Loading...
Search for:
manipulators
0.007 seconds
Total 229 records
Kinematics and singularity analysis of the hexaglide parallel robot
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 37-43 ; 9780791848722 (ISBN) ; Pendar, H ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
2009
Abstract
In the past few years, parallel manipulators have become increasingly popular in industry, especially, in the field of machine tools. Hexaglide is a 6 DOF parallel manipulator that can be used as a high speed milling machine. In this paper, the kinematics and singularity of Hexaglide parallel manipulator are studied systematically. At first, this robot has been modeled and its inverse and forward kinematic problems have been solved. Then, formulas for solving inverse velocity are derived and Jacobian matrix is obtained. After that, three different types of singularity for this type of robot have been investigated. Finally a numerical example is presented. Copyright © 2008 by ASME
Prescribed-time control for perturbed euler-lagrange systems with obstacle avoidance
, Article IEEE Transactions on Automatic Control ; 2021 ; 00189286 (ISSN) ; Assadian, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
This paper introduces a class of time-varying controllers for Euler-Lagrange systems such that the convergence occurs at an arbitrary finite time, independently of initial conditions, and free of chattering. The proposed controller is based on a mapping technique and is designed in two steps: First, a conventional (obstacle avoidance) asymptotically stable controller is specified for the nominal system; then, by a simple substitution, a prescribed-time (obstacle avoidance) controller is achievable for the perturbed system. It is proved that the proposed scheme is uniformly prescribed-time stable for unperturbed systems and prescribed-time attractive for perturbed systems as it rejects...
Intelligent Force Control for Hydraulic Manipulator within the Impedance Control Framework
, M.Sc. Thesis Sharif University of Technology ; Khayyat, Amir Ali Akbar (Supervisor)
Abstract
The main concept of this thesis is to simulate, develop, and analyze the performance of force control method by applying to a Unimate MK-II hydraulic manipulator. In this investigation, simulation studies are based on the concept of impedance control technique. Position-based formulation of impedance control is employed. First in this research, a PID controller is employed and is shown to be capable of performing position control task precisely despite the fact that inertia, joint stiction, valve deadband and other nonlinearities are presented. Although trajectory tracking is performed well after several investigations, we have concluded that the impedance control cannot perform a desirable...
Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators
, Article Robotica ; Volume 31, Issue 7 , 2013 , Pages 1073-1084 ; 02635747 (ISSN) ; Zohoor, H ; Korayem, M. H ; Sharif University of Technology
2013
Abstract
Discrete kinematic synthesis of discretely actuated hyper-redundant manipulators is a new practical problem in robotics. The problem concerns with determining the type of each manipulator module from among several specific types, so that the manipulator could reach several specified target frames with the lowest error. This paper suggests using a breadth-first search method and a workspace mean frame to solve this problem. To reduce errors, two heuristic ideas are proposed: two-by-two searching method and iteration. The effectiveness of the proposed method is verified through several numerical problems
Kinematic effects of gimbal joints on a 3URU parallel manipulator
, Article ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis, ESDA 2012 ; Volume 3 , 2012 , Pages 205-210 ; 9780791844861 (ISBN) ; Razban, F ; Osgouie, K. G ; Sharif University of Technology
2012
Abstract
Gimbal transmissions are non-linear direct transmissions and can be used in robotic arms replacing the traditional revolute joints. They offer potential advantages for critical cases such as joint space and task space singularities or where a different mechanical advantage is needed compared to what traditional revolute joints provide. This can be obtained by properly adjusting the different parameters of Gimbal joints used in different joints of the manipulator (such as their offset angle and/or chamfer angle). In this paper the concept of Gimbal mechanism as a joint is investigated. Then, as an example, Gimbal joints are used to replace the basic revolute joints of a 3-UPU parallel...
