A.G. Alleyne

• University of Illinois Urbana-Champaign

Provides society information that may include news, reviews or technical notes that should be of interest to practitioners and researchers.

In this paper we present a low-complexity hierarchical control approach to fan-coil-based HVAC systems, applicable to shopping centers as exemplified through a case study of a Danish shopping center. Although Model Predictive Control remains the optimal approach performance-wise, we show that we can recover 66 % of the performance with the proposed...

Electrification for mobile systems is a long-term trend that touches every mode of transport we currently use. As these systems proliferate, and increase in power levels, there is a strong desire to increase the power density of the electrified systems on board. A key barrier to increased electrical power density is the associated thermal managemen...

In this chapter, we delve deeper into understanding modeling and control approaches for one of the important subsystems in an intelligent building, the HVAC system. Specifically, Vapor Compression Systems (VCS) are the primary energy systems in building air conditioning, heat pump, and refrigeration systems. We will discuss standard methods for con...

The current trend of electrification in modern aircraft has driven a need to design and control onboard power systems that are capable of meeting strict performance requirements while maximizing overall system efficiency. Model-based control provides the opportunity to meet the increased demands on system performance, but the development of a suita...

This work presents a passivity-based stability guarantee for the decentralized control of nonlinear power flow systems. This class of systems is characterized using a graph-based modeling approach, where vertices represent capacitive elements that store energy and edges represent power flow between these capacitive elements. Due to their complexity...

Increased power levels in more electric aircraft (MEA) bring opportunities to optimize energy flow in multi-physics domains to benefit the power system's stability and aircraft fuel economy. This paper introduces thermal energy inherent in the cabin air and aircraft fuel as a dynamic management solution to offset stochastic load power in the MEA po...

In this paper a decentralized control algorithm for systems composed of $N$ dynamically decoupled agents, coupled by feasibility constraints, is presented. The control problem is divided into $N$ optimal control sub-problems and a communication scheme is proposed to decouple computations. The derivative of the solution of each sub-problem is used t...

Extended durations of liquid refrigerant ingestion by the compressor of a vapor compression system (VCS) can lead to damage or failure of this component. While this can be prevented by inserting an accumulator between the evaporator and compressor, this addition of hardware may be undesirable for applications in which the weight or size of the ther...

More electric aircraft (MEA) include higher power ratings and more power electronics than conventional aircraft. With electrification comes increased multi-physical interaction between power systems, especially in electrical and thermal domains. It is desirable to develop an accurate and fast system-level model that captures the dynamics of multipl...

Model-based control design has the ability to meet the strict closed-loop control requirements imposed by the rising performance and efficiency demands on modern engineering systems. While many modeling frameworks develop control-oriented models based on the underlying physics of the system, most are energy domain specific and do not facilitate the...

This paper develops a two-stage nonlinear nonconvex control approach for autonomous vehicle driving during highway cruise conditions. The goal of the controller is to track the centerline of the roadway while avoiding obstacles. An outer-loop nonlinear model predictive control is adopted for generating the collision-free trajectory with the resulta...

This paper integrates a previously developed iterative learning identification (ILI) (Liu, N., and Alleyne, A. G., 2016, "Iterative Learning Identification for Linear Time-Varying Systems," IEEE Trans. Control Syst. Technol., 24(1), pp. 310-317) and iterative learning control (ILC) algorithms (Bristow, D. A., Tharayil, M., and Alleyne, A. G., 2006,...

This paper presents a theoretical study on the dynamic shape control problem of deployable mesh reflectors (DMRs) via feedback approaches. The reflector structure is simplified from a nonlinear model to be quasi-static with respect to temperature variations but dynamic with respect to mechanical vibrations. The orbital cycle is segmented into multi...

Calcium phosphate (CaP) materials have been proven to be efficacious as bone scaffold materials, but are difficult to fabricate into complex architectures because of the high processing temperatures required. In contrast, polymeric materials are easily formed into scaffolds with near-net-shape forms of patient-specific defects and with domains of d...

