy ◽  
High Acceleration ◽  
Pick And Place ◽  
Very High

This paper analyzes the possible contribution of actuation redundancy in obtaining very high acceleration with parallel robot manipulators. This study is based on redundant and nonredundant Delta/Par4-like manipulators, which are frequently used for pick-and-place applications, and addresses the cases of translational manipulators (also called 3T manipulators) and manipulators with Schoenflies motions (also called 3T1R manipulators). A dynamic model, valid for both redundant and nonredundant manipulators, is used to analyze the moving platform’s acceleration capabilities: (i) at zero speed and in any direction and (ii) at zero speed in the “best” direction. The results show that actuation redundancy makes it possible to homogenize dynamic capabilities throughout the workspace and to increase the moving platform’s accelerations. Designs of redundant Delta/Par4-like manipulators capable of high acceleration pick-and-place trajectories are presented for both 3T and 3T1R manipulators.

scholarly journals Integrating Dynamics into Design and Motion Optimization of a 3-PRR Planar Parallel Manipulator with Discrete Time Transfer Matrix Method

2020 ◽  
Vol 2020 ◽  
pp. 1-23 ◽  
Author(s):  
Guoning Si ◽  
Mengqiu Chu ◽  
Zhuo Zhang ◽  
Haijie Li ◽  
Xuping Zhang
Keyword(s):  
Dynamic Model ◽  
Dynamic Modeling ◽  
Discrete Time ◽  
Parallel Manipulator ◽  
Robot Manipulators ◽  
Dynamic Performance ◽  
Parallel Robot ◽  
Time Transfer ◽  
Performance Indices ◽  
Planar Parallel Manipulator

This paper presents a novel method of dynamic modeling and design optimization integrated with dynamics for parallel robot manipulators. Firstly, a computationally efficient modeling method, the discrete time transfer matrix method (DT-TMM), is proposed to establish the dynamic model of a 3-PRR planar parallel manipulator (PPM) for the first time. The numerical simulations are performed with both the proposed DT-TMM dynamic modeling and the ADAMS modeling. The applicability and effectiveness of DT-TMM in parallel manipulators are verified by comparing the numerical results. Secondly, the design parameters of the 3-PRR parallel manipulator are optimized using the kinematic performance indices, such as global workspace conditioning index (GWCI), global condition index (GCI), and global gradient index (GGI). Finally, a dynamic performance index, namely, driving force index (DFI), is proposed based on the established dynamic model. The described motion trajectory of the moving platform is placed into the optimized workspace and the initial position is determined to finalize the end-effector trajectory of the parallel manipulator by the further optimization with the integrated kinematic and dynamic performance indices. The novelty of this work includes (1) developing a new dynamic model method with high computation efficiency for parallel robot manipulators using DT-TMM and (2) proposing a new dynamic performance index and integrating the dynamic index into the motion and design optimization of parallel robot manipulators.

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