bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of a Sensor Reduction in a Semi-Active Suspension System for a 4-Wheel Vehicle
Authors: Spelta Cristiano , Delvecchio Diego , Savaresi Sergio M. , Bonaccorso Gabriele , Ghirardo Fabio
Published: February 2011

This paper is devoted to the application of a comfort-oriented suspension semi-active control system to a four wheel vehicle with a minimal sensor layout. To this aim an algorithm recently developed (the Mix-1-Sensor) has been adopted. The Mix-1-Sensor has been shown to be a quasi-optimal control law for a quarter car suspension system equipped with a single sensor. Therefore a sensor layout of four accelerometers is necessary. This paper shows that it is possible to estimate the vertical acceleration of the four corners by means of only three accelerometers. The estimation suffers from high frequency noise that can be managed by filtering. However this induces a phase-shift of the estimated signal. The closed loop system shows that no phase-shift is preferred since the noise is effectively compensated without a dramatic loss of performances.
Coordinated Control of Fuel Cell Air Supply System Using Model Predictive Control
Authors: Tang Lie , Landers Robert G.
Published: February 2011

Oxidant (air flow) control is an important aspect of fuel cell reactant control system which is designed to fulfill two purposes: air flow rate control and pressure control. These tasks require coordinated valve operation to reduce pressure variation and stabilize flow rate. In this paper, a nonlinear model describing filling dynamics of the supply and return manifolds is presented. The nonlinear model is then linearized around the stack operating point, based on which a model predictive controller is designed to maintain a constant supply and manifold pressures, as well as a constant pressure on the cathode side. Simulation studies demonstrate the model predictive controller is capable of not only regulating constant pressures during steady state operation, but also substantially reducing pressure variations during transient periods. Simulation also indicates that the control system has good robustness against model uncertainty.
Output Regulation in Discrete-Time Bimodal Linear Systems Subject to Deterministic and Random Exogenous Input Signals
Authors: Wu Zhizheng , Ben Amara Foued
Published: February 2011

This paper considers an output regulation problem for a class of discrete-time switched bimodal linear systems against known deterministic exogenous signals in the presence of unknown random disturbances, which is motivated by the flying height regulation problem in hard disk drives. The regulation problem for the switched system against the known deterministic exogenous signals is approached by constructing a set of observer-based parameterized stabilizing controllers that satisfy a sufficient regulation condition for the switched system. An H2 performance constraint is then added to identify, from among the already constructed regulators, those that provide the best H2 performance against the unknown random disturbances. The proposed regulator is successfully evaluated on a bimodal switched mechanical system experimental setup to demonstrate the effectiveness of the proposed regulation approach.
Combined Use of Control Moment Gyros and Magnetic Torque Rods for Satellite Attitude Control
Authors: Elmas Tuba C. , Tekinalp Ozan
Published: February 2011

A new approach to the attitude control of an over actuated satellite is presented. A control moment gyroscopes cluster containing four actuators in a pyramid mounting configuration, and a set of three orthogonal magnetic torque rods are considered to steer the satellite. Two steering algorithms, Moore-Penrose pseudo inverse, and the recently developed blended-inverse, are considered. The success of the blended-inverse algorithm to select the desired actuators in the system is demonstrated. It is also shown through simulations that the blended-inverse algorithm successfully carries out the maneuver without getting trapped in singular configurations, while the classical Moore-Penrose pseudo inverse algorithm fails to realize.
Dynamic Security Analysis of Electric Power Systems: Passivity-Based Approach and Positive Invariance Approach
Authors: Hui Qing , Shen Jinglai , Qiao Wei
Published: February 2011

Security is a critical issue in modern power system operation. With the aid of analytic tools for large-scale and hybrid systems, this paper proposes two new safety verification methods for power systems. The first method is based on barrier certificates and passivity. This method provides a general safety verification framework for power systems with the port-Hamiltonian structure. The energy shaping technique is also exploited to attain safety conditions for controlled port-Hamiltonian systems. The second method, based on positive invariance, yields exact safety verification for power systems based on linearized models, particularly linear Hamiltonian systems. Decidability of exact safety verification is established via algebraic and positive invariance approaches; other analytic and numerical issues are addressed from the positive invariance perspective.
Wind Turbine Power Capture Control With Robust Estimation
Authors: Hawkins Tony , White Warren N. , Hu Guoqiang , Sahneh Faryad Darabi
Published: February 2011

A robust control scheme to optimize the power capture of a wind turbine is proposed. A novel identification technique is used both to estimate the unknown aerodynamic properties and to regulate the turbine speed. A Lyapunov-based approach is adopted to choose the set point change direction so that power capture can be maximized for the given wind speed and environmental parameters. The set point consists of the turbine tip speed ratio and the turbine blade pitch. The efficacy of the controller is demonstrated through simulation.
Design of Hardware Architecture and Control Algorithm for the Electronic Wedge Brake
Authors: Han Kwangjin , Huh Kunsoo , Chun Jaehyung , Kim Myoungjune , Kim Joogon
Published: February 2011

