bluuebunny/crossref_metadata_2025 huggingface dataset:
Bifurcations on Control-Transverse Dynamics
Authors: Kappos Efthimios
Published: February 2011

To every submanifold transverse to the control distribution of a given control system is associated in a canonical way a dynamical behavior. By varying this transverse manifold, we can effect bifurcations in these dynamics. In this paper we explain how this is done and draw the analogies with the more familiar aspects of bifurcation theory. The second crucial point is that the manifold can be made invariant for a control flow and the dynamics in the directions transverse to it can be assigned arbitrarily — in particular, the manifold can be made asymptotically stable.
Chemical Composition Modeling of a Two-Zone Control-Oriented Mixing Model for Homogeneous Charge Compression Ignition Engines
Authors: McCuen Matthew J. , Sun Zongxuan , Zhu Guoming
Published: February 2011

Due to the need for clean and efficient automobile propulsion systems, this paper models an important process in the enabling of homogeneous charge compression ignition (HCCI) engines. The need for a deep understanding of charge-residual mixing in residual-affected HCCI engines requires a model of the chemical composition during the mixing process. In this paper, a chemical composition model is developed specifically for a two-zone mixing model to account for important phenomena such as the presence of unburned fuel in the residual exhaust gas. The model is developed as a control-oriented model that can be used for real-time decision making and control. This paper develops the composition model for the major species present, and also presents the method that would be used to include other minor species. The model is simulated for variations in residual gas fraction equivalence ratio, a misfire situation, and its effects on air/fuel ratio.
Sliding Surface Envelope Control: Keeping the Vehicle Within a Safe State-Space Boundary
Authors: Bobier Carrie G. , Joe Shinichiro , Gerdes J. Christian
Published: February 2011

Stability control systems on the market today, while effective, operate without full information on the vehicle states and road friction properties. This paper presents a vehicle control scheme that takes into account vehicle state information on sideslip angle and yaw rate, as well as road coefficient of friction, to keep the vehicle within a safe region of the state space. The controller limits state growth outside of the safe area to a sliding surface defined by the distance to the closest operating point in the safe region. Experimental results validate a simple version of the controller on a low friction surface. The controller successfully stabilizes the vehicle using steer-by-wire as a control input.
Two-Port Synthesis for Retrofit Design of Electric Ship Control Surface Actuation Systems
Authors: LeSage Jonathan R. , Shutt William , Longoria Raul G.
Published: February 2011

This paper presents an approach for using two-port circuit synthesis methods as a basis for designing actuator subsystems. The development of this methodology is generally motivated by problems in retrofit design, where technology reinsertion is required to replace legacy systems, or for early stage design in new mechatronic systems. The particular problem of electric ship control surface actuation is used as an example application. A procedure that integrates two-port network synthesis methods with a model-basis conveyed using bond graphs is presented and applied to the problem of synthesizing a candidate actuation system for a submarine control surface. Studying the control surface actuator problem shows that a synthesis method is capable of providing insight into balancing passive compensation with actuation (active elements). The ability to partition active and passive system elements suggests promise in developing a means for integrating passive energy storage with actuation subsystems.
An Adaptive Amplitude-Based Self-Sensing Piezoelectrically-Driven Microcantilever Sensor
Authors: Faegh Samira , Eslami Sohrab , Jalili Nader
Published: February 2011

This paper presents an adaptive amplitude-based self-sensing strategy for ultrasmall tip mass estimation utilizing piezoelectrically-driven microcantilevers. The proposed configuration overcomes the inherent shortfalls (e.g., thermal drifts, electronic noise, and restriction to use in liquid media) currently exist in conventional systems. The microcantilever operates in self-sensing mode utilizing a piezoelectric patch deposited on the cantilever surface. The piezoelectric patch actuates the beam and at the same time senses the beam vibration through inverse and direct piezoelectric effects, respectively, which enables measurement of the surface induced stress. To remedy the measurement limitation at the microscale due to lack of sensitivity and temperature dependency of piezoelectric, an advanced auto-tunable self-sensing controller is proposed which balances the capacitance bridge network. Moreover, an optimization strategy is developed to minimize the error of the output voltage considering the fact that the individual time dependent coordinates are not measurable. Mathematical models and equations of motion are obtained using the Hamilton’s principle treating the microcantilever as a distributed-parameters system. Simulations are performed to demonstrate the effectiveness of the proposed technique.
Nonlinear Modeling for Interface Control in a Three-Lane Microfluidic Channel
Authors: Kim YongTae , LeDuc Philip R. , Messner William C.
Published: February 2011

