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On dynamic stiffness of spacecraft flexible appendages in deployment phase
, Article Aerospace Science and Technology ; Volume 47 , 2015 , Pages 1-9 ; 12709638 (ISSN) ; Malaek, S. M ; Sharif University of Technology
Abstract
Deployment inertial effects of a spacecraft appendage on its flexible dynamics are investigated. The Euler-Bernoulli beam theory and the actual deployment profile, in which appendage axial motion accelerates from static state and then decelerates to end at zero velocity and acceleration, are employed. The study is concentrated on the arm dynamic stiffness introduced by inertial effects of the arm deployment, and the resultant effects on the arm flexible motions. Lagrange's equations and some appropriate shape functions in the series approximation method are employed to study the arm lateral elastic displacements. Finally a system of ordinary differential equations with time varying...
Design of mixed fuzzy-GA controller for SCARA type robot
, Article 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2006, Beijing, 9 October 2006 through 15 October 2006 ; 2006 , Pages 2173-2178 ; 142440259X (ISBN); 9781424402595 (ISBN) ; Sayyaadi, H ; Sharif University of Technology
2006
Abstract
This paper presents a Mixed Fuzzy-GA Controller (MFGAC) for trajectory tracking of an industrial Selective Compliance Assembly Robot Arm (SCARA), which is one of the most employed manipulators in industrial environments. In this robot nonlinear effects due to centrifugal, coriolis and internal forces are more important than friction and gravity forces, unlike most industrial robots. The control procedure of MFGAC is consisting of a mixed fuzzy controller which is optimized by genetic algorithm. In this work we first design a Traditional Fuzzy Controller (TFC) from the viewpoint of a Single-Input Single-Output (SISO) system for controlling each degree of freedom of the robot. Then, an...
Control of Two-Arm Flexible Robot Carrying Fluid Tank With Constraint on the Elevation of the Liquid Free-Surface
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor) ; Kouchakzadeh, Mohammad Ali (Supervisor)
Abstract
Control of two-arm flexible robot is studied in this research. The goal is to control the robot in order to carry a fluid tank installed in the top of the last arm, while the vibration of fluid must be damped. The equations governing the system are extracted by the energy method while Euler-Bernoulli beam is selected to model the elastic members. In order to develop the equations, all of the potential and kinematic energies due to rigid and elastic motions are calculated, then a proper controller is designed for the system to accomplish the considered missions. Since the system is classified as an under-actuated system, the exact feedback linearization method is not practical to control the...
Design and development of an omnidirectional mobile manipulator for indoor environment
, Article 6th RSI International Conference on Robotics and Mechatronics, IcRoM 2018, 23 October 2018 through 25 October 2018 ; 2019 , Pages 152-158 ; 9781728101279 (ISBN) ; Hosseiniakram, P ; Havashinezhadian, S ; Rostami, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, a mobile manipulator is developed and studied in order to manipulate the complicated objects and navigate in an indoor environment. The arm consists of an actuator that makes the first linkage to move in two degrees of freedom in the first step of the task. In the next mode of the task, another actuator causes the second linkage to move in the third degree of freedom. In addition, the arm contains a gripper that grabs a variety of objects such as a screw. Therefore, the robotic arm can manipulate objects, and the mobile robot connected to the arm can detect, classify and track targets in its surrounding. Results carried out that the manufactured robot is able to manipulate and...
Separating Linkages in 3-Space
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Amiri, Nezamoddin (Supervisor)
Abstract
Here, the properties of separability of linkages are studied. In general, a linkage is a simple polygonal chain embedded in 3-space with disjoint, straight-line edges, which are fixed-length bars. The internal vertices are called joints. If the two end points are connected then the linkage is a closed linkage, otherwise it is an open linkage. By imposing restrictions on the way the bars in joints can move, three kinds of linkages as rigid, revolute and flexible can be introduced. A motion in a linkage is the motion of its vertices that preserves the length of the bars, and adheres the restrictions on joints. A collection of linkages are said to be separatable if for any distance d, there is...
