bluuebunny/crossref_metadata_2025 huggingface dataset:
Divergent effects of tumour necrosis factor‐alpha on apoptosis of human neutrophils
Authors: Van Den Berg J. M. , Weyer S. , Weening J. J. , Roos D. , Kuijpers T. W.
Published: September 2010

Apoptosis of neutrophils is a key mechanism to control the intensity of the acute inflammatory response. Previously, the cytokine TNF‐α was reported by some investigators to have pro‐apoptotic and by others to have antiapoptotic effects on neutrophils. The aim of this study was to explain these contradictory results.

We found that TNF‐α at low concentrations strongly decreased apoptosis of neutrophils. However, at higher concentrations, TNF‐α lost its protective effects, and also reversed the anti‐apoptotic effects of IFN‐γ and GM‐CSF. In fact, the combination of high concentrations of TNF‐α with either IFN‐γ or GM‐CSF caused even stronger apoptosis than that seen in the presence of TNF‐α alone. This ‘pro‐apoptotic’ effect of TNF‐α was blocked by anti‐CD11b and was absent in neutrophils from patients with Leukocyte Adhesion Deficiency (LAD), which lack expression of β2 integrins, and in neutrophils from patients with Chronic Granulomatous Disease (CGD), which cannot produce toxic oxygen metabolites. Under these circumstances, we found that TNF‐α retained its anti‐apoptotic effects, even at high concentrations.

In conclusion, the protective effects against apoptosis of IFN‐γ, GM‐CSF and TNF‐α itself are overruled when the concentration of TNF‐α is high enough to produce a respiratory burst. This process of reactive oxygen radical formation depends on neutrophil adhesion via the β2 integrin CD11b/CD18 and on an intact NADPH oxidase enzyme. These dual, concentration‐dependent effects of TNF‐α provide an explanation for previous controversial reports and support a dominant role for TNF‐α in neutrophil apoptosis.
Checklist-Based Assessment Methodology for Sustainable Design
Authors: Kishita Yusuke , Low Bi Hong , Fukushige Shinichi , Umeda Yasushi , Suzuki Atsushi , Kawabe Takao
Published: September 2010

The manufacturing industry is faced with a challenge to create products with less environmental impact targeting a sustainable society. To cope with this challenge, sustainable design or ecodesign plays one of the most important roles. Manufacturers often use ecodesign checklists that are intended for obtaining eco-labels, such as Eco Mark in Japan, in order to support design improvements of products in terms of environmental consciousness. Eco-label checklists are, however, insufficient to support designing products rationally because the relationships between individual requirements of checklists and environmental impact are undetermined. This paper proposes a method for supporting assessment for ecodesign by developing a weighted checklist from a conventional eco-label checklist. This weighted checklist assesses the environmental performance of a product based on the potential environmental improvement of each requirement, derived by life cycle simulation. Results of a case study involving a digital duplicator indicate that the proposed method successfully clarifies the requirements that should be improved in the present product. When the design improvements are applied, the assessment of the product’s CO2 emissions shows an improvement by 8%.
Integrated Sustainable Life Cycle Design: A Review
Authors: Ramani Karthik , Ramanujan Devarajan , Bernstein William Z. , Zhao Fu , Sutherland John , Handwerker Carol , Choi Jun-Ki , Kim Harrison , Thurston Deborah
Published: September 2010

Product design is one of the most important sectors influencing global sustainability, as almost all the products consumed by people are outputs of the product development process. In particular, early design decisions can have a very significant impact on sustainability. These decisions not only relate to material and manufacturing choices but have a far-reaching effect on the product’s entire life cycle, including transportation, distribution, and end-of-life logistics. However, key challenges have to be overcome to enable eco-design methods to be applicable in early design stages. Lack of information models, semantic interoperability, methods to influence eco-design thinking in early stages, measurement science and uncertainty models in eco-decisions, and ability to balance business decisions and eco-design methodology are serious impediments to realizing sustainable products and services. Therefore, integrating downstream life cycle data into eco-design tools is essential to achieving true sustainable product development. Our review gives an overview of related research and positions early eco-design tools and decision support as a key strategy for the future. By merging sustainable thinking into traditional design methods, this review provides a framework for ongoing research, as well as encourages research collaborations among the various communities interested in sustainable product realization.
Diesel Engine Selective Catalytic Reduction (SCR) Ammonia Surface Coverage Control Using a Computationally-Efficient Model Predictive Control Assisted Method
Authors: Hsieh Ming Feng , Wang Junmin
Published: September 2010

This paper presents a diesel engine selective catalytic reduction (SCR) control design based on a novel model predictive control (MPC)-assisted approach, which utilizes the advantages of MPC while keeping the computation demand under an acceptable level. The SCR control problem is featured by the challenges of time delay, significant time-varying characteristics, and limited control authority. Based on the understanding of the SCR reactions, the NH3 surface coverage ratio was selected as the control objective. The proposed MPC-assisted method was compared with conventional controllers such as PID and linear MPC (LMPC). Simulation results exhibited that the MPC-assisted approach can achieve a SCR ammonia surface coverage ratio control with much smaller root mean square error compared to these of other controllers while maintaining a manageable computational demand, and in turn better control of tailpipe NOx and ammonia emissions.
Energy Efficient Fluid Power in Autonomous Legged Robotics
Authors: Guglielmino Emanuele , Semini Claudio , Yang Yousheng , Caldwell Darwin , Kogler Helmut , Scheidl Rudolf
Published: September 2010

