bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast VR Application Development Based on Versatile Rigid Multi-Body Dynamics Simulation
Authors: Jung Thomas Josef , Rast Malte , Kaigom Eric Guiffo , Rossmann Juergen
Published: June 2012

More and more areas in research and development use Virtual Reality technologies. To quickly realize new applications at low costs, the reuse of existing functionality is of high importance. In the area of mobile robotics, physics based simulation components promise optimal reusability: The physical laws always stay the same and do not depend on the application. Hence, as long as the applications try to emulate reality, physics based simulation software will be reusable. Unfortunately, depending on the kind of application, different simulation models for different physical domains are needed: Particle models for fluids and soil, finite-elements for non-rigid bodies, multi-body systems and so on. However, for those applications developed at Institute for Man-Machine Interaction at the RWTH Aachen University, a multi-body dynamics component has taken a central role in the process of application development. It is fully integrated within a modern 3D-simulation and visualization tool. It is enhanced by generalized tools of contact graph analysis, which support the fast development of robust applications suitable for daily use. The paper discusses the benefit of this multi-body system as a platform for versatile application development, taking the following three applications as examples: The first example is the development of forest machine simulators for usage in education and training of machine operators. The existence of a purely kinematically realized, phenomenological implementation with widely equivalent range of functions allows a direct comparison of the programming efforts. The second example is the development of algorithms for space robot motion planning. The example demonstrates, how easy and effective innovative robotic simulation applications can be realized using a common, dynamics based simulation framework. The third example finally describes the development of a Virtual Testbed for legged lunar exploration robots. The Virtual Testbed example handles in detail the concept of “top-down-development” of simulation models. The refinement of the simulation of foot-soil-contact situations using a force exchange interface and the refinement of the actuator dynamics simulation using an energy exchange interface serve as examples.
Influence of Bearing Clearance on Load Sharing in Planetary Gears
Authors: Suzuki Atsushi , Aoyama Takayuki , Sugiura Noboru , Inagaki Mizuho , Shimizu Takashi
Published: June 2012

Load sharing among plural pinions in planetary gears should be equal to reduce gear noise and to secure the strength of the gears and bearings. This study investigates the influence of bearing clearance on load sharing using multibody dynamics analysis. One of the characteristics of this analysis is its capability to calculate dynamic gear meshes and bearing clearance nonlinearity. Contact analysis of the gears defines the tooth surface expressed by numerical formula involving modified surface geometry. Moreover, nonlinear stiffness is used to express the bearing clearance. The numerical method is verified by experiments that measure bearing loads on pinions using strain gauges. Subsequently, the influence of bearing clearance is examined numerically. The results confirm that the clearance of the carrier is dominant. In addition, unequal loads arise from reductions in the bearing loads and inclination of the carrier. Finally, this paper suggests an appropriate clearance for well-balanced load sharing.
Frequency Based Subsystem Identification Using Hybrid Primal-Dual Formulation
Authors: D’Ambrogio Walter , Fregolent Annalisa
Published: June 2012

The paper considers the identification of a structural subsystem, starting from the Frequency Response Functions of the assembled system, and from information about the remaining part of the structural system (residual subsystem), i.e. the so called decoupling problem. A possible approach is direct decoupling, which consists in adding to the coupled system a fictitious subsystem which is the negative of the residual subsystem. Starting from the 3-field formulation (dynamic balance, compatibility and equilibrium at the interface), the problem can be solved in a primal or in a dual manner. Compatibility and equilibrium can be required either at coupling DoFs only, or at additional internal DoFs of the residual subsystem. Furthermore DoFs used to enforce equilibrium might be not the same as DoFs used for compatibility: this generates the so called non collocated approach. In this paper, a hybrid primal-dual formulation is applied in combination with collocated and non collocated interface.
Modeling Constraints in Design Refresh Planning
Authors: Nelson Raymond , Sandborn Peter , Terpenny Janis P. , Zheng Liyu
Published: June 2012

