Sliding Mode Control

The main objective of this monograph is to present a broad range of well worked out, recent application studies as well as theoretical contributions in the field of sliding mode control system analysis and design. The contributions presented here include new theoretical developments as well as successful applications of variable structure controllers primarily in the field of power electronics, electric drives and motion steering systems. They enrich the current state of the art, and motivate and encourage new ideas and solutions in the sliding mode control area

Actuators for Intelligent Electric Vehicles

This book details the advanced actuators for IEVs and the control algorithm design. In the actuator design, the configuration four-wheel independent drive/steering electric vehicles is reviewed. An in-wheel two-speed AMT with selectable one-way clutch is designed for IEV. Considering uncertainties, the optimization design for the planetary gear train of IEV is conducted. An electric power steering system is designed for IEV. In addition, advanced control algorithms are proposed in favour of active safety improvement. A supervision mechanism is applied to the segment drift control of autonomous driving. Double super-resolution network is used to design the intelligent driving algorithm. Torque distribution control technology and four-wheel steering technology are utilized for path tracking and adaptive cruise control. To advance the control accuracy, advanced estimation algorithms are studied in this book. The tyre-road peak friction coefficient under full slip rate range is identified based on the normalized tyre model. The pressure of the electro-hydraulic brake system is estimated based on signal fusion. Besides, a multi-semantic driver behaviour recognition model of autonomous vehicles is designed using confidence fusion mechanism. Moreover, a mono-vision based lateral localization system of low-cost autonomous vehicles is proposed with deep learning curb detection. To sum up, the discussed advanced actuators, control and estimation algorithms are beneficial to the active safety improvement of IEVs

Brake-clutch squeal prediction and supression

This work studies the high frequency noise in brake–clutch systems known as squeal. The work is divided into two parts, the first is focused on the development of both a theoretical and experimental simplified model of a brake–clutch and the second is centred on squeal modelling in the real system. For the simple model, on the theoretical side, a FE model was developed including anisotropic material properties, pressure and speed dependent friction coefficient and friction damping. The pertinent characterisation tests were performed as needed. On the experimental side, squeal tests were performed in the test bench in order to check the ability of the system for squeal prediction. Once the model was thought as accurate enough, a methodology to decide over point structural modifications for squeal suppression based on the receptance function was designed. Using this process squeal was successfully eliminated from the simplified model both theoretically and experimentally. In the second part the modelling of squeal in a real brake–clutch system was tackled. With this objective a FE model of the whole system was developed and its validity was checked first by EMA and after, comparing the experimental squeal frequencies with the ones predicted by simulation. To finish, the methodology for structural modifications previously designed was applied to the system and several theoretical modifications were proposed and studied.Lan honetan balazta–enbrage unitate konbinatuetan agertzen den squeal izeneko frekuentzia altuko zarata aztertzen da. Lana bi zatitan banatuta dago: alde batetik, balazta–enbragearen eredu sinplifikatu bat garatu da, bai teorikoa zein esperimentala; bestetik, squeala sistema errealean modelizatu da. Eredu sinplean, alde teorikoari dagokionez, elementu finitutako eredu bat garatu da. Eredu honek marruskadura materialaren propietate anisotropoak, presio eta abiaduraren menpeko marruskadura koefizientea eta marruskadurak eragindako moteltzea kontutan hartzen ditu. Propietate hauek saiakuntza independentetan neurtu dira. Alde esperimentalean, squeal saiakuntzak burutu dira ereduak squeala aurreikusteko duen gaitasuna balioztatzeko asmoz. Behin eredua nahiko zehatza izanik, zarata kentzeko aldaketa estrukturalak proposatu eta baloratzeko metodologia bat diseinatu da. Proposatutako metodoa errezeptantzia funtzioan oinarrituta dago. Metodo honi esker squeala eredu teorikoan lehenengo eta ondoren saiakuntza bankuan kentzea posible izan da. Bigarren atalean, balazta–enbragearen modelizazioari ekin zaio squealari dagokionez. Helburu honekin, sistema osoaren eredu bat garatu da eta lehengo AME bidez eta gero squeal frekuentzia esperimentalak ereduak aurreikusitakoekin konparatuz balioztatu da. Azkenik, aldaketa estrukturalak proposatzeko metodologia sistema errealari aplikatu zaio eta aldaketa teoriko batzuk planteatu eta aztertu dira.El presente trabajo estudia el ruido de alta frecuencia que se da en los freno-embragues conocido como squeal. El trabajo se divide en dos partes, la primera enfocada en el desarrollo de un modelo simple tanto teórico como experimental del freno–embrague y la segunda centrada en la modelización del squeal en el sistema real. En lo referente al modelo simple, en la parte teórica se desarrolló un modelo de elementos finitos que incluía propiedades anisótropas para el material de fricción, un coeficiente de fricción dependiente de la presión y la velocidad y amortiguamiento por fricción. Estas propiedades se caraterizaron en los correspondientes ensayos independientes cuando fue necesario. En la parte experimental, se llevaron a cabo ensayos de squeal en banco con la idea de verificar la capacidad del modelo para predecir el squeal. Una vez que el modelo se consideró lo suficientemente exacto, se desarrolló una metodología para proponer y valorar modificaciones estructurales para la supresión de squeal. El método propuesto está basado en la función de receptancia. Gracias a este proceso fue posible eliminar el squeal del modelo primero en la teoría y a continuación en el banco de ensayos. En la segunda parte se aborda la modelización de squeal en un freno–embrague real. Con esto en mente se desarrolló un modelo de elementos finitos del sistema completo y se validó en primer lugar mediante AME y a continuación comparando las frecuencias experimentales de squeal con las predichas por la simulación. Por último, la metodología desarrollada para modificaciones estructurales se aplicó al sistema real y se propusieron y analizaron varias modificaciones teóricas

