scholarly journals Redundant Actuation of Parallel Manipulators

10.5772/5427 ◽  
2008 ◽  
Author(s):  
Andreas Mueller
Keyword(s):  
Parallel Manipulators ◽  
Redundant Actuation

Backlash elimination in parallel manipulators using actuation redundancy

Robotica ◽  
2011 ◽  
Vol 30 (3) ◽  
pp. 379-388 ◽  
Author(s):  
Roger Boudreau ◽  
Xu Mao ◽  
Ron Podhorodeski
Keyword(s):  
Nonlinear Optimization ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Redundant Actuation ◽  
Joint Torques ◽  
Accuracy Enhancement ◽  
Actuation Redundancy ◽  
Actuated Joints

SUMMARYIn this work, accuracy enhancement through backlash elimination is considered. When a nonredundantly actuated parallel manipulator is subjected to a wrench while following a trajectory, required actuator torque switching (going from positive to negative or vice versa) may occur. If backlash is present in the actuation hardware for a manipulator, torque switching compromises accuracy. When in-branch redundant actuation is added, a pseudoinverse torque solution requires smaller joint torques, but torque switching may still occur. A method is presented where concepts of exploiting a nullspace basis of the joint torques are used to ensure that single sense joint torques can be achieved for the actuated joints. The same sense torque solutions are obtained using nonlinear optimization. The methodology is applied to several examples simulating parallel manipulators in machining applications.

Dexterity and Adaptive Control of Planar Parallel Manipulators With and Without Redundant Actuation

2014 ◽  
Vol 10 (1) ◽  
Author(s):  
Weiwei Shang ◽  
Shuang Cong
Keyword(s):  
Adaptive Control ◽  
Parallel Manipulator ◽  
Adaptive Controller ◽  
Parallel Manipulators ◽  
The Other ◽  
Experimental Comparison ◽  
Redundant Actuation ◽  
Tracking Accuracy ◽  
Planar Parallel Manipulator ◽  
Planar Parallel Manipulators

The objective of this paper is to determine whether a planar parallel manipulator with redundant actuation has better tracking accuracy than a planar parallel manipulator without redundant actuation. The effects of the redundant actuation on tracking accuracy of parallel manipulators are studied by using two different experimental platforms. The first platform is the planar five-bar parallel manipulator with normal actuation, and the other one is the planar parallel manipulator with redundant actuation. The dexterity pictures and the kinematic configurations of the two platforms validate the kinematic advantages from the redundant actuation. In order to study the dynamic advantages of the redundant actuation further, a nonlinear adaptive controller is presented for the two platforms. The experimental comparison is implemented on two actual parallel manipulator platforms, and from the experimental results, one can find the tracking accuracy of the parallel manipulator with redundant actuation can be improved above 38% than that of the five-bar parallel manipulator without redundant actuation.

Types Synthesis of Redundant Actuation Parallel Robot

2011 ◽  
Vol 219-220 ◽  
pp. 953-956
Author(s):  
Jin Liang Gong ◽  
Yan Fei Zhang ◽  
Xiu Ting Wei
Keyword(s):  
Parallel Manipulators ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Redundant Actuation ◽  
View Point ◽  
Output Link ◽  
Practical Applications ◽  
Plücker Coordinates ◽  
Theoretical View ◽  
Kinematic Joint

Redundant parallel robots have been under increasing developments from a theoretical view point as well as for practical applications. Compared with the traditional parallel manipulators, they have such merits of more load, faster speed and higher accuracy. The method about how to build up redundant actuation parallel robot is introduced. Considering that the kinematic joint and limb are basic elements to constitute a proper parallel robot mechanism, special Plücker coordinates is adopted to describe the displacements of the output link of a limb or the robot mechanism. Then the principle for design of the redundant actuation parallel robot mechanisms is presented and example of the 2RRR&2PP parallel robot mechanism is brought forth and analyzed by this method.

Design methodology for translational parallel manipulators exhibiting actuation redundancy

2015 ◽  
Vol 230 (3) ◽  
pp. 425-436 ◽  
Author(s):  
Burkhard Corves ◽  
Jan Brinker ◽  
Michael Lorenz ◽  
Martin Wahle
Keyword(s):  
Selection Criteria ◽  
Design Methodology ◽  
Degrees Of Freedom ◽  
Parallel Manipulators ◽  
Positive Influence ◽  
Redundant Actuation ◽  
Positioning Accuracy ◽  
End Effector ◽  
Stiffness Characteristics ◽  
And Performance