A three-lane microfluidic system, where the central fluid stream is confined between two outer streams is well suited for delivering solutes selectively to regions of samples located in the outlet channel. We present a model for the control of the interfaces where the position of the central stream in this microfluidic channel is manipulated by regulating pressure at the two outer inlets. To allow the use of reservoirs of arbitrary size, we decouple the pressure modulation mechanism from the reservoirs. The mechanism simultaneously modulates a variable fluidic resistance mechanically coupled to squeeze pump located in the fluid network between the reservoir and the channel. We show that the linearized dynamics of our nonlinear mechanism explains the high bandwidth in our system. We use the linearized model to design a linear controller and demonstrate its effectiveness for the full nonlinear dynamics in simulation. We present experimental results short-term and long-term pressure regulation at the channel inlets for stable control of laminar flow interfaces. We envision that this approach will be useful for flow cytometry, chemical synthesis, drug delivery, and investigation of spatiotemporally integrated biological responses at molecular, cellular, and tissue levels.
Modeling Vehicle Lateral Dynamics by Gaussian Processes
Authors: Broderick David J. , Bevly David M. , Hung John Y.
Published: February 2011

A method of modeling a vehicle’s lateral dynamics is investigated. Gaussian processes (GP) are used to estimate the side slip and yaw rate of the vehicle. A method of clustering the inputs to the GPs is also investigated and the effects of a key parameter, the clustering threshold, are examined. Sensitivity of this parameter is considered and a compromise is found between model accuracy and computation time. A discussion of how these methods can be extended to online adaptation of the estimators is included.
Parameters and Driving Force Estimation of Cell Motility via Expectation-Maximization (EM) Approach
Authors: Milutinovic´ Dejan , Garg Devendra P.
Published: February 2011

Motility is an important property of immune system cells. To describe cell motility, we use a continuous stochastic process and estimate its parameters and driving force based on a maximum likelihood approach. In order to improve the convergence of the maximization procedure, we use expectation-maximization (EM) iterations. The iterations include numerical maximization and the Kalman filter. To illustrate the method, we use cell tracks obtained from the intravital video microscopy of a zebrafish embryo.
A New AFM Cantilever Design for Manipulation at the Nanoscale
Authors: Landolsi Fakhreddine , Ghorbel Fathi H. , Dabney James B.
Published: February 2011

Prototyping and fabrication of nanodevices require subnanometer tolerances and highly accurate sensing and actuation. Improved control on manipulating matter at the nanoscale is of relevance in different fields such as the automotive industry, biotechnology and communication. Limitations of existing nanomanipulation systems include constrained motion of manipulator end-effectors. In the present paper, a new AFM probe design suitable for nanomanipulation is proposed. The design includes a nanomanipulation piezotube that allows actuation and sensing of the tip motion in three directions. In addition, a piezopatch is attached to the cantilever holder for in-situ stiffness tuning needed for manipulating large and sticky nanosamples. Design considerations and path tracking performance of the proposed manipulator are analyzed.
Dynamic Reference Value Generation for the Control of a Diesel Engine With HP- and LP-EGR
Authors: Mrosek Matthias , Isermann Rolf
Published: February 2011

A combination of a low-pressure EGR and a high-pressure EGR for Diesel engines can effectively reduce the NOx emissions. In comparison to a conventional high-pressure EGR, the combination with a low-pressure EGR introduces an additional degree of freedom for the air path control. From control perspective the weaker couplings with the charging pressure and the dynamics of the gas composition in the intake and exhaust system are the major differences between the low-pressure and the high-pressure EGR. The lower gas temperature of the low-pressure EGR further reduces the emissions. A control oriented model is presented to control the gas composition in the intake system. Therefore a reference value transformation converts a desired air mass flow rate into a desired gas composition in the intake system. Depending on the dynamical gas compositions in the intake and exhaust system, the reference value of the desired gas composition results in a setpoint for a high-pressure EGR mass flow rate controller. Due to the faster dynamics of the high-pressure EGR, this controller accounts for the fast dynamical effects in the gas system. The presented control structure in combination with the reference value generation is invariant to model and sensor uncertainties and results stationary in an air mass flow rate control. As additional control variable, the intake temperature is controlled by the low-pressure EGR mass flow rate. A calibrated desired temperature delivers the setpoint for a low-pressure EGR mass flow rate controller.
Preliminary Evaluation of Myoelectric Control of an Active Transfemoral Prosthesis During Stair Ascent
Authors: Hoover Carl D. , Fite Kevin B.
Published: February 2011

This paper presents the development and preliminary validation of a control interface for a transfemoral prosthesis that enables EMG-based control of a powered knee during stair ascent. The approach uses results from non-amputee gait studies of stair ascent in the design of a control architecture that enables EMG modulation of knee torque in a manner biomechanically similar to that exhibited by non-amputee subjects. The myoelectric torque controller is formulated with a finite-state linear impedance model in stance and swing. The stance phase is modulated by surface EMG signals co-activated by antagonist residuum muscles. Preliminary results with a sound-limb subject using a knee immobilizer indicate that the EMG-based control architecture has the potential to enable the amputee to directly generate torque commands appropriate for stair ascent using an actively powered artificial limb.
Hazardous Spill Perimeter Detection and Monitoring via Multiple Autonomous Mobile Robotic Agents
Authors: Zhang Guoxian , Garg Devendra P. , Fricke Greg
Published: February 2011

