39,075 research outputs found

    Multi - objective sliding mode control of active magnetic bearing system

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    Active Magnetic Bearing (AMB) system is known to inherit many nonlinearity effects due to its rotor dynamic motion and the electromagnetic actuators which make the system highly nonlinear, coupled and open-loop unstable. The major nonlinearities that are associated with AMB system are gyroscopic effect, rotor mass imbalance and nonlinear electromagnetics in which the gyroscopics and imbalance are dependent to the rotational speed of the rotor. In order to provide satisfactory system performance for a wide range of system condition, active control is thus essential. The main concern of the thesis is the modeling of the nonlinear AMB system and synthesizing a robust control method based on Sliding Mode Control (SMC) technique such that the system can achieve robust performance under various system nonlinearities. The model of the AMB system is developed based on the integration of the rotor and electromagnetic dynamics which forms nonlinear time varying state equations that represent a reasonably close description of the actual system. Based on the known bound of the system parameters and state variables, the model is restructured to become a class of uncertain system by using a deterministic approach. In formulating the control algorithm to control the system, SMC theory is adapted which involves the formulation of the sliding surface and the control law such that the state trajectories are driven to the stable sliding manifold. The surface design involves the transformation of the system into a special canonical representation such that the sliding motion can be characterized by a convex representation of the desired system performances. Optimal Linear Quadratic (LQ) characteristics and regional pole-clustering of the closed-loop poles are designed to be the objectives to be fulfilled in the surface design where the formulation is represented as a set of Linear Matrix Inequality optimization problem. For the control law design, a new continuous SMC controller is proposed in which asymptotic convergence of the system’s state trajectories in finite time is guaranteed. This is achieved by adapting the equivalent control approach with the exponential decaying boundary layer technique. The newly designed sliding surface and control law form the complete Multi-objective SMC (MO-SMC) and the proposed algorithm is applied into the nonlinear AMB in which the results show that robust system performance is achieved for various system conditions. The findings also demonstrate that the MO-SMC gives better system response than the reported ideal SMC (I-SMC) and continuous SMC (C-SMC)

