A growing number of Cyber-Physical Systems (CPS) domains, such as environment, transportation, energy, and disaster response, involve humans in non-trivial ways. Humans act as sensors in these scenarios when they contribute data (either directly or via sensors they own) that a CPS application can use. Using humans as sensors (commonly known as social sensing or crowdsensing) is an emerging paradigm, which provides unprecedented opportunities to sense the physical world in an inexpensive, versatile and scalable manner. However, these benefits are based on the assumption that the human-sensed data are reliable, but this is not always the case. In order for social sensing to become a viable component in CPS feedback loops, there is a critical need to understand the correctness of collected observations from unreliable individuals. This challenge is referred to as reliable social sensing. The objective of this project is to develop a new Reliable Social Sensing Model (RSSM) and system prototype, which enables correct reconstruction of states of physical environment from unreliable human sensors. This project leverages and innovates techniques in estimation theory and CPS to fill a critical gap in the rigorous analysis of human-sensed information, thereby providing a reliable social sensing component to build robust CPS with humans-in-the-loop. This project contains three key components. First, a RSSM will be developed to formally reason about the correctness of collective human observations and accurately assess the quality of analysis results. Second, a new reliable social sensing system prototype will be built to integrate the proposed RSSM with the state-of-the-art data processing techniques to handle different types of human sensed data. Third, by evaluating the proposed model and system through a real world social sensing application, the project will effectively validate the correctness of the RSSM and provide new insights into modeling humans as sensors for future research. The success of the project and follow-up work inspired by it could lead to a paradigm shift in CPS with human-in-the-loop by explicitly incorporating rigorous accuracy assessment into the development of new theories, systems and applications that rely on the collective observations from massive human sensors. The proposal is timely due to the increasing interests in social networks, big data, and human-in-the-loop systems, as well as the proliferation of computing artifacts that interact with or monitor the physical world. This research project will also contribute to the curriculum of CPS and Social Sensing courses, and will engage undergraduate and graduate students in STEM disciplines and from underrepresented groups.

Buildings are complex systems with profound impact on human health, productivity, comfort, and energy consumption. Smart building technology promises to improve many aspects of building operation by applying sensor data toward more informed and precise building operation. Smart buildings are one important dimension of enabling sustainable Smart Cities. One of the challenges in smart buildings is the selection, placement, and installation of multiple sensors in the building. This can be both an expensive and time consuming process. Poor placement of sensors can have a significant adverse impact on the ability to obtain energy savings. This research project aims to improve the scalability of smart building applications by developing new techniques called collaborative sensing that estimate the sensor data of one building based on sensor data collected in other buildings. The technique exploits patterns in sensor data that result from common patterns in the design and construction of buildings. If successful, this technique will create a fundamental shift in the scalability of smart building applications, such that they can be applied to a new building without the need to install new instrumentation. Additionally, the underlying mathematical techniques will generalize to other aspects of the built environment where patterns in design, construction, or usage create patterns in sensor data. Smart building technology promises to improve many aspects of building operation by collecting and analyzing sensor data to support informed and precise building operation. However, adoption of smart building applications is inhibited by the fact that new sensors must be installed in every building, and that optimization of sensor placement may be difficult and require significant experimentation and effort. This research project develops an innovative approach based on the notion of collaborative sensing. In this approach the sensor data of one building is estimated based on sensor data collected in other buildings. The basic premise is that common design and construction patterns for buildings create a repeating structure in their sensor data. Thus, a sparse sensing basis can be used to represent sensor data from a broad range of buildings. A model of a building can be constructed from this sensing basis using only a small amount of data, such as utility meter readings, climate zone, and square footage. This low-dimensionality model can then be used to reconstruct sensor data for the building based on high-fidelity data collected in other buildings. This approach aims to create a shift to a new paradigm in which smart building functionality can be applied to new buildings without the need to install specialized instrumentation. Preliminary testing using publicly available sub-metering data from 100's of buildings indicate that this approach is not only more scalable but also sometimes more accurate than state-of-the-art alternatives. If successful, this research will create a fundamental shift in the scalability of smart building applications. The underlying mathematical techniques will generalize to other aspects of the built environment where patterns in design, construction, or usage create patterns in sensor data. These techniques will be encapsulated in a Web service that allows people anywhere in the world to apply the proposed techniques to their own building. The project will contribute to the National Science Foundation's dual missions of research and education, and both graduate and undergraduate researchers will be involved in all phases of this research.