This paper is concerned with the application of fluid power in autonomous robotics where high power density and energy efficiency are key requirements. A hydraulic drive for a bioinspired quadruped robot leg is studied. The performance of a classical valve-controlled (“resistive-type”) and of an energy saving (“switching-control mode”) hydraulic actuation system are compared. After describing the bio-inspired leg design and prototyping, models for both drives are developed and energy efficiency assessments are carried out. It is shown through simulation that the switching-control mode hydraulic actuation can meet the challenge of legged robotic locomotion in terms of energy efficiency with respect to improving robot power-autonomy. An energy saving of about 75% is achieved. Limitations of the current system are identified and suggestions for improvements are outlined.
Application of Extended Kalman Filter to On-Line Diesel Engine Cylinder Pressure Estimation
Authors: Al-Durra Ahmed , Canova Marcello , Yurkovich Steve
Published: September 2010

Cylinder pressure is one of the most important parameters characterizing the combustion process in an internal combustion engine. The recent developments in piezoelectric pressure transducers and progress in on-line computational throughput facilitate the use of cylinder pressure as a feedback signal for engine combustion control. However, a typical production cylinder pressure sensor is subject to noise and offset issues that require signal processing methods, including averaging over several engine cycles, in order to extract a pressure trace sufficiently accurate for combustion characterization. This limits the application of cylinder pressure sensing to off-line applications. In order to enable closed-loop combustion control using cylinder pressure feedback, this study proposes a real-time estimation algorithm that extracts the pressure signal on a crank-angle basis. A simplified thermodynamic model for Diesel engine combustion is derived to predict the in-cylinder pressure. The model is then adapted to model-based estimation, by applying an Extended Kalman Filter in conjunction with a recursive least squares estimation. The resulting estimator is tested on a high-fidelity Diesel engine model for different operating conditions. The results obtained show the effectiveness of the estimator in reconstructing the cylinder pressure and in rejecting measurement noise and modeling errors.
A Condensed Hybrid Optimization Algorithm Using Enhanced Continuous Tabu Search and Particle Swarm Optimization
Authors: Chen Cheng-Hung , Schoen Marco P. , Bosworth Ken W.
Published: September 2010

A novel Condensed Hybrid Optimization (CHO) algorithm using Enhanced Continuous Tabu Search (ECTS) and Particle Swarm Optimization (PSO) is proposed. The proposed CHO algorithm combines the respective strengths of ECTS and PSO. The ECTS is a modified Tabu Search (TS), which has good search capabilities on large search spaces. In this study, ECTS is utilized to define smaller search spaces, which are used in a second stage by the basic PSO to find the respective local optimum. The ECTS covers the global search space by using a TS concept called diversification and then selects the most promising areas in the search space. Once the promising regions in the search space are defined, the proposed CHO algorithm employs another TS concept called intensification in order to search the promising area thoroughly. The proposed CHO algorithm is tested with the multi-dimensional Hyperbolic and Rosenbrock problems. Compared to other four algorithms, the simulations results indicate that the accuracy and effectiveness of the proposed CHO algorithm.
Locomotion of Circular Robots With Diametrically Translating Legs
Authors: Steffan Eric , Das Tuhin
Published: September 2010

In this paper, we develop an analytical basis for designing the locomotion of mobile robots with a spherical or circular core and equispaced diametral legs. The mechanism has resemblance with certain cellular locomotions. Locomotion is generated by actuation of the legs in the radial direction. Two elementary regimes of motion are first developed using the geometry of the mechanism. The overall motion of the robot is generated by repeated switching between the two regimes. The paper addresses both the kinematics and dynamics of the mechanism enabling the prediction of trajectories and computation of constraint and actuation forces. Simulation results are provided in support of the theory developed.
Control-Oriented Vehicle Attitude Estimation With Online Sensors Bias Compensation
Authors: Panzani Giulio , Corno Matteo , Tanelli Mara , Savaresi Sergio M. , Fortina Andrea , Campo Sebastiano
Published: September 2010

In advanced vehicle stability control systems, the availability of online estimates of the vehicle attitude is essential. In four-wheeled vehicles, attitude information is deeply linked to vehicle sideslip angle and sideslip rate, since these variables are strictly related to instability phenomena, safety and handling performances. As direct measurements of such quantities cannot be performed with standard sensors equipment, the design of robust and efficient estimators is needed. In this paper, we tackle the problem by proposing a sideslip rate observer and by demonstrating how an existing sideslip estimation algorithm can be made robust and reliable by online compensation of the sensors bias via a recursive identification approach. The proposed method does not require any additional sensor, making the final solution suitable for industrial applications. Experimental results confirm the effectiveness of the sensors offset compensation and witness satisfactory results of the overall vehicle attitude estimation scheme.
Optimal Control of Complex Air-Path Systems for Advanced Diesel Engines
Authors: Yan Fengjun , Haber Benjamin , Wang Junmin
Published: September 2010