This study has proposed a method of improving vehicle ride quality capitalizing on repetitive driving. When the vehicle is driving over the same road features repetitively, a drive-history map is created, and an optimal suspension profile is generated for that road feature. When it is detected that the vehicle is travelling over the same road featu...

The challenge of managing heat dissipation and enforcing operational constraints on temperature within a high-performance tactical aircraft is considered. For these systems, power density of the electrical equipment and the associated thermal loads are quickly outpacing the means of conventional thermal management systems (TMS) to provide on-demand...

This paper demonstrates that the dynamic relationship between the power consumption of a vapor compression system under closed loop control and its evaporator and condenser fan inputs is well described about a nominal operating point by a Wiener model, which is useful for extremum seeking controller design. Information about the input dynamics from...

This two-part paper presents the development of a hierarchical control framework for the control of power flow throughout mobile systems. These vehicles are comprised of multiple interconnected systems each with multiple subsystems which exhibit dynamics over a wide range of timescales. These interconnections and the timescale separation pose a sig...

The effects of air humidity on the performance of refrigerant-to-air heat exchangers in vapor compression systems (VCSs) are non-negligible in modeling and control design for some applications. Such applications include both those in which the ambient humidity is expected to vary greatly over time and those in which control of the air outlet humidi...

This two-part paper presents the development of a hierarchical control framework for the control of power flow throughout large-scale systems. Part II presents the application of the graph-based modeling framework and three-level hierarchical control framework to the power systems of an aircraft. The simplified aircraft system includes an engine, e...

This article presents the initial integration of a new and novel additive manufacturing process with a web-based transport of a flexible substrate. The manufacturing process is the Electro-hydrodynamic Jet (E-Jet) printing process and the transport is a Roll-to-Roll (R2R) system. E-Jet printing affords a wide array of materials to be deposited at v...

A decentralized cooperative driving Non Linear Model Predictive Control (NLMPC) approach for path following and collision avoidance is presented in this paper. The proposed decentralized approach is based on an information network, which communicates when two or more vehicles are near and so they might collide. In the case in which vehicles are far...

Tailored optical output, such as color purity and efficient optical intensity, are critical considerations for displays, particularly in mobile applications. To this end, we demonstrate a replica molded photonic crystal structure with embedded quantum dots. Electrohydrodynamic jet printing is used to control the position of the quantum dots within...

This review gives an overview of techniques used for high-resolution jet printing that rely on electrohydrodynamically induced flows. Such methods enable the direct, additive patterning of materials with a resolution that can extend below 100 nm to provide unique opportunities not only in scientific studies but also in a range of applications that...

This paper presents a nonlinear control approach to achieve good performances in vehicle path following and collision avoidance when the vehicle is driving under cruise highway conditions. Nonlinear model predictive control (NLMPC) is adopted to achieve online trajectory control based on a simplified vehicle model. GMRES/Continuation algorithm is u...

The sensitivity of energy management strategies (EMS) with respect to variations in drive cycle and system parameters is considered. The design of three strategies is presented: rule-based, stochastic dynamic programming (SDP), and model predictive control (MPC). Each strategy is applied to a series hydraulic hybrid powertrain and validated experim...

Exergy-based analysis and optimization has been successfully used to design a variety of thermal systems to achieve greater efficiency. However, the advantages afforded by exergy destruction minimization (EDM) at the design stage have not been translated to closed-loop operation of thermal systems such as vapor compression systems (VCSs). Through o...

A predictive control scheme is designed to control a transport refrigeration system, such as a delivery truck, that includes a vapor compression cycle configured in parallel with a thermal energy storage (TES) unit. A novel approach to TES utilization is introduced and is based on the current and future estimate of the vehicle driving state and loa...

Most work in dynamic heat exchanger modeling for control design can be classified as either a finite volume or a moving boundary formulation. These approaches represent fundamentally different discretization approaches and are often characterized as contrasting accuracy with simulation speed. This work challenges that characterization by validating...

In the early stages of control system development, designers often require multiple iterations for purposes of validating control designs in simulation. This has the potential to make high fidelity models undesirable due to increased computational complexity and time required for simulation. As a solution, lower fidelity or simplified models are us...