Synthesis of a compensated kick pattern for humanoid robots using conservation laws
, Article 2006 ASME International Design Engineering Technical Conferences and Computers and Information In Engineering Conference, DETC2006, Philadelphia, PA, 10 September 2006 through 13 September 2006 ; Volume 2006 , 2006 ; 079183784X (ISBN); 9780791837849 (ISBN) ; Tamaddoni, S. H ; Jafari, F ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
The motivation of this work is to synthesize a kicking pattern for a humanoid robot with consideration of various objectives such as retaining its balance even after the kick is done and reducing the undesired angular momentum using both hands and torso. This kick pattern is designed so that a desirable ball velocity is achieved. In this paper, the law of conservation of angular momentum is used to generate a less energy consuming trajectory. Effectiveness of the proposed method is verified using computer simulation and is tested on Sharif CEDRA humanoid robot. Copyright © 2006 by ASME
Manipulability analysis for gimbal driven robotic arms
, Article 2009 IEEE International Conference on Robotics and Biomimetics, ROBIO 2009, 19 December 2009 through 23 December 2009 ; 2009 , Pages 1039-1044 ; 9781424447756 (ISBN) ; Hemmatian, I ; Ghaem Osgouie, K ; Sharif University of Technology
Abstract
Gimbal transmissions are non-linear direct transmissions and can be used in robotic arms replacing the traditional revolute joints. To investigate manipulability of robotic manipulators, the classical criterion of Manipulability Ellipsoid has been formulated. Thus by keeping a constant norm for robot joint torques vector, the effects of replacing some traditional revolute joints in robotic arms with Gimbal transmissions, have been analyzed. The results show that the magnitude of the maximum force applicable when employing Gimbal transmission can be considerably larger. Also, the joint angles in which this maximum occurs, can be adjusted, thanks to the behavior of Gimbal transmission. Two...
Robust control of smart beam with pizoelectric actuators
, Article Eight IASTED International Conference on Control and Applications, Montreal, QC, 24 May 2006 through 26 May 2006 ; Volume 2006 , 2006 , Pages 41-47 ; 0889865531 (ISBN); 9780889865532 (ISBN) ; Yousefi Koma, A ; Akbari, S ; Zadeh, B. T ; Sharif University of Technology
2006
Abstract
In this paper, a robust control system is developed for a flexible beam with piezoelectric actuators (called Smart Beam). The active control system of smart beam satisfied desired properties for all admissible measurement and plant noises, disturbances and model uncertainties. Thus it is the best candidate for sensitive industrial, medical and etc. robot arms and bases a new concept in the use of smart structures in robotics. The Frequency Response Function (FRF) of the smart beam was obtained from a Finite Element (FE) model. The corresponding transfer function was derived from the □ synthesis and several control schemes were then designed to suppress the vibration. Results showed the...
On the dynamics of the flexible robot arm in a real deployment profile
, Article 2010 IEEE International Conference on Robotics, Automation and Mechatronics, RAM 2010, Singapore, 28 June 2010 through 30 June 2010 ; 2010 , Pages 112-117 ; 9781424465033 (ISBN) ; Malaek, S. M ; Sharif University of Technology
2010
Abstract
The dynamics of the flexible robot arm subjected to tip mass during an actual deployment is studied. The Euler-Bernoulli beam theory and the real deployment are considered in the simulation. A new real axial velocity profile is developed. This new suggested profile simulates the actual deployment such that the arm movement starts from immovability and after attaining the final required length comes back again to the static state. Using Lagrange's equation, the equations of motion of the system are derived to study the system dynamics in this suggested deployment profile. A series approximation is used to represent the lateral elastic displacements. Using variables separation and also some...
Robotic Arm Manipulation Learning from Demonstration based on Reinforcement Learning
, M.Sc. Thesis Sharif University of Technology ; Khodaygan, Saeed (Supervisor)
Abstract
The field of learning from demonstration is the field in which researchers seek to create methods by which a robot can learn and reproduce a skill simply by using the demonstration of the skill. One of the main drawbacks of learning from demonstration methods is their inability to improve the learned skills. To answer this question, the reinforcement learning method can be used. The reinforcement learning approach has the potential to improve the initial skill due to the use of the experience of interacting with the environment. In this project, the dynamic movement primitives algorithm is considered as the learning from demonstration method. The research approach is that first, the dynamic...
Localization and Control of a Continuum Robot
, Ph.D. Dissertation Sharif University of Technology ; Nejat Pishkenari, Hossein (Supervisor) ; Alasty, Aria (Supervisor)
Abstract
Magnetic steering of continuum robots is a promising technology that uses a magnetic field to control the robot without contact and can improve the accessibility, safety, and accuracy of the robot. On the other hand, magnetic localization can also be used as a positioning method without direct line of sight in various applications. Common magnetic localization methods face the challenge of dependence on initial guess, divergence, and high computational cost. In this research, by eliminating the unknowns related to the orientation and rewriting the equations, a new method for magnetic localization has been presented. The advantage of the new method in convergence and increasing the speed of...
Equations of motion of a ring-like robot with a flexible body and creeping-rolling motion
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; 2010 , pp. 191-197 ; ISBN: 9780791843833 ; Alasty, A ; Sharif University of Technology
Abstract
The robots that can move on rough terrains are very important especially in Rescue operation, exploration, etc. In this research, a mechanism is introduced for a ring-like robot with a flexible body. This robot is moved by arms which are placed radially and have Reciprocating motion in this direction. By controlling the contraction and the extension of the arms which contact lhe ground, the robot will be forced to move which is called rolling-creeping motion. The robot is stable in stationary state.; also the maximum angle which it can be stable is determined. Considering the speed of contracted arm is the input parameter, the speed of the extended arm for locomotion of the robot has been...