This paper describes a linear optimal control approach for advanced diesel engines equipped with complex air-path systems including a dual-loop exhaust gas recirculation (EGR) and a two-stage turbocharger. Such complex air-path systems are instrumental to achieve smooth and stable transient operation of diesel engines running advanced multiple combustion modes such as low temperature diffusion combustion (LTDC) and homogeneous charge compression ignition (HCCI). A mean-value engine model was developed to capture the main dynamics of the advanced air-path system. A linear quadratic regulator (LQR) optimal controller was designed based on a linearized model at a fixed operating point. Simulation results using a high-fidelity detailed GT-Power engine model show the effectiveness of the controller.
Exploiting Nonlinearity to Provide Broadband Energy Harvesting
Authors: Moehlis Jeff , DeMartini Barry E. , Rogers Jeffrey L. , Turner Kimberly L.
Published: September 2010

Energy harvesters are a promising technology for capturing useful energy from the environment or a machine’s operation. In this paper we highlight ideas that might lead to energy harvesters that more efficiently harvest a portion of the considerable vibrational energy that is present for human-made devices and environments such as automobiles, trains, aircraft, watercraft, machinery, and buildings. Specifically, we consider how to exploit ideas based on properties of nonlinear oscillators with negative linear stiffness driven by periodic and stochastic inputs to design energy harvesters having large amplitude response over a broad range of ambient vibration frequencies. Such harvesters could improve upon proposed harvesters of vibrational energy based on linear mechanical principles, which only give appreciable response if the dominant ambient vibration frequency is close to the resonance frequency of the harvester.
Dimensionless Design of Variable Displacement Pumps
Authors: Manwaring Scott , Alleyne Andrew
Published: September 2010

External market forces constrain the design of engineered systems in much the same way that environmental conditions constrain the evolution of biological systems. Dimensional analysis is used to find functional relationships within biological systems and in turn can be used determine design relationships for engineered ones. This work applies these concepts to axial-piston swashplate variable displacement pumps. After presenting a pump model suitable for dimensional analysis, the necessary transformations are performed to create a pump model with completely dimensionless parameters and dynamics. Using a set of industry data, scale independent design information is extracted from successful industry pumps. This information is used to develop dimensionless design guidelines and strategies which allow for the specification of new designs dynamically similar to the original successful products.
An Analytical Mechatronic Model for Series DC Motors Using Manufacturer Test Data
Authors: Radcliffe Clark
Published: September 2010

Direct Current (DC) Motors are one of the most common mechatronic actuators. They are important for electromechanical servo systems, drivers for battery powered appliances and tools as well as electric vehicles. Both brushless DC motors and wound DC motors are common in electric and hybrid vehicles. The series wound DC motor is commonly used for high torque vehicle applications. The literature has many papers discussing permanent magnet DC motors but a very limited number of publications on analytical models for series wound DC motors, especially motor models that fit series wound DC motor test data available in the market place. An analytical model for a series wound DC motor is developed here based on physical principles including energy conservation. The model developed will be compared with models developed by other investigators. Available commercial test data for a series motor will be used to find model parameters for the analytical model and the accuracy of this model evaluated against the original test data. The model developed displays excellent accuracy well within the accuracy of the test data available. Typical model rms deviation from test data is under 2% for the commercial series wound DC motors evaluated.
A Condensation Procedure for Nonlinear Port-Based Models
Authors: Motato Eliot , Radcliffe Clark J.
Published: September 2010

A port based model is an external representation including pairs of input-output variables grouped into ports. Each port in a model is a representation of a mechanism for energy transfer into, or out of, the physical system modeled. Port based models always have an equal number of inputs and outputs because each port is composed of an input-output pair. The number of ports in such models must typically be reduced to decrease model size, protect proprietary internal topology or simply because the eventual user has no plans to make connections to them. The process of eliminating undesired model ports while maintaining useful ports is called condensation. The condensation of port-based linear system models was developed in [1]. This article extends the condensation process for port-based nonlinear models represented through Volterra series.
Numerical Simulation of the Performance of the SC-89 Jet Impact System
Authors: Chen Jiawang , Yin Kun , Peng Jianming , Gu Linyi , Zhou Bo
Published: September 2010