The problem of perimeter detection and monitoring has a variety of applications. In this paper, a hybrid system with finite states strategy is proposed for multiple autonomous robotic agents with the purpose of hazardous spill perimeter detection and tracking. In the system, each robotic agent is assumed to be in one of the following states: searching, pursuing, and tracking. The agents are prioritized based on their states, and a potential field is constructed for agents in each state. The location and velocity of an agent in the tracking state as well as those of its closest leading and trailing agents are utilized to control its movement. The convergence of the tracking algorithm is analyzed for multiple spills under certain conditions. Simulation results show that with the proposed method, the agents can successfully detect and track the spills of various sizes and movements.
State Estimation for Vehicle Stability Control: A Kinematic Approach Using Only GPS and VSC Sensors
Authors: Ryan Jonathan , Lu Jianbo , Bevly David
Published: February 2011

It is well known that the vehicle sideslip and roll angles are very important for vehicle stability control systems. There has been much work focusing on estimating these states, however much of this work assumes knowledge of vehicle parameters or requires sensors which are currently not available on passenger vehicles for cost reasons. This paper presents a method of applying GPS/INS integration strategies to this particular estimation problem. Using a single antenna GPS receiver with a reduced set of INS sensors common to vehicle stability control systems, estimates of the roll and sideslip angles which are robust to different road geometries and changing vehicle parameters can be achieved. While the future may afford the luxury of using more sensors of higher quality, this work offers results which are applicable in today’s market and which would also serve as a means of redundancy in the future.
Hovering Stability of Helicopters With Elastic Constraints
Authors: Pounds Paul E. I. , Dollar Aaron
Published: February 2011

Aerial vehicles are difficult to stabilize, especially when acted upon by external forces. A hovering vehicle in contact with objects and surfaces must maintain flight stability while subject to forces imparted to the airframe through the point of contact. These forces couple with the motion of the aircraft to produce distinctly different dynamics from free flight. While external contact is generally avoided, extending aerial robot functionality to include contact with the environment during flight opens up new and useful areas such as perching, object grasping and manipulation. In this paper, we present a general elastic contact constraint model and analyze helicopter stability in the presence of those contacts. As an example, we evaluate the stability of a proof-of-concept helicopter system for manipulating objects using a compliant gripper that can be modeled as an elastic linkage with angular reaction forces. An off-the-shelf PID flight controller is used to stabilize the helicopter in free flight, as well as during the aerial manipulation task. We show that the planar dynamics of the object-helicopter system in vertical, horizontal and pitch motion around equilibrium are shown to remain stable, within a range of contact stiffnesses, under unmodified PID control.
A Method for Incorporating Nonlinear Tire Behavior Into Model Predictive Control for Vehicle Stability
Authors: Beal Craig E. , Gerdes J. Christian
Published: February 2011

Given the increase in computing power over the last decade, model predictive control has received renewed attention as a technique for accomplishing high-level vehicle control. However, tire nonlinearities present a challenge for rapidly solving the optimization problem required to do model predictive control. This paper presents an approach which extracts the tire nonlinearities outside the MPC optimization, leaving a convex problem that can be solved rapidly and with guaranteed optimality. Experimental results are presented from an MPC controller using this technique that demonstrate the controller’s ability to handle tire nonlinearities during highly dynamic manuevers that saturate the tires and induce lateral-longitudinal force coupling effects.
Nonlinear Tracking Control of a Transient Hydrostatic Dynamometer for Hybrid Powertrain Research
Authors: Wang Yu , Sun Zongxuan , Stelson Kim A.
Published: February 2011

With its superior power to weight ratio, the hydrostatic dynamometer is an ideal candidate for transient engine or powertrain testing. Given its high bandwidth, the hydrostatic dynamometer can be further used as a virtual power source to emulate the dynamics of the automotive hybrid power sources. This will greatly expedite the investigation of various hybrid powertrain architectures and control methodologies without building the complete hybrid system. This paper presents the design, modeling, nonlinear tracking control and experimental investigation of a transient hydrostatic dynamometer. An electronically controlled load sensing mechanism is employed to facilitate the supply pressure control, and a two-stage high bandwidth valve is used as the primary actuator for the loading pressure control. To enable the model-based control, a 9th order physics-based model is formulated and then, identified and validated with experimental data. On this basis, model-based nonlinear tracking controls are designed for this multivariable nonlinear system to realize the precise engine speed tracking. A nonlinear model-based inversion plus PID control is first implemented and then, a state feedback control via feedback linearization is designed for reference tracking. Experimental results demonstrate precise tracking performance with less than 5% tracking error for both transient and steady state operations.
MIT-Skywalker: Preliminary Insights on Performance-Based Locomotor Training
Authors: Kim Seung-Jae , Krebs Hermano Igo
Published: February 2011

