On Uncalibrated Manipulators Visual Servo And Its Networked Control Technology

The image-based uncalibrated visual servoing(IBUVS)control outperforms the calibration-based visual servoing control scheme by its non-calibration,high flexibility and adaptions.IBUVS has been a hot topic in the control and robotics field.Nowadays,despite the positive progress in this field,there are problems in the IBUVS control field to be addressed.1 The dynamic stability of IBUVS remains to be improved.2Some IBUVS control schemes only suit the static feature point in the reference frame.3 The existing adaptive IBUVS schemes are sensitive to time delays.4)There are some problems in the investigation of multi-IBUVS systems to be addressed.Aiming at addressing these problems and basing on the existing literature in this field,we study IBUVS techniques in the following four aspects.Firstly,in order to improve the dynamic stability of IBUVS,we present a finitetime visual servoing control scheme.With the multiple estimated parameters and a nonsmooth,continuous function,the proposed control scheme improves the control quality of IBUVS from the asymptotic stability to the finite-time stability.The experimental research is conducted with different visual configurations and different systematic parameters,where the proposed scheme is compared with the existing counterparts.The experimental results show that the proposed scheme has improvement in system convergence of non-calibration visual servoing systems.Secondly,a novel tracking control scheme is proposed to solve the problem of the limitations of the static feature points w.r.t.the reference 3D frame.In the proposed scheme,adaptive laws and an image-velocity observer are presented to estimate the uncertainties in intrinsic parameters of cameras,the kinematic parameters of visual systems and the feature points online.The scheme makes the IBUVS control flexible and feasible in the presence of the dynamic feature points.Besides,because of avoiding using image-velocity,the controller is robust to image noise.Based on a shifter device of feature points,the experiments are conducted to verify the effectiveness of the proposed scheme with the dynamic feature points and the experimental results show a good performance of tracking and image robustness under the control of the proposed scheme.Thirdly,we consider the time-delay problem existing in the networked image-based visual servoing control system.We propose a delay-compensated adaptive Jacobian matrix and an adaptive controller to achieve the asymptotic stability of the closed-loop system,in the presence of delays and obtain delay-dependent criteria of stability.The proposed networked control scheme guarantees the adaptiveness of unknown models and enhances the robustness of the networked IBUVS system to delays.In order to verify the effectiveness,we build a distributed visual servoing control platform and add artificial time delays on the visual feedback channel.The experimental results demonstrate that the proposed method improves the robustness of the networked IBUVS system to different delays.Lastly,the synchronization problem of the multiple IBUVS systems is studied in this dissertation.In the premise of no prior knowledge of camera parameters and manipulator dynamics,and without using image velocities,we present the cooperative networked protocol with the distributed image velocity observers and delay-dependent coupling gains.The synchronization of multiple IBUVS systems with time-varying communicating delays is achieved.Basing on MATLAB/Simulink,we build a multiple IBUVS network control system.The simulating results show that the proposed network control scheme guarantees the fast-tracking performance to the desired trajectory and has the robustness to image noise.