The bistable fluid oscillator has been successfully applied to the liquid hammer for a long time. The purpose of this paper is to simulate the correlations between the flow field in bistable fluid oscillator and the piston motion in the SC89 jet impact system in a more credible and realistic manner. The one dynamic layering method of a general CFD Software was applied to both end centers of motion by user defined function. Three dimensional results are presented and the comparing analysis provides the performance changing with each working parameter respectively. Reasonable predictions have been obtained, which provide an insight into the effect of correlation between the attached-wall jet switching and the piston moving. The dynamic layering methods, in general, still face significant challenges due to the slim effusion between the cylinder and piston. The model is now under further development to improve its capabilities. The model simulations can provide the whole dynamic changing flow field and the range of value of the optimized parameters which are crucial for jet impact system design and optimization. The simulation can be remodeled by changing parameters reasonably and one new type of impact system can be designed with low frequency and high impact energy or high frequency and low impact energy.
Backstepping Based Nonlinear Ammonia Surface Coverage Ratio Control for Diesel Engine Selective Catalytic Reduction Systems
Authors: Hsieh Ming Feng , Wang Junmin
Published: September 2010

This paper presents an ammonia surface coverage ratio control approach based on the backstepping concept for diesel engine selective catalytic reduction (SCR) systems. SCR models with multiple cells connected in cascade provide more accurate representations of the actual SCR system dynamics by considering the spatial distribution. Control of SCR system ammonia coverage ratio is critically important and effective in terms of ensuring low tailpipe NOx and ammonia emissions. However, such a task is also very challenging primarily due to the nonlinearities of the SCR dynamics and limited ammonia injection control authority. Grounded in the understanding of the SCR nonlinear dynamic characteristics, a backstepping-based nonlinear control law is then proposed to regulate the ammonia surface coverage ratio of the last SCR cell in order to tightly control the tailpipe NOx and ammonia emissions. Lyapunov-based analyses show the stability of the designed control law. FTP75 test cycle simulation results based on a full-vehicle (including engine, chassis, and aftertreatment systems) model illustrated that, compared with a conventional PID controller, the nonlinear backstepping control law can more appropriately handle the SCR system dynamics and exhibits superior ammonia coverage ratio control capability.
Velocity Occupancy Space: Robot Navigation and Moving Obstacle Avoidance With Sensor Uncertainty
Authors: Bis Rachael , Peng Huei , Ulsoy Galip
Published: September 2010

In order to autonomously navigate in an unknown environment, a robotic vehicle must be able to sense obstacles, determine their velocities, and follow a clear path to a goal. However, the perceived location and motion of the obstacles will be uncertain due to the limited accuracy of the robot’s sensors. Thus, it is necessary to develop a system that can avoid moving obstacles using uncertain sensor data. The method proposed here is based on a certainty occupancy grid—which has been used to avoid stationary obstacles in an uncertain environment—in conjunction with the velocity obstacle concept—which allows a robot to avoid well-known moving obstacles. The combination of these two techniques leads to velocity occupancy space: a search space which allows the robot to avoid moving obstacles and navigate efficiently to a goal using uncertain sensor data.
Controlling an Autonomous Racing Vehicle: Using Feedforward and Feedback to Control Steering and Speed
Authors: Kritayakirana Krisada , Gerdes J. Christian
Published: September 2010

This paper describes the algorithms used for controlling an autonomous vehicle that operates at the limits of tire adhesion. The controller is designed to imitate a racecar driver by using both feedforward and feedback to command the steering, throttle, and brakes of the vehicle. The feedforward steering is based on the vehicle handling diagram, while the lanekeeping steering feedback is added to ensure vehicle stability and reduces tracking errors caused by disturbances or modeling errors. The feedforward speed is estimated based on the available friction, while the proportional speed feedback is introduced to mimic a race-car driver modulating the speed to trim the vehicle orientation. Two different speed feedback designs based on lookahead error and heading error are compared. The experiments demonstrate the superiority of heading error feedback, which enables the vehicle to operate at its limits while maintaining minimal lateral and heading errors from the desired trajectory.
Directional Variation of Active and Passive Ankle Static Impedance
Authors: Ho Patrick , Lee Hyunglae , Krebs Hermano Igo , Hogan Neville
Published: September 2010

Though ankle mechanical impedance plays an important role in posture and locomotion, it has been inadequately characterized. Unlike previous studies, which confined themselves to measurements along the primary axes of the ankle in an isolated fashion, the study reported here characterized the static component of ankle impedance in two degrees of freedom. In addition, the effect of active muscle contraction on ankle static impedance was measured. We found that ankle static impedance varied significantly with direction under passive conditions. We further observed that, while muscle contraction increased the magnitude of ankle static impedance, its directional variation was essentially unchanged.
Pseudo-Causal Tracking Control of a Nonminimum Phase System
Authors: Wang Pengfei , Sahinkaya M. Necip , Akehurst Sam
Published: September 2010