When an original equipment manufacturer no longer supplies and/or supports a product then the product is considered to be obsolete. Obsolescence is a significant problem for systems whose operational and support life is much longer than the procurement lifetimes of their constituent components. Unlike high-volume, commercial products, which are quickly evolved, long field life, low-volume systems, such as aircraft may require updates of their components and technology called design refreshes to simply remain manufacturable and supportable. However these systems can’t perform design refreshes all the time due to the high nonrecurring and re-qualification costs. One approach to optimally managing this problem is to use DRP (Design Refresh Planning), which is a strategic method for scheduling design refreshes such that the life cycle cost impact of obsolescence is minimized. The planning of these design refreshes is restricted by various constraints, which need to be implemented into the DRP process. These constraints can reflect technology roadmap requirements, obsolescence management realities, logistical restrictions, budget ceilings and management policy. In this paper, constraints imposed on the DRP process are explored, classified within a taxonomy, and implemented in the planning process. A communications system design example is included.
Optimal Trajectory Planning for Brachiation Robot on Ladder With Irregular Branches
Authors: Meghdari Ali , Hosseini Lavasani Seyyed Mohammad , Rahimi Mousavi Mir Saman , Norouzi Mohsen
Published: June 2012

This paper deals with control of the brachiation robot. The brachiation is a type of mobile robot that moves from branch to branch like a long-armed ape. Here, as a new innovation, Pontryagin’s minimum principle is used to obtain the optimal trajectories for two different problems. The first problem is “Brachiation between fixed branches with different distance and height” and the second is “Brachiating and catching the moving target branch”. Theoretical results show that the control effort in the proposed method is reduced by 25% in comparison with the “Target Dynamics” method which was proposed in prior articles for this robot. The obtained optimal trajectory also minimizes the brachiation time. A PD controller is investigated for tracking the proposed trajectories. Lastly, theoretical results are shown and validated with experimental test.
Application of a Bayesian Filter to Estimate Unknown Heat Fluxes in a Natural Convection Problem
Authors: Colac¸o Marcelo J. , Orlande Helcio R. B. , da Silva Wellington B. , Dulikravich George S.
Published: June 2012

Sequential Monte Carlo (SMC) or Particle Filter Methods, which have been originally introduced in the beginning of the 50’s, became very popular in the last few years in the statistical and engineering communities. Such methods have been widely used to deal with sequential Bayesian inference problems in fields like economics, signal processing, and robotics, among others. SMC Methods are an approximation of sequences of probability distributions of interest, using a large set of random samples, named particles. These particles are propagated along time with a simple Sampling Importance distribution. Two advantages of this method are: they do not require the restrictive hypotheses of the Kalman filter, and can be applied to nonlinear models with non-Gaussian errors. This papers uses a SMC filter, namely the ASIR (Auxiliary Sampling Importance Resampling Filter) to estimate a heat flux in the wall of a square cavity undergoing a natural convection. Measurements, which contain errors, taken at the boundaries of the cavity are used in the estimation process. The mathematical model, as well as the initial condition, are supposed to have some error, which are taken into account in the probabilistic evolution model used for the filter.
Kinematic Synthesis of Planar, Shape-Changing Rigid Body Mechanisms for Design Profiles With Significant Differences in Arc Length
Authors: Shamsudin Shamsul A. , Murray Andrew P. , Myszka David H. , Schmiedeler James P.
Published: June 2012

This paper presents a kinematic procedure to synthesize planar mechanisms capable of approximating a shape change defined by a general set of curves. These “morphing curves”, referred to as design profiles, differ from each other by a combination of displacement in the plane, shape variation, and notable differences in arc length. Where previous rigid-body shape-change work focused on mechanisms composed of rigid links and revolute joints to approximate curves of roughly equal arc length, this work introduces prismatic joints into the mechanisms in order to produce the different desired arc lengths. A method is presented to inspect and compare the profiles so that the regions are best suited for prismatic joints can be identified. The result of this methodology is the creation of a chain of rigid bodies connected by revolute and prismatic joints that can approximate a set of design profiles.
Determining the Ordinary Differential Equation From Noisy Data
Authors: Venkataraman P.
Published: June 2012

