Dongyu Li

This book presents a novel approach by decoupling the various modules of sharding blockchains and providing detailed insights into the functions and design methodologies of each key module. Previous sharding blockchain solutions suffered from tight coupling between functional modules, making it challenging to achieve optimal security, performance, and scalability. Building upon this foundation, the authors present a universal composable method for composing sharding blockchains in a flexible manner. Additionally, the authors propose a novel shard member configuration method that leverages proof-of-work and verifiable distributed randomness to guarantee that each shard maintains a sufficient proportion of honest nodes, preventing it from falling below the safety threshold. Furthermore, the authors offer a complete design methodology for creating secure and scalable sharding blockchains. This includes reducing the complexity of intra-shard transaction processing through aggregation-supported multi-signature. The authors ensure optimal sharding of computational, communication, and storage resources within a formal security framework. To facilitate flexible cross-shard transaction processing, the authors introduce a new cross-shard Byzantine fault tolerance protocol. Lastly, the authors explore practical applications of sharding blockchains in typical scenarios. In the context of zero-trust cloud-edge-end scenarios, the authors demonstrate how sharding blockchains enable scalable data cross-shard sharing. Simultaneously, the authors design a secure and universally applicable cross-domain device authentication scheme.

Inspired by the community behaviors of animals and humans, cooperative control has been intensively studied by numerous researchers in recent years. Cooperative control aims to build a network system collectively driven by a global objective function in a distributed or centralized communication network and shows great application potential in a wide domain. From the perspective of cybernetics in network system cooperation, one of the main tasks is to design the formation control scheme for multiple intelligent unmanned systems, facilitating the achievements of hazardous missions – e.g., deep space exploration, cooperative military operation, and collaborative transportation. Various challenges in such real-world applications are driving the proposal of advanced formation control design, which is to be addressed to bring academic achievements into real industrial scenarios. This book extends the performance of formation control beyond classical dynamic or stationary geometric configurations, focusing on formation maneuverability that enables cooperative systems to keep suitable spacial configurations during agile maneuvers. This book embarks on an adventurous journey of maneuverable formation control in constrained space with limited resources, to accomplish the exploration of an unknown environment. The investigation of the real-world challenges, including model uncertainties, measurement inaccuracy, input saturation, output constraints, and spatial collision avoidance, brings the value of this book into the practical industry, rather than being limited to academics.

Time-Synchronized Control and Applications for Autonomous Systems presents a pioneering approach to control problems by introducing time-synchronized stability, where every system state converges to the origin simultaneously. This innovative concept addresses unique finite, fixed, or predefined-time stability considerations, marking a significant advancement in control theory. The book offers readers a thorough understanding of both the theoretical foundations and practical implementations of time-synchronized control, emphasizing its potential to transform the management of autonomous systems. With clear explanations and real-world examples, it serves as an essential resource for engineers, researchers, and students involved in modern control systems. In addition to its core focus, the book explores a broad spectrum of practical applications, such as spacecraft attitude control, satellite orbit management, dynamic vessel positioning, and cooperative control of autonomous vehicles. It examines various control system models, including disturbed, chaotic, multi-input multi-output (MIMO), nonlinear, and Euler-Lagrange systems.

This book is concerned with nonlinear control with performance-related and system-ability-related constraints. It presents novel work on several kinds of commonly encountered nonlinear systems, including those with stricter transient performance requirements, those with two types of constraints, those with no initial-condition limitation, and those with limited resources. It shows how nonlinear systems with severe constraints can be successfully controlled with our powerful control design. Typically, the book discusses a Tunnel Prescribed Control for achieving enhanced performance; provides a comprehensive solution, namely, Saturation-tolerant Prescribed Control, to handle the conflict between constraints; and then develops a Self-adjustable Prescribed Control to address the defined Entry Capture Problem that performance constraints are satis?ed after (rather than from the beginning of) system operation. As such, the book will be of interest to researchers and graduate students in the fields of nonlinear systems, constrained control, and control engineering who would like to find out about the performance, robustness, and applications of constrained nonlinear systems.

Facing future-oriented aerospace applications, large-scale space construction and on-orbit services have rapidly developed. In such emerging and increasingly complex spacecraft maneuvering and control tasks, more precise control accuracy and higher performance guarantees need to be fully considered due to the need for safe close rendezvous movements.This book is dedicated to solving the aerospace system’s performance guaranteed and precise control challenges with the expected transient and strict steady-state constraints. It is designed so that the aerospace closed-loop system can theoretically meet the pre-defined or prescribed performance requirements with the simple parameter selection. Furthermore, the expected performance constraints or indicators of the aerospace system time-domain performance response, such as settling time, overshoot, steady-state error, and state amplitude, will be directly guaranteed in the control design. Moreover, this book systematically proposes a series of spacecraft performance guaranteed control algorithms based on the practical situation of the aerospace system. For individual spacecraft, control algorithms that consider practical problems such as control task requirements, settling time constraints, transient performance normalization, input command constraints, and optimization faced by the on-orbit spacecraft are proposed to achieve the precise control objectives of the system under constraints and various complex situations. For the pre-combination and post-combination control of multiple spacecraft, game algorithms based on performance guarantees are proposed and thoroughly discussed. For spacecraft formations, control algorithms that consider full-state constraints, nonlinear uncertainties, output feedback, and collision avoidance are proposed. This book provides the theoretical basis and simulation experience for scholars and engineers to develop high-performance, high-precision spacecraft control algorithms. Furthermore, it hopes that these will contribute to the development of the world’s aerospace technology.

