Loading...
Search for:
flexible-manipulators
0.007 seconds
Total 31 records
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...
Boundary control of a vertical nonlinear flexible manipulator considering disturbance observer and deflection constraint with torque and boundary force feedback signals
, Article International Journal of Systems Science ; Volume 53, Issue 4 , 2022 , Pages 704-725 ; 00207721 (ISSN) ; Najafi Ardekany, A ; Alasty, A ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
In this paper, boundary control (BC) laws are designed to find a BC solution for a single-link nonlinear vertical manipulator to suppress the link’s transverse vibrations and control the rigid body nonlinear large rotating motion. The governing equations of motions and boundary conditions, which all consist of a set of PDEs and ODEs have been derived based on the Hamilton principle. It is desired to regulate large angular orientation, suppress the flexible link’s transverse vibrations and compensate the boundary disturbance simultaneously. The amount of elastic boundary vibration has remained within the constraint range. By considering novel Barrier-Integral Lyapunov functional in order to...
Boundary control of a vertical nonlinear flexible manipulator considering disturbance observer and deflection constraint with torque and boundary force feedback signals
, Article International Journal of Systems Science ; 2021 ; 00207721 (ISSN) ; Najafi Ardekany, A ; Alasty, A ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
In this paper, boundary control (BC) laws are designed to find a BC solution for a single-link nonlinear vertical manipulator to suppress the link’s transverse vibrations and control the rigid body nonlinear large rotating motion. The governing equations of motions and boundary conditions, which all consist of a set of PDEs and ODEs have been derived based on the Hamilton principle. It is desired to regulate large angular orientation, suppress the flexible link’s transverse vibrations and compensate the boundary disturbance simultaneously. The amount of elastic boundary vibration has remained within the constraint range. By considering novel Barrier-Integral Lyapunov functional in order to...
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...
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 fuzzy based model coordination for two-level optimal control of robot manipulators
, Article Proceedings - International Conference on Tools with Artificial Intelligence, ICTAI, 9 November 2015 through 11 November 2015 ; Volume 2016-January , 2016 , Pages 1122-1128 ; 10823409 (ISSN) ; 9781509001637 (ISBN) ; Sadati, N ; Sharif University of Technology
IEEE Computer Society
2016
Abstract
In this paper, a new fuzzy based Model Coordination (F-MC) strategy is proposed for hierarchical control of large-scale systems (LSS). To solve the overall problem with a two-level optimal control strategy, we first decompose the system into several sub-systems at the first level. Then, at the second level, a fuzzy coordinator will be used to predict the interaction between subsystems. The proposed fuzzy based coordination approach is applicable to all types of LSS. Although in this paper, an optimal control of a 2DOF robot manipulator, as a LSS, will be considered. The obtained results are compared with the centralized optimization
Nonlinear robust adaptive Cartesian impedance control of UAVs equipped with a robot manipulator
, Article Advanced Robotics ; Volume 29, Issue 3 , Feb , 2015 , Pages 171-186 ; 01691864 (ISSN) ; Sayyaadi, H ; Sharif University of Technology
Robotics Society of Japan
2015
Abstract
In this paper, a new nonlinear robust adaptive impedance controller is addressed for Unmanned Aerial Vehicles (UAVs) equipped with a robot manipulator that physically interacts with environment. A UAV equipped with a robot manipulator is a novel system that can perform different tasks instead of human being in dangerous and/or inaccessible environments. The objective of the proposed robust adaptive controller is control of the UAV and its robotic manipulators end-effector impedance in Cartesian space in order to have a stable physical interaction with environment. The proposed controller is robust against parametric uncertainties in the nonlinear dynamics model of the UAV and the robot...
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....
