Optimal Configuration of a 4-DOF Dual-Arm Cam-Lock Manipulator

2007 ◽  
Author(s):  
Kambiz Ghaemi Osgouie ◽  
Ali Meghdari ◽  
Saeed Sohrabpour ◽  
Mehdi Salmani Jelodar
Keyword(s):  
Degrees Of Freedom ◽  
Robot Manipulators ◽  
The Other ◽  
Initial Population ◽  
Structural Stiffness ◽  
Task Space ◽  
Specific Point ◽  
Geometrical Constraints ◽  
Dual Arm ◽  
Cooperative Manipulators

The Dual-Arm Cam-Lock (DACL) robot manipulators are reconfigurable arms formed by two parallel cooperative manipulators. Some of their joints may lock into each other. Therefore, the arms normally operate redundantly. However, when higher structural stiffness is needed these two arms can lock into each other in specific joints and loose some degrees of freedom. In this paper, the dynamics of the DACL robot is discussed and parametrically formulated. On the other hand, the criteria and implementation of genetic algorithm (GA) to optimize the configuration of DACL robot manipulators at a specific point with the objective to maximize the cooperatively applicable task-space force in a desired direction are addressed. To obtain a more efficient process, an initial population is generated satisfying the geometrical constraints of the planar arms.

Optimal configuration of dual-arm cam-lock robot based on task-space manipulability

Robotica ◽  
2009 ◽  
Vol 27 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Kambiz Ghaemi Osgouie ◽  
Ali Meghdari ◽  
Saeed Sohrabpour
Keyword(s):  
Degrees Of Freedom ◽  
Optimal Configuration ◽  
Task Space ◽  
Specific Point ◽  
Optimum Configuration ◽  
Geometrical Constraints ◽  
Dual Arm

SUMMARYIn this paper obtaining the optimal configuration of the dual-arm cam-lock (DACL) robot at a specific point is addressed. The objective is to optimize the applicable task-space force in a desired direction. The DACL robot is a reconfigurable manipulator formed by two parallel cooperative arms. The arms normally operate redundantly but when needed, they can lock into each other in certain joints in order to achieve a higher stiffness, while losing some degrees of freedom. Furthermore, the dynamics of the DACL robot is discussed and parametrically formulated. Considering the geometrical constraints at a given point in the robot's workspace, the optimum configuration for maximizing the cooperatively applicable force by dual arms is determined.

Employing Neural Networks for Manipulability Optimization of the Dual-Arm Cam-Lock Robot

2010 ◽  
Author(s):  
B. R. Jouibary ◽  
K. G. Osgouie ◽  
A. Meghdari
Keyword(s):  
Neural Networks ◽  
Degrees Of Freedom ◽  
Robot Manipulators ◽  
Optimal Configuration ◽  
Computational Time ◽  
Optimum Configuration ◽  
The Neural Network ◽  
Geometrical Constraints ◽  
The Cost ◽  
Dual Arm

Cooperative systems have been extensively investigated in literature. Herein the criteria and implementation for employing neural networks artificial intelligence for finding the optimal configuration of the Dual-Arm Cam-Lock (DACL) robot manipulators at a specific point with the objective to optimize the applicable task-space force in a desired direction are addressed. The DACL robot manipulators are reconfigurable arms formed by two parallel cooperative manipulators which operate redundantly but they may lock into each other in specific joints to increase structural stiffness in the cost of losing some degrees of freedom. Obtaining the optimal configuration demands lots of computational time and is not practical in real-time applications. The neural network is trained to approximate the optimum configuration considering the geometrical constraints of the planar arms using genetic algorithm as a multi-objective optimizer.

Optimization of kinematic redundancy and workspace analysis of a dual-arm cam-lock robot

Robotica ◽  
2014 ◽  
Vol 34 (1) ◽  
pp. 23-42 ◽  
Author(s):  
Behnoush Rezaeian Jouybari ◽  
Kambiz Ghaemi Osgouie ◽  
Ali Meghdari
Keyword(s):  
Degrees Of Freedom ◽  
Shooting Method ◽  
Minimum Principle ◽  
Final Decision ◽  
Structural Stiffness ◽  
Task Space ◽  
Kinematic Redundancy ◽  
Performance Indices ◽  
Workspace Analysis ◽  
Dual Arm

SUMMARYIn this paper, the problem of obtaining the optimal trajectory of a Dual-Arm Cam-Lock (DACL) robot is addressed. The DACL robot is a reconfigurable manipulator consisting of two cooperative arms, which may act separately. These may also be cam-locked in each other in some links and thus lose some degrees of freedom while gaining higher structural stiffness. This will also decrease their workspace volume. It is aimed to obtain the optimal configuration of the robot and the optimal joint trajectories to minimize the consumed energy for following a specific task space path. The Pontryagin's Minimum Principle is utilized with a shooting method to resolve kinematic redundancy. Numerical examples are investigated to show optimal trajectories in different cam-locked configurations, and the final decision is made based on a selection table of the computed performance indices.

