Singularity robust balancing of parallel manipulators following inconsistent trajectories

2016-09-01
Ozdemir, Mustafa
Show full item record
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
139
views
0
downloads
When compared to serial manipulators, parallel manipulators have small workspaces mainly due to their closed-loop structure. As opposed to type I singularities (or inverse kinematic singularities) that are generally encountered at the workspace boundaries, type II singularities characteristically arise within the workspace, and around them, the inverse dynamic solution becomes unbounded. Hence, a desired trajectory passing through a type II singular position cannot be achieved by the manipulator, and its useful workspace becomes further and substantially reduced. It has been previously shown in the literature that if the trajectory is replanned in such a way that the dynamic equations of motion of the manipulator are consistent at a type II singularity, i.e. if the trajectory is consistent, then the manipulator passes through this singular configuration in a controllable manner, while the inverse dynamic solution remains finite. An inconsistent trajectory, on the other hand, is stated in the literature to be unrealizable. However, although seems a promising technique, trajectory replanning itself is also a deviation from the originally desired trajectory, and there might be cases in applications where, due to some task-specific reasons, the desired trajectory, although inconsistent, is not allowed to be replanned to satisfy the consistency conditions. In this paper, a method of singularity robust balancing is proposed for parallel manipulators passing through type II singular configurations while following inconsistent trajectories. By this means, an originally unrealizable inconsistent trajectory passing through a type II singularity can be followed without any deviation, while the required actuator forces remain bounded after the manipulator is balanced according to the design methodology presented in this study. The effectiveness of the introduced method is shown through numerical simulations considering a planar 3-DOF 2-PRR parallel manipulator under different balancing scenarios.
Parallel Manipulators, Inverse Dynamics, Singularities, Type II Singularities, Balancing
https://hdl.handle.net/11511/63443
Department of Mechanical Engineering, Article

Suggestions

Topological analysis of 6-joint serial manipulators and their inverse kinematic solutions
Özgören, Mustafa Kemal (2002-05-01)
The 6-joint serial manipulators are thoroughly investigated from the viewpoint of their inverse kinematic solutions. To do this systematically, the manipulators are classified according to their joint arrangements and two topological concepts are introduced as type number and conjugacy. The conditions of validity are stated and the valid manipulators are further classified into four groups according to their type numbers as type-3, type-4, type-5, and type-6. The concept of conjugacy leads to a reduction in...
Linearization and optimization of robot dynamics via inertial parameter design
Soylu, Reşit (1996-08-01)
In this article, the concept of linearity number (LN) is introduced to measure the ''linearity'' of the equations of motion of a serial manipulator. This number is computable in closed-form and is an average quantitative index of the degree of linearity of the robot over a specified region in the joint space. The definition is flexible, allowing the user to create custom-made definitions according to his or her specific needs. Using the concept of LN and the developed computer package CADLOR, one can design...
Invalid joint arrangements and actuator related singular configurations of a system of two cooperating SCARA manipulators
Ozkan, B; Özgören, Mustafa Kemal (2001-06-01)
In this study, the actuator related singular configurations (ASCs) of a system of two cooperating SCARA manipulators, are investigated. The ASC concept was First developed for planar pairs of cooperating manipulators, and it was shown that these ill-conditions could be different from the kinematic: singularities. (Ozkan B, Ozgoren MK. Torque related singular configurations of a planar system of two coodinated manipulators. In: Proceedings of International Machine Design and Production Conference, Sept. 9-11...
Results on characterizations of plateaued functions in arbitrary characteristic
Mesnager, Sihem; Özbudak, Ferruh; Sınak, Ahmet (2016-01-01)
Bent and plateaued functions play a significant role in cryptography since they can have various desirable cryptographic properties. In this work, we first provide the characterizations of plateaued functions in terms of the moments of their Walsh transforms. Next, we generalize the characterizations of Boolean bent and plateaued functions in terms of their second-order derivatives to arbitrary characteristic. Moreover, we present a new characterization of plateaued functions in terms of fourth power moment...
Optimal redundancy resolution for kinematically redundant parallel manipulators
Tunç, Tansel Sıtkı; Özgören, Mustafa Kemal; Department of Mechanical Engineering (2014)
In this study, the redundancy resolution of kinematically redundant parallel manipulators has been investigated as an optimization problem. The emerging optimization problem has been solved globally using a hybrid genetic algorithm. This algorithm has been applied as an example to a planar parallel manipulator which has four degrees of freedom. It has been assumed that the manipulator is used so that only the tip point of its end-effector is controlled. Therefore, the rotation angle of the end effector has ...
Citation Formats
M. Ozdemir, “Singularity robust balancing of parallel manipulators following inconsistent trajectories,” ROBOTICA, pp. 2027–2038, 2016, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/63443.
METU IIS - Integrated Information Service open@metu.edu.tr