28 research outputs found
Design and implementation of nonlinear and robust control for Hamiltonian systems: the passivity-based control approach
No full textRecently, control techniques that adopt the geometrical structure and physical properties of dynamical systems have gained a lot of interest. In this thesis, we address nonlinear and robust control problems for systems represented by port-controlled Hamiltonian (PCH) models using the interconnection and damping assignment passivity-based control(IDA-PBC) methodology, which is the most notable technique facilitating the PCH framework.In this thesis, a novel constructive framework to simplify and solve the partial differential equations (PDEs) associated with IDA-PBC for a class of underactuated mechanical systems is presented. Our approach focuses on simplifying the potential energy PDEs to shape the potential energy function which is the most important procedure in the stabilization of mechanical systems. The simplification is achieved by parametrizing thedesired inertia matrix that shapes the kinetic energy function, thus achieving total energy shaping. The simplification removes some constraints (conditions and assumptions) that have been imposed in recently developed methods in literature, thus expanding the class of systems for which the methods can be applied including the separable PCH systems(systems with constant inertia matrix) and non-separable PCH systems (systems with non-constant inertia matrix). The results are illustrated through software simulations and hardware experiments on real engineering applications.We also propose an integral control and adaptive control schemes to improve the robustness of the IDA-PBC method in presence of uncertainty. We first provide some results for the case of fully-actuated mechanical systems, and then extend those results to underactuated systems which are more complex. Integral action control on both the passive and non-passive outputs in the IDA-PBC construction, a strategy to ensure the robustness of the systems by preserving its stability in face of external disturbances, is introduced, establishing the input-to-state stability (ISS) property. The results are applied to both the separable and non-separable PCH systems and illustrated via several simulations. The extension to the non-separable case exhibits more complicated design as we need to take into account the derivative of the inertia matrix.Finally, the IDA-PBC method is employed to solve an important nonlinear phenomenon called ‘pull-in’ instability associated with the electrostatically actuated microelectromechanical systems (MEMSs). The control construction is an output-feedback controller that ensures global asymptotic stability and avoids velocity measurement which may not be practically available. Furthermore, the integral, adaptive and ISS control schemes proposed in this thesis for mechanical systems are extended to facilitate the stabilization of electromechanical systems which exhibit strong coupling between different energy domains
A simplified IDA-PBC design for underactuated mechanical systems with applications
No full textWe develop a method to simplify the partial differential equations (PDEs) associated to the potential energy for interconnection and damping assignment passivity based control (IDA-PBC) of a class of underactuated mechanical systems (UMSs). Solving the PDEs, also called the matching equations, is the main difficulty in the construction and application of the IDA-PBC. We propose a simplification to the potential energy PDEs through a particular parametrization of the closed-loop inertia matrix that appears as a coupling term with the inverse of the original inertia matrix. The parametrization accounts for kinetic energy shaping, which is then used to simplify the potential energy PDEs and their solution that is used for the potential energy shaping. This energy shaping procedure results in a closed-loop UMS with a modified energy function. This approach avoids the cancellation of nonlinearities, and extends the application of this method to a larger class of systems, including separable and non-separable port-controlled Hamiltonian (PCH) systems. Applications to the inertia wheel pendulum and the rotary inverted pendulum are presented, and some realistic simulations are presented which validate the proposed control design method and prove that global stabilization of these systems can be achieved. Experimental validation of the proposed method is demonstrated using a laboratory set-up of the rotary pendulum. The robustness of the closed-loop system with respect to external disturbances is also experimentally verifie
Robust IDA-PBC and PID-like control for port-controlled Hamiltonian systems
No full textInterconnection and damping assignment passivity based control (IDA-PBC) is a method that has been developed to (asymptotically) stabilize nonlinear systems formulated in portcontrolled Hamiltonian (PCH) structure. This method has gained increasing popularity and has been successfully applied to a wide range of dynamical systems. However, little is known about the robustness of this method in response to the effects of uncertainty which could result from disturbances, noises, and modeling errors. This paper explores the possibility of extending the IDAPBC method by adopting a robustness perspective, with the aim of maintaining (asymptotic) stability of the system in the presence of such perturbations which exist in any realistic problem. We propose constructive results on Robust IDA-PBC and PID-like controllers for a class of PCH systems. The results extend some existing methods and provide a new framework that allows the implementation of integral action control to underactuated PCH systems that are quite commonly found in practice. The results are applied to a Quanser inertia wheel pendulum and illustrated through numerical simulation
Position-feedback integral IDA-PBC for constant matched and unmatched disturbances
No full textThis work investigates the passivity-based control of a class of underactuated mechanical systems subject to constant matched and unmatched disturbances, for which the momenta are not measured. The main contribution is a new design of the integral interconnection-and-damping assignment passivity-based control that only relies on position feedback. Numerical simulations on a disk-on-disk system, on an Acrobot system, and on a rigid-link model representative of a soft continuum manipulator demonstrate the effectiveness of the new controller
IDA-PBC with dynamic extension for momenta observation of underactuated mechanical systems
No full textThis work investigates the passivity-based control of a class of underactuated mechanical systems for which the momenta are not measurable. To this end, a port-Hamiltonian formulation and a passivity-based control approach are employed. The main contribution is a new dynamic extension of the interconnection-and-damping assignment passivity-based control that only depends on the generalized position. Numerical simulations on an Acrobot system demonstrate that the proposed approach allows stabilizing the prescribed equilibrium by relying only on position feedback