Brake-by-wire (BBW) systems can be used for enhanced safety braking of intelligent vehicles and also for environmentally friendly vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs). The electronic wedge brake (EWB) is one of the brake-by-wire systems with a self-energizing effect. The EWB is faster than the conventional hydraulic brake and requires only about one-tenth the power to operate. However, the EWB can be unstable unless controlled properly since the self-energizing effect can unintentionally lock up the vehicle’s wheels. In addition, the self-energizing effect is very sensitive to environment and parametric variances, e.g. friction, temperature, speed, load, etc. In this paper, two control algorithms for the EWB are introduced and compared each other in performance. The performance of the proposed control algorithms is verified in simulations.
Development and Performance Evaluation of a Magnetorheological Valve Designed for Control Applications
Authors: Kostamo Jari T. , Kostamo Esa P. , Kajaste Jyrki T. , Pietola Matti T.
Published: February 2011

Magnetorheological fluids are often proposed for applications requiring fast response and good controllability but the dynamic characteristics of the MR devices are seldom analyzed in detail. The aim of this study is to present a magnetorheological valve optimized for fast dynamical response. The fundamental design criteria for fast MR valves are discussed and an experimental valve designed for high frequency actuation is analyzed. It is shown the performance figures generally reported for MR technology can be significantly improved. The results show a step pressure difference of 7 MPa can be controlled with a response time of 0.7 ms. The maximum rate of change for controllable pressure was measured to achieve 20.2 MPa in one millisecond.
Performance Upgrade of Pantograph Using Variable Stiffness Device
Authors: Yamashita Yoshitaka , Ikeda Mitsuru
Published: February 2011

This paper proposes a new technique to improve the current collection performance of pantographs. For this purpose, the pan springs, which are usually coil springs, are replaced with variable stiffness devices. The device described in this paper is comprised of two air springs facing each other. This paper firstly outlines the method for the improvement for current collection performance and exhibits some numerical simulation results, which supports the efficacy of the method. It then presents the prototype of the variable stiffness device and shows its basic characteristics. Finally, it shows the experimental results of the dynamic characteristics control of a pantograph using the variable stiffness devices.
A Nonlinear Time Series Analysis Method for Health Monitoring of Rolling Bearings
Authors: Liu Yongbin , Yan Ruqiang , Gao Robert X.
Published: February 2011

This paper presents a nonlinear time series analysis method for rotating machine damage detection and diagnostics. Specifically, the permutation entropy is investigated as a statistical measure for signal characterization. Through space reconstruction, the permutation entropy describes the complexity of the time series measured on a physical system, and takes its non-linear behavior into account. By identifying changes in the vibration signals measured on rotating machines, which are typical precursors of defect occurrence, permutation entropy can serve as a diagnostic tool. Experiments on a custom-designed gearbox system have confirmed its effectiveness for machine structural health monitoring applications.
PWM Control Accuracy for Scratch Drive Actuators
Authors: Piepmeier Jenelle Armstrong , Firebaugh Samara L.
Published: February 2011

In this paper we investigate the problem of controlling a scratch drive actuator that has two discrete modes of locomotion: forward motion in a straight line, and forward motion with fixed radius curvature. This type of device can be modeled as a two-wheeled vehicle (with the previously stated constraints). By alternating between these two modes of operation, the device can move along a variable-radius curved path. In practice, the robots do not move in a purely straight manner. This paper seeks to quantify the accuracy that can be achieved by switching between the two modes of locomotion. This type of low-level open-loop control facilitates the use of a higher level feedback controller designed for two-wheeled vehicles with a variable turning radius.
A Sampling Approach to Modeling and Control of a Large-Size Robot Population
Authors: Milutinovic´ Dejan , Garg Devendra P.
Published: February 2011

Motivated by the close relation between estimation and control problems, we explore the possibility to utilize stochastic sampling for computing the optimal control for a large-size robot population. We assume that the individual robot state is composed of discrete and continuous components, while the population is controlled in a probability space. Utilizing a stochastic process, we can compute the state probability density function evolution, as well as use the stochastic process samples to evaluate the Hamiltonian defining the optimal control. The proposed method is illustrated by an example of centralized optimal control for a large-size robot population.
Cascaded Control of Power Input and Welding Temperature During Sealing of Spent Nuclear Fuel Canisters
Authors: Cederqvist Lars , Garpinger Olof , Ha¨gglund Tore , Robertsson Anders
Published: February 2011

