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flexible-manipulators
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Finite time control of robotic manipulators with position output feedback
, Article International Journal of Robust and Nonlinear Control ; Volume 27, Issue 16 , 2017 , Pages 2982-2999 ; 10498923 (ISSN) ; Moravej Khorasani, M ; Haeri, M ; Sharif University of Technology
Abstract
This paper deals with the robust finite time tracking of desired trajectories for a wide group of robotic manipulators in spite of unknown disturbances, uncertainties, and saturations of actuators while only manipulator's positions are available and its velocities are not measurable physically. A new form of chattering-free second order fast nonsingular terminal sliding mode control scheme is introduced to design input torques for fulfilling the determined tracking objective in the adjustable total finite settling time. The proposed control algorithm is incorporated with two nonlinear observers to estimate disturbances and velocities of joints within finite settling times. The global finite...
Dynamic model of a mobile robot with long spatially flexible links
, Article Scientia Iranica ; Volume 16, Issue 5 B , 2009 , Pages 387-412 ; 10263098 (ISSN) ; Khorsandijou, S. M ; Sharif University of Technology
2009
Abstract
Using some agent variables, the general structure of the dynamic model of a spatial mobile robot with N long spatially flexible links and N revolute joints has been exposed. It is composed of a set of 5N + 6 nonlinear coupled partial differential motion equations under the influence of the boundary conditions. Non-conservative forces/moments have been neglected. While being considered, the general structure of the dynamic model will not change, but a few exciting/damping terms will arise within the agent variables. The base of the robot is an unconstrained rigid body in space and the links as 3D Euler-Bernoulli beams undergo tension-compression, torsion and two spatial bendings while elastic...
A class of globally convergent velocity observers for robotic manipulators
, Article IEEE Transactions on Automatic Control ; Volume 54, Issue 8 , 2009 , Pages 1956-1961 ; 00189286 (ISSN) ; Sharif University of Technology
2009
Abstract
We present a method for global estimation of joint velocities in rigid manipulators. A class of velocity observers with smooth dynamics are introduced whose structure depend on freely selectable functions and gains giving the flexibility of achieving multiple design objectives at the same time. Unlike most methods, no a priori knowledge of an upper bound for velocity magnitude is used. An adaptive version of the observer is also presented to handle a class of structured uncertainties in manipulator model. Simulation example illustrates low noise sensitivity of the globally convergent observer in comparison with semi-globally convergent observers. © 2009 IEEE
Optimal configuration of a 4-DOF dual-arm cam-lock manipulator
, Article 31st Mechanisms and Robotics Conference, presented at - 2007 ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC/CIE2007, Las Vegas, NV, 4 September 2007 through 7 September 2007 ; Volume 8 PART B , 2008 , Pages 1101-1107 ; 0791848027 (ISBN); 9780791848029 (ISBN); 0791848094 (ISBN); 9780791848098 (ISBN) ; Meghdari, A ; Sohrabpour, S ; Jelodar, M. S ; Sharif University of Technology
2008
Abstract
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...
Adaptive multi-model sliding mode control of robotic manipulators using soft computing
, Article Neurocomputing ; Volume 71, Issue 13-15 , 2008 , Pages 2702-2710 ; 09252312 (ISSN) ; Ghadami, R ; Sharif University of Technology
Elsevier
2008
Abstract
In this paper, an adaptive multi-model sliding mode controller for robotic manipulators is presented. By using the multiple models technique, the nominal part of the control signal is constructed according to the most appropriate model at different environments. Adaptive single-input-single-output (SISO) fuzzy systems or radial basis function (RBF) neural networks, regarding their functional equivalence property, are used to approximate the discontinuous part of control signal; control gain, in a classical sliding mode controller. The key feature of this scheme is that prior knowledge of the system uncertainties is not required to guarantee the stability. Also the chattering phenomenon in...