A challenging inverse problem is to identify the smooth function and the differential equation it represents from uncertain data. This paper extends the procedure previously developed for smooth data. The approach involves two steps. In the first step the data is smoothed using a recursive Bezier filter. For smooth data a single application of the filter is sufficient. The final set of data points provides a smooth estimate of the solution. More importantly, it will also identify smooth derivatives of the function away from the edges of the domain. In the second step the values of the function and its derivatives are used to establish a specific form of the differential equation from a particular class of the same. Since the function and its derivatives are known, the only unknowns are parameters describing the structure of the differential equations. These parameters are of two kinds: the exponents of the derivatives and the coefficients of the terms in the differential equations. These parameters can be determined by defining an optimization problem based on the residuals in a reduced domain. To avoid the trivial solution a discrete global search is used to identify these parameters. An example involving a third order constant coefficient linear differential equation is presented. A basic simulated annealing algorithm is used for the global search. Once the differential form is established, the unknown initial and boundary conditions can be obtained by backward and forward numerical integration from the reduced region.
A Hybrid Method for Haptic Feedback to Support Manual Virtual Product Assembly
Authors: Faas Daniela
Published: June 2012

Experience with current Virtual Reality (VR) systems that simulate low clearance assembly operations with haptic feedback indicate that such systems are highly desirable tools in the evaluation of preliminary designs, as well as virtual training and maintenance processes. The purpose of this research is to develop methods to support manual low clearance assembly using haptic (force) feedback in a virtual environment. The results of this research will be used in an engineering framework for assembly simulation, training, and maintenance. The proposed method combines voxel-based collision detection and boundary representation to support both force feedback and constraint recognition. The key to this approach is developing the data structure and logic needed to seamlessly move between the two representations while supporting smooth haptic feedback. Collision forces and constraint-guided forces are blended to provide support for low clearance haptic assembly. This paper describes the development of the method.
Dielectric Response of β-HMX at THz Frequencies Calculated by Density Functional Theory
Authors: Huang Lulu , Shabaev Andrew , Lambrakos Samuel G. , Bernstein Noam , Jacobs Verne L. , Finkenstadt Daniel , Massa Lou
Published: June 2012

We present calculations of ground state resonance structure associated with the high explosives β-HMX using density functional theory (DFT), which is for the construction of parameterized dielectric response functions for excitation by electromagnetic waves at compatible frequencies. These dielectric functions provide for different types of analyses concerning the dielectric response of explosives. In particular, these dielectric response functions provide quantitative initial estimates of spectral response features for subsequent adjustment with respect to additional information such as laboratory measurements and other types of theory based calculations. With respect to qualitative analysis, these spectra provide for the molecular level interpretation of response structure. The DFT software GAUSSIAN was used for the calculations of ground state resonance structure presented here.
Start-Up Simulations for Induction and Synchronous Motor Driven Compressor Trains
Authors: Srinivasan Anand , Weber Peter
Published: June 2012

3-phase motors (both induction and synchronous) have remained the workhorse of the turbomachinery industry for several decades now. It is well known that motor driven centrifugal compressors give rise to transient torques during start-up of the drive train. The torsional nature of the shaft torques necessitates a thorough analysis at the design stage in order to adequately size the mechanical components of the drive train. This paper summarizes the mathematical equations to predict the air-gap torque for induction and synchronous motors that are available readily from electrical engineering literature, and extends it to present the electro-mechanical equations of motion for the motor-compressor system. Drive train studies have been simulated for both the traditional across-the-line start voltage systems and a simplified version of the more modern soft-start (variable frequency drive) systems.
Towards MEMS Tester for Measuring Metal Nanofilm’s Lorenz Number
Authors: Xu Weihe , Chen Qi , Shi Yong
Published: June 2012

The Lorenz number of metals has been considered constant according to the Wiedemann-Franz law. But this has been questioned by the most recent research in nano-scale thermal transfer. To study the size effect of Lorenz number for thin film metals, a MEMS tester was designed and fabricated. The tester is capable of measuring the Lorenz number of thin films or nanowires with various dimensions. The ANSYS simulation showed the measurement error generated by the non-uniformity in the heating area is below 2%.
Multi-Modal Nonlinear Forced Vibrations of Circular Cylindrical Shells of Arbitrary Shapes
Authors: Pilgun Galyna , Amabili Marco
Published: June 2012