    Time-optimal trajectory and robust adaptive control for hybrid underwater glider

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    The undersea environment is generally still a mystery for the human race, although it has been with us for a long time. To explore under the sea, the underwater glider is the efficient equipment capable of sustainable operation for several months. For faster and longer duration performance, a new design of underwater glider (UG) shaping ray type is proposed. To have the shortest settling time, a new design of time-optimal trajectory (TOT) for controlling the states of the ray-type hybrid underwater glider (RHUG) is proposed. And for the stable flight control, a robust adaptive controller is designed for the RHUG with unknown parameters and environmental disturbances. The heading dynamics of the RHUG is presented with linear and quadratic damping. A closed form solution of the heading dynamics is realized for designing the time-optimal trajectory. The conventional and super-twisting sliding mode control will be constructed for tracking this trajectory. The tracking performance considering the disturbance effect will be discussed in simulations. For identification of unknown parameters of the system, the adaptive control is designed and implemented by the heading experiment. The RHUG uses the net buoyancy force for gliding under the water, so the depth control is essential. In this dissertation, a robust control algorithm with TOT will be carried out for the heaving motion using a hybrid actuation of the buoyancy engine and the propeller. The net buoyancy force with a constant rate is generated by the buoyancy engine for both descending and ascending motion. And the second actuator for the depth control is the propeller with quick response in producing thrusting force. To apply the robust control with TOT, the control input is designed for the buoyancy engine and thruster individually. And finally, the robust control with TOT using the buoyancy engine and thruster is simulated with consideration of external disturbances. When the RHUG is the underactuated system, a robust adaptive control is designed for the RHUG dynamics based on Lyapunov’s direct method using the backstepping and sliding mode control techniques. The performance of this controller is simulated for gliding motion and depth control with unknown parameters and bounded disturbances.Contents Contents i List of Tables iv List of Figures v Chapter 1. Introduction 1 1.1. Hybrid underwater glider 1 1.2. Time-optimal trajectory 4 1.3. Nonlinear control design 5 Chapter 2. Dynamics of RHUG 8 2.1 Dynamics of underwater vehicles 8 2.2 Design of RHUG platform 11 2.2.1 Hull design 11 2.2.2 Buoyancy engine and mass-shifter 12 2.2.3 Battery 13 2.2.4 Sensors 14 2.2.5 Assembly 16 2.3 Dynamics of RHUG 17 2.4 Hydrodynamic coefficients 19 2.5 Thruster modeling 21 2.6 Buoyancy engine modeling 22 2.7 Mass-shifter modeling 23 Chapter 3. Time-optimal trajectory with actuator saturation for heading control 25 3.1 Time-optimal trajectory 25 3.2 Heading motion 25 3.3 Analytic solution of heading dynamic equation 26 3.3.1 Right-hand direction 29 3.3.2 Left-hand direction 36 3.4 Time-optimal trajectory 42 3.5 Super-twisting sliding mode control 44 3.6 Computer simulation 46 3.6.1 Simulation 1 46 3.6.2 Simulation 2 47 3.6.3 Simulation 3 49 Chapter 4. Time-optimal trajectory for heaving motion control using buoyancy engine and propeller individually 51 4.1. Heave dynamics and TOT 51 4.2. Analytical solution of heave dynamics with buoyancy and thruster force individually 54 4.2.1 First segment with positive rate 54 4.2.2 Second segment with maximum input 55 4.2.3 Third segment with constant velocity 56 4.2.4 Fourth segment with negative rate 57 4.2.5 Fifth segment with minimum input 58 4.3. Time-optimal trajectory for depth motion 59 4.3.1 Find z1, w1 and w1 59 4.3.2 Find t2, z2, w2 and w2 61 4.3.3 Find w3, z4 and w4 62 4.3.4 Find z3, t3 and t4 63 4.3.5 Find α and t5 64 4.4. Sliding mode control for heave dynamics 64 4.5. Computer simulation 66 4.5.1. Simulation 1 66 4.5.2. Simulation 2 69 Chapter 5. Experimental study of direct adaptive control along TOT for heading motion 72 5.1. Motivation 72 5.2. Composition of RHUG 73 5.3. Robust adaptive control for heading dynamics 77 5.4. Computer simulation 79 5.5 Experiment 82 5.5.1 First experiment with k1=2.5,k2=30 82 5.5.2 Second experiment with k1=2,k2=30 83 5.5.3 Third experiment with k1=2,k2=50 85 Chapter 6. Robust adaptive control design for vertical motion 89 6.1. Dynamics of vertical plane 89 6.2. Adaptive sliding-mode control for pitch motion 91 6.3. Adaptive sliding-mode control for surge motion 93 6.4. LOS and PI depth-keeping guidance 95 6.5. Computer simulation 97 6.5.1 Simulation 1 97 6.5.2 Simulation 2 104 Chapter 7. Conclusion 111 Reference 113Docto

    A Study of Advanced Modern Control Techniques Applied to a Twin Rotor MIMO System

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    The twin rotor MIMO system (TRMS) is a helicopter-like system that is restricted to two degrees of freedom, pitch and yaw. It is a complicated nonlinear, coupled, MIMO system used for the verification of control methods and observers. There have been many methods successfully applied to the system ranging from simple proportional integral derivative (PID) controllers, to machine learning algorithms, nonlinear control methods and other less explored methods like deadbeat control and various optimal methodologies. This thesis details the design procedure for two different control methods. The first is a suboptimal tracking controller using a linear quadratic regulator (LQR) with integral action. The second is the design of several adaptive sliding mode controller to provide robust tracking control of the TRMS. Once the design is complete the controllers are tested in simulation and their performance is compared against a PID controller experimentally. The performance of the controllers are also compared against other controllers in the literature. The ability of the sliding mode controllers (SMC) to suppress chattering is also be explored

    Design and Experimental Evaluation of a Robust Position Controller for an Electrohydrostatic Actuator Using Adaptive Antiwindup Sliding Mode Scheme

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    A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities

