The Experts below are selected from a list of 7272 Experts worldwide ranked by ideXlab platform

Linjun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • adaptive boundary control for flexible two Link Manipulator based on partial differential equation dynamic model
    Iet Control Theory and Applications, 2013
    Co-Authors: Linjun Zhang
    Abstract:

    In this studies, adaptive boundary control for a flexible two-Link Manipulator with a changeable payload at the free-end. Taking into account the infinite-dimensionality of the flexural dynamics, this study proposes a partial differential equation (PDE) model, so that the problem of possible spillover instability caused by the neglect of flexible modes can be avoided. Based on the PDE model, an adaptive boundary control scheme is designed to regulate joint position and suppress elastic vibration while compensating for parametric uncertainties. The asymptotic stability of the closed-loop system is validated theoretically. The effectiveness of the control scheme is also verified by the numerical simulations.

  • Observer-based partial differential equation boundary control for a flexible two-Link Manipulator in task space
    IET Control Theory & Applications, 2012
    Co-Authors: Linjun Zhang
    Abstract:

    This study addresses the problem of trajectory control of a flexible two-Link Manipulator on the basis of the partial differential equation (PDE) dynamic model. One of the key contributions of this study is that a novel non-linear PDE observer is proposed to estimate distributed positions and velocities along flexible Links, which cannot be achieved by the typical ordinary differential equation observer. In addition, the rigidity-flexibility coupling dynamics is decomposed using the singular perturbation approach, thus providing convenience for control design. Based on the proposed observer and the decoupled PDE model, a boundary control scheme is designed to regulate the end effector along reference trajectory in task space and suppress vibration simultaneously. The asymptotic stability of both the proposed observer and the control algorithm is validated by theoretical analysis and demonstrated by simulation results, respectively.

Peter N. Nikiforuk - One of the best experts on this subject based on the ideXlab platform.

  • end effector trajectory tracking of a flexible Link Manipulator using integral manifold concept
    International Journal of Systems Science, 2011
    Co-Authors: M. Vakil, Reza Fotouhi, Peter N. Nikiforuk
    Abstract:

    A new controller for the end-effector trajectory tracking of a single flexible Link Manipulator is introduced. The linear dynamic model of the single flexible Link Manipulator is expressed in the singularly perturbed form. To reduce the end-effector trajectory tracking error, a corrective torque is added to the computed torque command of the rigid Link counterpart of the single flexible Link Manipulator. The corrective torque is derived based on the concept of the integral manifold of the singularly perturbed differential equations. This corrective torque is of order e2 where  [image omitted], and f is the fundamental natural frequency of the single flexible Link Manipulator. The implementation of the introduced technique does not require the full-state measurements since by designing an observer, the time derivative of the Link's lateral deflection is estimated. The stability proof of the new controller, which is based on the Lyapunov criterion, is presented. The results of the simulation and experimental studies are also included to, respectively, show the effectiveness and feasibility of the new controller.

  • application of the integral manifold concept for the end effector trajectory tracking of a flexible Link Manipulator
    American Control Conference, 2007
    Co-Authors: M. Vakil, Reza Fotouhi, Peter N. Nikiforuk
    Abstract:

    A new control strategy for the end- effector trajectory tracking (EETT) of a single flexible Link Manipulator (SFLM) is introduced. The linear dynamic model of the SFLM is expressed in the singularly perturbed form. To reduce the EETT error, a corrective torque is added to the "computed torque control" command of the rigid Link counterpart of the SFLM. This corrective torque is derived based on the concept of the integral manifold of the singularly perturbed differential equations. It is proven that the EETT error is a function of the fundamental natural frequency of the SFLM. That is, the order of the EETT error, after employing 3 2 this new method, is greater than epsiv3 and smaller than epsiv2 , where epsiv = 1(2pif) and f is the fundamental natural frequency of the SFLM. The implementation of the introduced technique does not require the full state measurements, since by designing an observer; the rate of the change of the flexible variables with respect to time is estimated. Thus only the measurements of the joint rotation, joint velocity, and flexible variables are required. The proof of the stability, based on the Lyapunov criteria, is given. The results of the simulation and experimental studies are also included. Making the error of the EETT smaller and reducing the number of state measurements are the main contributions of this work.

K Khorasani - One of the best experts on this subject based on the ideXlab platform.

  • brief nonlinear tip position tracking control of a flexible Link Manipulator theory and experiments
    Automatica, 2001
    Co-Authors: M Moallem, R V Patel, K Khorasani
    Abstract:

    This paper presents an observer-based inverse dynamics control strategy that results in small tip-position tracking errors while maintaining robust closed-loop performance for a class of multi-Link structurally flexible Manipulators. This is done by defining new outputs near the end points of the arms as well as by augmenting the control inputs by terms which ensure stable operation of the closed-loop system. As part of the control design, a nonlinear observer is introduced to estimate the rates of change of flexible modes. Experimental results are given for the case of a two-Link Manipulator with a flexible Link that further confirm the theoretical and simulation results.

  • uncertainty compensation for a flexible Link Manipulator using nonlinear h control
    International Journal of Control, 1998
    Co-Authors: Mohammad Javad Yazdanpanah, K Khorasani, R V Patel
    Abstract:

    In a flexible-Link Manipulator, in general the effect of some parameters such as payload, friction amplitude and damping coefficients cannot be exactly measured. One possibility is to consider the above as parameters with uncertainty. In this paper, constant as well as L2-bounded deviations of parameters from their nominal values are considered as uncertainties. These uncertainties make it difficult for a linear controller to achieve desired closed-loop performance. To remedy this problem, a nonlinear dynamical model of a flexible-Link Manipulator which has a constant input vector field (g in [xdot]=f(x) + g(x)u) is obtained. Based on recent results in nonlinear robust regulation with an H∞ constraint a nonlinear controller is designed for the flexible-Link Manipulator. The contribution of this paper is in demonstrating that the nonlinear controller has a larger domain of attraction than the linearized controller. In fact, for the single-Link flexible Manipulator considered in this paper, the linear H∞ co...