Virtual Structure Based Formation Tracking of Multiple Wheeled Mobile Robots: An Optimization Perspective

Today, with the increasing development of science and technology, many systems need to be optimized to find the optimal solution of the system. this kind of problem is also called optimization problem. Especially in the formation problem of multi-wheeled mobile robots, the optimization algorithm can help us to find the optimal solution of the formation problem. In this paper, the formation problem of multi-wheeled mobile robots is studied from the point of view of optimization. In order to reduce the complexity of the formation problem, we first put the robots with the same requirements into a group. Then, by using the virtual structure method, the formation problem is reduced to a virtual WMR trajectory tracking problem with placeholders, which describes the expected position of each WMR formation. By using placeholders, you can get the desired track for each WMR. In addition, in order to avoid the collision between multiple WMR in the group, we add an attraction to the trajectory tracking method. Because MWMR in the same team have different attractions, collisions can be easily avoided. Through simulation analysis, it is proved that the optimization model is reasonable and correct. In the last part, the limitations of this model and corresponding suggestions are given

Induction Motors

AC motors play a major role in modern industrial applications. Squirrel-cage induction motors (SCIMs) are probably the most frequently used when compared to other AC motors because of their low cost, ruggedness, and low maintenance. The material presented in this book is organized into four sections, covering the applications and structural properties of induction motors (IMs), fault detection and diagnostics, control strategies, and the more recently developed topology based on the multiphase (more than three phases) induction motors. This material should be of specific interest to engineers and researchers who are engaged in the modeling, design, and implementation of control algorithms applied to induction motors and, more generally, to readers broadly interested in nonlinear control, health condition monitoring, and fault diagnosis

Design, testing and validation of model predictive control for an unmanned ground vehicle

