ARC Researchers at the 2015 American Control Conference
(July 1-3, 2015, Palmer House Hilton, Chicago, IL, USA)
ARC researchers (principal investigators in bold) will be presenting their latest research developments at the ACC 2015. Below are their papers which may include non-ARC funded research (paper titles in bold are ARC funded).
Wednesday, July 1
WeB12 Regular Session
16:40-17:00 Paper WeC12.3 A Subsystem Identification Technique towards Battery State of Health Monitoring under State of Charge Estimation Errors
Univ. of Michigan: Xin Zhou, Tulga Ersal, Jeffrey L. Stein, (not ARC funded)
Keywords: Estimation, Identification
Abstract: Previous work framed the battery State of Health (SoH) monitoring problem as an inaccessible subsystem identification problem and conceived an approach to monitor SoH via side reaction current density estimation when State of Charge (SoC) is perfectly known. In practice, however, SoC is only estimated, and even an SoC estimation error of less than 1% can significantly undermine the accuracy of the SoH estimation. In this paper, the development of a new inaccessible subsystem identification technique, called the Two Step Filter, is presented in a linear setting to estimate the SoC error and SoH variable simultaneously and hence allow for SoH monitoring even under SoC estimation errors. The potential of the Two Step Filter is demonstrated on a linearized battery model example. The result shows that the filter can successfully track the side reaction current density despite the presence of an SoC estimation error of 1%.
WeA09 Invited Session
Battery Management Systems: Modeling, Estimation, Control and Diagnostics
10:20-10:40 Paper WeA09.2 Observability Analysis for Surface Sensor Location in Encased Battery Cells (I)
Univ. of Michigan: Nassim Samad, Jason B. Siegel, Anna G. Stefanopoulou
Ford Motor Company: Aaron Knobloch
(not ARC funded)
Keywords: Automotive, Modeling and simulation, Optimal control
Abstract: Compact battery pack design and cooling requirements present significant challenges for the placement of temperature sensors. Typically, temperature sensors are located near the edge of the battery, and away from the hottest regions, which leads to slower response times and increased errors in the prediction of interior cell temperature. New sensor technology allows for sensor placement between cells to improve sensor performance. With the ability to place sensors anywhere on the exterior of the cell, an observability analysis is necessary to determine the optimal locations for these sensors. The analysis is performed using a spatial discretization of a validated electrothermal model. This model describes a 5 Ah Li-ion cell harvested from a Ford C-max 2013 pack. Given that the spatial discretization of the heat partial differential equation (PDE) governing the system results in singular values that are very small (numerically zero), two methods are presented in this paper to quantify observability and address the issue of optimal sensor placement. The optimal sensor placement between cells yields a 240% improvement (for 3 sensors on the surface) and 15% improvement (for one sensor on the surface) in observability over existing sensor placement near the top edge of the cell. The pack geometry and airflow conditions impact sensor placement. It is preferable to place the sensors towards the outlet side of the airflow as opposed to the inlet side, resulting in a 13% improvement in observability.
11:20-11:40 Paper WeA09.5 Maximizing Charging Efficiency of Lithium-Ion and Lead-Acid Batteries Using Optimal Control Theory (I)
Clemson Univ.: Yasha Parvini, Ardalan Vahidi
Keywords: Optimal control, Control applications, Automotive
Abstract: Optimal charging of stand-alone lead-acid and lithium-ion batteries is studied in this paper. The objective is to maximize the charging efficiency. In the lithium-ion case two scenarios are studied. First only electronic resistance is considered and in the next step the effect of polarization resistance is also included. By considering constant model parameters for the lithium-ion battery analytical solutions exists for both scenarios using Pontryagins minimum principle. In lead-acid chemistry the variation of total internal resistance with state of charge (SOC) is considerable and the optimal charging problem results in a set of two nonlinear differential equations with one initial and a final condition to be satisfied. This so called two point boundary value problem is solved numerically.
Thursday, July 2
ThB14 Regular Session
Control Applications V
13:30-13:50 Paper ThB14.1 Simultaneous Identification and Torque Regulation of Permanent Magnet Synchronous Machines Via Adaptive Excitation Decoupling
Univ. of Michigan: David Reed, Jing Sun, Heath Hofmann
(not ARC funded)
Keywords: Control applications, Indirect adaptive control, Adaptive systems
Abstract: Parameter identification and output regulation are generally conflicting objectives. However, in the case of overactuated systems, there is an opportunity to achieve these objectives simultaneously. This paper presents a simultaneous identification and adaptive control design methodology for overactuated systems which is applied to the torque regulation problem for permanent magnet synchronous machines. Excitation and control inputs to the system are first designated. The excitation input is then treated as a disturbance which is decoupled from the regulated output via an excitation decoupling control law. Machine parameters are estimated with a normalized gradient-based algorithm, and necessary conditions for parameter convergence are established. Simulation results confirm the necessary conditions for parameter convergence, as well as the effectiveness of the resulting closed-loop torque regulator.>
Friday, July 3
FrA16 Regular Session
Delay Systems I
10:00-10:20 Paper FrA16.1 A Model-Free Predictor Framework for Tele-Operated Vehicles
Univ. of Michigan: Xinyi Ge, Jeffrey L. Stein, Tulga Ersal
U.S. Army TARDEC: Mark Brudnak, Paramsothy Jayakumar
Keywords: Delay systems, Automotive, Observers for nonlinear systems
Abstract: One important challenge with vehicle tele-operation is that the communication delays can negatively affect the driving performance. To address this challenge, this paper adopts a model-free predictor based framework that, unlike previously reported efforts, does not require the predictor to know and model the system dynamics. This is achieved by communicating only the state variables and their derivatives that appear in the output equation for the calculation of the coupling variables. The difference between the predictor’s states and the system states results in an error system that is described by a delay differential equation and its stability is established for constant delays. First, this idea is adopted into a generic vehicle tele-operation framework. Then, it is applied to a simulated vehicle-driver system to evaluate the performance of the approach over various constant delays, stochastic delays, and a real network connection. The conclusion is that the approach holds a significant potential to alleviate the negative impact of delay and improve the performance of tele-operated vehicles.
FrB08 Regular Session
Power Systems III
13:50-14:10 Paper FrB08.2 Interaction Analysis and Integrated Control of Hybrid Energy Storage and Generator Control System for Electric Ship Propulsion
Univ. of Michigan: Jun Hou, Jing Sun, Heath Hofmann
(not ARC funded)
Keywords: Power systems, Optimal control, Control applications
Abstract: Ship propulsion systems experience large power and torque fluctuations on their drive shaft due to hydrodynamic interactions and wave excitation. For electric propulsion, a hybrid energy storage system (HESS) could be an effective solution to address the negative impact of these fluctuations. However, the HESS, when introduced into the existing shipboard electrical propulsion system, will interact with the power generation control systems. In this paper, a model-based analysis is performed to evaluate the interactions of the multiple power sources when a hybrid energy storage system is incorporated. The study has revealed undesirable interactions when the controls are not coordinated properly, and leads to the conclusion that a system-level energy management strategy (EMS) will be needed. To evaluate the benefits of the system-level EMS, a comparative study is performed, and results show that the system-level EMS has advantages over other strategies in terms of many of the performance metrics.