This thesis discusses the possibility of attaining closed loop end piece control of a servo controlled manipulator by externally modifying the independent control loop set point of each robot link. This procedure leaves the existing servo control loops intact and thus has the benefit of acquiring the advantages of an advanced control strategy while retaining the inherent reliability and stability of the existing control loops. Algorithms are proposed for compensating for known disturbance torques, eliminating end piece position errors, and applying specified forces to the surroundings with the end piece. These algorithms are demonstrated for the three degree of freedom case using a simulation package ROBSIM.FOR which simulates the response of a servo controlled manipulator to set point inputs. To compensate for known disturbance torques the torques generated by the robot control system are assumed to be directly proportional to the changes in set points. These approximate relations are used to estimate the adjustment in set points necessary to generate the required additional joint torques. Simulation results show that this method is effective in compensating for gravity disturbance torques. The Jacobian relates changes in position of the end piece to changes in joint angles. Using the Jacobian combined with a weighting factor to prevent overshoot an algorithm is developed which drives end piece position errors to zero. The transpose of the Jacobian is used to relate forces exerted on the surroundings by the end piece to generated joint torques. The required torques are created by adjusting the set points. Simulation results indicate that this method can be used to exert specified forces. Force control is more difficult to achieve than position control because the robot interacts physically with its surroundings. The ability of the robot to exert forces depends strongly on the robot's configuration. All work in this thesis can be generated using the single program ROBSIM.FOR. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

The object of this thesis is (1) to demonstrate the value of an electronic analog computer for the solution of non-linear ordinary differential equations particularly when a large family of solutions is required; and (2) to obtain as a by-product results of practical applicability to servomechanism selection and analysis.

Call number: LD2668 .T4 1960 S75

Call number: LD2668 .T4 1966 F771 / Master of Science

A large spectrum of new technologies are being explored in the optical disk drive systems. Optics, lasers, media, and servomechanisms are a few examples. This thesis will be directed to the study of a servomechanism used in a majority of the optical disk drives, commonly referred to as the tracking servomechanism. The tracking servomechanism, consisting of a fine and a coarse actuator, is mechanically analyzed by the use of free body diagrams. A transfer function for each actuator is derived. Analog compensators are designed to achieve specific phase and gain margin requirements. A digital compensator is derived from the analog compensator by the use of a mapping technique. Major contributions of this thesis include studies to determine an acceptable sampling rate, number of bits, and computation delay associated with the implementation of a digital servo controller in a tracking servomechanism.

