Real-Time and Energy-Efficient Routing for Industrial Wireless Sensor-Actuator Networks

With the emergence of industrial standards such as WirelessHART, process industries are adopting Wireless Sensor-Actuator Networks (WSANs) that enable sensors and actuators to communicate through low-power wireless mesh networks. Industrial monitoring and control applications require real-time communication among sensors, controllers and actuators within end-to-end deadlines. Deadline misses may lead to production inefficiency, equipment destruction to irreparable financial and environmental impacts. Moreover, due to the large geographic area and harsh conditions of many industrial plants, it is labor-intensive or dan- gerous to change batteries of field devices. It is therefore important to achieve long network lifetime with battery-powered devices. This dissertation tackles these challenges and make a series of contributions. (1) We present a new end-to-end delay analysis for feedback control loops whose transmissions are scheduled based on the Earliest Deadline First policy. (2) We propose a new real-time routing algorithm that increases the real-time capacity of WSANs by exploiting the insights of the delay analysis. (3) We develop an energy-efficient routing algorithm to improve the network lifetime while maintaining path diversity for reliable communication. (4) Finally, we design a distributed game-theoretic algorithm to allocate sensing applications with near-optimal quality of sensing

Monitoring using Heterogeneous Autonomous Agents.

This dissertation studies problems involving different types of autonomous agents observing objects of interests in an area. Three types of agents are considered: mobile agents, stationary agents, and marsupial agents, i.e., agents capable of deploying other agents or being deployed themselves. Objects can be mobile or stationary. The problem of a mobile agent without fuel constraints revisiting stationary objects is formulated. Visits to objects are dictated by revisit deadlines, i.e., the maximum time that can elapse between two visits to the same object. The problem is shown to be NP-complete and heuristics are provided to generate paths for the agent. Almost periodic paths are proven to exist. The efficacy of the heuristics is shown through simulation. A variant of the problem where the agent has a finite fuel capacity and purchases fuel is treated. Almost periodic solutions to this problem are also shown to exist and an algorithm to compute the minimal cost path is provided. A problem where mobile and stationary agents cooperate to track a mobile object is formulated, shown to be NP-hard, and a heuristic is given to compute paths for the mobile agents. Optimal configurations for the stationary agents are then studied. Several methods are provided to optimally place the stationary agents; these methods are the maximization of Fisher information, the minimization of the probability of misclassification, and the minimization of the penalty incurred by the placement. A method to compute optimal revisit deadlines for the stationary agents is given. The placement methods are compared and their effectiveness shown using numerical results. The problem of two marsupial agents, one carrier and one passenger, performing a general monitoring task using a constrained optimization formulation is stated. Necessary conditions for optimal paths are provided for cases accounting for constrained release of the passenger, termination conditions for the task, as well as retrieval and constrained retrieval of the passenger. A problem involving two marsupial agents collecting information about a stationary object while avoiding detection is then formulated. Necessary conditions for optimal paths are provided and rectilinear motion is demonstrated to be optimal for both agents.PhDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111439/1/jfargeas_1.pd

Deep intelligence as a service: A real-time scheduling perspective

This thesis presents a new type of cloud service, called {\em deep intelligence as a service\/}, that is expected to become increasingly common in the near future to support emerging "smart" embedded applications. This work offers a real-time scheduling model motivated by the special needs of embedded applications that use this service. A simple run-time scheduler is proposed for the server and prove an approximation bound in terms of application-perceived service utility. The service is implemented on representative device hardware and tested with a machine vision application illustrating the advantages of our scheme. The work is motivated by the proliferation of increasingly ubiquitous but resource-constrained embedded devices (often referred to as the Internet of Things -- IoT -- devices) and the growing desire to endow them with advanced interaction capabilities, such as voice recognition or machine vision. The trend suggests that machine intelligence will be increasingly offloaded to cloud or edge services that will offer advanced capabilities to the otherwise simple devices. New services will feature farms of complex trainable (or pre-trained) classifiers that client-side applications can send data to in order to gain certain types of advanced functionality, such as face recognition, voice command recognition, gesture recognition, or other. These new services will revolutionize human interaction with their physical environment, but may impose interesting real-time scheduling challenges in order to maintain responsiveness while maximizing service quality. This work includes challenges, designs for an efficient real-time scheduling algorithm for the new machine intelligence service, and evaluation on an implemented prototype

