bluuebunny/crossref_metadata_2025 huggingface dataset:
A Hybrid Inference Approach for Health Diagnostics With Unexampled Faulty States
Authors: Tamilselvan Prasanna , Wang Pingfeng
Published: September 2013

System health diagnostics provides diversified benefits such as improved safety, improved reliability and reduced costs for the operation and maintenance of engineered systems. Successful health diagnostics requires the knowledge of system failures. However, with an increasing complexity it is extraordinarily difficult to have a well-tested system so that all potential faulty states can be realized and studied at product testing stage. Thus, real time health diagnostics requires automatic detection of unexampled faulty states through the sensory signals to avoid sudden catastrophic system failures. This paper presents a hybrid inference approach (HIA) for structural health diagnosis with unexampled faulty states, which employs a two-fold inference process comprising of preliminary statistical learning based anomaly detection and artificial intelligence based health state classification for real time condition monitoring. The HIA is able to identify and isolate the unexampled faulty states through interactively detecting the deviation of sensory data from the known health states and forming new health states autonomously. The proposed approach takes the advantages of both statistical approaches and artificial intelligence based techniques and integrates them together in a unified diagnosis framework. The performance of proposed HIA is demonstrated with a power transformer and roller bearing health diagnosis case studies, where Mahalanobis distance serves as a representative statistical inference approach.
Characterizing Optimal Control Strategy Parameters for Improving Fuel Economy of Hybrid Electric Vehicles in Velocity Planning
Authors: Wang Jinling , Lu Wen F.
Published: September 2013

Modern traffic prediction technologies enable real-time velocity planning of vehicles for less fuel consumption and polluting emissions by reducing the frequency of acceleration/deceleration, idle time, the number of stop, and variation of vehicle speeds. The fuel economy could be further improved if the optimal control strategy parameter could be used in the real-time velocity planning. However, it is difficult to find the optimal value of the control strategy parameter in this real-time velocity planning of vehicles. This paper aims to develop an advising system for control strategy parameters of HEVs in velocity planning. With this aim, the characteristics of the optimal control strategy parameters for various velocity profiles obtained from predictive velocity planning are studied in a parallel HEV. The optimal control strategy parameters with the effect of the average speed, stop frequency, and the traveling distance are investigated. The observed characteristics of the optimal parameters are obtained and can be used in the advising system to improve fuel economy in real-time velocity planning of HEVs.
Selecting and Optimizing a Regulation Compliant Robust Vehicle Portfolio Mix: An Approach and a Case Study
Authors: Maddulapalli Anil Kumar , Iyer Parameshwaran S. , Raghavan N. R. Srinivasa
Published: September 2013

Our goal is to select a robust vehicle portfolio mix and optimize its design attributes such that contribution margin is maximized while being regulation compliant under varying fuel prices. Compliance to regulation is measured in terms of the Corporate Average Fuel Economy or CAFE. We formulate this vehicle portfolio optimization problem as a mixed integer non-linear programming problem, both under static and varying fuel price scenarios. We demonstrate our approach using a case study in which an in-house market simulator is employed for incorporating consumer preferences in portfolio decisions. This market simulator uses real-time preferences from tens of thousands of shoppers and captures preference heterogeneity using different Logit coefficients for each shopper and hence is computationally expensive. Also, it does not explicitly model the influence of fuel price in predicting demand. To overcome these issues and to facilitate portfolio optimization we use meta-models of the market simulator. Our results show that while remaining regulation compliant it is also possible to achieve significant improvement in the portfolio’s contribution margin. In some scenarios, the improvements in contribution margin are more than 40% when compared to the traditional approach of using expert judgment to decide the portfolio mix.
Proposal of Design Support Method of Sustainability Scenarios in Backcasting Manner
Authors: Mizuno Yuji , Kishita Yusuke , Wada Haruna , Kobayashi Kazuhiro , Fukushige Shinichi , Umeda Yasushi
Published: September 2013

Describing sustainability scenarios is a hopeful approach for envisioning sustainable future visions of industries. However, describing sustainability scenarios is a difficult task and there is no computational support method. This article proposes a design support method of sustainability scenarios in a backcasting manner, which means thinking backward from targeted futures. For the design support method, we propose the following two methods; (i) a method for supporting backward thinking and constructing future visions using a logic tree and (ii) a method for drawing transition paths based on the logic tree. As a case study, we designed “Sustainable manufacturing scenario,” which envisions sustainable future visions of manufacturing industries. Through the case study, we identified the effectiveness of the proposed method. The proposed method supports designing the scenario in clarifying the future visions, drawing the transition paths, and describing them in scenario structurally.
Constraint Programming Simulation of a Distributed Set-Based Design Framework With Control Indicators
Authors: Canbaz Baris , Yannou Bernard , Yvars Pierre-Alain
Published: September 2013

