Multidisciplinary design optimization is a field of research that studies the application of numerical optimization techniques to the design of engineering systems involving multiple disciplines or components. Since the inception of multidisciplinary design optimization, various methods (architectures) have been developed and applied to solve multidisciplinary design-optimization problems. This paper provides a survey of all the architectures that have been presented in the literature so far. All architectures are explained in detail using a unified description that includes optimization problem statements, diagrams, and detailed algorithms. The diagrams show both data and process flow through the multidisciplinary system and computational elements, which facilitate the understanding of the various architectures, and how they relate to each other. A classification of the multidisciplinary design-optimization architectures based on their problem formulations and decomposition strategies is also provided, a...

Multidisciplinary design optimization: A survey of architectures

Formation control analysis and design problems for unmanned aerial vehicle (UAV) swarm systems to achieve time-varying formations are investigated. To achieve predefined time-varying formations, formation protocols are presented for UAV swarm systems first, where the velocities of UAVs can be different when achieving formations. Then, consensus-based approaches are applied to deal with the time-varying formation control problems for UAV swarm systems. Necessary and sufficient conditions for UAV swarm systems to achieve time-varying formations are proposed. An explicit expression of the time-varying formation center function is derived. In addition, a procedure to design the protocol for UAV swarm systems to achieve time-varying formations is given. Finally, a quadrotor formation platform, which consists of five quadrotors is introduced. Theoretical results obtained in this brief are validated on the quardrotor formation platform, and outdoor experimental results are presented.

Time-Varying Formation Control for Unmanned Aerial Vehicles: Theories and Applications

The availability of location information has become a key factor in today's communications systems allowing location based services. In outdoor scenarios, the mobile terminal position is obtained with high accuracy thanks to the global positioning system (GPS) or to the standalone cellular systems. However, the main problem of GPS and cellular systems resides in the indoor environment and in scenarios with deep shadowing effects where the satellite or cellular signals are broken. In this paper, we survey different technologies and methodologies for indoor and outdoor localization with an emphasis on indoor methodologies and concepts. Additionally, we discuss in this review different localization-based applications, where the location information is critical to estimate. Finally, a comprehensive discussion of the challenges in terms of accuracy, cost, complexity, security, scalability, etc. is given. The aim of this survey is to provide a comprehensive overview of existing efforts as well as auspicious and anticipated dimensions for future work in indoor localization techniques and applications.

Recent Advances in Indoor Localization: A Survey on Theoretical Approaches and Applications

Unmanned aerial vehicles (UAVs), or aerial drones, are an emerging technology with significant market potential. UAVs may lead to substantial cost savings in, for instance, monitoring of difficult-to-access infrastructure, spraying fields and performing surveillance in precision agriculture, as well as in deliveries of packages. In some applications, like disaster management, transport of medical supplies, or environmental monitoring, aerial drones may even help save lives. In this article, we provide a literature survey on optimization approaches to civil applications of UAVs. Our goal is to provide a fast point of entry into the topic for interested researchers and operations planning specialists. We describe the most promising aerial drone applications and outline characteristics of aerial drones relevant to operations planning. In this review of more than 200 articles, we provide insights into widespread and emerging modeling approaches. We conclude by suggesting promising directions for future research.

Optimization approaches for civil applications of unmanned aerial vehicles (UAVs) or aerial drones: A survey

Time-varying formation tracking analysis and design problems for second-order Multi-Agent systems with switching interaction topologies are studied, where the states of the followers form a predefined time-varying formation while tracking the state of the leader. A formation tracking protocol is constructed based on the relative information of the neighboring agents. Necessary and sufficient conditions for Multi-Agent systems with switching interaction topologies to achieve time-varying formation tracking are proposed together with the formation tracking feasibility constraint based on the graph theory. An approach to design the formation tracking protocol is proposed by solving an algebraic Riccati equation, and the stability of the proposed approach is proved using the common Lyapunov stability theory. The obtained results are applied to solve the target enclosing problem of a multiquadrotor unmanned aerial vehicle (UAV) system consisting of one leader (target) quadrotor UAV and three follower quadrotor UAVs. A numerical simulation and an outdoor experiment are presented to demonstrate the effectiveness of the theoretical results.