The friction stir welding procedure to seal copper canisters requires variable power input throughout the 45 minute long weld cycle to keep the welding temperature within the process window. This is due to variable thermal boundary conditions throughout the weld cycle which, together with fast disturbances in the spindle torque, requires control of both the power input and the welding temperature to achieve a stable and robust process. By using a cascaded loop that determines the power input requirement, the regulator will not be dependent on repeatability in the necessary power input between weld cycles. As a result, a more accurate and reliable closed-loop control of the welding temperature is acquired.
Unknown Multiple Narrow-Band Disturbance Rejection in Hard Disk Drives: An Adaptive Notch Filter and Perfect Disturbance Observer Approach
Authors: Chen Xu , Tomizuka Masayoshi
Published: February 2011

In this paper, an adaptive control scheme is developed to reject unknown multiple narrow-band disturbances in a hard disk drive. An adaptive notch filter is developed to efficiently estimate the frequencies of the disturbance. Based on the correctly estimated parameters, a disturbance observer with a newly designed multiple band-pass filter is constructed to achieve asymptotic perfect rejection of the disturbance. Evaluation of the control scheme is performed on a benchmark problem for HDD track following.
Development of Control System by Nonlinear Compensation Using Digital Acceleration Control
Authors: Emaru Takanori , Imagawa Kazuo , Hoshino Yohei , Kobayashi Yukinori
Published: February 2011

Proportional-Integral-Derivative (PID) control has been most commonly used to operate mechanical systems. In PID control, however, there are limits to the accuracy of the resulting movement because of the influence of gravity, friction, and interaction of joints. We have proposed a digital acceleration control (DAC) that is robust over these modeling errors. One of the most practicable advantages of DAC is robustness against modeling errors. However, it does not always work effectively. If there are modeling errors in the inertia term of the model, the DAC controller cannot control a mechanical system properly. Generally an inertia term is easily modeled in advance, but it has a possibility to change. Therefore, we propose an online estimation method of an inertia term by using a system identification method. By using the proposed method, the robustness of DAC is considerably improved. This paper shows the simulation results of the proposed method using 2-link manipulator.
Multi-Objective H2/H∞ Static Output Feedback Control: A Hybrid LMI/Genetic Algorithm Approach
Authors: El-Shaer Ahmed H. , Tomizuka Masayoshi
Published: February 2011

This paper is concerned with the synthesis of static output feedback (SOF) control satisfying multi-objective H2/H∞ performance for LTI systems. Given an initially stabilizing SOF gain Ko, an estimate of the set of stabilizing gains is obtained using Monte Carlo based randomized search. A synthesis algorithm which combines both linear matrix inequalities (LMIs) and genetic algorithms (GA) is proposed. To improve the efficiency of this hybrid algorithm, the GA employs a projection-like operation so that the solution candidates lie in the interior of the set of stabilizing gains in a neighborhood of Ko.
A Novel Wave-Form Command-Shaping Control With Application on Overhead Cranes
Authors: Alhazza Khaled A. , Masoud Ziyad N.
Published: February 2011

In this work, a novel continuous command-shaping control strategy for a simple harmonic oscillator is proposed and implemented on an overhead crane model. A Wave-Form (WF) acceleration command profile is derived analytically, and its performance is validated numerically. To enhance the performance of the proposed command-shaping control strategy, a Modulated Wave-Form (MWF) acceleration command profile is derived. It was determined that the proposed Wave-Form and Modulated Wave-Form command profiles are capable of eliminating the travel and residual oscillations. Furthermore, unlike traditional impulse and step command-shaping, the proposed command profiles have smoother intermediate acceleration, velocity, and displacement profiles.
Time Lapse Observation Based Modeling and Identification of Cell Behaviors in Angiogenic Sprout Development
Authors: Wood Levi B. , Kamm Roger D. , Asada H. Harry
Published: February 2011

This paper presents a method for deriving dynamic equations for Endothelial Cell (EC) motion and estimating parameters based on time lapse imagery of angiogenic sprout development. Angiogenesis is the process whereby a collection of endothelial cells sprout out from an existing blood vessel, degrade the surrounding scaffold and form a new blood vessel. Sprout formation requires that a collection of ECs all work together and coordinate their movements and behaviors. The process is initiated and guided by a collection of external growth factors. In addition, the individual cells communicate and respond to each other’s movements to behave in a coordinated fashion. The mechanics of cell coordination are extremely complex and include both chemical and mechanical communication between cells and between cells and the matrix. Despite the complexity of the physical system, with many variables that cannot be measured in real time, the ECs behave in a predictable manner based on just a few quantities that can be measured in real time. This work presents a methodology for constructing a set of simple stochastic equations for cell motion dependent only on quantities obtained from time lapse data observed from in vitro experiments. Model parameters are identified from time lapse data using a Maximum Likelihood Estimator.
Autonomous Vehicle Navigation With Dynamic Adaptation and Complete Coverage of Unknown Environments
Authors: Jin Xin , Luff Jacqueline M. , Gupta Shalabh , Ray Asok
Published: February 2011