    A novel structure design and control strategy for an aircraft active sidestick

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    This paper is concerned with a new design of an aircraft active sidestick based on Permanent Magnet Synchronous Machine (PMSM) and proposes an innovative robust control strategy based on an adaptive optimal sliding mode controller. Indeed, such an application requires high performance specifications which impose many constraints (torque, torques ripples, temperature). Here, a new design for the sidestick actuator is provided with a specific structure: a double airgap rotating one adapted to the considered process. Then, an optimization is performed to enhance the set of specifications of the PMSM w.r.t the aeronautical application. Also, a new adaptive optimal robust control for the designed actuator is provided based on the linear quadratic approach combined with the sliding mode control method. Then, an adaptive disturbances rejection is performed with the proposed strategy. Due to the considered design of the actuator (1/12 of a complete PMSM), a position control is achieved based on the LQRSliding mode approach to meet the required performances and to manage the plant parameter variation and load disturbances. Also, a varying parameter is used to adapt "on-line" the considered control to the varying level of disturbance that affect the system. First simulation results of the considered strategy applied to the newly designed actuator (compared to other strategies) proves the efficiency of the proposed solution for position control of the actuator and robustness considering load disturbances

    Recent advances on recursive filtering and sliding mode design for networked nonlinear stochastic systems: A survey

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    Copyright © 2013 Jun Hu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Some recent advances on the recursive filtering and sliding mode design problems for nonlinear stochastic systems with network-induced phenomena are surveyed. The network-induced phenomena under consideration mainly include missing measurements, fading measurements, signal quantization, probabilistic sensor delays, sensor saturations, randomly occurring nonlinearities, and randomly occurring uncertainties. With respect to these network-induced phenomena, the developments on filtering and sliding mode design problems are systematically reviewed. In particular, concerning the network-induced phenomena, some recent results on the recursive filtering for time-varying nonlinear stochastic systems and sliding mode design for time-invariant nonlinear stochastic systems are given, respectively. Finally, conclusions are proposed and some potential future research works are pointed out.This work was supported in part by the National Natural Science Foundation of China under Grant nos. 61134009, 61329301, 61333012, 61374127 and 11301118, the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grant no. GR/S27658/01, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany

    Optimal sliding mode controllers for attitude tracking of spacecraft

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    This paper studies two optimal sliding mode control laws using integral sliding mode control (ISM) for some spacecraft attitude tracking problems. Integral sliding mode control combining the first order sliding mode and optimal control is applied to quaternion-based spacecraft attitude tracking manoeuvres with external disturbances and an uncertainty inertia matrix. For the optimal control part the state dependent Riccati equation (SDRE) and Control Lyapunov function (CLF) approaches are used to solve the infinite-time nonlinear optimal problem. The second method of Lyapunov is used to show that tracking is achieved globally. An example of multiaxial attitude tracking manoeuvres is presented and simulation results are included to verify the usefulness of these controllers

    Sampled-data design for robust control of a single qubit

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    This paper presents a sampled-data approach for the robust control of a single qubit (quantum bit). The required robustness is defined using a sliding mode domain and the control law is designed offline and then utilized online with a single qubit having bounded uncertainties. Two classes of uncertainties are considered involving the system Hamiltonian and the coupling strength of the system-environment interaction. Four cases are analyzed in detail including without decoherence, with amplitude damping decoherence, phase damping decoherence and depolarizing decoherence. Sampling periods are specifically designed for these cases to guarantee the required robustness. Two sufficient conditions are presented for guiding the design of unitary control for the cases without decoherence and with amplitude damping decoherence. The proposed approach has potential applications in quantum error-correction and in constructing robust quantum gates.Comment: 33 pages, 5 figures, minor correction

    Sliding Mode Control of Two-Level Quantum Systems

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    This paper proposes a robust control method based on sliding mode design for two-level quantum systems with bounded uncertainties. An eigenstate of the two-level quantum system is identified as a sliding mode. The objective is to design a control law to steer the system's state into the sliding mode domain and then maintain it in that domain when bounded uncertainties exist in the system Hamiltonian. We propose a controller design method using the Lyapunov methodology and periodic projective measurements. In particular, we give conditions for designing such a control law, which can guarantee the desired robustness in the presence of the uncertainties. The sliding mode control method has potential applications to quantum information processing with uncertainties.Comment: 29 pages, 4 figures, accepted by Automatic
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