Large-amplitude nonlinear forced vibrations of a circular cylindrical panel with a complex base, clamped at the edges are investigated. The Sanders-Koiter and the Donnell nonlinear shell theories are used to calculate the strain energy; in-plane inertia is retained. A mesh-free technique based on classic approximate functions and the R-function theory is used to build the discrete model of the nonlinear vibrations. This allows for constructing the sequences of admissible functions that satisfy given boundary conditions in domains with complex geometries. The problem is solved in two steps: a linear analysis is conducted to identify natural frequencies and corresponding natural modes to be used in the second step as a basis for nonlinear displacements. The system of ordinary differential equations is obtained by using the Lagrange approach on both steps. Numerical responses are obtained in the spectral neighborhood of the lowest natural frequency. The convergence of nonlinear responses is investigated.
Coupled Sequential Process-Performance Simulation and Multi-Attribute Optimization of Thin-Walled Tubes
Authors: Najafi Ali , Rais-Rohani Masoud
Published: June 2012

Coupling of material, process, and performance models is an important step towards a fully integrated material-process-performance design. In this study, sheet-forming simulation is coupled with crush simulation to investigate the effect of manufacturing process and product design parameters on energy absorption characteristics of thin-walled tubes. The coupled process-performance simulation is integrated with a multi-objective design optimization approach for finding the optimum process and performance responses. Geometric attributes including the cross-sectional dimensions as well as manufacturing process parameters such as holder force, punch velocity, and friction coefficient are considered as design variables. Rupture and thinning are measured based on the result of deep drawing simulation in ABAQUS/EXPLICIT and the springback distortion is extracted from ABAQUS/STANDARD solver by including the residual stresses and dynamic and contact responses from deep drawing simulation. Energy absorption is measured by the mean and maximum crush force values from ABAQUS/EXPLICIT simulation that includes all the history variables from deep drawing and springback analyses. Surrogate models using radial basis functions are developed and used in multi-attribute process-performance optimization. Pareto optimal solutions are found and the sensitivity of process and performance responses to the selected design variables is evaluated. The results of coupled simulation and optimization are presented and discussed.
Prototype Design of a 6-DOF Compliant Parallel Micro-Manipulator
Authors: Yue Yi , Gao Feng , Ge Hao
Published: June 2012

This paper focuses on the prototype design of a 6-DOF compliant parallel micro-manipulator (PMM) with isotropic/decoupled performances. By investigating the incidence relation between inputs and outputs of the micro-manipulator, a design method for micro-manipulator is proposed and discussed based on screw theory. Using the method, a 6-DOF compliant PMM prototype driven by piezoelectric actuators is designed and manufactured. The PMM is designed with the monolithic structure, and its conventional joints are replaced by flexure hinges. In order to ensure the end-effector can reach the desired points with required orientations, the relation model between workspace and the parameters of piezoelectric actuator (PZT) is derived by considering input-force, payload, stiffness, displacement and the topology of the PMM. Finally, the experiment of the micro-manipulator prototype is performed to verify the above research results. The proposed method is systematic and useful for the design of 6-DOF PMMs.
Analysis of Oscillations in Fractional Order LTI Systems
Authors: Siami Milad , Tavazoei Mohammad Saleh
Published: June 2012

This paper is devoted to analysis of undamped oscillations generated by fractional order linear time invariant (LTI) systems. At first, the trajectories of marginally stable commensurate order systems are investigated. It is verified that we can not use the time-independent phase flow concept for this kind of systems. Also, the differences with the integer order case are highlighted. Then, it is shown that we can determine the Q-norm of the limit sets of a trajectory for these systems based on the Q-norm of the initial condition. Some numerical examples are brought to confirm the achievements of the paper.
Geometry and Constraint Based Design of Metamorphic Parallel Mechanisms
Authors: Zhang Ketao , Dai Jian S. , Fang Yuefa
Published: June 2012