This paper presents a Statistical Mechanics-inspired navigation algorithm with dynamic adaptation and complete coverage of unknown environments, which is built upon the concept of generalized Ising model. The algorithm enables autonomous vehicles to cover all areas in the environment, avoid unknown obstacles and adapt to target neighborhoods. Potential applications of this algorithm are humanitarian de-mining, hazard detection and floor-cleaning tasks. The algorithm has been validated on a Player/Stage simulator with an example of minesweeping.
Dynamic Modeling of Mechanical Draft Counter-Flow Wet Cooling Tower With Modelica
Authors: Li Xiao , Li Yaoyu , Seem John E.
Published: February 2011

Cooling towers are important equipments for the heating, ventilation and air conditioning systems in commercial buildings, rejecting the process heat generation to the atmosphere. Dynamic modeling of cooling tower is beneficial for control design and fault detection and diagnostics of the chilled-water systems. This paper proposes a simple and yet effective dynamic model for a typical mechanical draft counter-flow cooling tower. The finite volume method is applied to the one-dimensional heat and mass transfer analysis. With control volumes defined separately for the water and air sides, the dynamic equations are constructed with the mass and energy balances. The steady-state performance of the proposed model is evaluated with the experimental data from literature. The transient behavior is simulated under the changes of tower inlet conditions, with the performance to be evaluated in the future with field test data.
Selection of Outputs for Gas-Turbine Engines by Parameter Signatures
Authors: McCusker James R. , Danai Kourosh
Published: February 2011

A method of measurement selection is introduced that relies on parameter signatures to assess the identifiability of dynamic model parameters by different outputs. A parameter signature is a region in the time-scale plane wherein the sensitivity of the output with respect to one model parameter is much larger than the rest of output sensitivities. Since the existence of a parameter signature is synonymous with the uniqueness of the corresponding output sensitivity, parameter signatures are directly linked to parameter identifiability by outputs and, hence, can be used for output/measurement selection. The purpose of this paper is to introduce a strategy for measurement selection by parameter signatures and to demonstrate its applicability to the transient decks of turbo-jet engines. The validity of the selected outputs in providing observability to the engine model parameters is independently verified by successful estimation of parameters by nonlinear least-squares.
Transient Control of a Camless Valve Actuation System Using a Time-Varying Repetitive Controller
Authors: Gillella Pradeep , Sun Zongxuan
Published: February 2011

Camless valve actuation systems, also referred to as Fully Flexible Valve Actuation systems, use electronically controlled actuators to replace the camshaft in an internal combustion engine. This paper presents the control design for such an actuation system to enable the precise valve motion control during engine speed transients. The desired valve motion (reference) remains periodic in the crank angle domain, but becomes cyclic and aperiodic in the time domain when the engine speed changes in real-time. This phenomenon motivates the control design in the rotational angle domain. However, this approach results in a time-varying model for the plant. A systematic method for obtaining the discrete time-varying Input/Output representation of higher order systems is developed to enable the application of the newly developed time-varying repetitive control to plants with complex dynamics. The use of a variable sampling rate helps accurately represent complex reference signals using low dimensional models. The implementation of the simulations on a rapid control prototyping system helps identify and address potential issues that influence the controller execution time which directly affects the maximum engine speed at which it can be used.
Modeling of a Dynamic Mirror Actuator
Authors: Mynderse James A. , Chiu George T. C.
Published: February 2011

A novel dual-actuated dynamic mirror actuator (DMA) is presented for laser beam steering. The DMA is driven by a pair of piezoelectric stack actuaors (PESAs). The piezoelectric stacks are modeled using a linear model and five variations of constitutive models from literature. The resulting DMA models are simulated. While the constitutive models capture some higher order dynamics, the linear model provides the best combination of accuracy to experimental data and simplicty of model between DC and the first natural frequency of the DMA. For control of the DMA up to the first natural frequency of the DMA, a linear model should be adequate.
Nonlinear Predictor-Based Output Feedback Control for a Class of Uncertain Nonlinear Systems
Authors: Morel Yannick , Leonessa Alexander
Published: February 2011

The presented work addresses the output feedback control problem for a large class of uncertain nonlinear systems. The control algorithm relies on an output predictor, designed to predict the system’s measured output with arbitrary accuracy, for any admissible control signal. This output predictor is constructed using a derivative estimator, which allows the algorithm to only require limited knowledge of the system’s dynamics in general, and of the input matrix in particular. The output predictor, which is designed to be controllable, is then controlled using a backstepping control algorithm. The output feedback control problem is thus solved by controlling the predictor’s output, as opposed to controlling the actual system’s output, as is more commonly the case in the literature. Ultimately, it is shown that the predictor’s output is made to simultaneously converge to the actual system’s output and to a given desired output trajectory. It follows that the system’s output itself converges to the desired trajectory. Numerical simulation results are provided to illustrate the algorithm performance.
Zero Vibration Multi-Switch Bang-Bang Commands for a Floating Oscillator System
Authors: Robertson Michael J. , O’Brien Richard T.
Published: February 2011