In the New Product Development processes, there are usually multiple players interacting through coupled design activities with conflicting design objectives. We use Set-based design approach and Constraint Satisfaction Problem solving techniques to deal with the multiplayer, multi-objective design problem. In order to observe the states of the players during the design process, we develop satisfaction and progress indicators and combine them into a wellbeing indicator. In this paper we simulate different player behaviors on a two-player, multi-objective engineering design problem of a hollow cylindrical cantilever beam. During the simulation cases, at each simulation iteration automatic players are prioritized regarding their wellbeing states for proposing constraints in order to find a set of consistent solutions that improve their satisfaction states. Therefore during the simulation process, while solution space converges to a single solution, epistemic uncertainty is reduced and players’ satisfaction states are improved in wellbeing equilibrium.
Toward Integration of a Semantic Framework With a Commercial PLM System
Authors: Eddy Douglas , Krishnamurty Sundar , Grosse Ian , Liotta Alexander , Wileden Jack
Published: September 2013

Product lifecycle management (PLM) systems formally represent product information across the different functional departments of an organization throughout an entire product lifecycle. Integrating the PLM systems with the emerging semantic web will improve the knowledge management capabilities of these systems. In recent works, the authors have developed the e-Design framework, a collaborative web-based semantic environment for improving communication by formally defining an information model for documentation and sharing of engineering design knowledge throughout the entire design process.

This paper addresses the integration of the e-Design semantic framework with a commercial PLM system. A key feature of this integration approach is a semantic extraction process that executes the interface from commercial PLM software to a framework compatible with the semantic web, while maintaining the PLM’s multilevel bill of materials (BOM) structure. This extraction process includes application of semantic queries to categorize information imported from a PLM system. The development and implementation of this semantic extraction process for integrating product information from PLM systems into the e-Design framework is demonstrated with the aid of an illustrative case study using PTC’s Windchill PLM system. Our findings show that the resulting design execution within the e-Design framework facilitates dynamic linking of product information throughout the design process. It also preserves and propagates the BOM related information from PLM in all design phases.
Foil Bearing Design Guidelines for Improved Stability
Authors: Schiffmann J. , Spakovszky Z. S.
Published: September 2013

Experimental evidence in the literature suggests that foil bearing supported rotors can suffer from sub-synchronous vibration. While dry-friction between top foil and bump foil is thought to provide structural damping, sub-synchronous vibration is still an unresolved issue and has been recently attributed to the non-linearity of the bump-foil support stiffness. A non-linear rotordynamic model corroborates this hypothesis, however a forcing is required to excite the system. The current paper aims to shed new light onto this matter and discusses the impact of various design variables on stable foil bearing supported rotor operation. It is shown that, while a time domain integration of the equations of motion of the rotor coupled with the Reynolds equation for the fluid film is necessary to quantify the evolution of the rotor orbit, the underlying mechanism and the onset speed of instability can be predicted by coupling a reduced order foil bearing model with a rigid-body, linear rotordynamic model. Using this model it is shown that the excitation source inducing sub-synchronous vibration is a classical aerodynamic instability resulting from bearing fluid film forces. A sensitivity analysis suggests that structural damping has limited effect on stability. It is shown that the location of the axial feed line of the top foil significantly influences the bearing load capacity and stability. The analysis further indicates that the static fluid film pressure distribution governs rotordynamic stability. Therefore selective shimming is introduced to tailor the unperturbed pressure distribution for improved stability. The required pattern is found via multi-objective optimization using the foil bearing supported rotor model. A critical mass parameter is introduced as a measure for stability, and a criterion for whirl instability onset is proposed. It is shown that with an optimally shimmed foil bearing, the critical mass parameter can be improved by more than two orders of magnitude. The optimum shim patterns are summarized for a variety of foil bearing geometries with different L/D ratios and different degrees of foil compliance in a first attempt to establish more general guidelines for stable foil bearing design. At low compressibility (Λ < 2) the optimum shim patterns vary little with bearing geometry, thus a generalized shim pattern is proposed for low compressibility numbers.
Instantaneous Center Manifolds and Nonlinear Modes of Vibration
Authors: Ardeh Hamid A. , Allen Matthew S.
Published: September 2013