In general, spatial manipulation of objects can be accomplished by parallel manipulators, whose number of actuators is equal to the demanded number of degrees of freedom. In order to improve, for example, positioning accuracy, stiffness characteristics, and transmission behavior, redundant drives can be added to the manipulator. Accordingly, this paper presents a methodology for the design of a translational parallel manipulator with redundant actuation. Based on the results of systematic structural syntheses and developed selection criteria, two valid configurations (i.e. 3-PŘŘŘ and 3-PUU) are analyzed. Since feasibility and performance of these configurations are dependent on the base geometry, five types of base geometries are introduced. First, the geometric parameters of each of the resulting 10 combinations of nonredundant configurations and base geometries are optimized by minimizing the maximal actuation force within a prescribed workspace. Second, the best combinations are used to generate redundant configurations with six legs. These redundant configurations are then analyzed with respect to the potential of improvement concerning homogenization of end-effector forces using force polytopes. It is shown that redundant actuation significantly improves the distribution of end-effector forces. This improvement has a positive influence on positioning accuracy and acceleration capabilities. In addition to these aspects, for further analysis it is planned to investigate the influence of homogenized end-effector forces on the dimensioning of actuators and finally on the energy efficiency of the entire configuration.

FORCE-MOMENT CAPABILITIES OF PLANAR-PARALLEL MANIPULATORS USING DIFFERENT REDUNDANT-ACTUATION CONFIGURATIONS

2005 ◽  
Vol 29 (4) ◽  
pp. 669-678 ◽  
Author(s):  
Scott B. Nokleby
Keyword(s):  
Parallel Manipulators ◽  
Redundant Actuation ◽  
Scaling Factors ◽  
Preliminary Results ◽  
Maximum Moment ◽  
Revolute Joints ◽  
Force Moment ◽  
Redundantly Actuated ◽  
Planar Parallel Manipulators ◽  
Wrist Joints

This work investigates the force-moment capabilities of different redundant-actuation configurations for planar-parallel manipulators. A previously developed methodology for determining the force-moment capabilities of redundantly-actuated parallel manipulators using optimization and scaling factors is employed. The preliminary results show that different, symmetric redundant-actuation schemes yield substantial variations in the force-moment capabilities for the three-branch, three-revolute joints per branch (3-RRR) manipulator. Configurations where all base and wrist joints are actuated or all elbow and wrist joints are actuated yielded better force-moment capabilities when compared to the actuation configuration where all base and elbow joints are actuated. The biggest difference in terms of force-moment capabilities was found to be the maximum moment that could be sustained. The actuation configuration where all base and elbow joints were actuated yielded the lowest maximum moment that could be sustained.

On the terminology and geometric aspects of redundant parallel manipulators

Robotica ◽  
2012 ◽  
Vol 31 (1) ◽  
pp. 137-147 ◽  
Author(s):  
Andreas Müller
Keyword(s):  
Vector Fields ◽  
Kinematic Model ◽  
Parallel Manipulators ◽  
Redundant Actuation ◽  
Parallel Kinematics ◽  
Kinematic Redundancy ◽  
Control Vector ◽  
Serial Manipulators ◽  
Actuation Redundancy ◽  
Parallel Kinematics Machines

SUMMARYParallel kinematics machines (PKMs) can exhibit kinematics as well as actuation redundancy. While the meaning of kinematic redundancy has been already clarified for serial manipulators, actuation redundancy, which is only possible in PKMs, is differently classified in the literature. In this paper a consistent terminology for general redundant PKM is proposed. A kinematic model is introduced with the configuration space (c-space) as central part. The notion of kinematic redundancy is recalled for PKM. C-space, output, and input singularities are distinguished. The significance of the c-space geometry is emphasized, and it is pointed out geometrically that input singularities can be avoided by redundant actuation schemes. In order to distinguish different actuation schemes of PKM, a nonlinear control system is introduced whose dynamics evolves on c-space. The degree of actuation (DOA) is introduced as the number of independent control vector fields, and PKMs are classified as full-actuated and underactuated machines. Relating this DOA to degree of freedom allows to classify the actuation redundancy.

Analysis of Hybrid Cable-Actuated Parallel Manipulators With a Constraining Leg for Lower-Degree-of-Freedom Operation

2009 ◽  
Author(s):  
Mahir Hassan ◽  
Amir Khajepour
Keyword(s):  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Lower Degree ◽  
Redundant Actuation ◽  
Task Space ◽  
Cable Tension ◽  
Task Constraints ◽  
Rigid Link ◽  
Moving Platform

This paper presents a kinetostatic analysis of a class of hybrid cable-driven parallel manipulators consisting of cables and a rigid-link serial leg for lower-degree-of-freedom tasks. The serial leg provides the task constraints and the cables provide the required actuation to move the platform in the task space. Having a rigid-link serial leg providing the required constraints for the moving platform in lower-degree-of-freedom applications reduces the number of cables required to support the moving platform in the task space. As a result, the manipulator can be designed with fewer cables and actuators. In order for the manipulator to balance arbitrary applied wrenches, redundant actuation is required. This redundant actuation can be obtained from a redundant actuator mounted on one (or more) serial-leg joint(s). Conditions for analyzing the capability of the redundant actuation to generate cable tension are explained in the paper. A discussion is also given on the optimization of the cable layout and the redundant actuator forces to minimize the tension generated in the cables.

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