Gait rehabilitation promotes the reduction of gait deficits resulting from neurological pathologies by enhancing activity-dependent plasticity in the central nervous system. To maximize the therapeutic benefit of gait training, the key components appear to be subjects’ active participation and intensity. In this paper we discuss a performance-based training scheme for a novel gait trainer (MIT-Skywalker) that can challenge patients by systematically adjusting the treadmill speed and visual feedback. In our algorithm, the speed is adjusted based on gait performance of step length symmetry and subject’s ability to cope with the treadmill speed. Computer simulations demonstrate that the gait speed controller adapts to changes in walking performance, suggesting a potential scheme for gait therapy.
An Agent Based Simulation for Building Energy System Modeling
Authors: Hu Mengqi , Wen Jin , Li Fan , Haghnevis Moeed , Khodadadegan Yasaman , Sanchez Luis Mejia , Wang Shanshan , Zhuang Xiaotian , Wu Teresa
Published: February 2011

Extensive research has been done on the centralized building energy system modeling and simulation. However the centralized structure is limited to study and simulate the energy interaction between different buildings at different locations. This paper reviews the building energy consumption model, energy storage system and energy generation system in the Net-zero buildings. Incorporate with the real-time price rate model, this paper develops an agent based simulation framework for distributed building energy system under uncertainty. Each sub system is developed as an agent in the simulation model, and a virtual decision agent is designed to simulate the operation strategy. The energy flow between different agents can be easily monitored from the simulation. The differences between on-peak and off-peak control are demonstrated from the simulation result.
Identification of Combustion Engines With Special Orthogonal Excitation Signals
Authors: Schreiber Alexander , Isermann Rolf
Published: February 2011

This article shows a new excitation method for the identification of combustion engines. The method is based on the combination of statistical stationary engine measurement (Design of Experiments - DoE) and dynamic identification techniques for nonlinear multi-input systems. The dynamics are excited by special amplitude-modulated pseudo-random-multilevel-signals (APRMS), which act on the engine simultaneously, in order to allow a short measurement time period. Because the used dynamic excitation signals are orthogonal, they allow a better separation of the input signals for system identification.
Development of a New Lateral Stability Control System Enhanced With Accelerometer Based Tire Sensors
Authors: Erdogan Gurkan , Borrelli Francesco , Tebano Riccardo , Audisio Giorgio , Lori Giulia , Sannazzaro Jacopo
Published: February 2011

Vehicles are usually equipped with driver assistance systems such as anti-lock brake, traction control and lateral stability control systems. Although the forces maneuvering a vehicle are generated inside the tire contact patch, state of the art control systems have no feedback directly from the tires. Instead, observers based on indirect measurements are employed to close the control loop. Wireless sensors embedded inside the tires can be used to extract valuable information from the tire deformations such as forces. These forces can be used to develop adaptive stability control systems which update their parameters in real-time depending on the road and vehicle conditions. Furthermore, controllers can selectively regulate tire forces by changing brake/drive torques at each tire. This paper examines the integration of accelerometer based tire sensors with lateral stability control system (ESP). Its aim is to present the main components of a smart-tire enabled ESP and a preliminary study on potential performance improvements.
Non-Invasive Hybrid Sensory System for Direct Brain Control of Artificial Limbs
Authors: Shoureshi Rahmat A. , Aasted Christopher M. , Sarusi Benjamin
Published: February 2011

Current commercially available motorized replacement limbs rely on the activation of remaining muscle tissue or a different portion of the body to operate joints in the prosthetic, which requires training to use and may never feel natural. Research to improve artificial limb technology is focused on using implants to monitor electrical activity in the nervous system or rerouting nerve endings to healthy muscle tissue, both of which require a medical procedure to be performed. This paper presents results of research which has been focused on the feasibility of using a non-invasive prosthetic control system that utilizes a hybrid of feedforward and feedback sensors. This research examines the correlation between brain activity across the primary motor cortex and muscle activity during upper body limb movement. The hybrid sensory system is composed of an optical imager for the detection of localized brain activities, electroencephalography (EEG) and electromyography (EMG) sensors. This paper will present design of the sensory system, the proposed control architecture, and human subject results. The improved accuracy of the brain intention determination algorithm as well as integration with a learning control loop will be presented and discussed.
Torque Converter Clutch Low Slip Speed Detection and Control
Authors: Otanez Paul G. , Lee Chunhao J. , Chen Xu , Kao Chi-Kuan , Samie Farzad
Published: February 2011