High resolution elevation mapping is useful for precise field operations. To achieve a good operation performance, the requirement of the field shape accuracy can be centimeter-level in some tasks. This paper presents a method of conducting high resolution elevation mapping with vehicle-borne sensors. To achieve this purpose, a laser range sensor o...

As the cost and complexity of modern aircraft systems advance, emphasis has been placed on model-based design as a means for cost effective subsystem optimization. The success of the model-based design process is contingent on accurate prediction of the system response prior to hardware fabrication, but the level of fidelity necessary to achieve th...

This paper presents a two degree of freedom (DOF) controller for combine harvester header height control (HHC). Fundamental limitations to the tracking and disturbance rejection bandwidth for feedback control designs exist in the HHC system due to the considerable actuator delay and underactuated and noncollocated mechanical design. In this work, w...

With vapor compression systems consuming a significant portion of the overall U.S. energy consumption each year, extensive efforts have been made toward the development of control strategies which aim to maximize system efficiency while providing the desired cooling. However, previous control strategies under-utilize a degree of freedom correspondi...

This brief presents a bumpless transfer filter to attenuate signal magnitude bumps at transitions between exogenous feedforward (FF) signals in a feedback/FF control architecture. Importantly, this filter does not modify the carefully constructed exogenous FF signal at time indices away from a signal transition. Filter architecture, stability crite...

Refrigeration is important to sustain high foodstuff quality and lifetime. Keeping the foodstuff within temperature thresholds in supermarkets is also important due to legislative requirements. Failure to do so can result in discarded foodstuff, a penalty fine to the shop owner, and health issues. However, the refrigeration system might not be dime...

We consider the problem of designing a scalable control architecture for large-scale variable-refrigerant-flow (VRF) systems. Using a gray-box modeling approach, and by exploiting the one-way coupling between the fluid dynamics and thermal dynamics, we derive individual linearized models for each class of dynamics. This sufficiently reduces the com...

This paper studies the problem of decentralized control design for thermal control in buildings, to achieve a satisfactory trade-off between underlying performance and robustness objectives. An output-feedback, model predictive framework is used for decentralized control which is based on a reduced order system representation. It entails the use of...

Fundamental understanding of the self-assembly of domains in block-copolymers (BCPs) and capabilities in control of these processes are important for their use as nanoscale templates in various applications. This paper focuses on the self-assembly of spin-cast and printed poly(styrene-block-methyl methacrylate) BCPs on patterned surface wetting lay...

This paper introduces an integrated design and control method for improving the header height control performance of combine harvesters. Due to the legacy design of the mechanical system, the bandwidth of feedback control is limited, which induces a performance bottleneck in further improving the harvesting productivity. To solve this problem, the...

With the advancement of computational power and modeling techniques, automotive and aerospace companies are beginning to utilize highly detailed models throughout the phases of system design and development. Often these systems consist of highly coupled subsystems that span mechanical, electrical, thermal, hydraulic, and pneumatic energy domains. H...

Fabrication of nano/micro-scale functional devices, in the context of a continuous or semi-continuous manufacturing process, is often performed via successive processes in multiple localized zones. As the substrate traverses downstream in the process flow, proper registration of the pre-existing features is necessary prior to entering the next fabr...

Multi-evaporator vapor compression systems (ME-VCSs) are becoming widely used to meet the cooling needs for multiple thermal loads via a single system. As the number of evaporators increases, the size of these systems can make a centralized control approach impractical and computationally expensive; thus, motivating a decentralized control design....

We demonstrate the enhancement of a liquid-based homogenous fluorescence assay using the resonant electric fields from a photonic crystal (PC) surface. Because evanescent fields are confined to the liquid volume nearest to the photonic crystal, we developed a simple approach for integrating a PC fabricated on a silicon substrate within a fluid chan...

This paper presents a design method for robust two degree-of-freedom (DOF) controllers that optimize the control performance with respect to both model uncertainty and signal measurement uncertainty. In many situations, non-causal feedforward is a welcome control addition when closed loop feedback bandwidth limitations exist due to plant dynamics s...