Timoshenko versus Euler-Bernoulli beam theories for high speed two-link manipulator
, Article Scientia Iranica ; Volume 20, Issue 1 , 2013 , Pages 172-178 ; 10263098 (ISSN) ; Kakavand, F ; Sharif University of Technology
2013
Abstract
In this paper, a two-link flexible manipulator is considered. For a prescribed motion, Timoshenko and Euler-Bernoulli beam models are considered. Using the Galerkin method, nonlinear equations of motion are solved. The Runge-Kutta method is employed for the time response integration method. A comparative study is made between the Euler-Bernoulli and Timoshenko beam models, with and without foreshortening effects. It is demonstrated that for two-link manipulators, both theories provide good models, and the results for both theories are very similar for all ranges of slenderness ratio. The findings suggest that for two-link manipulators with relatively high slenderness ratios, there is a...
Vibration analysis of a new type of compliant mechanism with flexible-link, using perturbation theory
, Article Mathematical Problems in Engineering ; Volume 2012 , February , 2012 ; 1024123X (ISSN) ; Zohoor, H ; Kargarnovin, M. H ; Sharif University of Technology
2012
Abstract
Vibration analysis of a new type of compliant parallel mechanism with flexible intermediate links is investigated. The application of the Timoshenko beam theory to the mathematical modeling of the intermediate flexible link is described, and the equations of motion of the flexible links are obtained by using Lagrange's equation of motion. The equations of motion are obtained in the form of a set of ordinary differential equations by using assumed mode method theory. The governing differential equations of motion are solved using perturbation method. The assumed mode shapes and frequencies are to be obtained based on clamped-clamped boundary conditions. Comparing perturbation method with...
Global adaptive estimation of joint velocities in robotic manipulators
, Article IET Control Theory and Applications ; Volume 4, Issue 12 , December , 2010 , Pages 2672-2681 ; 17518644 (ISSN) ; Namvar, M ; Sharif University of Technology
2010
Abstract
This study presents a method for global estimation of joint velocities in robotic manipulators. The authors consider a non-minimal model of a robotic manipulator and design an adaptive observer capable of handling uncertainties in robot dynamics. Smoothness of the dynamics of the proposed observer allows its easy implementation in comparison with non-smooth observers. Dimension of the proposed observer is shown to be at least 3n where n stands for the manipulator's degrees of freedom. This number is less than the dimension of most existing globally convergent adaptive observers. Global asymptotic convergence of state estimates to their true values is achieved under no persistency of...
Robust control of robotic manipulators based on -synthesis
, Article 17th International Congress on Sound and Vibration 2010, ICSV 2010, Cairo, 18 July 2010 through 22 July 2010 ; Volume 1 , 2010 , Pages 525-532 ; 9781617822551 (ISBN) ; Bakhtiari Nejad, F ; Sadighi, M ; Ahmadian, M. T ; Sharif University of Technology
2010
Abstract
A robotic manipulator is modelled as a cantilever rotating Euler-Bernoulli beam. Two dynamic transfer functions are derived to describe beam tip motion and angular rotation in terms of the desired angular rotation. Torque disturbance, imprecision in the payload mass, unknown properties of the manipulator link are sources of uncertainty. The objective is to achieve a desired angular rotation while the vibration of manipulator tip is suppressed. The control input of the system is an external driving torque. The -synthesis control approach is used and an H optimal robust controller is developed based on the DK-iteration algorithm. Results show that the designed controller guarantees the robust...
A globally convergent observer for velocity estimation in robotic manipulators with uncertain dynamics
, Article Proceedings - IEEE International Conference on Robotics and Automation, 3 May 2010 through 7 May 2010, Anchorage, AK ; 2010 , Pages 4645-4650 ; 10504729 (ISSN) ; 9781424450381 (ISBN) ; Namvar, M ; Sharif University of Technology
2010
Abstract
We present a method for global estimation of joint velocities in robot manipulators. A non-minimal model of a robotic manipulator is used to design an adaptive observer capable of handling uncertainties in robot dynamics. Dimension of the proposed observer is shown to be at least 3n where n stands for the manipulator degrees of freedom. This number is less than the dimension of most of existing globally convergent adaptive observers. Global asymptotic convergence of system state estimates to their true values is achieved under no persistency of excitation condition. Smoothness of the dynamics of the proposed observer allows its easy implementation in comparison with non-smooth observers....
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...
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...
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
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...
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...