This EAGER project on Smart and Connected Communities focuses on developing new fundamental models of urban parking in order to address issues of congestion that negatively impact mobility and health. Traffic congestions are increasingly becoming bottlenecks to sustainable urban growth as infrastructures are being stretched to their limits. A significant amount-up to 40%-of all surface level traffic in urban areas stems from drivers looking for parking. This project will develop new parking management tools (algorithms for cities and apps for drivers) that allow municipalities to achieve better congestion control and enable drivers to act more efficiently. These tools are more targeted, robust and accurate than the current control scheme of only using price to influence the average occupancy rate over a city. This project will result in fundamental advances in queuing theory and mechanism design. Specifically, the models study circulating traffic at block level resolution and the role of information plays in driver decisions. The three main thrusts of the project are: 1) Develop a queue-flow network model of traffic informed by real data that captures network topology and spatio-temporal behavior. 2) Impose a game theoretic structure on the queue-flow network that captures the strategic nature of heterogeneous users. 3) Create a living lab experimental platform in collaboration with the city of Seattle and industry partners for validation of our theories. This project engages with the City of Seattle, industrial partners such as Sidewalk Labs, and undergraduate students. Seattle will provide data and the opportunities to test and validate the results developed, industrial partners will provide technical support, and students will develop mobile apps and learn how a modern smart city can be managed. If successful, this project provides a demonstration of how cities, academia, and industry can partner to conduct rigorous research that will have short-term, practical impact.

Many complex engineering systems involve interactions among a large number of agents with coupled dynamics and decisions due to their shared environment and resources. Such systems are often operated using a hierarchical architecture, where a coordinator determines some macroscopic control signal to steer the population to achieve a desired group objective while respecting local preferences and constraints for individual agents. Examples include electricity demand response programs, ground and air transportation systems, data center power management, robotic networks, among others. The goal of this project is to establish new control and game theoretic foundations, along with numerical algorithms, to enable formal and scalable design of hierarchical population control systems. In contrast to the existing literature that primarily focuses on static strategic agents, this project will consider both strategic and non-strategic agents with nontrivial dynamics. The project involves three tasks. (i) First, it will establish control theoretic foundations for hierarchical population control of non-strategic agents (HPCN). Each non-strategic agent is associated with a predefined local response rule and is modeled as a hybrid system. A novel approach based on abstraction of stochastic hybrid systems (SHS) will be investigated to solve the HPCN problem. (ii) The project will also develop a uniform-price dynamic mechanism design framework for hierarchical population control of strategic agents (HPCS). The framework is based the near-Nash equilibrium concept that can facilitate the analysis of the game-theoretic population behaviors. Advanced bi-level optimization algorithms will also be developed to address the computational challenges associated with the proposed mechanism design approach. (iii) The two proposed hierarchical population control frameworks will be used to study important demand response applications for the future power grid. This research will significantly advance our understanding in complex engineering systems that involve coordination of a large population of dynamic agents. In collaboration with the Pacific Northwest National Laboratory, the project is also expected to yield practical algorithms and numerical tools for the design of electricity demand response programs. Moreover, the project will impact several education activities such as use of new pedagogical tools in teaching, involvement of undergraduate students in research, and research integration with teaching.