Genetic algorithm based optimization for dual-arm cam-lock robot configuration
, Article 2007 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM, Zurich, 4 September 2007 through 7 September 2007 ; December , 2007 ; 1424412641 (ISBN); 9781424412648 (ISBN) ; Meghdari, A ; Sohrabpour, S ; Salmani Jelodar, M ; Sharif University of Technology
2007
Abstract
Cooperative systems have been extensively investigated in literature. Herein the criteria and implementation 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. 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. The dynamics of the DACL robot is...
Optimal control of robot manipulators using fuzzy interaction prediction system
, Article 2006 IEEE International Conference on Robotics and Biomimetics, ROBIO 2006, Kunming, 17 December 2006 through 20 December 2006 ; 2006 , Pages 1071-1076 ; 1424405718 (ISBN); 9781424405718 (ISBN) ; Emamzadeh, M. M ; Sharif University of Technology
2006
Abstract
In this paper, a new fuzzy coordination method based on Interaction Prediction Principle (IPP) is presented for the optimal control of robot manipulators. For this purpose, the robot manipulator is considered as a two-level large-scale system where in the first level, the overall system is decomposed into several subsystems. Each subsystem can include one or more consecutive links and joints. 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 evaluation of its performance. The simulation results of using the proposed novel approach ,for optimal control of robot manipulators, show its...
Prescribed-Time control for perturbed euler-lagrange systems with obstacle avoidance
, Article IEEE Transactions on Automatic Control ; Volume 67, Issue 7 , 2022 , Pages 3754-3761 ; 00189286 (ISSN) ; Assadian, N ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
This article 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...
High-precision impedance control method for flexible base moving manipulators
, Article Advanced Robotics ; Volume 23, Issue 1-2 , 2009 , Pages 65-87 ; 01691864 (ISSN) ; Vossoughi, G. R ; Sharif University of Technology
2009
Abstract
The general problem of impedance control is addressed for a robotic manipulator with a moving flexible base. Impedance control imposes a relation between force and displacement at the contact point with the environment. The concept of impedance control of flexible base moving manipulators (FBMMs) is rather new and is being considered. The dynamic of the manipulator is decomposed into slow and fast dynamics using the singular perturbation method. A new sliding mode impedance control (SMIC) method using an element on the end-effector is proposed for high-precision impedance control of FBMMs. The SMIC method as a robust impedance control law is derived for the slow dynamics. The asymptotic...
An optimization-based approach to control of robotic manipulators
, Article Proceedings - IEEE International Conference on Robotics and Automation, 12 May 2009 through 17 May 2009, Kobe ; 2009 , Pages 3347-3352 ; 10504729 (ISSN); 9781424427895 (ISBN) ; Karimi-Ghartemani, M ; Namvar, M ; Sharif University of Technology
2009
Abstract
This paper proposes a method to suboptimally tune the control parameters in a conventional Lyapunov-Based method which shares the same concept of control design with sliding mode approach as applied to the robot manipulators. Optimal tuning of such parameters involves handling of nonlinearities in system dynamics and cost functions, which makes the problem challenging. We propose a step-by-step numerical algorithm that select suboptimal parameters while ensuring system stability. The controller is, suboptimal due to the facts that (1) it is in the form of a Slotine-type sliding mode control, (2) the numerical recursive algorithm might fall into a local minimum, and (3) the controller...
A novel approach for robust control of single-link manipulators with visco-elastic behavior
, Article 10th International Conference on Computer Modelling and Simulation, EUROSIM/UKSim2008, Cambridge, 1 April 2008 through 3 April 2008 ; 2008 , Pages 685-690 ; 0769531148 (ISBN); 9780769531144 (ISBN) ; Jahed, M ; Sharif University of Technology
2008
Abstract
Overwhelming number of control laws has been studied for control of robot manipulators with rigid links and joints. However controllers designed under this assumption may not accurately control the manipulator link due to visco-elastic properties that appear in the link behavior. In this study, a novel approach for robust control of a single-link manipulator is presented to force the link to have rigid motions, while it has visco-elastic behavior. In this regard, initially robot dynamics is extracted, followed by the design of four appropriate controllers through the loop-shaping approach. The obtained model is first represented in state space, however later converted to transfer function...