  • end point control of a flexible Link Manipulator theory and experiments
    IEEE Transactions on Control Systems and Technology, 1997
    Co-Authors: H Geniele, R V Patel, K Khorasani
    Abstract:

    This paper focuses on the tip-position control of a single flexible Link which rotates in the horizontal plane. The dynamic model is derived using a Lagrangian assumed modes method based on Euler-Bernoulli beam theory. The model is then linearized about an operating point. An output feedback control strategy that uses the principle of transmission zero assignment achieves tracking for this nonminimum phase linear time-invariant system. The control strategy consists essentially of two parts. The first part is an inner (stabilizing) control. Loop that incorporates a feedthrough term to assign the system's transmission zeros at desired locations in the complex plane, and a feedback term to move the system's poles to appropriate positions in the left-half plane. The second part is a feedback servo loop that allows tracking of the desired trajectory. The controller is implemented on an experimental test-bed.

Ian D Walker - One of the best experts on this subject based on the ideXlab platform.

  • teleoperation mappings from rigid Link robots to their extensible continuum counterparts
    International Conference on Robotics and Automation, 2016
    Co-Authors: Chase G Frazelle, Apoorva D Kapadia, Katelyn E Fry, Ian D Walker
    Abstract:

    We present a novel approach to teleoperation of continuum robots. In contrast to previous approaches restricted to three Degree-of-Freedom (DoF) joysticks, a six degree-of-freedom rigid-Link Manipulator is used as the input device. Mappings from the rigid-Link arm to the continuum robot are synthesized and analyzed, focusing on their potential for creating a more intuitive operational interface. The approach was implemented using a six degree-of-freedom rigid-Link Manipulator as input device for teleoperation of a three section, nine degree-of-freedom continuum robot. Tests were conducted across a range of planar and spatial tasks, using fifteen participant operators. The results demonstrate the feasibility of the approach, and suggest that it can be effective independent of the prior robotics, gaming, or teleoperative experience of the operator.

  • task space tracking control of robot Manipulators via quaternion feedback
    International Conference on Robotics and Automation, 2004
    Co-Authors: Bin Xian, M S De Queiroz, D M Dawson, Ian D Walker
    Abstract:

    In this paper, we consider the problem of task-space tracking control of robot Manipulators. Based on a quaternion representation of the end-effector orientation, we design a class of task-space controllers that ensure asymptotic end-effector position and orientation tracking. To facilitate the control design, we first develop model-based and adaptive full-state feedback controllers. We then present a model-based output feedback controller that eliminates Link velocity measurements via a model-based observer. The application of the proposed control strategy to redundant robots is also discussed. Simulation results based on a six-Link Manipulator system are presented for the output feedback controller.

M. Vakil - One of the best experts on this subject based on the ideXlab platform.

  • end effector trajectory tracking of a flexible Link Manipulator using integral manifold concept
    International Journal of Systems Science, 2011
    Co-Authors: M. Vakil, Reza Fotouhi, Peter N. Nikiforuk
    Abstract:

    A new controller for the end-effector trajectory tracking of a single flexible Link Manipulator is introduced. The linear dynamic model of the single flexible Link Manipulator is expressed in the singularly perturbed form. To reduce the end-effector trajectory tracking error, a corrective torque is added to the computed torque command of the rigid Link counterpart of the single flexible Link Manipulator. The corrective torque is derived based on the concept of the integral manifold of the singularly perturbed differential equations. This corrective torque is of order e2 where  [image omitted], and f is the fundamental natural frequency of the single flexible Link Manipulator. The implementation of the introduced technique does not require the full-state measurements since by designing an observer, the time derivative of the Link's lateral deflection is estimated. The stability proof of the new controller, which is based on the Lyapunov criterion, is presented. The results of the simulation and experimental studies are also included to, respectively, show the effectiveness and feasibility of the new controller.

  • application of the integral manifold concept for the end effector trajectory tracking of a flexible Link Manipulator
    American Control Conference, 2007
    Co-Authors: M. Vakil, Reza Fotouhi, Peter N. Nikiforuk
    Abstract:

    A new control strategy for the end- effector trajectory tracking (EETT) of a single flexible Link Manipulator (SFLM) is introduced. The linear dynamic model of the SFLM is expressed in the singularly perturbed form. To reduce the EETT error, a corrective torque is added to the "computed torque control" command of the rigid Link counterpart of the SFLM. This corrective torque is derived based on the concept of the integral manifold of the singularly perturbed differential equations. It is proven that the EETT error is a function of the fundamental natural frequency of the SFLM. That is, the order of the EETT error, after employing 3 2 this new method, is greater than epsiv3 and smaller than epsiv2 , where epsiv = 1(2pif) and f is the fundamental natural frequency of the SFLM. The implementation of the introduced technique does not require the full state measurements, since by designing an observer; the rate of the change of the flexible variables with respect to time is estimated. Thus only the measurements of the joint rotation, joint velocity, and flexible variables are required. The proof of the stability, based on the Lyapunov criteria, is given. The results of the simulation and experimental studies are also included. Making the error of the EETT smaller and reducing the number of state measurements are the main contributions of this work.