This project aims to develop innovative design automation methodologies and algorithms for software synthesis of cyber-physical systems (CPS), which have applications in key sectors such as automotive, aerospace, healthcare, and industrial automation. Software has become critical and drives future innovations for many such systems, but faces significant challenges in its development, in particular regarding the formulation, exploration and validation of timing constraints. The results from this project will address critical timing challenges in CPS software development, and lead to correct, predictable and efficient software implementations. In addition to disseminating the results through publications and workshops, the PI will collaborate with industry partners on transitioning the research findings into practice. Leveraging the research activities, the PI will develop an integrated education program that focuses on the interdisciplinary education of K-12, undergraduate and graduate students, through Lego Mindstorms labs development and contest organization, new CPS course development, and textbook writing. The project will develop, a software synthesis framework that addresses the timing challenges in CPS by quantitatively exploring timing constraints for multiple conflicting design metrics and across multiple abstraction layers, and using these timing constraints to drive the design space exploration. Developing the framework includes three closely-related research themes: (1) formulating and exploring timing contracts to co-design functionality and software architecture with respect to various design metrics (e.g., performance, security, schedulability) and to carry out hierarchical refinement across abstraction layers, (2) exploring the generation of software tasks from functional models and the mapping of those tasks onto hardware platforms with holistic timing consideration throughout the synthesis process, and (3) co-simulating functional and architectural models with explicit representation and evaluation of timing contracts to complement the proposed analytical synthesis algorithms.

CPS: Synergy: Collaborative Research: Learning control sharing strategies for assistive cyber-physical systems Assistive machines - like powered wheelchairs, myoelectric prostheses and robotic arms - promote independence and ability in those with severe motor impairments. As the state- of-the-art in these assistive Cyber-Physical Systems (CPSs) advances, more dexterous and capable machines hold the promise to revolutionize ways in which those with motor impairments can interact within society and with their loved ones, and to care for themselves with independence. However, as these machines become more capable, they often also become more complex. Which raises the question: how to control this added complexity? A new paradigm is proposed for controlling complex assistive Cyber-Physical Systems (CPSs), like robotic arms mounted on wheelchairs, via simple low-dimensional control interfaces that are accessible to persons with severe motor impairments, like 2-D joysticks or 1-D Sip-N-Puff interfaces. Traditional interfaces cover only a portion of the control space, and during teleoperation it is necessary to switch between different control modes to access the full control space. Robotics automation may be leveraged to anticipate when to switch between different control modes. This approach is a departure from the majority of control sharing approaches within assistive domains, which either partition the control space and allocate different portions to the robot and human, or augment the human's control signals to bridge the dimensionality gap. How to best share control within assistive domains remains an open question, and an appealing characteristic of this approach is that the user is kept maximally in control since their signals are not altered or augmented. The public health impact is significant, by increasing the independence of those with severe motor impairments and/or paralysis. Multiple efforts will facilitate large-scale deployment of our results, including a collaboration with Kinova, a manufacturer of assistive robotic arms, and a partnership with Rehabilitation Institute of Chicago. The proposal introduces a formalism for assistive mode-switching that is grounded in hybrid dynamical systems theory, and aims to ease the burden of teleoperating high-dimensional assistive robots. By modeling this CPS as a hybrid dynamical system, assistance can be modeled as optimization over a desired cost function. The system's uncertainty over the user's goals can be modeled via a Partially Observable Markov Decision Processes. This model provides the natural scaffolding for learning user preferences. Through user studies, this project aims to address the following research questions: (Q1) Expense: How expensive is mode-switching? (Q2) Customization Need: Do we need to learn mode-switching from specific users? (Q3) Learning Assistance: How can we learn mode-switching paradigms from a user? (Q4) Goal Uncertainty: How should the assistance act under goal uncertainty? How will users respond? The proposal leverages the teams shared expertise in manipulation, algorithm development, and deploying real-world robotic systems. The proposal also leverages the teams complementary strengths on deploying advanced manipulation platforms, robotic motion planning and manipulation, and human-robot comanipulation, and on robot learning from human demonstration, control policy adaptation, and human rehabilitation. The proposed work targets the easier operation of robotic arms by severely paralyzed users. The need to control many degrees of freedom (DoF) gives rise to mode-switching during teleoperation. The switching itself can be cumbersome even with 2- and 3-axis joysticks, and becomes prohibitively so with more limited (1-D) interfaces. Easing the operation of switching not only lowers this burden on those already able to operate robotic arms, but may open use to populations to whom assistive robotic arms are currently inaccessible. This work is clearly synergistic: at the intersection of robotic manipulation, human rehabilitation, control theory, machine learning, human-robot interaction and clinical studies. The project addresses the science of CPS by developing new models of the interaction dynamics between the system and the user, the technology of CPS by developing new interfaces and interaction modalities with strong theoretical foundations, and the engineering of CPS by deploying our algorithms on real robot hardware and extensive studies with able-bodied and users with sprinal cord injuries.