In this thesis, we investigate the global robust output regulation problem for nonlinear systems subject to time-varying or nonlinear exosystems. / One of the crucial issues in output regulation problem is the design of the appropriate internal model. Internal model is a dynamical compensator which possesses an essential ability of generating all possible steady-state input information asymptotically, and it should not only lead to a well-defined augmented system but also ensure the stabilizability of the augmented system. Besides, stabilization techniques for the augmented system should also be carefully chosen to meet the needs in different scenarios, e.g. the time-varying settings. Efforts are put on both sides throughout the thesis. / Output regulation problem, also known as servomechanism problem, is one of the central topics in control theory. The control objective is to design a feedback control law for the given plant so as to achieve asymptotic tracking for a class of reference signals and asymptotic rejection for a class of disturbance signals while maintaining the stability of closed-loop system. The reference or the disturbance signals are assumed to be generated from a dynamical system called the exosystem. Normally, the exosystem is a linear autonomous system, e.g. a harmonic oscillator, and the exogenous signals represent step or ramp signals, or sinusoidal signals contains finite number of harmonics. The extensions of the exosystem, from linear to nonlinear, autonomous to non-autonomous, significantly enlarge the categories of the exogenous signals, and more importantly, such extensions motivate the development of the output regulation theory in both scientific research and practical application. / Paying special attention to the appearance of time-varying or nonlinear exosystems, our research is mainly conducted under the general framework for tackling the output regulation problem. In general, first we convert the output regulation problem of the original plant into the stabilization problem of the augmented system which is composed of the plant and the designed internal model. Second, we achieve the global stabilization of the augmented system by robust and adaptive control approaches, according to both parameter uncertainty and dynamic uncertainty in either plant or the exosystem. / The main contributions of the thesis are outlined as follows. 1. A framework for handling the robust output regulation problem for general timevarying nonlinear systems subject to time-varying exosystem is proposed. Especially, certain existence conditions of a time-varying internal model is given, and problem conversion can be achieved. As an application of this framework, we give the solvability conditions of the output regulation problem for the time-varying nonlinear systems in output feedback form. Further, when parameter uncertainties occurred in the time-varying exosystem, we solve the corresponding adaptive robust output regulation problem resorting to some adaptive control methods. These results can also be applied to the time-varying nonlinear systems in lower triangular form. 2. The global robust output regulation problem for nonlinear systems subject to nonlinear exosystem is considered. A new class of internal models is introduced which relaxes the existence conditions of the former one. Also, this class of internal models has the merit that it is zero input globally asymptotically stable which greatly facilitates the global stabilization of the augmented system. Compared with the existing results, the new method solves the global robust output regulation problem without restrictions on the initial conditions or trajectory bounds of the exosystems, and the bound of the parameter uncertainties of the plant is not necessarily known. Moreover, utilizing the Nussbaum gain technique, the unknown control direction case can also be handled by modifying the control law. 3. The theoretical results have been applied to several practical control problems, such as the global disturbance rejection problem for FitzHugh-Nagumo model with Mathieu equation, the synchoniztion of periodically-forced pendulum with Rayleigh equation, etc .. / Yang, Xi. / Adviser: Jie Huang. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 123-134). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Wang Hesheng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 70-73). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Contents --- p.v / List of Figures --- p.vii / List of Tables --- p.viii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Visual Servoing --- p.1 / Chapter 1.1.1 --- Position-based Visual Servoing --- p.4 / Chapter 1.1.2 --- Image-based Visual Servoing --- p.5 / Chapter 1.1.3 --- Camera Configurations --- p.7 / Chapter 1.2 --- Problem Definitions --- p.10 / Chapter 1.3 --- Related Work --- p.11 / Chapter 1.4 --- Contribution of This Work --- p.15 / Chapter 1.5 --- Organization of This Thesis --- p.16 / Chapter 2 --- System Modeling --- p.18 / Chapter 2.1 --- The Coordinates Frames --- p.18 / Chapter 2.2 --- The System Kinematics --- p.20 / Chapter 2.3 --- The System Dynamics --- p.21 / Chapter 2.4 --- The Camera Model --- p.23 / Chapter 2.4.1 --- Eye-in-hand System --- p.28 / Chapter 2.4.2 --- Eye-and-hand System --- p.32 / Chapter 3 --- Adaptive Image-based Visual Servoing --- p.35 / Chapter 3.1 --- Controller Design --- p.35 / Chapter 3.2 --- Estimation of The Parameters --- p.38 / Chapter 3.3 --- Stability Analysis --- p.42 / Chapter 4 --- Simulation --- p.48 / Chapter 4.1 --- Simulation I --- p.49 / Chapter 4.2 --- Simulation II --- p.51 / Chapter 5 --- Experiments --- p.55 / Chapter 6 --- Conclusions --- p.63 / Chapter 6.1 --- Conclusions --- p.63 / Chapter 6.2 --- Feature Work --- p.64 / Appendix --- p.66 / Bibliography --- p.70