This paper presents two general metamorphic kinematic units which employ only revolute joints. The two kinematic units with reconfigurability are mapped from independent set of line vectors with different geometry. The underlying principle of the metamorphosis of this kind of reconfigurable kinematic units is unraveled by investigating the dependency of corresponding screw system comprised with line vectors. Limb structure that can be used for constructing new parallel mechanisms is proposed. Subphases of the limb are enumerated accompanying to the phase change of the embodied metamorphic units and constraints corresponding to each phase are analyzed based on reciprocity of screws. Two metamorphic parallel mechanisms which can change their configuration from fully 6-DOF phase to 3-DOF translational subphase and 3-DOF spherical subphase are proposed according to geometric conditions that must be met by limbs. The mobility changes of the platform induced by phase change of limbs are addressed.
Integrated Design Approaches for Controlled Flexible Multibody Systems
Authors: Seifried Robert , Held Alexander
Published: June 2012

In industrial manipulators and machine tools modern lightweight designs result in low energy consumption and often allow high working speeds. However, undesired vibrations occur due to the flexibility of the bodies and the control of flexible multibody systems is often a challenging task. In order to achieve good end-effector tracking performance the mechanical design and the control design must be considered concurrently in the sense of an integrated design process. In this paper three different optimization based integrated design approaches for controlled flexible multibody systems are presented.
Multi-Objective Ease-Off Optimization of Hypoid Gears for Their Efficiency, Noise and Durability Performances
Authors: Artoni Alessio , Gabiccini Marco , Guiggiani Massimo , Kahraman Ahmet
Published: June 2012

Micro-geometry optimization has become an important phase of gear design that can remarkably enhance gear performance. For spiral bevel and hypoid gears, micro-geometry is typically represented by ease-off topography. The optimal ease-off shape can be defined as the outcome of a process where generally conflicting objective functions are simultaneously minimized (or maximized), in the presence of constraints. This matter naturally lends itself to be framed as a multi-objective optimization problem. This paper proposes a general algorithmic framework for ease-off multi-objective optimization, with special attention to computational efficiency. Its implementation is fully detailed. A simulation model for loaded tooth contact analysis is assumed to be available. The proposed method is tested on a face-hobbed hypoid gear set. Three objectives are defined: maximization of mechanical efficiency, minimization of loaded transmission error, minimization of maximum contact pressure. Bound constraints on the design variables are imposed, as well as a nonlinear constraint aimed at keeping the loaded contact pattern inside a predefined allowable contact region. The results show that the proposed method can obtain optimal ease-off topographies that significantly improve the basic design performances. It is also evident that the method is general enough to handle geometry optimization of any gear type.
On the Minimum Harmonic Trajectory Pattern for Point-to-Point Motion
Authors: Rastegar Jahangir , Feng Dake
Published: June 2012

In this paper, the lowest harmonic trajectory pattern for point-to-point motions with zero end point velocity, acceleration and jerk of fully controlled nonlinear dynamics systems that can be synthesized is proved to be a unique combination of a fundamental frequency harmonic and its second harmonic. For fully controlled dynamic systems such as robot manipulators and other computer controlled machines with rigid links, it is shown that such a trajectory pattern would yield the minimum number of harmonic in the required actuation forces/torques. Such trajectory patterns are therefore suitable for point-to-point motion synthesis of high-precision and high-speed computer controlled machinery and can also be synthesized to minimize excitation of the system natural modes of vibrations.
Quantitative Performance Analysis of Haptic Devices With Parallelogram Subsystems
Authors: Lee Leng-Feng , Zhou Xiaobo , Krovi Venkat N.
Published: June 2012

