Active suspension control of electric vehicle with in-wheel motors

In-wheel motor (IWM) technology has attracted increasing research interests in recent years due to the numerous advantages it offers. However, the direct attachment of IWMs to the wheels can result in an increase in the vehicle unsprung mass and a significant drop in the suspension ride comfort performance and road holding stability. Other issues such as motor bearing wear motor vibration, air-gap eccentricity and residual unbalanced radial force can adversely influence the motor vibration, passenger comfort and vehicle rollover stability. Active suspension and optimized passive suspension are possible methods deployed to improve the ride comfort and safety of electric vehicles equipped with inwheel motor. The trade-off between ride comfort and handling stability is a major challenge in active suspension design. This thesis investigates the development of novel active suspension systems for successful implementation of IWM technology in electric cars. Towards such aim, several active suspension methods based on robust H∞ control methods are developed to achieve enhanced suspension performance by overcoming the conflicting requirement between ride comfort, suspension deflection and road holding. A novel fault-tolerant H∞ controller based on friction compensation is in the presence of system parameter uncertainties, actuator faults, as well as actuator time delay and system friction is proposed. A friction observer-based Takagi-Sugeno (T-S) fuzzy H∞ controller is developed for active suspension with sprung mass variation and system friction. This method is validated experimentally on a quarter car test rig. The experimental results demonstrate the effectiveness of proposed control methods in improving vehicle ride performance and road holding capability under different road profiles. Quarter car suspension model with suspended shaft-less direct-drive motors has the potential to improve the road holding capability and ride performance. Based on the quarter car suspension with dynamic vibration absorber (DVA) model, a multi-objective parameter optimization for active suspension of IWM mounted electric vehicle based on genetic algorithm (GA) is proposed to suppress the sprung mass vibration, motor vibration, motor bearing wear as well as improving ride comfort, suspension deflection and road holding stability. Then a fault-tolerant fuzzy H∞ control design approach for active suspension of IWM driven electric vehicles in the presence of sprung mass variation, actuator faults and control input constraints is proposed. The T-S fuzzy suspension model is used to cope with the possible sprung mass variation. The output feedback control problem for active suspension system of IWM driven electric vehicles with actuator faults and time delay is further investigated. The suspended motor parameters and vehicle suspension parameters are optimized based on the particle swarm optimization. A robust output feedback H∞ controller is designed to guarantee the system’s asymptotic stability and simultaneously satisfying the performance constraints. The proposed output feedback controller reveals much better performance than previous work when different actuator thrust losses and time delay occurs. The road surface roughness is coupled with in-wheel switched reluctance motor air-gap eccentricity and the unbalanced residual vertical force. Coupling effects between road excitation and in wheel switched reluctance motor (SRM) on electric vehicle ride comfort are also analysed in this thesis. A hybrid control method including output feedback controller and SRM controller are designed to suppress SRM vibration and to prolong the SRM lifespan, while at the same time improving vehicle ride comfort. Then a state feedback H∞ controller combined with SRM controller is designed for in-wheel SRM driven electric vehicle with DVA structure to enhance vehicle and SRM performance. Simulation results demonstrate the effectiveness of DVA structure based active suspension system with proposed control method its ability to significantly improve the road holding capability and ride performance, as well as motor performance

Discrete Time Systems

Discrete-Time Systems comprehend an important and broad research field. The consolidation of digital-based computational means in the present, pushes a technological tool into the field with a tremendous impact in areas like Control, Signal Processing, Communications, System Modelling and related Applications. This book attempts to give a scope in the wide area of Discrete-Time Systems. Their contents are grouped conveniently in sections according to significant areas, namely Filtering, Fixed and Adaptive Control Systems, Stability Problems and Miscellaneous Applications. We think that the contribution of the book enlarges the field of the Discrete-Time Systems with signification in the present state-of-the-art. Despite the vertiginous advance in the field, we also believe that the topics described here allow us also to look through some main tendencies in the next years in the research area

Measurements, Models, Systems and Design

531 s.