A geometric approach to fault detection and isolation in robotic manipulators
, Article Proceedings of the IEEE Conference on Decision and Control, 17 December 2018 through 19 December 2018 ; Volume 2018-December , 2019 , Pages 391-396 ; 07431546 (ISSN); 9781538613955 (ISBN) ; Namvar, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
We present a geometric approach for fault detection and isolation (FDI) in robotic manipulators in presence of model uncertainty. A systematic procedure is introduced for representing robotic system model being affine with respect to faults and disturbances. The proposed residual generator has smooth dynamics with freely selectable functions and it does not require high gains or threshold adjustment for the FDI purpose. No assumption on amplitude of faults and their rate is used. The solvability conditions for the FDI problem lead to a quotient observable subspace unaffected by all unknown inputs except the faults. Simulation example demonstrates localization of faults in presence of...
A geometrical approach for configuration and singularity analysis of a new non-symmetric 2DOF 5R spherical parallel manipulator
, Article Mechanism and Machine Theory ; Volume 147 , 2020 ; Farahmand, F ; Behzadipour, S ; Mirbagheri, A. R ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
A new non-symmetric 5R-SPM is introduced and a geometrical approach is developed to analyze its configurations and singularities. The proposed methodology determines the type of configuration of a 5R-SPM, i.e. regular, singular, or out-of-workspace and also the type of singularity, i.e. instantaneous or finite, only based on geometric parameters and without solving verbose kinematic equations. It also provides insights into the workspace and singularities of 5R-SPMs, in the preliminary stage of design. The mechanism was analyzed by both the new geometrical approach and conventional methods for comparison. The geometrical approach could intuitively detect all the singularities observed by the...
A novel fuzzy reinforcement learning approach in two-level intelligent control of 3-DOF robot manipulators
, Article 2007 IEEE Symposium on Approximate Dynamic Programming and Reinforcement Learning, ADPRL 2007, Honolulu, HI, 1 April 2007 through 5 April 2007 ; 2007 , Pages 20-25 ; 1424407060 (ISBN); 9781424407064 (ISBN) ; Sadati, N ; Sharif University of Technology
2007
Abstract
In this paper, a fuzzy coordination method based on Interaction Prediction Principle (IPP) and Reinforcement Learning is presented for the optimal control of robot manipulators with three degrees-of-freedom. For this purpose, the robot manipulator is considered as a two-level large-scale system where in the first level, the robot manipulator is decomposed into several subsystems. In the second level, a fuzzy interaction prediction system is introduced for coordination of the overall system where a critic vector is also used for evaluating its performance. The simulation results on using the proposed novel approach ,for optimal control of robot manipulators show its effectiveness and...
Stability enhancement of mobile manipulators via soft computing
, Article International Journal of Advanced Robotic Systems ; Volume 3, Issue 3 , 2006 , Pages 191-198 ; 17298806 (ISSN) ; Meghdari, A ; Naderi, D ; Eslami, S ; Sharif University of Technology
InTech Europe
2006
Abstract
Nowadays the size and dimension of mobile manipulators have been decreased for being usable in various regions. This leads several problems such as danger of instability. Therefore, many researches have been done to overcome the problem of overturning of a mobile manipulator. In this paper, an algorithm for increasing the stability of a mobile manipulator is presented based on the optimization of a performance index. The path of vehicle and the desired task of the end-effector are predefined. In order to apply the optimal stability criterion, it is more convenient that the manipulator be of a redundant. Considering the interaction between the vehicle and the manipulator and using the genetic...
Analysis of singularities of a 3DOF parallel manipulator based on a novel geometrical method
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Sadeghian, H ; Roozbehani, H ; Zohoor, H ; Sharif University of Technology
2006
Abstract
In this article singular points of a parallel manipulator are obtained based on a novel geometrical method. Here we introduce the constrained plain method (CPM) and some of its application in parallel mechanism. Given the definition of constraint plane (CP) and infinite constraint plane (ICP) the dependency conditions of constraints is achieved with the use of a new theorem based on the Ceva geometrical theorem. The direction of angular velocity of a body is achieved by having three ICPs with the use of another theorem. Finally, with the use of the above two novel theorems singularities of the 3UPF_PU mechanism are obtained. It should be emphasized that this method is completely geometrical,...