This paper presents a method for creating multi-switch bang-bang commands to produce rest-to-rest command inputs for a floating oscillator system. The advantage of the proposed method is its simplicity and robustness. The amplitude and switch times of the input commands are computed from the 1) desired move distance, 2) the system parameters and 3) the desired level of robustness. The robustness of the commands to model uncertainty is measured by the percent overshoot of the step response. For the proposed method, numerical simulations of the floating oscillator demonstrate that both the number of switches in the command and the duration of the command affect the overall robustness.
A Global-Local Emission-Model for NOx and Soot Emissions of Turbocharged CR-Diesel Engines
Authors: Sequenz Heiko , Mrosek Matthias , Isermann Rolf
Published: February 2011

Stationary and dynamic models for the emissions of a CR-Diesel engine are developed using a global-local model approach. Results for the NOx and soot emissions are presented. All model inputs are measurable air path states and combustion parameters. They determine the emission formation before the combustion takes place. Therefore the model can be used for emission prediction and simulation. The combustion process is regarded as a batch process, such that the dynamics are introduced as external dynamics to the model via the inputs. Thus a stationary model structure can be applied. As the space of possible air path states varies widely for different engine operation points, several input and output transformations are given that linearize the input and output space. This improves the model quality and extends the operation range of the model. Modeling results are shown for stationary and dynamic data as well as for local and global model operation.
Parametric Uncertainty Modeling and Multiple Controller Design for Hard Disk Drives
Authors: Yazdi Ehsan Azadi , Sepasi Mohammad , Sassani Farrokh , Nagamune Ryozo
Published: February 2011

This paper proposes a new design procedure for track-following control systems in hard disk drives. The procedure is automated, in the sense that, for given experimental frequency response data of the suspension arm dynamics and a model structure, it automatically derives a transfer function set with uncorrelated parametric uncertainties. Subsequently, for the transfer function set, a given controller structure, and closed-loop performance specifications in the frequency domain, it automatically designs a partition of the uncertainties and corresponding multiple robust controllers. Experiments on actual hard disk drives demonstrate the usefulness and efficiency of the proposed procedure.
Automated Set Point Change of an Industrial Glass Feeder
Authors: Malchow Florian , Sawodny Oliver
Published: February 2011

A glass feeder in the container glass production connects a forming machine to the glass furnace. The molten glass flows through the feeder and using numerous gas burners a desired temperature profile is regulated using feedback controllers and temperature measurements. Since this temperature profile depends on product specific parameters, it has to be adjusted in some situations e.g. during product changes. These adjustments often require big set point changes. However the feedback controllers are designed with a good disturbance reaction but show a slow response to set point changes. Consequently set point changes are usually operated in manual mode. This treatise describes the automation of set point changes of an industrial glass feeder. First a model is proposed, consisting of multiple 1st order partial differential equations with coupling in the boundary conditions. Then a feedforward control approach is presented allowing for the calculation of the control inputs from the trajectories of an equal number of system outputs. Finally the implementation of the approach at an industrial glass feeder is described and experimental results of an automated set point change are included.
Contact Force Estimation for an Elastic Beam Using Optimal High-Gain Disturbance Observer
Authors: Liu Yan , So¨ffker Dirk
Published: February 2011

This contribution presents a contact force estimation approach based on an optimal high-gain disturbance observer for an elastic beam using noisy measurements. The reconstruction of contact forces as an example for unknown input estimation represents a class of typical mechanical engineering problems related to the estimation of unknown effects for disturbance rejection or accommodation or fault diagnosis and isolation. The high-gain disturbance observers applied here is able to estimate estimate unknown external inputs together with system states. But choosing observer gains is a difficult task because of the influence of measurement noise. The important advantage of the proposed approach in comparison with classical high-gain disturbance observer is the self adjustment of the observer gains according to the actual estimation situation. Estimation results based on real measurements from known high-gain disturbance observer and the proposed optimal one are compared. It can be shown that the proposed algorithm allows optimized disturbance observer gains calculation, being able to be situatively adapted.
Reducing Multiple Modes of Vibration by Digital Filtering and Input Shaping
Authors: Vaughan Joshua , Singhose William
Published: February 2011

The residual vibration of flexible systems can be reduced by properly shaping the reference command. There has been substantial evidence presented that input shaping is better than notch filtering for shaping reference commands to suppress vibration in mechanical systems. Much of this evidence is empirical comparisons between traditional filters and robust input shapers. Recently, a proof showing that notch filters are always equal to or longer in duration than an input shaper with identical single-mode vibration suppression constraints was presented. This paper expands on that previous result by extending the proof to multi-mode systems. The important ramification of this proof is that multi-mode input shapers suppress vibration more quickly than multi-mode notch filters. Ease of design, computation, and implementation are also discussed. Simulations of an industrial bridge crane demonstrate the key differences between the two methods.
A Comfort Oriented Control Strategy for Semi-Active Suspensions Based on Half Car Model
Authors: Spelta Cristiano , Delvecchio Diego , Savaresi Sergio M.
Published: February 2011