Time-Varying Formation Tracking for Second-Order Multi-Agent Systems Subjected to Switching Topologies With Application to Quadrotor Formation Flying

In this paper, the synchronized position tracking controller is incorporated in formation flight control for multiple flying wings. With this technology, the performance and effectiveness of the formation controller are improved when the virtual structure approach is utilized to maintain formation geometry. Simulations are conducted on the nonlinear model of two flying wings to verify the proposed controller.

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Formation UAV flight control using virtual structure and motion synchronization

Finite-range sensing and communication are factors in the connectivity of a dynamic mobile-robot network. State estimation becomes a difficult problem when communication connections allowing information exchange between all robots are not guaranteed. This paper presents a decentralized state-estimation algorithm guaranteed to work in dynamic robot networks without connectivity requirements. We prove that a robot only needs to consider its own knowledge of network topology in order to produce an estimate equivalent to the centralized state estimate whenever possible while ensuring that the same can be performed by all other robots in the network. We prove certain properties of our technique and then it is validated through simulations. We present a comprehensive set of results, indicating the performance benefit in different network connectivity settings, as well as the scalability of our approach.

Decentralized Localization of Sparsely-Communicating Robot Networks: A Centralized-Equivalent Approach

Unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) have received much attention in the research and development community due to their strong potential in certain high-risk missions. In applications that involve multiple vehicles, the inter-vehicle communication and cooperation becomes a critical challenge to a successful mission. An effective co-operative control framework is required to co-ordinate the system-level decision making process and information flow among the multiple agents such that the collective mission is optimally achieved. In this paper, a cooperative control framework for a hierarchical UAV/UGV platform is proposed. A top-level mobile mission controller provides effective mission planning and system-level decision making such that mission completion time and resource expenditure are optimized. The mobile mission controller can monitor the dynamic environment with its own sensing capabilities and coordinate UAVs/UGVs in their actions. This paper discusses the potential application of the proposed hierarchical vehicle platform to high-risk missions, specifically in the context of wildfire fighting. The task generation and allocation problems and proposed approaches are presented under the given control framework.

A cooperative UAV/UGV platform for wildfire detection and fighting

In this paper, a gust load alleviation system based on model-predictive control is developed for a very flexible aircraft. Two main contributions presented in this work are as follows. First, a unified dynamics framework is developed to represent the full six-degrees-of-freedom rigid body alongwith the structural dynamics. This allows for an integrated control design to account for maneuverability (flying qualities) and aeroelasticity simultaneously, leading to a new and improved configuration for a very flexible aircraft. Second, an improved model-predictive control formulation is proposed for stabilization and gust load alleviation. The performance of the model-predictive control is further improved by introducing an additional feedback loop to increase the prediction accuracy. To demonstrate the effectiveness of the proposed approach, the integrated formulation is compared with existing approaches. Further, the load alleviation performance is evaluated for various discrete and continuous gusts.

Model-Predictive Gust Load Alleviation Controller for a Highly Flexible Aircraft

In this paper a multidisciplinary design optimization framework is developed that integrates control system design with aerostructural design. The equations of motion are derived for a flexible aircraft and used to perform aeroservoelastic analysis. The objective of this framework is to go beyond the current limits of aircraft performance through simultaneous design optimization of aerodynamic shape, structural sizing and control system. The control system uses load alleviation to reduce the critical structural loads. Time-domain analysis of the aircraft performing an altitude change maneuver and encountering an atmospheric gust is included in the design process. The optimal trade-off between aerodynamics, structures and control system is found by maximizing the endurance subjected to stress and maneuverability constraints. Two cases — with and without load alleviation system — are considered. Due to the proposed MDO framework, the inclusion of load alleviation system in design leads to a significant increase in endurance performance.

Hugh H. T. Liu

Papers

Formation UAV flight control using virtual structure and motion synchronization

Decentralized Localization of Sparsely-Communicating Robot Networks: A Centralized-Equivalent Approach

A cooperative UAV/UGV platform for wildfire detection and fighting

Model-Predictive Gust Load Alleviation Controller for a Highly Flexible Aircraft

Aeroservoelastic Design Optimization of a Flexible Wing