Optimal control of robot manipulators with a new two-level gradient-based approach
, Article Electrical Engineering ; Volume 88, Issue 5 , 2006 , Pages 383-393 ; 09487921 (ISSN) ; Babazadeh, A ; Sharif University of Technology
2006
Abstract
In this paper, a new approach for optimal control of robot manipulators is presented. For this purpose, the system is considered as a two-level large-scale system where a gradient-based coordination strategy is used to coordinate the overall system. This is achieved within a decomposition-coordination framework, where the robot manipulator is first decomposed into several sub-systems at the first level, and then, the coordination is done at the second level. The solution is based on Interaction Prediction Principle, where in the first level, the optimization is done by a gradient method and in the second level, the coordination is done by a new method based on the gradient of interaction...
Adaptive multi-model CMAC-based supervisory control for uncertain MIMO systems
, Article ICTAI 2005: 17th IEEE International Conference on Tools with Artificial Intelligence, ICTAI'05, Hong Kong, 14 November 2005 through 16 November 2005 ; Volume 2005 , 2005 , Pages 457-461 ; 10823409 (ISSN); 0769524885 (ISBN); 9780769524887 (ISBN) ; Bagherpour, M ; Ghadami, R ; Sharif University of Technology
2005
Abstract
In this paper, an adaptive multi-model CMAC-based controller (AMCBC) in conjunction with a supervisory controller is developed for uncertain nonlinear MIMO systems. AMCBC is a kind of adaptive feedback linearizing controller where nonlinearity terms are approximated with multiple CMAC neural networks With the help of a supervisory controller, the resulting close-loop system is globally stable. The proposed control system is applied to control a robotic manipulators, where some varying tasks are repeated but information on the load is not defined; it is unknown and varying. It is shown how the proposed controller is effective because of its capability to memorize the control skill for each...
Adaptive fuzzy decentralized control of robot manipulators
, Article ICIECA 2005: International Conference on Industrial Electronics and Control Applications 2005, Quito, 29 November 2005 through 2 December 2005 ; Volume 2005 , 2005 ; 0780394194 (ISBN); 9780780394193 (ISBN) ; Elhamifar, E ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
In this paper an adaptive fuzzy decentralized control algorithm for trajectory tracking of robot manipulators is developed. The proposed decentralized control algorithm allows the overall closed-loop system to be stabilized while making the tracking error to be uniformly ultimately bounded (UUB), without having any prior knowledge of the robot manipulator dynamics. The interconnections in the dynamic equations of each subsystem are considered with unknown nonlinear bounds. The adaptive fuzzy neural networks (AFNNs) are proposed to model the unknown nonlinear dynamics of the robots and the interconnection terms. Using Lyapunov method, the stability of the overall system is investigated. ©...
An adaptive neural network sliding mode controller for robotic manipulators
, Article 2005 IEEE International Conference on Industrial Technology, ICIT 2005, Hong Kong, 14 December 2005 through 17 December 2005 ; Volume 2005 , 2005 , Pages 1246-1251 ; 0780394844 (ISBN); 9780780394841 (ISBN) ; Ghadami, R ; Bagherpour, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2005
Abstract
In this paper, an adaptive neural network sliding mode controller (ANNSMC) for robotic manipulators is proposed to alleviate the problems met in practical implementation using classical sliding mode controllers. The chattering phenomenon is eliminated by substituting single-input single-output radial-basis-function neural networks (RBFNN's), which are nonlinear and continuous, in lieu of the discontinuous part of the control signals present in classical forms. The weights of the hidden layer of the RBFNN's are updated in an online manner to compensate the system uncertainties. The key feature of this scheme is that prior knowledge of the system uncertainties is not required to guarantee the...