This paper is devoted to the design of a novel semi-active comfort-oriented control strategy based on the “half-car” modeling of the vehicle. The half car model is an effective description of the vertical behaviors in a vehicle like a motorcycle, since it is able to represent both the heave and pitch dynamics. A recent control strategy (the “Mix-1-Sensor”) have been proven to be the quasi-optimal control strategy when the system is described with a quarter car model and the comfort objective is the control goal. This paper presents an analysis of the performances of the Mix-1-Sensor implemented in a half car: this strategy is able to guarantee a quasi optimal performance in terms of heave dynamics but it is not able to manage the pitch dynamics efficiently. A pitch-oriented extension of this strategy is proposed in order to guarantee a better filtering of the pitch dynamics.
Dynamics, Sensing, and Control of a Thin-Film Piezoelectric Vertical Micro-Stage
Authors: Oldham Kenn , Lin Xianke , Qiu Zhen , Wang Thomas , Pulskamp Jeffrey S. , Polcawich Ronald G.
Published: February 2011

A novel thin-film piezoelectric vertical actuator with integrated strain gage position sensor is described, with sensor performance in simulated sliding mode control examined. The actuator utilizes four bending-beam thin-film lead-zirconate-titanate (PZT) legs to generate net translational out-of-plane motion of almost 100 μm, with higher speed and lower voltages than most MEMS vertical actuators. In addition, a portion of the top platinum electrode on the piezoelectric thin-film is used to perform position sensing, and shown to have good sensitivity during experimental operation of the actuator. A dynamic model of the stage based on a hysteresis model derived to fit experimental piezoelectric strain coefficient behavior is presented, and used to predict stage performance during sliding mode control using the integrated strain gage.
An Internal Model Control Based Static Anti-Windup Scheme With Improved Performance
Authors: Wu Wei
Published: February 2011

This paper considers the synthesis of static anti-windup (AW) compensation within the internal model control (IMC) AW framework for stable plants subject to input saturation. Built on the conventional IMC AW scheme which preserves the stability and the stability robustness of the unconstrained system, the proposed static AW compensation improves the constrained system performance. L2 gain performance of the constrained system is considered for the static AW controller synthesis, resulting in a linear matrix inqualitiy. The effectiveness of this AW scheme is demonstrated by comparison with two AW methods from the literature through using two numerical examples.
Particle Filter for Plasma Insulin Estimation
Authors: Kiriakidis Kiriakos
Published: February 2011

Bergman’s Minimal Model (MM) captures simply but accurately the homeostasis of glucose and insulin in plasma. The MM has been proposed as an estimator of insulin for Diabetes Mellitus. Along this line of research, the present work takes into account the error between Bergman’s simple compartmental model and the complex physiologic system it depicts. The author employs a Particle Filter (PF) in order to construct the posterior probability density of insulin from data. As a sequential Bayesian estimator, the PF can handle nonlinear state equations, such as the MM, as well as non-Gaussian modeling error. These advantages of the PF over the Kalman Filter warrant further consideration for insulin estimation and, in turn, avoidance of hyperinsulinemia.
Topology Optimization for Piecewise Dynamic Models Using a Genetic Algorithm
Authors: Liu Yi , Djurdjanovic Dragan
Published: February 2011

It has been demonstrated in the previous research that the node connectivity in the graph encoding the topological neighborhood relationships between local models in a piecewise dynamic model may significantly affect the cooperative learning process. It was shown that a graph with a larger connectivity leads to a quicker learning adaption due to more rapidly decaying transients of the estimation of local model parameters. In the same time, it was shown that the accuracy could be degraded by a larger bias in the asymptotic portion of the estimations of local model parameters. The efforts in topology optimization should therefore strive towards a high accuracy of the asymptotic portion of the estimator of local model parameters while simultaneously accelerating the decay of the estimation transients. In this paper, we pursue minimization of the residual sum of squares of a piecewise dynamic model after a predetermined number of training steps. The optimization of inter-model topology is implemented via a genetic algorithm that manipulates adjacency matrices of the graph underlying the piecewise dynamic model. An example of applying the topology optimization procedure on a peicewise linear model of a highly nonlinear dynamic system is provided to show the efficacy of the new method.
Observer Based Transient Fuel Utilization Control for Solid Oxide Fuel Cells
Authors: Das Tuhin , Slippey Andrew
Published: February 2011

Transient control is important for prolonging the life of SOFCs and broadening their applications. This paper develops an observer based method for transient control. The essential idea is to regulate the fuel cell current using the estimated state, incorporated within a steady-state invariant property of the SOFC. The objective is to directly address hydrogen starvation in SOFCs through control of transient fuel utilization. The method is demonstrated for two different SOFC systems. The applicability across configurations indicates the possible validity of this approach for SOFCs in general. The control design is supported by simulation results.
Velocity Occupancy Space for Differential Drive Vehicles
Authors: Bis Rachael A. , Peng Huei , Ulsoy A. Galip
Published: February 2011