Nonlinear Normal Modes (NNM) have been defined in various ways; first by Rosenberg as a subset of periodic solutions of a nonlinear system and then by Shaw and Pierre as invariant manifolds tangent to the vector field of a nonlinear system at its equilibrium point. This work presents an alternative approach, namely Instantaneous Center Manifold (ICM), that extends the concept of modes of vibration to nonlinear systems, using both periodicity and invariance properties. Instantaneous Center Manifolds are invariant manifolds that contain all of the periodic invariant solutions of the nonlinear oscillatory system. The ICM approach is explained through three simple analytical examples, and is shown to be capable of finding solutions that have been remaining latent using the aforementioned approaches. New branches of nonlinear normal modes, separate from the main branches that are a continuation of linear modes, are illustrated. It is shown that these new branches connect the main branches of Rosenberg’s NNMs, and make it possible to travel from one main branch to another. Some natural extensions and applications of the ICM approach are briefly discussed in the conclusion.
Variation of the Workspace of Cable-Driven Two-Link Planar Manipulators due to Cable Attachment Points
Authors: Bryson Joshua T. , Agrawal Sunil K.
Published: September 2013

The design of cable-driven robots is complicated by the fact that cables can only apply force in one direction using tension, requiring a minimum of n+1 cables to fully constrain an n-DOF mechanism. Underconstrained systems with fewer than n+1 cables are not able to resist an arbitrary force, but may still be operational within a subset of their reachable workspace depending on the design of the mechanism. This paper focuses on an underconstrained two-link planar manipulator controlled using two cables. The equations of motion are presented and the system is numerically analyzed to determine the joint-angles and end-effector positions which can be achieved under quasi-static equilibrium with positive cable tensions. The positive tension workspace of the mechanism is shown to be governed by a collection of discrete constraint curves, which are presented and analyzed. The effects of changing cable configuration on the positive tension workspace are explored, and the cable configurations which result in the largest manipulator reachable workspace and dexterity are identified.
Optimal Design of Lightweight Machines Using Flexible Multibody System Dynamics
Authors: Seifried Robert , Held Alexander
Published: September 2013

In many machine and robotic applications energy efficiency is an increasingly crucial issue. In order to achieve energy efficiency lightweight structural designs are necessary. However, undesired elastic deformations might occur due to the light wight design. In order to achieve good system performance the actual dynamic loads must be taken into account in the design of the system’s components. In this paper optimization approaches for lightweight machine designs are employed to improve the tracking behavior the systems. Thereby, fully dynamical simulations of flexible multibody systems are coupled with both shape or topology optimization for the elastic members of the multibody system. It is shown, that by these approaches the end-effector trajectory tracking error of light wight manipulators can be decreased significantly.
Stiffness Estimation and Experiments for the Exechon Parallel Self-Reconfiguring Fixture Mechanism
Authors: Li Xiong , Zlatanov Dimiter , Zoppi Matteo , Molfino Rezia
Published: September 2013

The Exechon X150, a new smaller member of a successful series of parallel kinematic machines, has been recently developed as a component of a mobile self-reconfigurable fixture system within an inter-European project. This paper is the first to address the stiffness analysis of the parallel mechanism on which the design is based. The stiffness modeling method uses reciprocal screw theory as well as the virtual work principle, resulting in a simpler formulation and more convenient than ones obtained with traditional stiffness-modeling methods. Based on this model, the stiffness map within the workspace is obtained. The stiffness of the mechanism at a typical configuration is carried out. The complete finite element analysis and simulation used to verify the effectiveness of the stiffness model. Using geometric spatial decomposition, numerical examples of the mechanism at three typical configurations are presented.
A Method to Calculate Function and Component Failure Distributions Using a Hierarchical Bayesian Model and Frequency Weighting
Authors: O’Halloran Bryan M. , Hoyle Chris , Stone Robert B. , Tumer Irem Y.
Published: September 2013

This paper presents a method to calculate function and component parameter distributions during the design process. Frequency Weighting, a unique style of weighting proposed in this research, is applied to a Hierarchical Bayesian model to account for the number of times a component has solved a function. During the design process, functions are systematically solved by components to transition from a functional model to a physical design. This research contributes to an ongoing effort toward predicting reliability in early design, specifically during functional modeling and concept generation. In general, reliability prediction methods are applied after concept generation. There currently does not exist a statistical method to calculate functional failure rates to aid reliability prediction during and before concept generation. The method presented in this paper also captures uncertainty in the early stages of design. This is important because uncertainty in this stage of the design process can be significant. A description of the process used to calculate the function and component level failure rate distributions is presented. The level of detail provided is meant for reapplication to other examples. Three examples are worked out and graphical results are presented. These results show an effect of the Frequency Weighting on the function level distribution. Changing the occurrence vector, which is used to show the number of times a set of components has solved a function, from (1, 1, 1, 1) to (1, 1, 2, 5) results in the function level distribution mean value shifting from 5.53E−06 to 4.84E−06. In addition, an example is provided to demonstrate how this method can be applied while components are being selected during the design process. A two part reliability goal is generated for the combined failure rate of the design and the probability a design will meet that goal. Function level distributions are used to show which components should initially be selected to maintain reliability values that meet the reliability goal. Combinations of compatible component level distributions are also used to calculate a combined failure rate distribution for each design. A probability is calculated for each distribution to show which designs meet the probability portion of the reliability goal.
Multi-Linear Modeling for Characterization of Nonlinear Behavior of Anisotropic Materials
Authors: Furukawa Tomonari , Pan Jan Wei , Cheng Jinquan , Michopoulos John G. , Wada Yoshitaka
Published: September 2013