Deep Learning-Based Machinery Fault Diagnostics

This book offers a compilation for experts, scholars, and researchers to present the most recent advancements, from theoretical methods to the applications of sophisticated fault diagnosis techniques. The deep learning methods for analyzing and testing complex mechanical systems are of particular interest. Special attention is given to the representation and analysis of system information, operating condition monitoring, the establishment of technical standards, and scientific support of machinery fault diagnosis

Third International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Third International Symposium on Magnetic Suspension Technology was held at the Holiday Inn Capital Plaza in Tallahassee, Florida on 13-15 Dec. 1995. The symposium included 19 sessions in which a total of 55 papers were presented. The technical sessions covered the areas of bearings, superconductivity, vibration isolation, maglev, controls, space applications, general applications, bearing/actuator design, modeling, precision applications, electromagnetic launch and hypersonic maglev, applications of superconductivity, and sensors

The entropy of suffering : an inquiry into the consequences of the 4-Hour Rule for the patient-doctor relationship in Australian public hospitals

As a medical practitioner, predominantly working in Australian public hospitals, I have always been interested in the factors that shape and influence my and my colleagues’ performance in the practice of medicine. In 2011, the Australian Government instituted a range of reforms to the public health-care system, including some directed at improving access for patients to Emergency Departments, which had, over many years, become increasingly overwhelmed by the number and complexity of presentations. This included a target of four hours within which patients in Emergency Departments were to be discharged, admitted or transferred to alternative institutions. These reforms generated widespread strong emotional responses from medical and other health staff with whom I worked, and I was prompted to consider the origins of these powerful human reactions to the administrative intervention. Emergency Departments are often described, derisively, as chaotic working environments. However, this epithet may instead be describing something quite profound about the ontological nature of hospitals and Emergency Departments — that they are, indeed, non-linear dynamical physical systems in which phenomena of complexity exist. Other human-centred interactional and transactional systems have been successfully examined from a complexity perspective, including economics and human physiology. Framing inquiry into Emergency Departments, and the humans who encounter each other within them, from a complexity perspective might also then prove useful in defining and characterising the complex and manifold relationships and interactions between people, technology and systemic organising principles. This health services research evaluates the lived experience of four medical practitioners through the paradigm of phenomenological inquiry, as actors on a performance landscape of clinical encounters and as key sources of information about the structure and functions of that performance manifold. Inquiry into and analysis of these rich descriptive data yield strong inferences that non-linear dynamics are operating across scales — from the cellular to the organisational. The complexity perspective provides a unifying explanatory power for making sense of how energetic transactions and transformations between patients, health-care practitioners, technology and the hospital system unfold to result in the recovery from injury and trauma. Specifically, literature on interoception suggests that human biological systems are exquisitely sensitive to changes in dynamic steady-states that might indicate increased entropy. This inquiry suggests that suffering is a phenomenological experience of sudden increases in entropy. An explanatory model in complexity, using the Second Law of Thermodynamics in open systems, suggests that entropy — that is, suffering — can be understood as being transferred and expelled from patient to doctor. Framing in this explanatory model would suggest that the patient-doctor relationship is a powerful systemic attractor in a dynamic system. Elaborating this construct of energetic dynamics further suggests that insertion of system controllers, such as time-based targets, can have profound non-linear effects on the function of these dynamics and, hence, the outcomes of these patient-doctor encounters. The implications of this inquiry include a new and powerful reframing of the ontological characterisation of the practice of medicine in Emergency Departments in terms of nonlinear open thermodynamic functions operating at distance from equilibrium. It recommends a more thoughtful consideration of human experiences such as suffering and its relief. Giving priority and visibility to suffering within health-care, a recrudescence of times past when technology in medicine was limited, may elucidate ways of practising that improve patient experiences and health outcomes. Furthermore, the findings suggest that medical practitioners, health workers and administrators are called on to deeply consider embracing complex dynamics as problem framing references, and to engage with methodologies that build better theories about the nature of phenomena under investigation. Rather than seeking to diminish or extinguish the complexities of Emergency Departments, researchers and practitioners might acknowledge and engage with the next wave of complexity-informed health-care research to better understand how and why health-care relieves suffering and restores human function