The goal of this project is to enable greater sharing of crowd-sensed data, while achieving provable privacy guarantees. Our approach is to limit knowledge of the location traces of crowd-sensed data to exclude the origin and destination, and then consider the system using techniques from distributed control and differential privacy: this enables exploration of the theoretical bounds on the cost of privacy. The achieved results will create a new approach for building and analyzing networked cyber-physical systems (CPS) that permits users to make decisions on crowd-sensed data, and at the same time protects their privacy in a rigorous sense. The project has focused outreach activities in developing a software environment for students to explore privacy-performance trade-offs in transportation operations and an advanced course on security and privacy of CPS. In our technical approach, we focus on the privacy of user inputs, such as the origin (initial state), destination (preference), and utility functions. This enables us to model and analyze how the crowd-sensed data can be used to infer these sensitive inputs, using techniques adapted from the fields of distributed control and differential privacy. The various notions of privacy will support a broad research program, including performance limits of private network control, design principles for different classes of cyber-physical systems, and new location privacy metrics that take into account location popularity. These contributions advance the field of formal analysis of probabilistic models, and the burgeoning subfield of privacy in control and optimization. The theoretical research will be motivated by and evaluated on simulations and proof-of-concept implementations in the context of crowd-sourced congestion detection.

Battery-free sensors are annually attached to billions of items including pharmaceutical drugs, clothes, and manufacturing parts. The fundamental challenge with these sensors is that they are only reliable at short distances. As a result, today's systems for communicating with and localizing battery-free sensors are crippled by the limited range. This research proposes a cyber-physical system architecture that can overcome this challenge to enable sensing, communicating with, and localizing these sensors at an unprecedented scale. In doing so, the research promises to address multi-billion-dollar challenges facing multiple industries today in shrinkage, inventory control, and finding misplaced items. It can also drastically reduce energy consumption in the internet-of-things by demonstrating how to boost the communication range of battery-free sensors. The research results will be disseminated by publishing in academic venues, working closely with industry, public outreach initiatives, interdisciplinary classes, and releasing software libraries and hardware schematics to the research community. Realizing this vision requires addressing challenges along three fronts: power, accuracy, and interference. First, the low-power nature of battery-free sensors fundamentally limits their communication range to within tens of centimeters to few meters. Second, mapping these sensors to the physical world not only requires the ability to detect them but also to accurately localize them. Finally, cyber-physical systems at scale need to manage wireless interference from thousands or tens of thousands of sensors. The proposal pioneers a cyber-physical system that combines the agility of drones with the sensing capabilities of radio signals to address these challenges. Technically, it introduces a new breed of communication relays, designed particularly for cyber-physical systems, and describes the algorithms that enable localization, sensing, and navigation through drone-mounted relays. The resulting system will be evaluated empirically via software-hardware implementation and real-world deployment.