Optimal in-depth trapping by tuning the correction collar of a dry objective lens
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 39, Issue 12 , 2022 , Pages 3209-3215 ; 07403224 (ISSN) ; Mahdavi, S. M ; Reihani, S. N. S ; Sharif University of Technology
Optica Publishing Group (formerly OSA)
2022
Abstract
Optical tweezers are proven and indispensable micro-manipulation tools. It is very common to use an immersion-assisted high NA objective for optical trapping of micrometer-sized beads. However, such objectives suffer from low working depth range. Here we show, both by theory and experiment, that a dry objective can be utilized for optimal trapping of even sub-micrometer objects. For the first time, to the best of our knowledge, we were able to stably trap polystyrene beads with radii of 270 and 175 nm in 3D using an objective with numerical aperture of 0.9. © 2022 Optica Publishing Group
Design and Analysis of a Cable Based Robot Similar to a Human Hand
, M.Sc. Thesis Sharif University of Technology ; Zohoor, Hassan (Supervisor)
Abstract
The application of manipulators is becoming more and more popular in objects handling especially when it is desired to have access to remote areas in destructive or hazardous taskspaces. For this purpose, a hand-like mechanism must be designed to be used as an end-effector, which can grasp objects. In this paper a cable driven grasping mechanism has been presented. In the proposed mechanism each finger consists of three phalanxes which are actuated by a single motor. Also, locking and unlocking constraints are used in the mechanism in order to generate an anthropomorphic motion, in which, the order of reaching phalanxes to the object is sequential, in such a way that each phalanx starts...
Solving the Path Planning Problem in 3D Continues Space with Application in Elastic Manipulator
, M.Sc. Thesis Sharif University of Technology ; Asghari, Mohsen (Supervisor)
Abstract
Nowadays, robots are become more common in many important applications, such as academic and industrial issues. One of the most important robots are Multi-Arm manipulators which are used in many application such as moving objects, coloring, automatic welding and etc. Working with this kind of robots needs some vital attentions like planning their moving path. It is Because of the large number of obstacles that they face with in the path. Therefore, not only robots are not allowed to collision with themselves, but also they must not touch the obstacles. In the other words, they need Path planning. Generally, the equations of these robots are nonlinear. Therefore, computers and numerical...
Planar molecular dynamics simulation of Au clusters in pushing process
, Article International Journal of Nanomanufacturing ; Vol.5, No.3/4 , 2010 , pp.288-296 ; Meghdari, A. (Ali) ; Jalili, N. (Nader) ; Amiri, F. (Farshid) ; Sharif University of Technology
Abstract
Based on the fact that the manipulation of fine nanoclusters calls for more precise modelling, the aim of this paper is to conduct an atomistic investigation for interaction analysis of particle-substrate system for pushing and positioning purposes. In the present research, 2D molecular dynamics simulations have been used to investigate such behaviours. Performing the planar simulations can provide a fairly acceptable qualitative tool for our purpose while the computation time is reduced extremely in comparison to 3D simulations. To perform this study, Nose-Hoover dynamics and Sutton-Chen interatomic potential will be used to investigate the behaviour of the aforementioned system. Pushing of...
Control of nonholonomic mobile manipulators for cooperative object transportation
, Article Scientia Iranica ; Vol. 21, issue. 2 , 2014 , p. 347-357 ; Babaee, M ; Sharif University of Technology
Abstract
In this paper, a methodology for transporting objects with a group of wheeled nonholonomic mobile manipulators is presented. A full dynamic model of a mobile manipulator with a three wheeled mobile base and a three DOF manipulator is derived using the Gibbs-Appell method. Since the dynamical equations of a mobile robot are highly nonlinear, an input-output linearization technique is used to control individual robots. Transporting the object is divided into two steps. First, the robots use a decentralized behavior-based method to approach and surround the object. Then, a virtual structure method is used to control the robots to transport the object cooperatively. A numerical simulation study...
The clutch: Two-handed mobile multi-touch 3D object translation and manipulation
, Article 2015 IEEE International Symposium on Haptic, Audio and Visual Environments and Games, HAVE 2015 - Proceedings, 11 October 2015 ; Oct , 2015 , Page(s): 1 - 5 ; 9781467391757 (ISBN) ; Chegini, M ; Shirmohammadi, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Nowadays, handheld devices such as smartphones provide users with multi-touch input screens. Displaying interactive and touch-enabled 3D environments in such handheld devices has become popular in different applications like games or virtual reality. Technologies such as Web3D and WebGL have made the creation and display of 3D environments in mobile devices easier than ever. However, object manipulation techniques are not as well developed. For example, moving an object within the 3D environment or other similar object-specific manipulations are neither intuitive nor easy to perform. Current manipulation techniques like Gizmo that are successful in systems that use mouse and keyboard are not...