Parallel-architecture haptic devices offer significant advantages over serial-architecture counterparts in applications requiring high stiffness and high accuracy. To this end, many haptic devices have been created and deployed by modularly piecing together several serial-chain arms to form an in-parallel system. Furthermore, recent haptic devices design such as the Sensable’s PHANToM Premium line of haptic devices and Quanser’s High Definition Haptic Device (HD)2 placed the 2nd actuated joint (of a 2-DOF RR serial manipulator) at the base of the device that allowed the control of the 2nd joint through a parallelogram/fourbar structure. This design is favorable from the view point of reducing the overall weight that the first motor has to carry. However, such design choices can affect the overall system performance which depends both on the nature of the individual arms as well as their interactions. In this paper, we build on the rich theoretical background of constrained articulated mechanical systems to provide a systematic framework for formulation of system-level kinematic performance from individual-arm characteristics. Specifically, we discuss: (i) development of pertinent symbolic equations; (ii) generalization to arbitrary architectures; and (iii) combined symbolic/numeric analyses of performance, focusing on manipulability and stiffness. These aspects are illustrated using the example of Quanser High Definition Haptic Device (HD)2 — an in-parallel haptic device formed by coupling two 3-link PHANToM 1.5 type serial chain manipulators with appropriate passive joints.
A Comparative Study of 4-Cable Planar Manipulators Based on Cylindrical Algebraic Decomposition
Authors: Chablat Damien , Ottaviano Erika , Moroz Guillaume
Published: June 2012

The aim of this paper is to present a systematic method for verifying the force-closure condition for general 3-DOF fully-constrained cable manipulators with four cables as based on the CAD (Cylindrical Algebraic Decomposition). A fundamental requirement for a cable manipulator to be fully controllable is that all its cables must be in tension at any working configurations. In other words, all the cable forces must be positive (assuming a positive cable force representing a tension and a negative cable force being a compression). Such a force feasibility problem is indeed referred to a force-closure problem (also called vector-closure problem assuming that the vectors of interest are the row vectors of the Jacobian matrix of the manipulator). The boundaries of the workspace can be obtained by the study of the Jacobian matrix of the manipulator. Therefore, this is equivalent to study the singularity conditions of four 3-RPR parallel robots. By using algebraic tools, it is possible to determine the singularity surfaces and their intersections yielding the workspace. Thus, it will be shown that the use of the CAD allows to get an implicit representation of the workspace as a set of cells. A comparative workspace analysis of three designs of mobile platforms, a line, a square and a triangle will be presented and discussed in this paper for a planar 4-cable fully-constrained robot.
Unifying Theory of Quantitative Atomic Force Microscopy Using Piezo Excitation in Liquids
Authors: Kiracofe Daniel R. , Raman Arvind
Published: June 2012

Base-excitation of microcantilevers using a dither piezoelectric element, also known as acoustic excitation, is one of the most popular methods for dynamic atomic force microscopy (AFM) because it is inexpensive, easy to use and does not require special cantilevers. However, in liquid environments there are problems using this method for quantitative force spectroscopy. The problems arise due spurious peaks in the driving spectrum (also known as “forest of peaks”) caused by piezo and fluid cell resonances, as well as a large base motion, which make it very hard to quantify the exciting forces. Although some groups have tried to overcome these limitations, it is has generally been accepted that acoustic excitation is unsuitable for quantitative force spectroscopy in liquids. In this work the authors show that a thorough understanding of the excitation forces and base motions reveals a method by which quantitative analysis is in fact possible with acoustic excitation in liquid environments, thus opening this popular method for quantitative dynamic AFM in liquids. This method is validated by experiments using a scanning laser Doppler vibrometer, which can measure the actual base motion. Finally, the method is demonstrated by performing force spectroscopy on solvation shells of octamethylcyclotetrasiloxane (OMCTS) molecules on mica.
A Spatial Thin Beam Finite Element Based on the Absolute Nodal Coordinate Formulation Without Singularities
Authors: Nachbagauer Karin , Gruber Peter G. , Vetyukov Yury , Gerstmayr Johannes
Published: June 2012

A three-dimensional nonlinear finite element for thin beams is proposed within the absolute nodal coordinate formulation (ANCF). The deformation of the element is described by means of displacement vector, axial slope and axial rotation parameter per node. The element is based on the Bernoulli-Euler theory and can undergo coupled axial extension, bending and torsion in the large deformation case. Singularities — which are typically caused by such parameterizations — are overcome by a director per element node. Once the directors are properly defined, a cross sectional frame is defined at any point of the beam axis. Since the director is updated during computation, no singularities occur. The proposed element is a three-dimensional ANCF Bernoulli-Euler beam element free of singularities and without transverse slope vectors. Detailed convergence analysis by means of various numerical examples and comparison to analytical solutions shows the performance and accuracy of the element.
Towards Sustainable Product Design
Authors: Liu Jun , Wang Qing
Published: June 2012

