This paper presents control and coordination algorithms for groups of vehicles. The focus is on autonomous vehicle networks performing distributed sensing tasks where each vehicle plays the role of a mobile tunable sensor. The paper proposes gradient descent algorithms for a class of utility functions which encode optimal coverage and sensing policies. The resulting closed-loop behavior is adaptive, distributed, asynchronous, and verifiably correct.

Coverage control for mobile sensing networks

Convex bodies: the brunn–minkowski theory

“Multivalued Analysis” is the theory of set-valued maps (called multifonctions) and has important applications in many different areas. Multivalued analysis is a remarkable mixture of many different parts of mathematics such as point-set topology, measure theory and nonlinear functional analysis. It is also closely related to “Nonsmooth Analysis” (Chapter 5) and in fact one of the main motivations behind the development of the theory, was in order to provide necessary analytical tools for the study of problems in nonsmooth analysis. It is not a coincidence that the development of the two fields coincide chronologically and follow parallel paths. Today multivalued analysis is a mature mathematical field with its own methods, techniques and applications that range from social and economic sciences to biological sciences and engineering. There is no doubt that a modern treatise on “Nonlinear Functional Analysis” can not afford the luxury of ignoring multivalued analysis. The omission of the theory of multifunctions will drastically limit the possible applications.

SET-Valued Analysis

Microgrids energy management systems: A critical review on methods, solutions, and prospects

This paper presents a test benchmark model for the evaluation of fault detection and accommodation schemes. This benchmark model deals with the wind turbine on a system level, and it includes sensor, actuator, and system faults, namely faults in the pitch system, the drive train, the generator, and the converter system. Since it is a system-level model, converter and pitch system models are simplified because these are controlled by internal controllers working at higher frequencies than the system model. The model represents a three-bladed pitch-controlled variable-speed wind turbine with a nominal power of 4.8 MW. The fault detection and isolation (FDI) problem was addressed by several teams, and five of the solutions are compared in the second part of this paper. This comparison relies on additional test data in which the faults occur in different operating conditions than in the test data used for the FDI design.

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Fault-Tolerant Control of Wind Turbines: A Benchmark Model

Some remarks on potential field constructions in a multi-obstacle environment

The present paper deals with the interplay between healthy and faulty sensor functioning in a multisensor scheme based on a switching control strategy. Fault tolerance guarantees have been recently obtained in this framework based upon the characterisation of invariant sets for state estimations in healthy and faulty functioning. A source of conservativeness of this approach is related to the issue of sensor recovery. A common working hypothesis has been to assume that once a sensor switches to faulty functioning it can no longer be used by the control mechanism even if at an ulterior moment it switches back to healthy functioning. In the current paper, we present necessary and sufficient conditions for the acknowledgement of sensor recovery and we propose and compare different techniques for the reintegration of sensors in the closed-loop decision-making mechanism.

A discussion on sensor recovery techniques for fault tolerant multisensor schemes

This paper proposes an interval observer-based sensor fault detection and isolation (FDI) approach for the closed-loop systems. In this proposed approach, residuals are defined in such a way that their components are independent of each other at the time instant after fault occurrence, namely kf + 1, where kf denotes the fault occurrence time instant. In this way, it is guaranteed that at kf + 1 the changes in each component of the residuals are only related to the fault in the corresponding sensor. By detecting the threshold violation of the corresponding residual interval components, the proposed method can detect and isolate sensor faults at that time instant. At the end of this paper, a numerical example is used to present the effectiveness of the approach.

/pdf/sensor-fault-detection-and-isolation-using-interval-3oax5mcfto.pdf

Sensor-fault detection and isolation using interval observers

Motion planning problems benefit greatly from the properties of differential flatness, which are widely employed for trajectory generation and controller design. This paper aims to highlight the fact that various flat representations of a system can have different implications in the trajectory generation and tracking objectives. In particular, we consider a fixed-wing UAV (Unmanned Aerial Vehicle) and analyze various flat representations. We reformulate the trajectory generation and tracking problem in terms of different flat outputs and analyze the optimal cost, constraints satisfaction, tracking error and computational complexity. Insights on the future work complete the analysis. The research shows promising directions, especially in the area of disturbance rejection and robust control.

Analysis of alternative flat representations of a UAV for trajectory generation and tracking

The paper proposes a cheap hybrid ground-air sensor network for environmental parameter measurements. The ground sensors are grouped into clusters, each cluster having several sensory nodes connected to a cluster head that sends the relevant data to the aerial, mobile nodes - unmanned aerial vehicles (UAVs). Thus, using optimal trajectories, the UAVs are used both for measuring directly environmental parameters, as well as for collecting data from ground sensors. The authors present the modules' implementation of the hybrid system: ordinary sensory nodes, cluster heads, ground control stations, communication modems and UAV platforms. Finally, the performances of the realized hybrid network are analyzed from multiple points of view: energy consumption, time, and data acquisition efficiency.

Florin Stoican

Papers

Some remarks on potential field constructions in a multi-obstacle environment

A discussion on sensor recovery techniques for fault tolerant multisensor schemes

Sensor-fault detection and isolation using interval observers

Analysis of alternative flat representations of a UAV for trajectory generation and tracking

Hybrid Sensor Network for Monitoring Environmental Parameters