The concept of velocity occupancy space was developed in order to facilitate a vehicle in avoiding moving and stationary obstacles and navigating efficiently to a goal using only uncertain sensor data. However, the original velocity occupancy space concept was designed for holonomic vehicles that are capable of instantaneous velocity changes — capabilities that are not possessed by most actual vehicles. This paper presents two methods by which velocity occupancy space can be adapted to work within the kinodynamic constraints of a differential drive vehicle, a common configuration for experimental robots, with bounded acceleration capabilities. These two different adaptations of the velocity occupancy space concept are proposed and evaluated in light of their respective suitability under different vehicle conditions.
Robust Consensus Output Tracking of Multi-Agent Systems With Directed Communications
Authors: Wang Z. , Zhang W. , Guo Y.
Published: February 2011

In this paper, we study the consensus output tracking control for multi-agent systems with high-order dynamics under directed communication topology. Time-varying reference is assumed to be available to a subgroup of a team. A leader-follower scheme is applied and robust consensus control is developed so that the reference is treated as disturbances to those agents with no access to the reference. The control scheme avoids estimation of the derivatives of neighbor’s states through measurement as done in previous work and guarantees a finite L2-gain from the reference to an transformed output. Simulation results show satisfactory performances.
Gravity Powered Locomotion and Active Control of Three Mass System
Authors: Tavakoli Ali , Hurmuzlu Yildirim
Published: February 2011

This paper presents the latest results of our research effort to develop a family of energetically efficient robotic locomotors and introduce new gait patterns for them. We study a chain of mechanisms that span from the very simple to the progressively more complicated. These mechanisms can be as simple as a bouncing ball or as complex as a five link biped. This paper presents the results of our study for a three mass dynamical system. We show that this system can generate a rich set of passive gaits such as hopping, tapping, walking. We developed a nonlinear robust controller for the hybrid dynamics of three mass system that is insensitive to parameter variations of the system. The active control scheme generates the passive gaits on arbitrary ground slope angles.
Coordinating Cognitive Assistances With PID-Based Control Approaches
Authors: Cai Hua , Lin Yingzi , Breugelmans Jeffrey
Published: February 2011

In human-machine cooperation, machines may assist operators in a variety of ways. This paper discusses the coordination of various assistances on cognitive basis through a PID-based control approach. Cognitive assistance can be viewed as a two-dimensional problem. The question of when to provide assistance can be viewed as a control problem, and the question of what assistance to provide can be viewed as an interface problem. This research proposes pairing cognitive engagement level and performance relevant situation criticality with a PID control approach to determine the appropriate moment to provide proper assistance. Based on the stage of human cognitive processing, the interfaces of cognitive assistance are grouped into three levels: soft aid, soft intervention, and hard intervention. This paper took driving assistance as an exemplary application to validate the approach of cognitive assistances coordination. In the experiment, an intelligent machine driver monitored drivers’ real-time performance by measuring the time headway to front obstacles and the lateral deviation to lane center. Simultaneously, it monitored drivers’ cognitive state by measuring the eye movement with an eye tracker. With five sessions of driving, coordinated cognitive assistance was compared with no aid, soft aid, soft intervention, and hard intervention, respectively. The experimental results confirmed that coordinated cognitive assistance is the most effective approach to assist both primary and secondary tasks. It also proves to be a more enjoyable and less obtrusive assistance system when compared to other individual types of assistance. In addition, coordinated cognitive assistance can be extended to other real-time control relevant tasks.
A 1+1D Thermal Dynamic Model of a Li-Ion Battery Cell
Authors: Muratori Matteo , Ma Ning , Canova Marcello , Guezennec Yann
Published: February 2011

Li-ion batteries are today considered the prime solution as energy storage system for EV/PHEV/HEV, due to their high specific energy and power. Since their performance, life and reliability are influenced by the operating temperature, great interest has been devoted to study different cooling solutions and control algorithms for thermal management. In this context, this paper presents a computationally efficient modeling approach to characterize the internal temperature distribution of a Li-ion battery cell, conceived to serve as a tool to aid the design of cooling systems and the development of thermal management systems for automotive battery packs. The model is developed starting from the unsteady heat diffusion equation, for which an analytical solution is obtained through the integral transform method. First, a general one-dimensional thermal model is developed to predict the temperature distribution inside a prismatic Li-ion battery cell under different boundary conditions. Then, a specific case with convective boundary conditions is studied with the objective of characterizing a cell cooled by a forced air flow. To characterize the effects of the cooling system on the temperature distribution within the cell, the one-dimensional solution is then extended to a 1+1D model that accounts for the variability of the boundary conditions in the flow direction. The calibration and validation of the specific model presented will be presented, adopting a detailed 2D FEM simulator as a benchmark.
A Model Order Reduction Method for the Temperature Estimation in a Cylindrical Li-Ion Battery Cell
Authors: Muratori Matteo , Ma Ning , Canova Marcello , Guezennec Yann
Published: February 2011