A novel method is described to implement noncausal feedforward compensators causally, i.e. without requiring any future value of the reference input trajectory. A hardware-in-the loop test facility developed for continuously variable transmissions is utilized in this paper. The test facility includes two induction motors to emulate engine and vehicle characteristics. Software models of an engine and vehicle, running in real-time, provide reference torque and speed signals for the motors, which are connected to a transmission that is the hardware in the loop. Speed control of the output motor that emulates the vehicle dynamics is used to demonstrate an application of the proposed technique. A feedforward compensator, based on transfer function inversion, is used to compensate for the nonminimum phase motor and drive system dynamics. The vehicle model cannot be run ahead of time to provide the future values required by the noncausal inversion technique because it requires the current torque at the output of the transmission. Therefore, the feedforward controller has to be applied causally. A frequency domain estimation technique and a multi-frequency test signal are utilized to estimate, within the frequency range of interest, a low relative order transfer function of the closed loop system incorporating a manually added delay in the feedback loop. A noncausal feedforward controller is designed for the delayed output of the system based on the identified transfer function. It has been shown experimentally that this compensator offers excellent tracking performance of the motor when subjected a multi-frequency speed demand signal.
Inner-Loop Control for Electro-Hydraulic (EHA) Actuation Systems
Authors: El Sayed Mohammed A. , Habibi Saeid
Published: September 2010

This article presents the development of a multiple inner-loop control strategy for improving the performance of hydrostatic actuation systems. In these actuators, the presence of non-linearities associated with pump/motor static friction and backlash, pressure drop in the piping system, and nonlinear friction at the load have a significant effect on the performance and positional accuracy of the system. The effect of nonlinear friction at the pump/motor interface has been overcome by the use of a high gain pump-speed inner-loop control strategy. In this article, the concept of inner-loop control will be extended to target specific sources of performance degradation. Velocity feedback will be incorporated in this manner to decrease the effects of pump backlash and nonlinear friction at the load. Simulation results supported by theoretical analysis indicate that a considerable improvement in performance can be achieved by the implementation of this control strategy.
Fluid Flow in the Vicinity of a Vibrating Ionic Polymer Metal Composite: Part 1—Experimental Study
Authors: Peterson Sean D. , Porfiri Maurizio , Rovardi Alessandro
Published: September 2010

Low power consumption and activation voltage combined with high flexibility and minimal weight make Ionic Polymer Metal Composites (IPMCs) well-suited for miniaturized underwater propulsion systems. In this series of papers, we comprehensively discuss the flow field induced by an IPMC strip vibrating in a quiescent aqueous environment by performing complementary physical experiments and numerical simulations. The experimental results are presented in this paper. Planar particle image velocimetry is used to measure the time-averaged flow field of a vibrating IPMC. The momentum transferred to the fluid is computed to estimate the mean thrust generated by the vibrating actuator. We find that the mean thrust increases with the Reynolds number, defined by the maximum tip speed and IPMC length, and is only marginally affected by the relative vibration amplitude. Detailed understanding of the flow environment induced by a vibrating IPMC can guide the optimization of IPMC-based propulsion systems for bio-mimetic robotic swimmers.
A 2D Bristle Friction Force Model for Contact Dynamics Simulation
Authors: Ma Ou , Liang Jianxun , Fillmore Steven
Published: September 2010

This paper describes a 2D bristle contact friction model which is capable of modeling and simulating frictional behavior in both sliding and sticking regimes occurring in general 3D rigid-body contact. The model extends the 1D integrated bristle friction model to a 2D space by allowing the “bristle spring” to not only stretch along the direction of the relative velocity but also rotate due to the direction change of the velocity or motion trend in the common tangential plane of the contacting surfaces involved at the contact point of interest. With such an extension, the resulting friction model can be readily used to compute 3D contact friction forces in both sticking and sliding regimes for a general 3D contact dynamics model working with a multibody dynamics simulation application. Several simulation examples are provided to demonstrate the effectiveness of the model for predicting the experimentally seen frictional behavior such as sticking, stickslip, and sliding.
Pressure Control for a Continuous Micro-Flow Seawater Hydraulic System
Authors: Hou Jiwei , Li Shilun , Chen Ying , Chen Jiawang
Published: September 2010

To simulate the deep sea hydrothermal environment, a continuous micro-flow hydraulic system using seawater as working fluid is built with a flow range from 0.01 ml/min to 5ml/min, a pressure range from 0.1MPa to 60MPa and a temperature range from room temperature to 400°C. To precisely control the pressure of the continuous micro-flow seawater hydraulic system, a special nozzle-flapper proportional valve has been developed successfully. Moreover, a fuzzy self-tuning proportional-integral controller is proposed to accomplish the steady pressure control in the face of the severe parameter uncertainties and strong interference effects between pressure and different temperature or flow rate. Experimental results demonstrate that the developed proportional valve is competent to the pressure control of the continuous micro-flow seawater hydraulic system, and the fuzzy self-tuning mechanism ensures the robustness and effectiveness of the proposed controller for the nonlinearity in the system. The pressure value can be controlled within the desired range of ±0.1MPa.
Modal Control of an Electrohydrostatic Flight Simulator Motion System
Authors: Plummer Andrew R. , Guinzio Paulo Serena
Published: September 2010