The rapid increase in designing, manufacturing, and using autonomous robots has attracted numerous researchers and industries in recent decades. The logical motivation behind this interest is the wide range of applications. For instance, perimeter surveillance, search and rescue missions, agriculture, and construction. In this thesis, motion planning and control based on model predictive control (MPC) for unmanned ground vehicles (UGVs) is tackled. In addition, different variants of MPC are designed, analysed, and implemented for such non-holonomic systems. It is imperative to focus on the ability of MPC to handle constraints as one of the motivations. Furthermore, the proliferation of computer processing enables these systems to work in a real-time scenario. The controller's responsibility is to guarantee an accurate trajectory tracking process to deal with other specifications usually not considered or solved by the planner. However, the separation between planner and controller is not necessarily defined uniquely, even though it can be a hybrid process, as seen in part of this thesis. Firstly, a robust MPC is designed and implemented for a small-scale autonomous bulldozer in the presence of uncertainties, which uses an optimal control action and a feed-forward controller to suppress these uncertainties. More precisely, a linearised variant of MPC is deployed to solve the trajectory tracking problem of the vehicle. Afterwards, a nonlinear MPC is designed and implemented to solve the path-following problem of the UGV for masonry in a construction context, where longitudinal velocity and yaw rate are employed as control inputs to the platform. For both the control techniques, several experiments are performed to validate the robustness and accuracy of the proposed scheme. Those experiments are performed under realistic localisation accuracy, provided by a typical localiser. Most conspicuously, a novel proximal planning and control strategy is implemented in the presence of skid-slip and dynamic and static collision avoidance for the posture control and tracking control problems. The ability to operate in moving objects is critical for UGVs to function well. The approach offers specific planning capabilities, able to deal at high frequency with context characteristics, which the higher-level planner may not well solve. Those context characteristics are related to dynamic objects and other terrain details detected by the platform's onboard perception capabilities. In the control context, proximal and interior-point optimisation methods are used for MPC. Relevant attention is given to the processing time required by the MPC process to obtain the control actions at each actual control time. This concern is due to the need to optimise each control action, which must be calculated and applied in real-time. Because the length of a prediction horizon is critical in practical applications, it is worth looking into in further detail. In another study, the accuracies of robust and nonlinear model predictive controllers are compared. Finally, a hybrid controller is proposed and implemented. This approach exploits the availability of a simplified cost-to-go function (which is provided by a higher-level planner); thus, the hybrid approach fuses, in real-time, the nominal CTG function (nominal terrain map) with the rest of the critical constraints, which the planner usually ignores. The conducted research fills necessary gaps in the application areas of MPC and UGVs. Both theoretical and practical contributions have been made in this thesis. Moreover, extensive simulations and experiments are performed to test and verify the working of MPC with a reasonable processing capability of the onboard process