The thermal characterization of Li-ion batteries for EVs, HEVs and PHEVs is a topic of great relevance, especially for the evaluation of the battery pack state of health (SoH) during vehicle operations and for battery life estimation. This work proposes a reduced-order model that estimates the thermal dynamics of a cylindrical Li-ion battery cell, with respect to time-varying current demands. Unlike most “black-box” dynamic models, based on system identification techniques, the proposed approach relies on the definition of a boundary-value problem for heat conduction, in the form of a linear partial differential equation. The problem is then converted into a low-order linear model by applying model-order reduction method in the frequency domain. The resulting model predicts the temperature dynamics at the center and at the external surface in relation with the rate of heat generation and the coolant temperature. In this paper, the model is applied to estimate the internal temperature of a cylindrical cell during a discharging transient. The model uses electrical data acquired from experimental tests and is validated by comparison with experimental data and 3D FEM thermal simulation.
An Energy Optimal Gait for the MSU Active Synthetic Wheel Biped
Authors: Flynn Louis L. , Jafari Rouhollah , Hellum Aren , Mukherjee Ranjan
Published: February 2011

In this paper, we have determined an analytical solution for a zero-work gait for the MSU Synthetic Wheel Biped [1, 2] by choosing proper constraints. The new optimized gait ensures that the total energy of the system is the same at the beginning and the end of each step. This results in zero total work, regardless of the initial velocity of the leg or step length provided there are no losses due to friction. Furthermore, the correct choice of the gait constraints completely eliminates the ground impact forces during the foot transition. The previously developed nominal gait and the new optimized gait are implemented on a hardware prototype and a comparison of the energy consumption of these two different gait functions indicates a significant reduction in mechanical cost of transport.
Sensor and Control Design Issues for Developing Real-Time Deposition Rate Control for Plasma Spray
Authors: Gevelber Michael , Wroblewski Donald , Cannamela Michael , Basu Soumendra N. , Radgowski Dennis , Tuttle Matthew
Published: February 2011

Real-time control offers the potential to reduce plasma spray variations that affect yield and coating quality. Important factors for designing such controllers are discussed including sensor issues, dominant nonlinearities, and cross-coupling interactions. The performance of several alternative strategies to achieve better coating thickness control is evaluated.
Autonomous Navigation in Unknown Road-Like Environments Using Support Vector Machines
Authors: Tennety Srinivas , Kumar Manish
Published: February 2011

In this paper enhancements have been done to the previously proposed Support Vector Machines (SVM) based path planning algorithm [1]. SVM, a data classification technique has been applied in conjunction with k-Nearest Neighbors (k-NN) algorithm for autonomous navigation in unknown road-like environments. The features of the road such as lane markers and the obstacles in the robot’s visibility are divided into two classes using k-nearest neighbors (k-NN) algorithm and then a maximum margin hyperplane is obtained using SVM that optimally separates both the classes. This hyperplane represents a collision-free path. The proposed algorithm has been tested in a variety of environments and the scenarios where it was unsuccessful have been identified and addressed for improvement. The simulation results of the enhanced algorithm have been presented and its performance has been compared with vfh+, a purely local obstacle avoidance algorithm based on artificial potential field method.
Adaptive Equivalent Consumption Minimization Strategy for Hybrid Electric Vehicles
Authors: Onori Simona , Serrao Lorenzo , Rizzoni Giorgio
Published: February 2011

This paper proposes a new method for solving the energy management problem for hybrid electric vehicles (HEVs) based on the equivalent consumption minimization strategy (ECMS). After discussing the main features of ECMS, an adaptation law of the equivalence factor used by ECMS is presented, which, using feedback of state of charge, ensures optimality of the strategy proposed. The performance of the A-ECMS is shown in simulation and compared to the optimal solution obtained with dynamic programming.
Vehicle Evasive Maneuver Trajectory Optimization Using Collocation Technique
Authors: Soudbakhsh Damoon , Eskandarian Azim , Chichka David
Published: February 2011

Vehicle evasive maneuvers or sudden lane changes pose stringent conditions on trajectory control, which require not only a desired path following but also a complete consideration of lateral forces and vehicle dynamic stability. Experienced drivers steer the vehicle on a desired path, as much as possible, without creating large lateral forces beyond the stability limits. Steering control systems have been developed to perform similar lane change or evasive maneuvers automatically but with limitations. A control method is developed to find desired trajectory automatically based on the defined design criteria using constrained optimization via collocation technique. The results are compared with two known suitable trajectories. The results show that the proposed control method produces peak lateral acceleration that are lower than the 5th order polynomial trajectory, and overall lateral accelerations that are lower than a comparable trapezoidal acceleration profile.