Lam Kin Kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 67-70). / Abstracts in English and Chinese. / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Visual Servoing --- p.1 / Chapter 1.1.1 --- System Architectures --- p.2 / Chapter 1.1.1.1 --- Position-based Visual Servoing --- p.2 / Chapter 1.1.1.2 --- Image-based Visual Servoing --- p.3 / Chapter 1.1.2 --- Camera Configurations --- p.4 / Chapter 1.2 --- Problem Definition --- p.5 / Chapter 1.3 --- Related Work --- p.6 / Chapter 1.4 --- Contribution of This Work --- p.9 / Chapter 1.5 --- Organization of This Thesis --- p.10 / Chapter 2. --- System Modeling --- p.11 / Chapter 2.1 --- Coordinate Frames --- p.11 / Chapter 2.2 --- System Kinematics --- p.13 / Chapter 2.3 --- System Dynamics --- p.14 / Chapter 2.4 --- Camera Model --- p.15 / Chapter 2.4.1 --- Eye-in-hand Configuration --- p.18 / Chapter 2.4.2 --- Eye-and-hand Configuration --- p.21 / Chapter 3. --- Adaptive Visual Servoing Control --- p.24 / Chapter 3.1 --- Controller Design --- p.24 / Chapter 3.2 --- Parameter Estimation --- p.27 / Chapter 3.3 --- Stability Analysis --- p.30 / Chapter 4. --- Experimental Studies --- p.34 / Chapter 4.1 --- Experimental Setup --- p.34 / Chapter 4.1.1 --- Hardware Setup --- p.34 / Chapter 4.1.2 --- Image Pattern Recognition --- p.35 / Chapter 4.1.3 --- Experimental Task --- p.36 / Chapter 4.2 --- Control Performance with Different Proportional Gains and Derivative Gains --- p.39 / Chapter 4.3 --- Control Performance with Different Adaptive Gains --- p.41 / Chapter 4.4 --- Gravity Compensator --- p.50 / Chapter 4.5 --- Control Performance with Previous Image Positions --- p.51 / Chapter 4.6 --- Kinematic Controller --- p.56 / Chapter 5. --- Conclusions --- p.61 / Chapter 5.1 --- Conclusions --- p.61 / Chapter 5.2 --- Future Work --- p.62 / Appendix --- p.63 / Bibliography --- p.67

Shen Yantao. / "April 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 117-122). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

One of the major problems that obstruct the development of adaptive visual servoing is the fact that the image Jacobian or the interaction matrix cannot be linearly parameterized by the unknown parameters. To solve this problem, we propose a depth-independent interaction matrix, which is obtained by eliminating the depth in the traditional interaction matrix. Using this depth-independent interaction matrix in controller design, it is possible to make the unknown parameters appear linearly in the closed-loop dynamics. As a result, we can use an adaptive algorithm, similar to that proposed by Slotine and Li [1], to estimate the unknown parameters on-line. To guarantee the convergence of the image errors, in the parameter adaptation we combine the Slotine-Li algorithm with an on-line gradient descending minimization algorithm of the errors between the real and estimated image coordinates of the feature points. On the basis of the depth-independent interaction matrix and the new adaptive algorithm, we first propose an adaptive controller for image-based visual servoing of point features using both uncalibrated eye-in-hand and fixed cameras. Then, we extend the controller to visual servoing using line features with an eye-in-hand camera. Next, we present a dynamic controller for trajectory tracking of feature points on a robot manipulator in 3D general motion using fixed uncalibrated camera. To avoid performance decaying caused by measurement errors of the visual velocity, we also propose a new controller for dynamics visual tracking without using visual velocities. Finally, we design a new controller for locking a moving object in 3-D space at a particular position on the image plane of a camera mounted on a robot by actively moving the camera. The asymptotic stabilities of the system under the control of the proposed methods are rigorously proved by the Lyapunov theory with the nonlinear robot dynamics fully taken into account. The performances of the controllers have been verified by experiments on a 3 DOF robot manipulator. / The contribution of this thesis can be summarized as follows: First, a depth-independent interaction matrix is proposed for mapping the image errors onto the joint space. Second a new adaptive algorithm has been developed to estimate the unknown parameters. Finally, new methods to position and tracking control of robots with uncalibrated visual feedback in both eye-in-hand and fixed camera configuration are proposed. / Visual servoing is an approach to control motion of a robot manipulator using visual feedback signals from a vision system and has received extensive attention in recent years. Many existing methods work based on an assumption that the parameters of the vision system are accurately calibrated, while the calibration process is tedious. Furthermore, most of the controllers are designed using the kinematics relationship only, without considering the nonlinear dynamics of robots, so that they are not suitable for high performance and fast visual servoing tasks. Aiming at solving those two problems, this thesis addresses dynamic position and tracking control of robots with uncalibrated visual feedback. Both the fixed camera and eye-in-hand camera configurations are considered. / Wang, Hesheng. / "August 2007." / Adviser: Yun-Hui Liu. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1294. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 160-169). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.