High-performance control of continuously variable transmissions

Nowadays, developments with respect to the pushbelt continuously variable transmission (CVT) are mainly directed towards a reduction of the fuel consumption of a vehicle. The fuel consumption of a vehicle is affected by the variator of the CVT, which transfers the torque and varies the transmission ratio. The variator consists of a metal V-belt, i.e., a pushbelt, which is clamped between two pulleys. Each pulley is connected to a hydraulic cylinder, which is pressurized by the hydraulic actuation system. The pressure in the hydraulic cylinder determines the clamping force on the pulley. The level of the clamping forces sets the torque capacity, whereas the ratio of the clamping forces determines the transmission ratio. When the level of the clamping forces is increased above the threshold for a given operating condition, the variator efficiency is decreased, whereas the torque capacity is increased. When the level of the clamping forces is decreased below the threshold for a given operating condition, the torque capacity is inadequate, which deteriorates the variator efficiency and damages the pulleys and the pushbelt. Since this threshold is not known, the level of the clamping forces is often raised for robustness, which reduces the variator efficiency. The challenge for the control system is to reduce the clamping forces towards the level for which the variator efficiency is maximized, although the variator efficiency is not measured. Furthermore, avoiding a failure of the variator in view of torque disturbances and tracking a transmission ratio reference are necessarily required. Two state-of-the-art control strategies are presently used, i.e., safety control and slip control. These control strategies involve limitations that follow from the model knowledge and/or the sensor use that underlies the control design. For this reason, the objectives of the research in this thesis are oriented towards improvements with respect to the model knowledge of both the hydraulic actuation system and the variator, which is subsequently exploited in the control design of both components, to improve the performance. The resources of the control designs are restricted to measurements from sensors that are standard. A cascade control configuration is proposed, where the inner loop controls the hydraulic actuation system and the outer loop controls the combination of the inner loop and the variator. The elements of the cascade control configuration are the subject of the research in this thesis. For the hydraulic actuation system, modeling via first principles and modeling via system identification are pursued. Modeling via first principles provides a nonlinear model, which is specifically suited for closed-loop simulation and optimization of design parameters. A modular approach is proposed, which reduces the model complexity, improves the model transparency, and facilitates the analysis of changes with respect to the configuration. The nonlinear model is validated by means of measurements from a commercial CVT. Modeling via system identification provides a model set, which is subsequently used for the hydraulic actuation system control design. A model set of high-quality is constructed, which is achieved by the design of the identification experiments that deals with the limited signal-to-noise ratio (SNR) that arises from actuators and sensors of low-quality. The hydraulic actuation system control design is multivariable, which is caused by the interaction between the hydraulic cylinders that is inherently introduced by the variator. Stability and performance are guaranteed for the range of operating conditions that is normally encountered, which is demonstrated with the experimental CVT. A variator control design is proposed that deals with both the transmission ratio and the variator efficiency in terms of performance variables, where the transmission ratio is measured, while the variator efficiency is not measured. The variator control design uses the standard measurement of the angular velocities, from which the transmission ratio is constructed, as well as the standard measurement of the pressure. Essentially, the variator control design exploits the observation that the maximum of the transmission ratio and the maximum of the variator efficiency are achieved for pressure values that nearly coincide. This observation is derived from both simulations with a nonlinear model and experiments with the experimental CVT. This motivates the use of the pressure-transmission ratio map, although the location of the maximum is not known. For this reason, the maximum of the input-output map is found by a so-called extremum seeking control (ESC) design, which aims to adapt the input in order to maximize the output. A robustness analysis shows that an input side disturbance that resembles a depression of the accelerator pedal and an output side disturbance that resembles the passage of a step bump are effectively handled. Finally, the ESC design is extended with a so-called tracking control (TC) design, which enables that optimizing the variator efficiency and tracking a transmission ratio reference are simultaneously achieved. The variator control design that is composed of the ESC design and the TC design is evaluated with the experimental CVT. Simulation of a driving cycle shows that the final variator control design outperforms the conventional variator control design in terms of the variator efficiency

Nonlinear Systems

Open Mathematics is a challenging notion for theoretical modeling, technical analysis, and numerical simulation in physics and mathematics, as well as in many other fields, as highly correlated nonlinear phenomena, evolving over a large range of time scales and length scales, control the underlying systems and processes in their spatiotemporal evolution. Indeed, available data, be they physical, biological, or financial, and technologically complex systems and stochastic systems, such as mechanical or electronic devices, can be managed from the same conceptual approach, both analytically and through computer simulation, using effective nonlinear dynamics methods. The aim of this Special Issue is to highlight papers that show the dynamics, control, optimization and applications of nonlinear systems. This has recently become an increasingly popular subject, with impressive growth concerning applications in engineering, economics, biology, and medicine, and can be considered a veritable contribution to the literature. Original papers relating to the objective presented above are especially welcome subjects. Potential topics include, but are not limited to: Stability analysis of discrete and continuous dynamical systems; Nonlinear dynamics in biological complex systems; Stability and stabilization of stochastic systems; Mathematical models in statistics and probability; Synchronization of oscillators and chaotic systems; Optimization methods of complex systems; Reliability modeling and system optimization; Computation and control over networked systems

Design and Control of Power Converters 2019

In this book, 20 papers focused on different fields of power electronics are gathered. Approximately half of the papers are focused on different control issues and techniques, ranging from the computer-aided design of digital compensators to more specific approaches such as fuzzy or sliding control techniques. The rest of the papers are focused on the design of novel topologies. The fields in which these controls and topologies are applied are varied: MMCs, photovoltaic systems, supercapacitors and traction systems, LEDs, wireless power transfer, etc