A torque converter clutch (TCC) is an important element of automatic transmissions because it affects fuel economy and driveability. Although torque converters are ideal launch devices for transmissions, they are inefficient in steady-state operations. For that reason, a TCC is used to control and minimize the slip between the torque converter pump and turbine, thereby increasing the efficiency of the driveline and improving fuel economy. However, low TCC slip speeds increase the likelihood that disturbances cause the TCC to have zero slip or crash. In the absence of TCC slip, it is essential to quickly restore slip and regain driveline isolation to maintain driveability. To recover TCC slip, pressure to the TCC must be reduced significantly to overcome the effects of clutch material nonlinearities and hydraulic hysteresis. Unfortunately, large pressure reductions can also result in undesirable slip overshoot. In this investigation, the truncated sequential probability ratio test is used to achieve fast and robust detection at the low signal-to-noise ratios caused by the low TCC slip speeds. In the event of a crash, two unique TCC pressure command sequences are presented which maximize the response of the system hydraulics while also minimizing clutch slip overshoot. The effectiveness of the proposed methods are evaluated using experimental results from small and large vehicles equipped with automatic front and rear-wheel drive transmissions.
Analysis of EMG-Force Relation Using System Identification and Hammerstein-Wiener Models
Authors: Sebastian Anish , Kumar Parmod , Schoen Marco P. , Urfer Alex , Creelman Jim , Naidu D. Subbaram
Published: February 2011

Surface Electromyographic (sEMG) signals have been exploited for almost a century, for various clinical and engineering applications. One of the most compelling and altruistic applications being, control of prosthetic devices. The study conducted here looks at the modeling of the force and sEMG signals, using nonlinear Hammerstein-Weiner System Identification techniques. This study involved modeling of sEMG and corresponding force data to establish a relation which can mimic the actual force characteristics for a few particular hand motions. Analysis of the sEMG signals, obtained from specific Motor Unit locations corresponding to the index, middle and ring finger, and the force data led to the following deductions; a) Each motor unit location has to be treated as a separate system, (i.e. extrapolation of models for different fingers cannot be done) b) Fatigue influences the Hammerstein-Wiener model parameters and any control algorithm for implementing the force regimen will have to be adaptive in nature to compensate for the changes in the sEMG signal and c) The results also manifest the importance of the design of the experiments that need to be adopted to comprehensively model sEMG and force.
Impedance-Based Control of the MIT-Skywalker
Authors: Artemiadis Panagiotis K. , Krebs Hermano Igo
Published: February 2011

Walking impairments are a common sequela of neurological injury, severely affecting the quality of life of both adults and children. Gait therapy is the traditional approach to ameliorate the problem by re-training the nervous system and there have been some attempts to mechanize such approach. In this paper, we present a novel impedance controller for the MIT-Skywalker. In contrast to previous approaches in mechanized gait therapy, the MIT-Skywalker does not impose a rigid kinematics pattern of normal gait on impaired walkers. Instead, it takes advantage of the concept of passive walkers and the natural dynamics of the lower extremity in order to deliver more “ecological” therapy. The proposed closed-loop control scheme can regulate the interaction between the walker and the treadmill and can provide the appropriate feedback to the walker during stance phase as well as at heel-strike and toe-off. Simulation results prove the feasibility of the impedance-based control scheme.
Tracking Control of Periodic Signals With Varying Magnitude and Its Application to Hybrid Powertrain
Authors: Song Xingyong , Gillella Pradeep , Sun Zongxuan
Published: February 2011

Internal model based repetitive control for linear time invariant (LTI) system has been widely applied to track or reject periodic signals with only the period known. It is well understood that the discrete generating dynamics of the periodic signal can be obtained by finite sampling, and embedding it as the internal model will yield asymptotic performance. However, the traditional repetitive control framework will no longer work for periodic signals with varying peak to peak amplitude. As will be revealed in this paper, the generating dynamics of this kind of signals is time varying, and thus simply embedding its generating dynamics as the internal model will no longer ensure asymptotic performance. The necessity of investigating tracking or rejecting varying magnitude periodic signals comes from a wide class of anticipated applications, one example of which is the hybrid vehicle powetrain vibration reduction. In the hybrid vehicles, engine starting and stopping occur frequently to switch between power sources, which could cause driveline vibration. With proper formulation, the oscillation signal becomes periodic with varying magnitude. To suppress such vibration, in this paper, the generating dynamics of this unique signal is first derived, and then its corresponding controller design method is presented. After a series of simulations and case studies, the proposed control framework is demonstrated to be a promising solution for the hybrid powertrain vibration reduction problem.
Control of Eukaryotic Cell Migration Through Modulation of Extracellular Chemoattractant Gradients
Authors: Farahat Waleed A. , Asada H. Harry
Published: February 2011