This paper presents a multi-linear modeling technique to characterize the nonlinear behavior of anisotropic materials. The nonlinear behavior of anisotropic materials is represented with a multi-linear stress-strain model under the assumption that the material is path-, rate- and temperature-independent. The multi-linear model is constructed by adopting the energy-based characterization, which equates the applied external work to the induced strain energy and inversely solves for the multi-linear model. A numerical technique based on Kalman filter stochastically identifies multi-linear coefficients and constructs the multi-linear model by modeling prior knowledge and empirical knowledge probabilistically. Since the coefficients are estimated with their associated variance, differential entropy can measure the certainty of all estimated coefficients as a single quantity. The validity of the proposed technique in estimating the multi-linear coefficients has been first demonstrated using pseudo-experimental data created by the finite element analysis. Further investigation of the effectiveness of the proposed technique under different measurement noises show its stable ability for nonlinear characterization of anisotropic materials.
Controller Design and Preliminary Testing of a Powered Below-Knee Prosthetic Device
Authors: Sun Jinming , Voglewede Philip A.
Published: September 2013

A powered lower limb prosthesis, which consists of a four bar mechanism, a torsional spring and a brushed DC motor, was previously designed and fabricated. To regulate the motor power input, a two level controller was proposed and built. The control algorithm includes a higher level finite state controller and lower level PID controllers. A digital signal processor (DSP) control board and MATLAB Simulink are used to realize the higher level control and a DC motor controller is used to realize the lower level PID control. Controller Area Network (CAN) communication was used to communicate between the two level controllers. To preliminarily test if the motor can generate required power, a bench test was performed. The results show that the motor needs to be overpowered to achieve the required moment.
Concept Analysis for Reconfigurable Products
Authors: Literman Brian , Cormier Phil , Lewis Kemper
Published: September 2013

There has been a significant amount of research investigating the design task of concept analysis, and much research on reconfigurable system design. Despite previous efforts, further research is still needed that explores how concept analysis should best be conducted for reconfigurable systems. Because reconfigurable systems have multiple configurations and different performance levels, additional information is required to understand each concept, making the design selection process more demanding. Desirable functions, concepts for each phase, and concepts for transition methods between configurations all need to be evaluated. In this paper, the fundamental challenges of reconfigurable system analysis are identified. A framework is then developed to evaluate the many options a designer may face when performing the concept analysis phase of reconfigurable system design, identifying the influence of reconfigurable systems on the process. A mini unmanned aerial vehicle case study is used to demonstrate how the framework is applied, and how existing concept analysis tools can be adapted to account for additional criteria. The paper concludes with a review of the contributions of this work and identifies areas of future work.
First Industrial Strength Multi-Axial Robotic Testing Campaign for Composite Material Characterization
Authors: Michopoulos John G. , Hermanson John C. , Iliopoulos Athanasios
Published: September 2013

In this paper we are reporting on the first successful campaign of systematic, automated and massive multiaxial tests for composite material constitutive characterization. The 6 degrees of freedom system developed at the Naval Research Laboratory (NRL) called NRL66.3, was used for this task. This was the in-augural run that served as the validation of the proposed overall constitutive characterization methodology. It involved accomplishing performing 1152 tests in 12 business days reaching a peak throughput of 212 tests per day. We describe the context of the effort in terms of the reasoning and the actual methods behind it. Finally, we present representative experimental data and associated constitutive characterization results for representative loading paths.
Direct Strain Imaging for Full Field Measurements
Authors: Iliopoulos Athanasios , Michopoulos John G.
Published: September 2013

