Inertia equivalence principle and adaptive control of parallel manipulators with redundant actuation

2002 ◽  
Author(s):  
G.F. Liu ◽  
Y.K. Yiu ◽  
Z.X. Li
Keyword(s):  
Adaptive Control ◽  
Equivalence Principle ◽  
Parallel Manipulators ◽  
Redundant Actuation

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.

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.

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.

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