Cell migration is fundamental to a wide range of biological and physiological functions including: wound healing, immune defense, cancer metastasis, as well as the formation and development of biological structures such as vascular and neural networks. In these diverse processes, cell migration is influenced by a broad set of external mechanical and biochemical cues, particularly the presence of (time dependent) spatial gradients of soluble chemoattractants in the extracellular domain. Many biological models have been proposed to explain the mechanisms leading to the migratory response of cells as a function of these external cues. Based on such models, here we propose approaches to controlling the chemotactic response of eukaryotic cells by modulating their micro-environments in vitro (for example, using a microfluidic chemotaxis chamber). By explicitly modeling i) chemoattractant-receptor binding kinetics, ii) diffusion dynamics in the extracellular domain, and iii) the chemotactic response of cells, models for the migration processes arise. Based on those models, optimal control formulations are derived. We present simulation results, and suggest experimental approaches to controlling cellular motility in vitro, which can be used as a basis for cellular manipulation and control.
Parametrization of LTI Controllers for Multirate Systems
Authors: Cimino Mauro , Pagilla Prabhakar R.
Published: February 2011

In this work we consider the problem of parametrizing the set of all stabilizing Linear Time-Invariant (LTI) controllers for multirate systems such that model matching is achieved with a desired transfer function. We consider those systems where the plant output can be measured at a rate (measurement update rate) slower than the control signal updates rate. The solution to the parametrization problem is provided for the two cases: (1) model matching at the control update rate, (2) model matching at the measurement update rate. Unlike model matching at the measurement update rate, model matching at the control update rate allows us to directly improve and characterize the transient response of the continuous-time system. Tools such as up-sampling and down-sampling operators, and modified Z-transforms are utilized to model the closed-loop multirate system and to parametrize the sets of LTI controllers.
Cooperative Kalman Filtering With Data Fusion in Time Varying Communication Networks
Authors: Spinello Davide , Stilwell Daniel J.
Published: February 2011

We consider a time varying sensor network comprised of a group of agents equipped with communication capabilities, and we address applications where communication between agents is highly bandwidth limited as for instance in underwater missions. We use the Bayesian formalism to derive data fusion equations in which each sensor maintains an individual estimate of the state of a dynamical process. Data sharing between agents is defined by a time-varying network topology. We show that error covariances associated to estimates obtained with the independent opinion pool fusion scheme asymptotically agree if the communication network is partially asynchronous.
A New Robust Control Design for Linear Systems With Norm Bounded Time Varying Real Parameter Uncertainty
Authors: Devarakonda Nagini , Yedavalli Rama K.
Published: February 2011

In this paper, a new methodology for robust control design of linear systems with time varying real parameter uncertainty is presented. The distinctive feature of this method is that it specifically offers robustness guarantees to real parameter uncertainty thereby providing a much needed alternative design method compared to existing design methods such as H∞ and μ-synthesis methods which tend to be conservative when specialized to real parameter uncertainty. The proposed robust control design method is inspired by sign (qualitative) stability idea from ecology, leading to a specific structure in the desired closed loop system matrix involving pseudosymmetry. The design procedure is simple and straightforward without requiring intensive computation. The proposed design algorithm is illustrated with aerospace applications. This algorithm is quite promising with considerable scope for extensions and improvements, finally adding to the bank of available control design methods for linear state space systems.
Road Bank Estimation on Uneven Terrain for Unmanned Ground Vehicles
Authors: Brown Lowell S. , Dawkins Jeremy J. , Hill Ryan S. , Bevly David M.
Published: February 2011

Knowledge of non-negligible bank angle is important for preventing rollover on uneven terrain. This article shows the effect of uneven terrain on rollover and explores a method to calculate the bank of the uneven terrain. An Extended Kalman Filter (EKF) is implemented to estimate the total roll of the vehicle. Information on the relative roll of the vehicle is acquired from suspension geometry and suspension deflections. The combination of EKF estimated roll and measured suspension deflections yields an estimate of the road bank angle.
Battery Health-Conscious Plug-In Hybrid Electric Vehicle Grid Demand Prediction
Authors: Bashash Saeid , Moura Scott J. , Fathy Hosam K.
Published: February 2011

This paper examines the problem of predicting the aggregate grid load imposed by battery health-conscious plug-in hybrid electric vehicle (PHEV) charging. The paper begins by generating a set of representative daily PHEV trips using the National Household Travel Survey (NHTS) and a set of federal and real-world drive cycles. Each trip is then used in a multiobjective genetic optimizer, along with a PHEV model and a battery degradation model, to simultaneously minimize PHEV energy cost and battery degradation. The optimization variables include the parameters of the PHEV charge pattern, defined as the timing and rate with which the PHEV receives electricity from the grid. For several weightings of the optimization objectives, total PHEV power demand is predicted by accumulating the charge patterns for individual PHEVs. Two charging scenarios, i.e., charging at home only versus charging at home and work, are examined. Results indicate that the main PHEV peak load occurs early in the morning (between 5.00–6.00a.m.), with approximately 45%–60% of vehicles simultaneously charging from the grid. Moreover, charging at work creates additional peaks in this load pattern.
Process Dynamics and Control Analysis for Electrospinning Nanofibers
Authors: Yan Xuri , Gevelber Michael
Published: February 2011