3D Dynamic analysis of a flexible deploying arm subjected to base angular motions
, Article International Journal of Structural Stability and Dynamics ; Volume 13, Issue 2 , March , 2013 ; 02194554 (ISSN) ; Malaek, S. M ; Sharif University of Technology
2013
Abstract
Problems related to the three-dimensional (3D) dynamics of the deploying flexible arms subjected to base angular motions are studied with simulated tip payloads and actual deployment trajectories. To facilitate the solution, an equivalent dynamical system is developed by introducing the inertial reaction forces on the arm, while the equations of motion are derived in the non-Newtonian reference frame attached to the arm. The dynamic behavior of the arm is investigated both by the finite element and assumed Modes methods for the purpose of verification. This study reveals that base angular motions lead to considerable couplings between the two lateral displacements and axial motions....
Optimal configuration of dual-arm cam-lock robot based on task-space manipulability
, Article Robotica ; Volume 27, Issue 1 , 2009 , Pages 13-18 ; 02635747 (ISSN) ; Meghdari, A ; Sohrabpour, S ; Sharif University of Technology
2009
Abstract
In 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...
Buckling analysis of tapered composite beams using a higher order finite element formulation
, Article Journal of Reinforced Plastics and Composites ; Volume 29, Issue 17 , 2010 , Pages 2663-2683 ; 07316844 (ISSN) ; Ganesan, R ; Sharif University of Technology
2010
Abstract
Tapered composite beams are increasingly being used in various engineering applications such as helicopter yoke, robot arms, and turbine blades. In the present work, the buckling analysis of laminated tapered composite beams is conducted using a higher order finite element formulation. In tapered laminates, the material and geometric discontinuities at ply drop-off locations lead to significant discontinuities in stress distributions. Higher order formulation ensures the continuity of the stress distribution through the thickness of a laminate as well as across the element interfaces, which is very important for the analysis of tapered laminates. In addition, higher order finite element...
On the coupled dynamics of small spacecraft and elastic deployable appendages
, Article Multibody System Dynamics ; 2016 , Pages 1-26 ; 13845640 (ISSN) ; Malaek, S. M ; Abedian, A ; Sharif University of Technology
Springer Netherlands
2016
Abstract
A thorough investigation of the dynamics of finite-mass satellites with a deployable elastic arm is presented. This work is focused on the interaction between spacecraft rigid body motion and its flexible arm dynamics during the deployment process. The classical Newton–Euler formulation and the Lagrangian approach are applied to the study of the dynamics of spacecraft and its deploying arm. Utilizing a non-Newtonian floating frame to define the arm elastic deformation field, the interactions between the spacecraft and its moving arm have been simulated. Complete equations of motion show that the spacecraft motion induces dynamical stiffness on the arm; in addition, axial and lateral motions...
On the coupled dynamics of small spacecraft and elastic deployable appendages
, Article Multibody System Dynamics ; Volume 40, Issue 3 , 2017 , Pages 235-260 ; 13845640 (ISSN) ; Malaek, S. M ; Abedian, A ; Sharif University of Technology
Springer Netherlands
2017
Abstract
A thorough investigation of the dynamics of finite-mass satellites with a deployable elastic arm is presented. This work is focused on the interaction between spacecraft rigid body motion and its flexible arm dynamics during the deployment process. The classical Newton–Euler formulation and the Lagrangian approach are applied to the study of the dynamics of spacecraft and its deploying arm. Utilizing a non-Newtonian floating frame to define the arm elastic deformation field, the interactions between the spacecraft and its moving arm have been simulated. Complete equations of motion show that the spacecraft motion induces dynamical stiffness on the arm; in addition, axial and lateral motions...
Modeling and intelligent control of a robotic gas metal arc welding system
, Article Scientia Iranica ; Volume 15, Issue 1 , 2008 , Pages 75-93 ; 10263098 (ISSN) ; Eftekharian, A. A ; Sharif University of Technology
Sharif University of Technology
2008
Abstract
Welding is an important manufacturing process that can be automated and optimized. This paper focuses on the development of a robotic arc welding system, wherein a three-degree-of-freedom Selective Compliance Assembly Robot Arm (SCARA) is interfaced to a Gas Metal Arc Welding (GMAW) process. The entire system is composed of a robot linked to a GMAW system. Set points are derived using the desired mass and heat input, along with the weld speed. The stick-out and the current of the welding process are controlled using an Adaptive Neural Network Controller (ANNC). The trajectory of the robot or the weld profile is also controlled by implementing a Mixed Fuzzy-GA Controller (MFGAC) on a...