The Electrohydrodynamic-jet (E-jet) printing process combines high resolution printing with a large variety of printing materials, making E-jet suitable for applications ranging from flexible electronics to high resolution biosensors. In this article, we explore a novel E-jet printing application fabricating high-resolution micro-optical devices. E...

Fabrication of nano/micro-scale functional devices oftentimes involves multiple steps. In the context of a continuous or semi-continuous manufacturing process, each fabrication step is performed successively in multiple localized zones. As the substrate or the web traverses downstream in the process flow, proper registration of the pre-existing fea...

This paper combines previously developed non-lifted norm optimal iterative learning control (NNOILC) with a cross coupled formulation resulting in a cross-coupled non-lifted norm optimal iterative learning control (cross-coupled NNOILC). The objective is to improve the contour tracking performance in precision motion control of multi-axis systems w...

In the study, a model inversion based two degree-of-freedom (DOF) controller is proposed to achieve optimal robust performance for multi-input-multi-output (MIMO) system with existence of both model and signal uncertainties. The original plant dynamics are modified by a pre-compensator and a post-compensator to obtain a diagonally dominant matrix,...

This paper studies the problem of thermal control of buildings from the perspective of partitioning them into clusters for decentralized control. A measure of deviation in performance between centralized and decentralized control in the model predictive control framework, referred to as the optimality loss factor, is derived. Another quantity calle...

Self-assembly of block-copolymers provides a route to the fabrication of small (size, <50 nm) and dense (pitch, <100 nm) features with an accuracy that approaches even the demanding specifications for nanomanufacturing set by the semiconductor industry. A key requirement for practical applications, however, is a rapid, high-resolution method for pa...

Maintaining foodstuff within predefined temperature thresholds is important due to legislative requirements and to sustain high foodstuff quality. This is achieved using a refrigeration system. However, these systems might not be dimensioned for hot summer days or possible component performance degradation. A learning based algorithm is proposed in...

This work demonstrates performance improvement in motion control under a particular set of machine system constraints. A high performance industrial magnetic micro-manipulation system, the Minimag, is introduced and modeled with both first principles and system identification. The form of the closed loop controller is constrained by operational bou...

In this paper, learning/repetitive control is proposed for improvement of existing feedback control loops for temperature regulation in buildings. A single zone office building is used as an example, with real weather data for Phoenix Arizona and realistic occupancy load schedules. Simulations have shown a decrease in the average set point tracking...

Recent advances in micro/nano-scale manufacturing have transitioned from batch modes of fabrication on rigid substrates to continuous modes of fabrication on flexible substrates. The majority of these continuous systems utilize a Roll to Roll (R2R) system approach. To maximize the effectiveness of the R2R system it is important to maintain high pre...

In this paper, we focus on improving the performance of an Iterative Learning Identification (ILI) algorithm for identifying discrete, Single-Input Single-Output (SISO), Linear Time- Varying (LTV) plants that are able to repeat their trajectories. The identification learning laws are determined through an optimization framework, which is similar in...

The high degree of coupling in multi-evaporator vapor compression systems (ME-VCSs) makes independent control of the cooling capacity for each evaporator difficult. This paper examines the sources of coupling in these systems and the importance of this coupling when making control decisions. Structured singular value (SSV) analysis is used to quant...

This paper presents a method to design a robust two DOF (Degree of Freedom) controller for LTI systems with delay. The delay places bandwidth limitations on the feedback control loop which limits the system's response to rapidly changing exogenous signals i.e. reference and/or disturbances. A non-causal feedforward controller augments feedback to e...

This paper explores research into hydraulic hybrids that span a wide range of applications from heavy-duty vehicles, such as city buses, to small passenger vehicles. This case study also highlights the importance of having a well-designed energy management strategy if one is to maximize benefit of the hybrid powertrain. There is potential for hydra...

This paper investigates fundamental performance limitations in the control of a combine harvester's header height control system. There are two primary subsystem characteristics that influence the achievable bandwidth by affecting the open loop transfer function. The first subsystem is the mechanical configuration of the combine and header while th...