In many emerging, high value electrospinning applications, the diameter distribution of electrospun fibers has important implications for the product’s performance and process reproducibility. However, the current state-of-the-art electrospinning process results in diameter distribution variations, both during a run and run-to-run. To address these problems, a vision-based, open loop system has been developed to better understand the process dynamics. The effects of process parameters on fiber diameter distributions are investigated, process dynamics are identified, and the relation between measurable variables and the resulting fiber diameter distribution is analyzed.
Modeling and Global MPPT Control for Photovoltaic Array With Variable Shading
Authors: Lei Peng , Li Yaoyu , Seem John E.
Published: February 2011

The photovoltaic (PV) systems are often subject to shading in practical operation. Non-uniform shading for PV array with bypass diodes leads to mismatch in power generation, and thus resulting in multi-peak power-voltage (P-V) characteristics. Most existing maximum power point tracking (MPPT) control strategies are local optimum oreinted, as based on the gradient search or its variations, e.g. perturbation-and-observation (P&O) or extremum seeking control (ESC). The multi-modal P-V characteristics for PV array with variable shading demands for global search for the optimum to avoid the signifiant power loss otherwise. This study investigates both the P-V and the current-voltage (I-V) characteristics of the PV panel under variable shading. Analytical model is established based on an approximate model of the PV device. The stair-case profile of the I-V relationship is shown to have close and consistent correspondence to the shading distribution. The voltage breakpoints for the multipeak curve are also within predictable ranges. With such results, the global search can be achieved with multiple local search within finite number of intervals. Simulation results validate the analytical modeling and the ESC based global ESC for partially shaded PV panels.
Sliding Mode Control of Piezoelectric Valve Regulated Pneumatic Actuator for MRI-Compatible Robotic Intervention
Authors: Wang Yi , Su Hao , Harrington Kevin , Fischer Gregory S.
Published: February 2011

This paper presents the design of a magnetic resonance imaging (MRI) compatible pneumatic actuator regulated by piezoelectric valve for image guided robotic intervention. After comparing pneumatic, hydraulic and piezoelectric MRI compatible actuation technologies, we present a piezoelectric valve regulated pneumatic actuation system consisted of PC, custom servo board driver, piezoelectric valves, sensors and pneumatic cylinder. The system was proposed to investigate the control schemes of a modular actuator; which offers fully MRI compatible actuation; the initial goal is to control our MRI compatible prostate biopsy robot, but the controller and system architecture are suited to a wide range of image guided surgical application. We present the mathematical modeling of the pressure regulating valve with time delay and the pneumatic cylinder. Three sliding mode control schemes are proposed to compare the system performance. Preliminary simulation results are presented to validate the control algorithm.
Control and Experimental Results for Post Stroke Gait Rehabilitation With a Prototype Mobile Medical Exoskeleton
Authors: Swift Tim A. , Strausser Katherine A. , Zoss Adam B. , Kazerooni H.
Published: February 2011

Repetitive task-oriented exercises are accepted in traditional gait rehabilitation and have given rise to driven gait orthoses, but both methods suffer from limited rehabilitation time for the patient. The presented device proposes a control strategy and implementation unique for a mobile rehabilitation exoskeleton as well as results from initial subject testing. This anthropomorphically designed device has knee and hip joints that are actuated in the sagittal plane using hydraulic actuators. The presented control strategy allows the user or therapist to directly specify the level of rehabilitation assistance desired between complete machine control and a zero impedance joint. The device was experimentally tested on three chronic stroke patients with noticeable gait improvements based on the metric of joint flexion. Other results of step time and step length are presented that do not demonstrate as clear improvements but these are believed to be a function of the limited patient testing time.
Constrained Model Predictive Control of an Industrial Drying Process for Viscose Staple Fibres
Authors: Schuster Alexander , Kozek Martin , Voglauer Bernhard , Voigt Andreas
Published: February 2011

The paper presents the implementation of a model based predictive control algorithm of an industrial drying process for Viscose staple fibres. A short review of the earlier published modelling procedure presents the linearised multi-input multi-output (MIMO) state space formulation of the design model. The design of the predictive control scheme incorporates constraints on the manipulated variables, set-points for the manipulated variables, and active disturbance rejection for the main disturbance variables of the drying process. Some simulation results demonstrate the beneficial effects of this structure, and the choice of proper weightings is also briefly discussed. Implementation issues and various measured results are presented. The problem of redundant but biased measurements of fibre humidity is addressed and the superior performance of the new concept compared to the existing PID-control is demonstrated. Both energy consumption and variation of humidity in the final product are significantly reduced by the successful implementation.
Variable-Velocity Exponential Input Shaping for Position Controlled Robotic Systems
Authors: Iravani P. , Sahinkaya M. N.
Published: February 2011