Optimization and Communication in UAV Networks

UAVs are becoming a reality and attract increasing attention. They can be remotely controlled or completely autonomous and be used alone or as a fleet and in a large set of applications. They are constrained by hardware since they cannot be too heavy and rely on batteries. Their use still raises a large set of exciting new challenges in terms of trajectory optimization and positioning when they are used alone or in cooperation, and communication when they evolve in swarm, to name but a few examples. This book presents some new original contributions regarding UAV or UAV swarm optimization and communication aspects

Deep learning for the internet of things

The proliferation of IoT devices heralds the emergence of intelligent embedded ecosystems that can collectively learn and that interact with humans in a human-like fashion. Recent advances in deep learning revolutionized related fields, such as vision and speech recognition, but the existing techniques remain far from efficient for resource-constrained embedded systems. This dissertation pioneers a broad research agenda on Deep Learning for IoT. By bridging state-of-the-art IoT and deep learning concepts, I hope to enable a future sensor-rich world that is smarter, more dependable, and more friendly, drawing on foundations borrowed from areas as diverse as sensing, embedded systems, machine learning, data mining, and real-time computing. Collectively, this dissertation addresses five research questions related to architecture, performance, predictability and implementation. First, are current deep neural networks fundamentally well-suited for learning from time-series data collected from physical processes, characteristic to IoT applications? If not, what architectural solutions and foundational building blocks are needed? Second, how to reduce the resource consumption of deep learning models such that they can be efficiently deployed on IoT devices or edge servers? Third, how to minimize the human cost of employing deep learning (namely, the cost of data labeling in IoT applications)? Fourth, how to predict uncertainty in deep learning outputs? Finally, how to design deep learning services that meet responsiveness and quality needed for IoT systems? This dissertation elaborates on these core problems and their emerging solutions to help lay a foundation for building IoT systems enriched with effective, efficient, and reliable deep learning models

Power System State Estimation and Renewable Energy Optimization in Smart Grids

The future smart grid will benefit from real-time monitoring, automated outage management, increased renewable energy penetration, and enhanced consumer involvement. Among the many research areas related to smart grids, this dissertation will focus on two important topics: power system state estimation using phasor measurement units (PMUs), and optimization for renewable energy integration. In the first topic, we consider power system state estimation using PMUs, when phase angle mismatch exists in the measurements. In particular, we build a measurement model that takes into account the measurement phase angle mismatch. We then propose algorithms to increase state estimation accuracy by taking into account the phase angle mismatch. Based on the proposed measurement model, we derive the posterior Cramér-Rao bound on the estimation error, and propose a method for PMU placement in the grid. Using numerical examples, we show that by considering the phase angle mismatch in the measurements, the estimation accuracy can be significantly improved compared with the traditional weighted least-squares estimator or Kalman filtering. We also show that using the proposed PMU placement strategy can increase the estimation accuracy by placing a limited number of PMUs in proper locations. In the second topic, we consider optimization for renewable energy integration in smart grids. We first consider a scenario where individual energy users own on-site renewable generators, and can both purchase and sell electricity to the main grid. Under this setup, we develop a method for parallel load scheduling of different energy users, with the goal of reducing the overall cost to energy users as well as to energy providers. The goal is achieved by finding the optimal load schedule of each individual energy user in a parallel distributed manner, to flatten the overall load of all the energy users. We then consider the case of a micro-grid, or an isolated grid, with a large penetration of renewable energy. In this case, we jointly optimize the energy storage and renewable generator capacity, in order to ensure an uninterrupted power supply with minimum costs. To handle the large dimensionality of the problem due to large historical datasets used, we reformulate the original optimization problem as a consensus problem, and use the alternating direction method of multipliers to solve for the optimal solution in a distributed manner