Valve-controlled electro-hydraulic actuators in a Stewart platform configuration have become established as a good way of meeting the performance required for flight simulator motion systems. However, valve-controlled actuators are very inefficient, and thus an electrohydrostatic motion system, controlled using servomotor driven pumps, has been developed by Thales, and is now in production. This paper presents a simulation study of a multi-axis controller which can improve the dynamic response of the new motion system. A modal control approach is used — i.e. the modes of vibration of the system are controlled individually. These modes are dependent on the inertial properties of the platform and the compliance of the actuators. The modes change as the motion system moves throughout its workspace, and so the controller has to adapt to the current operating point. Simulation results are presented based on a partially validated model of the motion system.
Model-Based Nonlinear Control of Ionic Polymer-Metal Composite Actuators
Authors: Chen Zheng , Tan Xiaobo
Published: September 2010

Ionic polymer-metal composites (IPMCs) are soft materials that can generate large deformation under a low voltage. IPMCs have many potential applications in biomedical, robotic and micro/nano manipulation systems. In this paper, we first present a distributed, nonlinear circuit model for IPMC, which incorporates the nonlinear capacitance, the nonlinear DC resistance, and the effect of surface resistance. The bending displacement is proportional to the total stored charge in IPMC. After discretizing the model in the length direction, we obtain a multiple-segment model which can be represented in the state space for nonlinear control design. The model is validated using experimental data, and we show that a one-segment model can predict the current and displacement response reasonably well. A model-based nonlinear controller is proposed for IPMC actuators, where feedback linearization is applied. Simulation results show that model-based nonlinear controller delivers better performance than a traditional PI controller in terms of the tracking error, control effort, and robustness to sensing noises.
Stochastic Model of Glutamatergic PFC-NAc Synapse Predicts Cocaine-Induced Changes in Receptor Occupancy
Authors: Mohan Ashwin , Pendyam Sandeep , Enke Bradley C. , Kalivas Peter , Nair Satish S.
Published: September 2010

Neurotransmitter homeostasis in and around synapses involves random processes such as diffusion, molecular binding and unbinding. A three-dimensional stochastic diffusion model of a synapse was developed to provide molecular level details of neurotransmitter homeostasis not predicted by alternative models based on continuum approaches. This framework was used to estimate effective diffusion and provide a more accurate prediction of geometric tortuosity in the perisynaptic region. The stochastic model was used to predict the relative contributions of non-synaptic sources to extracellular concentration in control, natural reward seeking, and chronic cocaine cases; and estimation of molecular influx rates required to maintain tone on presynaptic autoreceptors. Also, this was the first stochastic model to confirm the prediction of down-regulation of glutamate transporters by 40% after chronic cocaine. The model can be further generalized to study the role of diffusion path length in supporting neurotransmitter gradients and isolating the synapse.
Adaptive Calibration and Control of Cascade Processes With Unknown Measurement Model and Actuator Dynamics and Its Application to Paper Manufacturing
Authors: Liu Zeyu , Li Perry
Published: September 2010

Many industrial processes are in cascade configuration in which the material being processed goes through a sequence of processing units. The output of an upstream processing unit is fed into the input of the unit downstream. In many cases, the variables of interests are only available via related uncertain surrogate measurements in the all the upstream stages, and directly measured at the output of the last stage. The problem of controlling such systems by adaptively calibrating the surrogate measurement model and the use of a pre-emptive control strategy was studied in [9]. In this paper, the unknown actuator dynamics is taken into account in the adaptive calibration and pre-emptive control as well. A Lyapunov based nonlinear control algorithm is derived. The proposed control algorithm is applied to a vacuum dewatering process in paper manufacturing industry. Simulation results show that the proposed control strategy can regulate the exiting moisture content of each unit at the desired value.
Equilibrium Analysis of Drifting Vehicles for Control Design
Authors: Hindiyeh Rami Y. , Gerdes J. Christian
Published: September 2010

This paper presents an analysis of the dynamics of a rear wheel drive vehicle during cornering at high sideslip angles (“drifting”) using a three-state bicycle model. This model builds upon previous work with a two-state bicycle model by incorporating longitudinal dynamics and a nonlinear tire model with simplified lateral-longitudinal force coupling. Analysis of this model reveals the existence of unstable “drift equilibria” corresponding to steady state cornering at high sideslip angles with significant longitudinal force applied at the rear tire. These equilibria are saddle points, with characteristics that exhibit low sensitivity to friction and speed variation. The analysis of the equilibria provides insight into vehicle dynamics in an operating regime responsible for major safety concerns in everyday driving. It also sheds light upon aspects of the system dynamics that account for behavior observed in autonomous drift experiments and must be considered in future controller designs.
Target Tracking Using the Smooth Variable Structure Filter
Authors: Gadsden Andrew , Habibi Saeid
Published: September 2010