Full field strain measurement techniques are based on computing the spatial derivatives of the approximation or interpolation of the underlying displacement fields extracted from digital imaging methods. These methods implicitly assume that the medium satisfies the compatibility conditions, which for any practical reason is only true in the case of a continuum body that remains continuum throughout the history of its mechanical loading. In the present work we introduce a method that can be used to calculate the strain components directly from typical digital imaging data, without the need of the continuum hypothesis and the need for displacement field differentiation. Thus it allows the imaging and measurement of strain fields from surfaces with discontinuities (i.e. small cracks). Numerical comparisons are performed based on synthetic data produced from an analytical solution for an open hole domain in tension. Mean absolute error distributions are calculated for the cases of both the traditional mesh free random grid method and the direct strain method introduced in the paper are given. It is established that the more refined representation of strain provided by this approach is more accurate everywhere in the domain, but most importantly, near the boundaries of the representation domain, where the error is higher for traditional methods.
Model Validation Metric and Model Bias Characterization for Dynamic System Responses Under Uncertainty
Authors: Xi Zhimin , Fu Yan , Yang Ren-Jye
Published: September 2013

Quantification of the accuracy of analytical models (math or computer simulation models) and characterization of the model bias are two essential processes in model validation. Available model validation metrics, whether qualitative or quantitative, do not consider the influence of the number of experimental data for model accuracy check. In addition, quantitative measure from the validation metric does not directly reflect the level of model accuracy, i.e. from 0% to 100%, especially when there is a lack of experimental data. If the original model prediction does not satisfy accuracy criteria compared to the experimental data, instead of revising the model conceptually, characterization of the model bias may be a more practical approach to improve the model accuracy because there is probably no ideal model which can predict the actual physical system with no error. So far, there is a lack of effective approaches that can accurately characterize the model bias for multiple dynamic system responses. To overcome these limitations, the first objective of this study is to develop a model validation metric for model accuracy check considering different number of experimental data. Specifically, a validation metric using the Bhattacharya distance (B-distance) is proposed with three notable benefits. First of all, the metric directly compares the distributions of two set of uncertain system responses from model prediction and experiment rather than the distribution parameters (e.g. mean and variance). Second, the B-distance quantitatively measures the degree of accuracy from 0% to 100% between the distributions of the uncertain system responses. Third, reference accuracy metric with respect to different number of experimental data can be effectively obtained so that hypothesis test can be performed to identify whether the two distributions are identical or not in a probability manner. The second objective of this study is to propose an effective approach to accurately characterize the model bias for dynamic system responses. Specially, the model bias is represented by a generic random process, where realizations of the model bias at each time step could follow arbitrary distributions. Instead of using the traditional Bayesian or Maximum Likelihood Estimation (MLE) approach, we propose a novel and efficient approach to identify the model bias using a generic random process modeling technique. A vehicle safety system with 11 dynamic system responses is used to demonstrate the effectiveness of the proposed approach.
A Framework for Parallel Sampling of Design Space With Application to Vehicle Crashworthiness Optimization
Authors: Hamza Karim , Shalaby Mohammed
Published: September 2013

This paper presents a framework for simulation-based design optimization of computationally-expensive problems, where economizing the generation of sample designs is highly desirable. Various meta-modeling schemes are used in practice in order to approximate the input-output relationships in the designed system and suggest candidate locations in the design space where high quality designs are likely to be found. One such popular approach is known as Efficient Global Optimization (EGO), where an initial set of design samples is used to construct a Kriging model, which approximates the system output and provides a prediction of the uncertainty in the approximations. Variations of EGO suggest new sample designs according to various infill criteria that seek to maximize the chance of finding high quality designs. The new samples are then used to update the Kriging model and the process is iterated. This paper attempts to address one of the limitations of EGO, which is the generation of the infill samples often becoming a difficult optimization problem in its own right for a larger number of design variables. This is done by adapting a previously developed approach for locating the optimum of a Kriging model to a modified EGO infill sampling criterion. The new implementation also allows the generation of multiple new samples at a time in order to take advantage of parallel computing. After testing on analytical functions, the algorithm is applied to vehicle crashworthiness design of a full vehicle model of a Geo Metro subject to frontal crash conditions.
Reduced Order Model for the Geometric Nonlinear Response of Complex Structures
Authors: Perez Ricardo , Wang X. Q. , Matney Andrew , Mignolet Marc P.
Published: September 2013

This paper focuses on the development of nonlinear reduced order modeling techniques for the prediction of the response of complex structures exhibiting “large” deformations, i.e. a geometrically nonlinear behavior, and modeled within a commercial finite element code. The present investigation builds on a general methodology successfully validated in recent years on simpler beam and plate structures by:

(i) developing a novel identification strategy of the reduced order model parameters that enables the consideration of the large number of modes (> 50 say) that would be needed for complex structures, and

(ii) extending an automatic strategy for the selection of the basis functions used to represent accurately the displacement field.