Inspired by the community behaviors of animals and humans, cooperative control has been intensively studied by numerous researchers in recent years. Cooperative control aims to build a network system collectively driven by a global objective function in a distributed or centralized communication network and shows great application potential in a wide domain. From the perspective of cybernetics in network system cooperation, one of the main tasks is to design the formation control scheme for multiple intelligent unmanned systems, facilitating the achievements of hazardous missions – e.g., deep space exploration, cooperative military operation, and collaborative transportation. Various challenges in such real-world applications are driving the proposal of advanced formation control design, which is to be addressed to bring academic achievements into real industrial scenarios. This book extends the performance of formation control beyond classical dynamic or stationary geometric configurations, focusing on formation maneuverability that enables cooperative systems to keep suitable spacial configurations during agile maneuvers. This book embarks on an adventurous journey of maneuverable formation control in constrained space with limited resources, to accomplish the exploration of an unknown environment. The investigation of the real-world challenges, including model uncertainties, measurement inaccuracy, input saturation, output constraints, and spatial collision avoidance, brings the value of this book into the practical industry, rather than being limited to academics.

Facing future-oriented aerospace applications, large-scale space construction and on-orbit services have rapidly developed. In such emerging and increasingly complex spacecraft maneuvering and control tasks, more precise control accuracy and higher performance guarantees need to be fully considered due to the need for safe close rendezvous movements.This book is dedicated to solving the aerospace system’s performance guaranteed and precise control challenges with the expected transient and strict steady-state constraints. It is designed so that the aerospace closed-loop system can theoretically meet the pre-defined or prescribed performance requirements with the simple parameter selection. Furthermore, the expected performance constraints or indicators of the aerospace system time-domain performance response, such as settling time, overshoot, steady-state error, and state amplitude, will be directly guaranteed in the control design. Moreover, this book systematically proposes a series of spacecraft performance guaranteed control algorithms based on the practical situation of the aerospace system. For individual spacecraft, control algorithms that consider practical problems such as control task requirements, settling time constraints, transient performance normalization, input command constraints, and optimization faced by the on-orbit spacecraft are proposed to achieve the precise control objectives of the system under constraints and various complex situations. For the pre-combination and post-combination control of multiple spacecraft, game algorithms based on performance guarantees are proposed and thoroughly discussed. For spacecraft formations, control algorithms that consider full-state constraints, nonlinear uncertainties, output feedback, and collision avoidance are proposed.This book provides the theoretical basis and simulation experience for scholars and engineers to develop high-performance, high-precision spacecraft control algorithms. Furthermore, it hopes that these will contribute to the development of the world’s aerospace technology.

Previous research on fixed/finite-time sliding-mode control focuses on forcing a system state (vector) to converge within a certain time moment, regardless of how each state element converges. This book introduces a control problem with unique finite/fixed-time stability considerations, namely time-synchronized stability, where at the same time, all the system state elements converge to the origin, and fixed-time-synchronized stability, where the upper bound of the synchronized settling time is invariant with any initial state. Accordingly, sufficient conditions for (fixed-) time-synchronized stability are presented. These stability formulations grant essentially advantageous performance when a control system (with diversified subsystems) is expected to accomplish multiple actions synchronously, e.g., grasping with a robotic hand, multi-agent simultaneous cooperation, etc. Further, the analytical solution of a (fixed) time-synchronized stable system is obtained and discussed. Applications to linear systems, disturbed nonlinear systems, and network systems are provided. In addition, comparisons with traditional fixed/finite-time sliding mode control are suitably detailed to showcase the full power of (fixed-) time-synchronized control.

Previous research on fixed/finite-time sliding-mode control focuses on forcing a system state (vector) to converge within a certain time moment, regardless of how each state element converges. This book introduces a control problem with unique finite/fixed-time stability considerations, namely time-synchronized stability, where at the same time, all the system state elements converge to the origin, and fixed-time-synchronized stability, where the upper bound of the synchronized settling time is invariant with any initial state. Accordingly, sufficient conditions for (fixed-) time-synchronized stability are presented. These stability formulations grant essentially advantageous performance when a control system (with diversified subsystems) is expected to accomplish multiple actions synchronously, e.g., grasping with a robotic hand, multi-agent simultaneous cooperation, etc. Further, the analytical solution of a (fixed) time-synchronized stable system is obtained and discussed. Applications to linear systems, disturbed nonlinear systems, and network systems are provided. In addition, comparisons with traditional fixed/finite-time sliding mode control are suitably detailed to showcase the full power of (fixed-) time-synchronized control.