Close to one million lives could be saved each year in the United States alone by organ transplantation if a sufficient number of organs were available, potentially preventing 35% of all deaths in the nation. In contrast, due to critical shortages of organs, only about 28,000 organ transplants are performed each year, with a waiting list of 120,000 people. A promising potential solution to this shortage is the high quality and production-scale 3D printing of human organs by bio-additive manufacturing (Bio-AM). However, as articulated in the 2016 NSF workshop on Additive Manufacturing for Healthcare, the current use of Bio-AM is impeded by poor organ quality, resulting in part from inadequate process monitoring and lack of integrated process control strategies. As a result, despite enormous strides, it is still not possible to scale Bio-AM to the stringent quality standards mandated for organ transplants. This research will address the compelling need to incorporate advanced process models into sensor-based process control strategies needed to prevent cell damage, decrease cell placement errors, and improve tissue functioning in Bio-AM. If successful methods for reliable, high-volume, high-quality, and safe Bio-AM can be realized, it will have profound socioeconomic benefits in terms of public health, medical safety, and drug discovery. The project will engage grade 6-12 STEM teachers through the Research Experiences for Teachers (RET) Innovation-based Manufacturing Program by providing opportunities for teachers to engage in cutting edge research in Bio-AM. The goal of the project is to reliably produce viable 3D printed biological constructs (mini-tissues). The central approach is to couple in-situ heterogeneous sensor-based monitoring and real-time closed-loop process control approaches for ensuring the reliable printing of biological constructs. The work involves the following four objectives: (1) using experimentation and modeling to understand the causal effect of process-material interactions on specific Bio-AM defects, (2) employing sensors to detect incipient defects during printing, (3) diagnosing the root causes of detected defects by analyzing sensor data using real-time decision-theoretic models, and (4) preventing propagation of defects through closed-loop process control. The investigation will contribute: (1) fundamental understanding of the causal bio-physical process interactions that govern the quality of printed biological tissue constructs through empirical investigation and sensor-based data analytics, (2) new mathematical models for predicting the layer quality by taking into consideration the complex and dynamic tissue maturation phenomena, (3) real-time and computationally efficient decision-making for accurate classification of defects from sensor data, and (4) a two-stage, real-time, closed-loop quality control approach for preventing propagation of defects by executing smart corrective actions during the printing process.

Realizing the vision of pervasive Internet of Things (IoT) that will endow a myriad of physical objects that include sensors, wearables, mundane objects, and connected vehicles, with cyber capabilities, is contingent upon effectively managing the interwoven synergies across its cyber and physical realms. The overarching goal of this project is to develop a novel cyber-physical system (CPS) science that can enable effective modeling, optimization, and management of the IoT as a fully-fledged CPS. Developing this science will, in turn, catalyze the deployment of the IoT and its numerous services that range from smart healthcare, to smart buildings and intelligent transportation, thus having a broad societal impact. Enabling the IoT will also expedite the transformation of cities and communities, into truly smart environments thus enhancing the quality of life of their residents. The proposed research is coupled with an educational plan that includes substantial involvement of graduate and undergraduate students in cross-cutting CPS research, as well as IoT-centric outreach activities targeted at local high school students from the under-represented groups. This synergistic integration of research and education will contribute to training a new workforce that is equipped with the necessary CPS skills needed to work in the emerging IoT domains. The proposed research will develop a foundational framework for the modeling and performance analysis of the IoT that will facilitate the management of resources, such as energy and computation, jointly across its cyber and physical realms. By leveraging interdisciplinary tools from stochastic geometry, distributed optimization, and operations research, the proposed framework will yield a number of results that include new statistical models and CPS performance metrics for characterizing the cyber-physical operation of IoT as well as novel distributed optimization algorithms that will adapt the cyber-physical operational state of the IoT devices to the dynamics of the CPS environment, while being cognizant of their stringent resource constraints. The developed theory will be validated using extensive simulations as well as basic experiments. The ensuing outcomes are expected to yield a fundamentally new CPS science that will transform the way in which the IoT is modeled, analyzed, and optimized. The foundational nature of this research will further ensure that its impacts will cut across multiple CPS domains, ranging from energy to transportation and healthcare.