A Robust IDA-PBC Approach for Handling Uncertainties in Underactuated Mechanical Systems
No full textInterconnection and damping assignment passivity based control (IDA-PBC) is a method that has been developed to (asymptotically) stabilize nonlinear systems formulated in port-controlled Hamiltonian (PCH) structure. This method has gained increasing popularity and has been successfully applied to a wide range of dynamical systems. However, little is known about the robustness of this method in response to the effects of uncertainty which could result from disturbances, noises, and modeling errors. This paper explores the possibility of extending some energy shaping methods, taking into account the robustness aspects, with the aim of maintaining (asymptotic) stability of the system in the presence of perturbations which inevitably exist in any realistic applications. We propose constructive results on robust IDA-PBC controllers for underactuated mechanical systems that are quite commonly found in practice and have the most challenging control problems within this context. The proposed results extend some existing methods and provide a new framework that allows the implementation of integral and input-to-state stability controllers to underactuated mechanical syste<br/
IDA-PBC for a class of underactuated mechanical systems with application to a rotary inverted pendulum
No full textWe develop a method to simplify the partial differential equations (PDEs) associated to the potential energy for interconnection and damping assignment passivity based control (IDA-PBC) of a class of underactuated mechanical systems. Solving the PDEs, also called the matching equations, is the main difficulty in the construction and application of the IDA-PBC. With the proposed method, a simplification to the potential energy PDE is achieved through a particular parametrization of the closed-loop inertia matrix that appears as a coupling term with the inverse of original inertia matrix. The results are applied to the Quanser rotary inverted pendulum and illustrated through numerical simulations
A Deep Transfer Learning Framework for Sleep Stage Classification with Single-Channel EEG Signals
No full textThe polysomnogram (PSG) is the gold standard for evaluating sleep quality and disorders. Attempts to automate this process have been hampered by the complexity of the PSG signals and heterogeneity among subjects and recording hardwares. Most of the existing methods for automatic sleep stage scoring rely on hand-engineered features that require prior knowledge of sleep analysis. This paper presents an end-to-end deep transfer learning framework for automatic feature extraction and sleep stage scoring based on a single-channel EEG. The proposed framework was evaluated over the three primary signals recommended by the American Academy of Sleep Medicine (C4-M1, F4-M1, O2-M1) from two data sets that have different properties and are recorded with different hardware. Different Time–Frequency (TF) imaging approaches were evaluated to generate TF representations for the 30 s EEG sleep epochs, eliminating the need for complex EEG signal pre-processing or manual feature extraction. Several training and detection scenarios were investigated using transfer learning of convolutional neural networks (CNN) and combined with recurrent neural networks. Generating TF images from continuous wavelet transform along with a deep transfer architecture composed of a pre-trained GoogLeNet CNN followed by a bidirectional long short-term memory (BiLSTM) network showed the best scoring performance among all tested scenarios. Using 20-fold cross-validation applied on the C4-M1 channel, the proposed framework achieved an average per-class accuracy of 91.2%, sensitivity of 77%, specificity of 94.1%, and precision of 75.9%. Our results demonstrate that without changing the model architecture and the training algorithm, our model could be applied to different single-channel EEGs from different data sets. Most importantly, the proposed system receives a single EEG epoch as an input at a time and produces a single corresponding output label, making it suitable for real time monitoring outside sleep labs as well as to help sleep lab specialists arrive at a more accurate diagnoses
Design of a Smart Factory Based on Cyber-Physical Systems and Internet of Things towards Industry 4.0
No full textThe rise of Industry 4.0, which employs emerging powerful and intelligent technologies and represents the digital transformation of manufacturing, has a significant impact on society, industry, and other production sectors. The industrial scene is witnessing ever-increasing pressure to improve its agility and versatility to accommodate the highly modularized, customized, and dynamic demands of production. One of the key concepts within Industry 4.0 is the smart factory, which represents a manufacturing/production system with interconnected processes and operations via cyber-physical systems, the Internet of Things, and state-of-the-art digital technologies. This paper outlines the design of a smart cyber-physical system that complies with the innovative smart factory framework for Industry 4.0 and implements the core industrial, computing, information, and communication technologies of the smart factory. It discusses how to combine the key components (pillars) of a smart factory to create an intelligent manufacturing system. As a demonstration of a simplified smart factory model, a smart manufacturing case study with a drilling process is implemented, and the feasibility of the proposed method is demonstrated and verified with experiments
Particle Swarm Optimization of a Passivity-Based Controller for Dynamic Positioning of Ships
No full textDynamic positioning (DP) control system is an essential module used in offshore ships for accurate maneuvering and maintaining of ship’s position and heading (fixed location or pre-determined track) by means of thruster forces being generated by controllers. In this paper, an interconnection and damping assignment-passivity based control (IDA-PBC) controller is developed for DP of surface ships. The design of the IDA-PBC controller involves a dynamic extension utilizing the coordinate transformation which adds damping to some coordinates to ensure asymptotic stability and adds integral action to enhance the robustness of the system against disturbances. The particle swarm optimization (PSO) technique is one of the the population-based optimization methods that has gained the attention of the control research communities and used to solve various engineering problems. The PSO algorithm is proposed for the optimization of the IDA-PBC controller. Numerical simulations results with comparisons illustrate the effectiveness of the new PSO-tuned dynamic IDA-PBC controller