This paper proposes a computationally efficient iterative learning control (ILC) approach termed non-lifted norm optimal ILC (N-NOILC). The objective is to remove the computational complexity issues of previous 2-norm optimal ILC approaches, which are based on lifted system techniques, while retaining the iteration domain convergence properties. Th...

This paper introduces an exergy-based objective function for the steady-state optimization and control of integrated energy systems (IESs). The use of exergy destruction as the metric for minimization enables the objective function to be scalable with respect to (1) subsystem configuration and (2) subsystem capacity, thereby rendering the approach...

We consider the problem of stabilizing multi-evaporator vapor-compression cycle (ME-VCC) systems using decentralized controllers. ME-VCC systems, sometimes termed variable-refrigerant-flow systems, are prevalent in large buildings that maintain independent cooled spaces with a single heat rejection unit. We exploit the time-scale separation charact...

Selective catalytic reduction (SCR) is coming into worldwide use for diesel engine emissions reduction of on- and off-highway vehicles. These applications are characterized by broad operating range as well as rapid and unpredictable changes in operating condition. Significant nonlinearity, input, and output constraints, and stringent performance re...

Modern air vehicles face increasing internal heat loads that must be appropriately understood in design and managed in operation. This paper examines one solution to creating more efficient and effective thermal management systems (TMSs): vapor cycle systems (VCSs). VCSs are increasingly being investigated by aerospace government and industry as a...

This paper reports the use of advanced forms of electrohydrodynamic jet (e-jet) printing for creating micro- and nanoscale patterns of proteins on various surfaces ranging from flat silica surfaces to structured plasmonic crystals, suitable for micro/nanoarray analysis and other applications in both fluorescent and plasmonic detection modes. The ap...

This paper presents a two degree of freedom (DOF) controller for combine harvester header height control (HHC). Previous work [1] identified fundamental limitations to the tracking and disturbance rejection bandwidths for feedback control designs. In this work, we utilize H∞ optimal control design to ensure closed loop stability and robust performa...

This article presents a new identification method for discrete-time, single-input single-output, linear time-varying (LTV) plant utilizing the input and output data. This method applies specifically to plants that are able to repeat their trajectories. The identification learning law is determined through an optimization framework, which is similar...

This paper presents a study of how different methods for designing energy management strategies (EMS) are affected by variations in drive cycle and system parameters. Specifically a rule-based strategy extracted from analysis of dynamic programming results over the Federal Urban Drive Cycle and a model predicative controller are considered. These s...

To effectively control vapor compression cycle (VCC) systems whose dynamics are highly nonlinear, it is necessary to develop plant models and control laws for different operating regions. This paper presents a first-principles modeling framework that captures four operation modes over the operating envelope to construct an invariant-order switched...

This article presents dynamic modeling approaches to predict system performance characteristics of cooling-/heating-mode switch cycling operation, a commonly used temperature regulation approach in refrigerated transport systems. A dynamic model of a commercially available transport refrigeration system is presented, which describes the system dyna...

In this study we present a procedure for the design and implementation of a control strategy to optimize energy use within a light weight hydraulic hybrid passenger vehicle. The hydraulic hybrid utilizes a high pressure accumulator for energy storage which has superior power density than conventional battery technology. This makes fluid power attra...

This work investigates an additive manufacturing process, micro-Robotic Deposition (μRD), and its utility in fabricating advanced architecture synthetic bone grafts. The objective of this research is to develop a method to integrate different regions with different porous microstructures into a single scaffold; there is evidence that scaffolds with...

This paper discusses the design and implementation of a multi-nozzle printhead for simultaneous Electrohydrodynamic jet (E-jet) printing for high resolution devices. The E-jet process combines high resolution printing with a large variety of printing materials, making E-jet suitable for applications ranging from flexible electronics to high resolut...

In this study we present a procedure for the design and implementation of a control strategy to optimize energy use within a light weight hydraulic hybrid passenger vehicle. The hydraulic hybrid utilizes a high pressure accumulator for energy storage which has superior power density than conventional battery technology. This makes fluid power attra...