The above novel developments are successfully validated on the nonlinear static response of a 9-bay panel structure modeled with 96,000 degrees of freedom within Nastran.
A Framework for the Integration of System Engineering and Functional Analysis Techniques to the Goal and Scope of Life Cycle Assessment
Authors: Esterman Marcos , Fumagalli Maria E. , Thorn Brian , Babbitt Callie
Published: September 2013

With the increased concern over the impact that product and processes have on the environment several tools for environmental impact assessment have been developed. Life Cycle Assessment (LCA) is perhaps the most broadly known and used. The use of LCA is common in industry and there is a growing interest to improve the approach since several unresolved problems have been identified with its use. One important issue to resolve is the proper definition of the functional unit. The stated primary goal of the functional unit in LCA is to ensure comparability of LCA results; however, when reviewing the literature, LCA practitioners remark that comparing LCA studies is a very difficult task. The attributed reasons for this problem are the lack of standardized assumptions and practices, including the definition of the functional unit. Even though several unresolved problems present in LCA have had solutions proposed, a clear and actionable solution to the specific problem of functional unit definition is still not available. This paper will introduce system engineering and functional analysis concepts to the goal and scope definition phase of LCA in order to provide a framework for system definition, system boundary definition, and reference flows identification. System engineering principles and functional analysis have been extensively used to aid the design process, yet these approaches have not been effectively applied to the LCA domain. The benefits associated with the proposed framework include improved comparability of LCAs, dynamic updating of LCAs, and the integration of LCA into early stage product development.
Modular Product Optimization to Alleviate Poverty: An Irrigation Pump Case Study
Authors: Wood Charles D. , Lewis Patrick K. , Mattson Christopher A.
Published: September 2013

Modular products have the potential to significantly reduce the financial risks associated with purchasing an income generating product in the developing world. Their modular nature allows a product to adapt to the changing needs of the customer (changing views of affordability due to increase in income potential). In a previous work by the authors, an optimization-based modular product design method was developed and implemented in the design of a modular irrigation pump for poverty alleviation. This paper revisits this modular pump example with the purpose of physically validating the ability of the method to identify theoretical progressively affordable modular products. This paper gives a summary of the method, presents the theoretical pump design, and compares the performance of the theoretical design to a physical prototype of the pump. Based on observations from this comparison, the authors conclude that the method is a feasible approach to engineering-based poverty alleviation.
Structural Fault Diagnosis of a Reciprocating Compressor Using Bond Graph Approach
Authors: Mollasalehi Ehsan , Zareian Jahromi Seyed Abdolali , Forcinito Mario , Hu Wei , Sun Qiao
Published: September 2013

Condition monitoring and fault diagnosis of operating machinery have been of the main interests for many years. Existing systems employ data driven models which has limited prediction capability. On the contrary, a physics based model can predict phenomena that the system has not seen before. It also provides a means for root cause analysis. However, major obstacles include the complexity involved and real-time feasibility. In this paper, we use the bond graph technique to construct an analytical, physics-based model. We use a reciprocating compressor as an example since it is a good representation of multi-domain processes with a variety of possible failure modes. The bond graph model is cross examined with a finite element model and ultimately validated. To show how one can benefit from this approach, cracked piston rod is simulated to generate vibration signals that can potentially be picked up from accelerometers mounted on the exterior surface of the compressor.
Evaluating Mobility Behavior of Fluid Filled Fiber-Reinforced Elastomeric Enclosures
Authors: Krishnan Girish , Bishop-Moser Joshua , Kim Charles , Kota Sridhar
Published: September 2013

Fluid filled Fiber Reinforced Elastomeric Enclosures (FREE) have been popular choices for actuators in prosthetics and soft robots owing to their large power density and cost effective manufacturing. While a narrow class of FREEs known as McKibben’s actuators have been extensively studied, there is a wide unexplored class that could be potentially used as actuators and load bearing members. This paper analyzes the mobility of a large class of FREEs based on simple geometric relationships that originate due to the inextensibility of fibers and incompressibility of fluids. The analysis conducted on various families of fibers reveal certain configurations that are locked under fluidic actuation. Furthermore the analysis reveals unrestricted motion in certain directions (freedom) and restrictions in certain other directions (constraint). Such an analysis is deemed to be useful as a preliminary design tool to pick the appropriate geometry for use in design of soft robots and actuators.
Large Stroke Comb-Drive Actuators Using Reinforced, Clamped, Paired Double Parallelogram (C-DP-DP) Flexure
Authors: Olfatnia Mohammad , Sood Siddharth , Awtar Shorya
Published: September 2013