This article discusses the application of the smooth variable structure filter (SVSF) on a target tracking problem. The SVSF is a relatively new predictor-corrector method used for state and parameter estimation. It is a sliding mode estimator, where gain switching is used to ensure that the estimates converge to true state values. An internal model of the system, either linear or nonlinear, is used to predict an a priori state estimate. A corrective term is then applied to calculate the a posteriori state estimate, and the estimation process is repeated iteratively. The results of applying this filter on a target tracking problem demonstrate its stability and robustness. Both of these attributes make using the SVSF advantageous over the well-known Kalman and extended Kalman filters. The performances of these algorithms are quantified in terms of robustness, resilience to poor initial conditions and measurement outliers, tracking accuracy and computational complexity.
A Base-Excitation Approach to Polynomial Chaos-Based Estimation of Sprung Mass for Off-Road Vehicles
Authors: Pence Benjamin L. , Fathy Hosam K. , Stein Jeffrey L.
Published: September 2010

This paper presents a novel method for identifying in real-time the sprung mass of a 2-DOF quarter-car suspension model. It does so by uniquely combining the base-excitation concept with polynomial chaos estimation. This unique combination of the two methods provides two important benefits. First, the base-excitation concept makes it possible to estimate the sprung mass without explicitly measuring or knowing the terrain profile prior to estimation. Second, the polynomial chaos estimation strategy makes it possible to perform such mass estimation using sprung and unsprung acceleration measurements without pseudo-integration filters that can be difficult to tune. This paper derives the proposed method in detail and presents computer simulations to evaluate its convergence speed and accuracy. The simulation results consistently converge to within 10% of the true mass value typically within 120 seconds.
On Internal Resonance of Nonlinear Nonuniform Beams
Authors: Caruntu Dumitru I.
Published: September 2010

This paper reports the case of internal resonance three-to-one with frequency of excitation near natural frequency in the case of bending vibrations of nonuniform cantilever with small damping. The case of nonlinear curvature, moderately large amplitudes, is considered. The method of multiple scales is applied directly to the nonlinear partial-differential equation of motion and boundary conditions. The phase-amplitude equations are analytically determined. Steady-state response is reported.
Decentralized LPV Gain-Scheduled PD Control of a Robotic Manipulator
Authors: Abbas H. , Hashemi S. M. , Werner H.
Published: September 2010

In this paper, low-complexity linear parameter-varying (LPV) modeling and control of a two-degrees-of-freedom robotic manipulator is considered. A quasi-LPV model is derived and simplified in order to facilitate LPV controller synthesis. An LPV gain-scheduled, decentralized PD controller in linear fractional transformation form is designed, using mixed sensitivity loop shaping to take — in addition to high tracking performance — noise and disturbance rejection into account, which are not considered in model-based inverse dynamics or computed torque control schemes. The controller design is based on the existence of a parameter-dependent Lyapunov function — employing the concept of quadratic separators — thus reducing the conservatism of design. The resulting bilinear matrix inequality (BMI) problem is solved using a hybrid gradient-LMI technique. Experimental results illustrate that the LPV controller clearly outperforms a decentralized LTI-PD controller and achieves almost the same accuracy as a model-based inverse dynamics and a full-order LPV controllers in terms of tracking performance while being of significantly lower complexity.
Autonomous Motion Control of a Wheel Loader
Authors: Ghabcheloo Reza , Hyvo¨nen Mika , Uusisalo Jarno , Karhu Otso , Ja¨ra¨ Juha , Huhtala Kalevi
Published: September 2010

This paper addresses the problem of autonomous control of a hydraulically actuated articulated-frame-steering (AFS) mobile machine— a wheel loader. Our autonomous motion control system includes a mission planning graphical user interface, an improved odometry algorithm and a GPS device for navigation purposes, together with a model based path-following control strategy, and speed control. The test platform is a small prototype wheel loader based on Avant-635 whose hydraulic components are substituted by electrically controlled equivalents. System development and preliminary calibrations are done using GIMsim— an elaborated semi-empirical hardware-in-the-loop simulator. Some field experiments are presented that demonstrate satisfactory performance of the system at this stage. Further tunings are required to reach a desired performance.
Adaptive Robust Control for a Class of Nonlinear Uncertain System With Unknown Input Backlash
Authors: Guo Jian , Yao Bin , Jiang Jun , Chen Qingwei
Published: September 2010

An adaptive robust control (ARC) algorithm is developed for a class of nonlinear dynamic system with unknown input backlash, parametric uncertainties and uncertain disturbances. Due to the non-smooth dynamic nonlinear nature of backlash, existing robust adaptive control methods mainly focus on using approximate inversion of backlash by on-line parameter adaptation. But experimental results show that a linear controller alone can perform better than a controller including the selected backlash inverter with a correctly estimated or overestimated backlash gap. Unlike many existing control schemes, the backlash inverse is not constructed in this paper. A new linearly parameterized model for backlash is presented. The backlash nonlinearity is linearly parameterized globally with bounded model error. The proposed adaptive robust control law ensure that all closed-loop signals are bounded and achieves the tracking within the desired precision. Simulations results illustrate the performance of the ARC.
Optimization of Bayesian Filters and Hammerstein-Wiener Models for EMG-Force Signals Using Genetic Algorithm
Authors: Sebastian Anish , Kumar Parmod , Anugolu Madhavi , Schoen Marco P. , Urfer Alex , Naidu D. Subbaram
Published: September 2010