This paper considers the problem of partitioning a building or any other complex energy system into clusters for its decentralized thermal control. Using a Model Predictive Control (MPC) framework, a measure of deviation in performance between centralized controland decentralized control, called the Optimality Loss Factor (OLF) is derived. For a gi...

In this paper, we develop a modeling and optimization procedure for minimizing the operating costs of a combined cooling, heating, and power (CCHP) plant at the University of California, Irvine, which uses co-generation and Thermal Energy Storage (TES) capabilities. Co-generation allows the production of thermal energy along with electricity, by re...

Electrohydrodynamic jet (E-jet) printing has emerged as a high-resolution alternative to other forms of direct solution-based fabrication approaches, such as ink-jet printing. This paper discusses the design, integration and operation of a unique E-jet printing platform. The uniqueness lies in the ability to utilize multiple materials in the same o...

We report electrohydrodynamic jet printing to deposit 2-27 μm diameter polymer droplets onto microcantilever sensors. The polymer droplets were deposited as single droplets or organized patterns, with sub-μm control over droplet diameter and position. The droplet size could be controlled through a pulse-modulated source voltage, while droplet posit...

This paper discusses the development of a sensing and feedback–feedforward control system for Electrohydrodynamic jet (E-jet) printing. E-jet printing is a nano-manufacturing process that uses electric field induced fluid jet printing through nano-scale nozzles for achieving better control and resolution than traditional jet printing processes. The...

Two basic requirements in iterative learning control (ILC), among others, are trial-to-trial trajectory invariance and system dynamics invariance. The ILC algorithm must be reinitiated if either the trajectory or system dynamics vary in-between trials. Here, we introduce a framework that flexibly applies ILC such that trajectory and system dynamics...

It is well known that pore design is an important determinant of both the quantity and distribution of regenerated bone in artificial bone tissue scaffolds. A requisite feature is that scaffolds must contain pore interconnections on the order of 100-1000 μm (termed macroporosity). Within this range, there is not a definitive optimal interconnection...

This paper presents an Iterative Learning Control (ILC) algorithm for iterative parameter update in a semi-active system. The ILC law is designed to minimize a cost function, for example, the mean squared tracking error. First, a parametrized lifted domain representation of a linear parameter-varying system is developed explicitly. Based on this li...

This paper investigates multiple degree of freedom (MDOF) optimization of steady-state vapor-compression cycle (VCC) operation. Five degrees of freedom (DOFs) of the VCC are optimized using an objective function which minimizes the rate of exergy destruction in the cycle. The use of exergy is motivated by its ability to capture the physics of both...

In this paper, a model predictive control (MPC) approach is presented for solving the energy management problem in a parallel hydraulic hybrid vehicle. The hydraulic hybrid vehicle uses a variable displacement pump/motor combination to transfer energy between the mechanical and hydraulic domains and a high pressure accumulator for energy storage. T...

This paper presents a new approach for identifying the lateral dynamics of an automated off-highway agricultural vehicle. A second order model is proposed to represent the vehicle lateral dynamics. An Iterative Learning Identification (ILI) method is used to identify the model parameters. Simulation and experimental results show the convergence of...

The problem of partitioning a building into clusters is considered in this paper, with reference to its decentralized thermal control. Optimal control schemes for these systems are often centralized and address both the thermal comfort and energy efficiency requirements. However, due to robustness considerations, a decentralized architecture may be...

In below-rated wind conditions, a wind turbine operates to maximize the amount of available power harvested from the wind and is said to be operating in region 2. In above-rated wind conditions, where regulation is the main objective to prevent over power and speed faults and to mitigate loads, the turbine is said to be in region 3. There is no sta...

Refrigerant mass migration and redistribution are regarded as key factors affecting the cycling performance of air conditioning and refrigeration systems. A dynamic model of an R134a automotive air conditioning system is presented as an example in this paper to capture the refrigerant migration during compressor shut-down and start-up operations. M...