This paper reports in-plane electrostatic comb-drive actuators with stroke as large as 245 μm, achieved by employing a novel Clamped Paired Double Parallelogram (C-DP-DP) flexure mechanism. For a given flexure beam length (L1), comb gap (G), and actuation voltage (V), this is currently the largest comb-drive actuator stroke reported in the literature. The C-DP-DP flexure mechanism design offers high bearing direction stiffness (Kx) while maintaining low motion direction stiffness (Ky), over a large range of motion direction displacement. The resulting high (Kx /Ky) ratio mitigates the on-set of sideways snap-in instability, thereby offering significantly greater actuation stroke compared to existing designs. Further improvement is achieved by reinforcing the individual beams in this flexure mechanism. While the traditional Paired Double Parallelogram (DP-DP) flexure design with G = 3 μm, L1 = 1 mm results in a 50 μm stroke before snap-in, the reinforced C-DP-DP design with G = 3μm achieves a stroke of 141 μm. The same C-DP-DP flexure design provides a 215 μm stroke with G = 4 μm, and a 245 μm stroke with G = 6 μm. The presented work includes closed-form stiffness values for the reinforced C-DP-DP flexure, a design procedure for selecting dimensions of the overall comb-drive actuator, micro-fabrication of some representative actuators, and experimental measurements demonstrating the large stroke.
Prediction of Load and Shear of Ultra-Thin Multi-Species Surface Films
Authors: Chong W. W. F. , Teodorescu M. , Rahnejat H.
Published: September 2013

Unless protected by an inert gas atmosphere, micro-scale conjunctions are often separated by molecularly-thin adhered films. Therefore, predicting contact load, friction or adhesion, must consider the contribution of this layer to the overall contact problem. The contribution of an adhered layer can be accounted for using a simplified solution (e.g. an adjustment to the energy of adhesion to account for the liquid film). However, these methods cannot account for layers consisting of multiple species of molecules. The most common approach, which accounts for inter-molecular forces between molecules of various species, is a molecular dynamics simulation. However, this is time consuming, and therefore, often limited for small volumes of fluid and small scale contacts. The current paper proposes an alternative approach, where the pressure and shear between two smooth surfaces separated by an ultra-thin film is predicted using a statistical mechanics based model. This method accounts for the chemical structure of each species of molecules comprising the ultra-thin film, their concentration, intermolecular forces and adsorption to the wall. This approach is very fast, therefore, it can be easily included in a larger scale code predicting the behavior of the entire micro-scale mechanism. It was found that for a specified material of the solid boundary the model can predict the optimal concentration of each species of molecule in the intervening ultra-thin film, to minimize friction or adhesion.
Motion-Aware Adaptive Dead Reckoning Algorithm for Distributed Virtual Reality Systems
Authors: Kharitonov Vasily Y.
Published: September 2013

Dead reckoning algorithms are employed in distributed virtual reality systems (DVR systems) for predicting objects states at any given moment of time that makes it possible to minimize bandwidth requirements while maintaining required data consistency. However, existing implementations often do not take into account information on the object motion dynamics and, in general, apply static prediction models. In this paper a novel motion-aware adaptive dead reckoning algorithm is introduced based on dynamical prediction model selection depending on the object motion pattern. The results show that considerable reduction in update messages can be achieved without sacrificing prediction accuracy. In addition, it becomes possible to dynamically adjust the size of update messages according to the motion pattern and, thus, provide more flexible use of network bandwidth.
Automatically Annotated Mapping for Indoor Mobile Robot Applications
Authors: Özkil Ali Gürcan , Howard Thomas
Published: September 2013

This paper presents a new and practical method for mapping and annotating indoor environments for mobile robot use. The method makes use of 2D occupancy grid maps for metric representation, and topology maps to indicate the connectivity of the ‘places-of-interests’ in the environment. Novel use of 2D visual tags allows encoding information physically at places-of-interest. Moreover, using physical characteristics of the visual tags (i.e. paper size) is exploited to recover relative poses of the tags in the environment using a simple camera. This method extends tag encoding to simultaneous localization and mapping in topology space, and fuses camera and robot pose estimations to build an automatically annotated global topo-metric map. It is developed as a framework for a hospital service robot and tested in a real hospital. Experiments show that the method is capable of producing globally consistent, automatically annotated hybrid metric-topological maps that is needed by mobile service robots.
Reduced Order Modeling for Power Electronics Applications
Authors: Chen Bing-Chung , Wei Lixiang
Published: September 2013

In this work, a model order reduction (MOR) technique for system-level modeling for motor drive dynamic system is presented. As the power electronics continues towards higher switching speed, higher packaging density, and power dissipation, it is critical to have a compact electro-thermal model, easily transferred into a micro-processor, to predict the online temperature dynamics, for self-production, especially at low output-speed conditions when the power chip could potentially operate at over temperature conditions.