scholarly journals Kinematic and dynamic modeling of a 3gdl robot for educational purposes

2020 ◽  
pp. 1-7
Author(s):  
Aleyda Irene Reyes-González ◽  
José Luis Ortiz-Simón ◽  
Martha Isabel Aguilera-Hernández ◽  
Gustavo Emilio Rojo-Velázquez
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Model ◽  
Dynamic Modeling ◽  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
The Other ◽  
Final Position ◽  
Specific Point ◽  
Simulink Model

The following article presents the process to obtain the kinematic and dynamic model of a Cartesian robot with 3 degrees of freedom. The robot that is used was designed for educational purposes, it allows two linear movements and one angular. The kinematic model has two forms, direct and inverse, the first provides the final position of the robot if desired values are given to each of the robot's joints, the second provides the values of the joints if there are desired values for the effector final. On the other hand, the obtaining of the dynamic model is presented in detail, which obtains the torques and forces necessary for the robot to be able to move to a specific point. The procedure includes kinematic analysis using Denavit-Hartenberg parameters and dynamic analysis using Jacobeans. As a result, responses obtained from a Simulink model are presented that show the behavior of the developed models.

scholarly journals No-go trials in task switching: effects on the task-set and task-space level

2021 ◽  
Author(s):  
Juliane Scheil ◽  
Thomas Kleinsorge
Keyword(s):  
Task Switching ◽  
The Other ◽  
Specific Task ◽  
Task Space ◽  
Response Level ◽  
Task Set ◽  
Common Marker ◽  
Task Sets ◽  
And Task

AbstractA common marker for inhibition processes in task switching are n − 2 repetition costs. The present study aimed at elucidating effects of no-go trials on n − 2 repetition costs. In contrast to the previous studies, no-go trials were associated with only one of the three tasks in the present two experiments. High n − 2 repetition costs occurred if the no-go task had to be executed in trial n − 2, irrespective of whether a response had to be withheld or not. In contrast, no n − 2 repetition costs were visible if the other two tasks were relevant in n − 2. Whereas this n − 2 effect was unaffected by whether participants could reliably exclude a no-go trial or not, effects of no-gos in trial n were determined by this knowledge. The results differ from effects of no-go trials that are not bound to a specific task. It is assumed that the present no-go variation exerted its effect not on the response level, but on the level of task sets, resulting in enhanced salience of the no-go task that leads to higher activation and, as a consequence, to stronger inhibition. The dissociation of the effects on no-gos in trials n − 2 and n as a function of foreknowledge suggests that the balance between activation and inhibition is shifted not only for single trials and tasks, but for the whole task space.

Cooperation and Null-Space Control of Networked Omni-Directional Mobile Manipulators

2020 ◽  
Author(s):  
Michael John Chua ◽  
Yen-Chen Liu
Keyword(s):  
Degrees Of Freedom ◽  
Null Space ◽  
Kinematic Model ◽  
Mobile Manipulator ◽  
Main Task ◽  
Mobile Manipulators ◽  
Robot Arm ◽  
Task Space ◽  
End Effector ◽  
Mobile Base

Abstract This paper presents cooperation and null-space control for networked mobile manipulators with high degrees of freedom (DOFs). First, kinematic model and Euler-Lagrange dynamic model of the mobile manipulator, which has an articulated robot arm mounted on a mobile base with omni-directional wheels, have been presented. Then, the dynamic decoupling has been considered so that the task-space and the null-space can be controlled separately to accomplish different missions. The motion of the end-effector is controlled in the task-space, and the force control is implemented to make sure the cooperation of the mobile manipulators, as well as the transportation tasks. Also, the null-space control for the manipulator has been combined into the decoupling control. For the mobile base, it is controlled in the null-space to track the velocity of the end-effector, avoid other agents, avoid the obstacles, and move in a defined range based on the length of the manipulator without affecting the main task. Numerical simulations have been addressed to demonstrate the proposed methods.