This paper demonstrates a new form of Input Shaping for vibration reduction applied to robotic systems that manipulate flexible loads. The method is based on using an exponential function to define asymptotic and vibration-free trajectories for the flexible system. The required control input is calculated analytically by using inverse dynamics which ensures the desired end-effector trajectory. The method is demonstrated experimentally on the control of point-to-point movements of a robotic manipulator.
Time-Domain Input-Output Transient Performance Validation for Modular Control Systems: Method and Examples
Authors: Sharma Deepak , Tilbury D. M. , Seno Lucia
Published: February 2011

This paper presents results that can be used to validate input-output transient performance for modular control systems. If bounds in the time-domain are specified for inputs of an LTI SISO system, the techniques in this paper can determine the minimum set containing all possible outputs. If both input and output bounds are given, they can determine whether these specifications are met. Network delay affecting the input of the system is also considered. Finally, this paper extends the techniques for MIMO systems. The results are derived using the theory of convex sets. Several examples are presented to illustrate the results and demonstrate their application.
Trapping and Steering a Magnetic Microbead Using 3D Magnetic Tweezers
Authors: Zhang Zhipeng , Menq Chia-Hsiang
Published: February 2011

The development of a magnetic micromanipulation system that is capable of trapping and steering a magnetic microbead in three dimensions is presented in this paper. Hexapole magnetic tweezers were designed and implemented to realize three-dimensional (3D) magnetic actuation. Because magnetic actuation is inherently unstable without feedback control, visual measurement based on computer processing of video images was employed to detect the displacement of the microbead, facilitating real-time feedback control. An analytical magnetic force model was developed to characterize the nonlinearity and position dependency of the magnetic force exerted on the magnetic bead by the hexapole magnetic tweezers. Its inverse model was then derived and employed in feedback linearization. A proportionalintegral controller along with feedback linearization was implemented and the motion of the magnetic bead was successfully stabilized. The control results in terms of 100-nanometer stepping and 3D motion steering were experimentally demonstrated.
Implementation of a Quadruped Robot Pronking/Bounding Gait Using a Multipart Controller
Authors: Nikolakakis Alexandros , Kontolatis Ioannis , Cherouvim Nicholas , Chatzakos Panagiotis , Papadopoulos Evangelos
Published: February 2011

This paper presents a multipart pronking/bounding controller for a quadruped robot, as well as the corresponding experimental results. The controller achieves given apex height and forward velocity in a quadruped robot with only one actuator per leg. A quadruped is designed and built and described in some detail. Experimental results obtained using internal sensors and high-speed camera captions show that the implemented quadruped robot performs pronking gaits and achieves bounding gaits with the desired characteristics.
Using an Adaptive High-Gain Extended Kalman Filter With a Car Efficiency Model
Authors: Sebesta Kenneth D. , Boizot Nicolas , Busvelle Eric , Sachau Juergen
Published: February 2011

The authors apply the Adaptive High-Gain Extended Kalman Filter (AEKF) to the problem of estimating engine efficiency with data gathered from normal driving. The AEKF is an extension of the traditional Kalman Filter that allows the filter to be reactive to perturbations without sacrificing noise filtering. An observability normal form of the engine efficiency model is developed for the AEKF. The continuous-discrete AEKF is presented along with strategies for dealing with asynchronous data. Empiric test results are presented and contrasted with EKF-derived results.
Synchronization of a Network With Piecewise-Linear Dynamics
Authors: Gall Walter , Zhou Ying , Salisbury Joseph
Published: February 2011

We consider two and three phase-oscillators as in the Kuramoto model of coupled oscillators, replacing the sine wave interaction with a sawtooth wave. We show that for the case of non-uniform input-symmetric coupling strengths, the non-smooth, piecewise-linear dynamics synchronizes when the coupling strengths are large enough to overcome the differences in the natural frequencies of the oscillators. Stability is analyzed separately in the regions where the dynamics is linearized. These regions are separated by the switching boundaries where the vector field is discontinuous.
Kullback-Leibler Divergence, Cost Density-Shaping, Stochastic Optimal Control With Applications to Vibration Suppression
Authors: Zyskowski Matthew , Sain Michael , Diersing Ronald
Published: February 2011

The “k cost cumulant” (kCC) control performs competitively with other structural controllers in protecting buildings from natural disasters. These applications constitute vibration suppression problems involving lightly-damped structures with multiple degrees of freedom. While kCC control has delivered excellent performance in such applications, it gives the designer little direct influence over the shape of the cost’s density. The goal of this work is to present the Minimum Kullback-Leibler Divergence Cost Density-Shaping (MKLD-CDS) control paradigm, which enables the designer to shape the cost’s density according to a pre-specified target mean and variance. This new theory is applied to the first-generation Active Mass Driver (AMD) benchmark problem, where the application of MKLD-CDS with the Statistical Target Selection (STS) design method enables a family of stablizing MKLD-CDS controllers to be computed based on parametric targets. MKLD-CDS controllers are found that exceed the performance of a nominal 2CC controller while not compromising this controller’s robust stability.