The compact model generation process starts with electro-thermal modeling with the commercial finite element package to generate full-order system matrices. The corresponding reduced model is then constructed by retrieving the original full-order system matrices then projecting these matrices into a low-order Krylov subspace. This subspace is spanned by orthogonal basis vectors, obtained by an Arnoldi algorithm. The generated compact model is then incorporated into system-level modeling simulator such as Simplorer or Simulink for fast transient and frequencies simulation. It is demonstrated that the reduced order models are at two orders of magnitude smaller than the full model and still preserve the dynamics characteristics and required accuracy for industrial applications. Due to their compact size, the compact models give significantly speed-up and allow product design engineers to accurately predict temperature response of motor drive at product prototype stage, not otherwise obtainable without this technology.
Influence of Excitation Conditions in Dual-Frequency Tapping-Mode Atomic Force Microscopy
Authors: Dick Andrew J. , Huang Wei
Published: September 2013

In this work, the influence of excitation conditions on the performance of a dual-frequency version of tapping-mode atomic force microscopy is studied. In the authors’ previous work, a relationship was identified between the interaction force regime(s) influencing the response of the probe and the specific spectral components observed to be significant in the response. Numerical studies are performed with a three-mode approximation of an atomic force microscope (AFM) probe. This study is conducted by modifying the excitation strength to vary the free response magnitude and the response magnitude ratio, by varying the phase difference between the two excitation components, and by exploring other frequencies for the secondary excitation component. This study reveals undesirable amplitude discontinuities when the influence of the secondary excitation component is too strong, conditions where the accuracy of the relationship is improved, how the selection of the excitation phase difference can influence the results, and the potential of alternative frequency combinations. Through an improved understanding of the relationship, it may provide the means to perform simultaneous imaging and characterization with improved performance using standard AFM systems and AFM probes.
Affordances in Technology Modeling
Authors: Ciavola Benjamin T. , Gershenson John K.
Published: September 2013

Understanding the mechanisms of technology change is essential for planning multi-generational products, especially for complex systems where subsystem interaction plays a central role. Recently, affordance theory has been proposed as an alternative modeling perspective to the current function-based approach. Using the affordance formulation of Gibson and the technology model of Heidegger, we demonstrate an affordance-based approach providing novel analytical insight into the nature of technical artifacts. This model accounts for the core of function-based methods and provides insight into static and dynamic accounts of performance level, principle of operation, and technology architecture. Implications of this affordance approach are discussed and future research is proposed. Implications include the possibility of reconciling and integrating function and affordance theory, accounting for the fundamental nature of technology change, and augmenting technology theory with a number of affordance-derived analytical principles. Opportunities for future research include development of practical tools for analyzing over-time dynamics and exploration of affordance theory’s implications for modular and product family design.
A Case Study in Challenging Engineering Requirements
Authors: Crouch Seth R. , Mocko Gregory M.
Published: September 2013

Requirements are an essential element to engineering design as they are used to focus idea generation during conceptual design, provide criteria for decision making during concept selection, and verify the chosen concept fulfills product needs. Because they are essential to the entire design process, emphasis must be placed on ensuring that they are correct. This research focuses on a value-based methodology useful for challenging and validating established requirements. A case study was conducted on an industry-sponsored project to use this value-based process on the requirements that constrain the design of an automotive seat. A human anthropomorphic model, comfort value model, occupant safety model, and a model of an automotive seat are integrated to establish an H-point travel window to maximize the safety and comfort of an automotive seating structure. This case study shows that this approach provides evidence to establish requirements based on value to the human rather than legacy seating requirements.
The Scope for a Compliant Homokinetic Coupling Based on Review of Compliant Joints and Rigid-Body Constant Velocity Universal Joints
Authors: Farhadi Machekposhti Davood , Tolou N. , Herder J. L.
Published: September 2013

Many applications require a compliant mechanism to transmit rotation from one direct to another direct with constant velocity. This paper presents a literature survey towards the design of compliant constant velocity universal joints. The traditional constant velocity universal joints available from the literature were studied, classified and their mechanical efficiencies were compared. Also the graph representation of them was studied. In the same manner, literature review for different kind of compliant joints suitable for the Rigid-Body-Replacement of constant velocity universal joints was also performed. For the first time a comparison with analytical data of compliant joints was performed. All of compliant universal joints are non-constant velocity and designed based on rigid Hooke’s universal joint. Also we show there are no equivalent compliant joints for some rigid-body joints such as cylindrical joint, planar joint, spherical fork joint and spherical parallelogram quadrilateral joint. However, we may achieve them by combining numbers of available compliant joints. The universal joints found are non-compliant non-constant velocity universal joint, non-compliant constant velocity universal joint or compliant non-constant velocity universal joint. A compliant constant velocity universal joint has a great horizon for developments, for instance in medical or rehabilitation devices.