Footbridges as an important part of a system: the context as an experience

2021 ◽  
Author(s):  
Toon Maas ◽  
Mohamad Tuffaha ◽  
Laurent Ney
Keyword(s):  
Design Process ◽  
Degrees Of Freedom ◽  
The Other ◽  
Infrastructure Projects ◽  
Good Design ◽  
Cultural Processes ◽  
The Relationship

<p>“A bridge has to be designed”. Every bridge is the exploration of all degrees of a freedom of a project: the context, cultural processes, technology, engineering and industrial skills. A successful bridge aims to dialogue with these degrees of freedom to achieve a delicate equilibrium, one that invites the participation of its users and emotes new perceptions for its viewers. In short, a good design “makes the bridge talk.”</p><p>Too often, the bridge, as an object, is reduced to its functionality. Matters of perceptions and experiences of the users are often not considered in the design process; they are relegated to levels of chance or treated as simple decorative matter. The longevity of infrastructure projects, in general, and bridges, in particular, highlights the deficiencies of such an approach. The framework to design bridges must include historical, cultural, and experiential dimensions. Technology and engineering are of paramount importance but cannot be considered as “an end in themselves but a means to an end”. This paper proposes to discuss three projects by Ney &amp; Partners that illustrate such a comprehensive exploration approach to footbridge design: the Poissy and Albi crossings and the Tintagel footbridge.</p><p>The footbridges of Poissy and Albi dialogue most clearly with their historical contexts, reconfiguring the relationship between old and new in the materiality and typology use. In Tintagel, legend replaces history. Becoming a metaphor for the void it crosses, the Tintagel footbridge illustrates the delicate dialogue of technology and engineering on one side and imagination and experience on the other.</p>

On the Inherent Characteristics of the Dynamics of Robot Manipulators

1991 ◽  
Author(s):  
Q. Tu ◽  
J. Rastegar
Keyword(s):  
Path Length ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Robot Manipulators ◽  
Control Point ◽  
Coordinate Space ◽  
Relative Significance ◽  
Harmonic Content ◽  
Trajectory Pattern ◽  
Dynamics Models

Abstract The inherent characteristics of the (nonlinear) dynamics of robot manipulators are studied. The study is based on a new method, referred to as the trajectory pattern method. The inverse dynamics models of the manipulator are divided into classes of inverse dynamics models, each corresponding to a different trajectory pattern. For each trajectory pattern, the structure of the resulting inverse dynamics model is fixed and is used to study the characteristics of the dynamics of the manipulator by examining the harmonic content of the required actuation torques (forces) and the relative significance of each harmonic. The harmonic content of the actuating torques is shown to be a function of the path length in the joint coordinate space and the harmonic content of the selected trajectory pattern, but is independent of the number of degrees-of-freedom of the manipulator. The relative contribution of each harmonic is a function of the path length, direction of motion, the position of the path of motion within the workspace of the manipulator, and the magnitude of the fundamental frequency. The study provides a systematic approach to path and trajectory planning from the vibration control point of view. As an example, the characteristics of the dynamics of a spatial 3R manipulator is studied for motions with two different path lengths, starting from a specified point and extending in different directions.

Sodium Benzoate Inhibits Growth of or Inactivates Listeria monocytogenes

1988 ◽  
Vol 51 (7) ◽  
pp. 525-530 ◽  
Author(s):  
MOUSTAFA A. EL-SHENAWY ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Incubation Period ◽  
Sodium Benzoate ◽  
The Other ◽  
Complete Inhibition ◽  
Initial Population ◽  
Limited Growth ◽  
Complete Inactivation ◽  
Low Concentrations ◽  
Slight Growth

The ability of Listeria monocytogenes to grow or survive was determined using tryptose broth at pH 5.6 or 5.0, supplemented with 0, 0.05. 0.1, 0.15. 0.2. 0.25 or 0.3% sodium benzoate, and incubated at 4,13,21 or 35°C. The bacterium grew in benzoate-free controls under all conditions except at 4°C and pH 5.0. At pH 5.6 and 4°C, after 60 d, L. monocytogenes (initial population ca. 103/ml) was inactivated by 0.2, 0.25 and 0.3% sodium benzoate. Other concentrations of benzoate permitted slight growth during the first 36 d of incubation followed by a decrease in populations of the pathogen. At pH 5.0 and 4°C, from 0.15 to 0.3% benzoate completely inactivated the pathogen in 24 to 30 d, whereas the other concentrations caused a gradual decrease in the population during the 66-d incubation period. At 13°C and pH 5.6, L. monocytogenes grew (more at lower than higher concentrations of benzoate) in the presence of all concentrations of benzoate except 0.25 or 0.3%, which prohibited growth throughout a 264-h incubation period. Reducing the pH to 5.0 minimized growth at the two low concentrations of benzoate and caused slight decreases in population at the other concentrations of benzoate. At 21 and 35°C and pH 5.6, appreciable growth of L. monocytogenes occurred in the presence of 0.2% or less sodium benzoate, whereas higher concentrations were inhibitory, permitting little if any growth by the pathogen. Reducing the pH to 5.0 allowed limited growth of the pathogen at 21 and 35°C when the medium contained 0.05 or 0.1% sodium benzoate. Higher concentrations caused either complete inhibition or inhibition plus partial or complete inactivation of the pathogen during incubations of 117 h at 21°C or 78 h at 35°C.

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