Processing electromyographic (EMG) signals for force estimation has many unknown variables that can influence the outcome or interpretation of the recorded EMG signal significantly. An array of filtering methods have been proposed over the past few years with the objective to classify motion for use in prosthetic hands. In this paper, we explore the optimal parameter settings of a set of Bayesian based EMG filters with the objective to use the filtered EMG data for system identification. System identification is utilized to establish a relationship between the measured EMG data and the generated force developed by fingers in a human hand. The proposed system identification is based on nonlinear Hammerstein-Wiener models. Optimization is also applied to find the optimal parameter settings for these nonlinear models. Genetic Algorithm (GA) is used to conduct the optimization for both, the optimal parameter settings for the Bayesian filters as well as the Hammerstein-Wiener model. The experimental results and optimization analysis indicate that the optimization can yield significant improvement in data accuracy and interpretation.
Adaptive Kalman Filter-Based Yaw Rate Estimation Using Accelerometers and Wheel Speed Sensors
Authors: Hrgetic´ Mario , Deur Josˇko , Pavkovic´ Danijel , Lakehal-Ayat Mohsen , Tseng Eric
Published: September 2010

This paper presents a kinematic yaw rate estimator which combines measurements obtained from a pair of accelerometers and ABS wheel speed sensors of the non-driven wheels. The Extended Kalman Filter methodology has been used for realization of this sensor fusion-based estimator. The estimator adapts to variations in reliability levels of individual sensors. The estimator performance is validated and corresponding estimation errors are analyzed by computer simulations for different driving maneuvers.
Model Predictive Control as an Energy Management Strategy for Hybrid Electric Vehicles
Authors: Sampathnarayanan Balaji , Serrao Lorenzo , Onori Simona , Rizzoni Giorgio , Yurkovich Steve
Published: September 2010

The energy management strategy in a hybrid electric vehicle is viewed as an optimal control problem and is solved using Model Predictve Control (MPC). The method is applied to a series hybrid electric vehicle, using a linearized model in state space formulation and a linear MPC algorithm, based on quadratic programming, to find a feasible suboptimal solution. The significance of the results lies in obtaining a real-time implementable control law. The MPC algorithm is applied using a quasi-static simulator developed in the MATLAB environment. The MPC solution is compared with the dynamic programming solution (offline optimization). The dynamic programming algorithm, which requires the entire driving cycle to be known a-priori, guarantees the optimality and is used here as the benchmark solution. The effect of the parameters of the MPC (length of prediction horizon, type of prediction) is also investigated.
Dynamics Analysis and Control Method of a Novel Spherical Robot
Authors: Sun Hanxu , Zheng Yili , Jia Qingxuan
Published: September 2010

A novel omni-directional rolling spherical robot equipped with a high-rate flywheel (BYQ-V) is presented; the mechanical structure of the robot are given, and the gyroscopic effects of high-rate flywheel can improve the dynamic stability of the robot. The simplified dynamic model of the robot is derived based on the constrained Lagrangian method. Moreover, a Linear Quadratic Regulator (LQR) controller and a Percentage Derivative (PD) controller are designed to implement the pose and velocity control of the robot respectively, Finally, the control method are validated through continuous circle motion experiment. This robot is designed for territory or lunar exploration in the future.
Load-Predictive Temperature Control of an Air Conditioning and Refrigeration System
Authors: Li Bin , Mohs William , Alleyne Andrew
Published: September 2010

In air conditioning and refrigeration (ACR) systems, the established industry method of capacity control is compressor ON/OFF cycling operations. This paper presents the design of load-predictive controller using compressor ON/OFF operations for temperature regulation with a target application of transport refrigeration systems. A dynamic ACR system model, which consists of a refrigerated cargo space, and a vapor compressor cycle (VCC) system, is developed. The validated VCC model is presented that captures compressor ON/OFF duty cycling dynamics. The dynamic cargo space model is described to accommodate varying conditions, such as door openings. The load-predictive controller tracks the pre-cool and predictive refrigeration load information which is generated based on the operating conditions in the next door-opening event, and decides to operate the VCC system with either normal ON/OFF control or pre-cool actions. Simulation results show that improved cargo space temperature regulation is obtained by implementing the load-predictive control strategy over the baseline industrial hysteretic control scheme in the coupled VCC/cargo space system.
Controlled Synchronization of Robotic Manipulators in the Task Space
Authors: Liu YenChen , Chopra Nikhil
Published: September 2010

Due to its practical applicability, recently several algorithms for robot synchronization have been developed in the literature. However, the focus of these control schemes has primarily been on joint-space control and in the absence of communication unreliabilities between the agents. In this paper, we study the problem of task space synchronization and trajectory tracking for heterogeneous robots under dynamic uncertainties. Exploiting passivity based synchronization results developed previously, a new control algorithm is proposed to guarantee task space synchronization for a group of robotic manipulators. Both non-redundant and redundant robots are considered and the proposed scheme is validated by a numerical example.