The aim of this paper is to propose a framework to guide engineers’ use of LCA tools to optimize three important stages of a product’s life cycle. The three phases are product concept design, manufacturing process and products end of life recycle. A mountain bike has been used as an example to demonstrate how engineers are guided by the proposed framework. The proposed framework does not only lead industry in a sustainable design direction but also guide them to embed sustainable thinking into every stage of a product life cycle based on their existing resources. Some design tools and techniques have been incorporated with life cycle assessment tools to achieve the sustainable optimization of the products.
A Computational Workbench for Remote Full Field 3D Displacement and Strain Measurements
Authors: Michopoulos John G. , Iliopoulos Athanasios
Published: June 2012

The present paper reports on the progress towards the development of a computational workbench infrastructure that implements the Meshless Random Grid (MRG) method for the remote (non contact) measurement of displacement and strain fields in 3D space. The method is applicable to structures bounded by flat surfaces that deform under various mechanical and generalized loading conditions in and out of plane. A brief description of the 3D MRG method is followed by the description of the current prototype of a software workbench developed for the computational implementation of the algorithms involved with the analysis display and export of the experimental results associated with any specific applications of the method.
Design for Emerging Bottom of the Pyramid Markets: A Product Service System (PSS) Based Approach
Authors: Schafer Carson , Parks Richard , Rai Rahul
Published: June 2012

Multi billion people exist at the bottom of the global economic pyramid (BOP). Increased consumer demand and enormous volume has helped turn these BOP into emerging markets with substantial profit potential. Current approaches for designing product and service solutions for BOP markets are ad-hoc in nature. Product Service Systems (PSS), products intertwined with services, can be highly adaptable to these emerging markets and provide an unique framework for designing solutions in the emerging BOP markets. This paper systematically approaches the problem of designing customized PSSs for emerging markets. The approach is based on results of an empirical study of multiple cases of existing successful products and services designed for BOP markets. As part of the study various cases are analyzed and high level principles for designing PSSs are derived from the empirical data. The utility of the approach is demonstrated through the conceptual design of a healthcare PSS for emerging markets.
Design of a Four-DOF Modular Self-Reconfigurable Robot With Novel Gaits
Authors: Chu Khoa D. , Hossain S. G. M. , Nelson Carl A.
Published: June 2012

Throughout the modern age, exploration of the unknown has been an attractive pursuit to seekers of knowledge. One of the primary frontiers for exploration today involves planetary and lunar environments. Exploration in these environments can involve many different types of tasks in a broad range of environmental conditions. Modular Self-Reconfigurable Robots (MSRs) would be beneficial for completing these tasks in unstructured environments, while having the ability to complete multiple assigned functions. Since payload is a critical concern, a lighter and more dexterous MSR is preferable. This research focuses on the design of a robot that has these qualities. A chain-type modular robot with four degrees of freedom per module has been designed with the goal of reducing weight and size while increasing range of motion. Forward kinematic transformations were derived to analyze the available workspace provided by the MSR. Radio communication and proximity sensing ability were provided in the individual MSR modules to locate each other. The modules are designed to maneuver independently using their individual navigation capability as well as connect to each other by means of a docking mechanism. Locomotion gaits for such multi-module robot chains are also described.
Co-Design Methodology for the Development of Sustainable and Renewable Energy Systems for Underserved Communities: A Case Study With the Pinoleville Pomo Nation
Authors: Shelby Ryan , Perez Yael , Agogino Alice
Published: June 2012

The notion of developing sustainable communities is generally accepted as a way to reduce the negative environmental impacts associated with human activities, increase the health of citizens, and increase the economic vitality of communities within a country. In order to further the development of sustainable communities, federal and local governments have placed significant attention upon designing sustainability and renewable energy technologies, such as photovoltaic (solar) and grey water recycling systems to reduce (1) fossil fuel based energy consumption, (2) water consumption, and (3) climate changing greenhouse gas (GHG) emissions associated anthropogenic activities. The Pinoleville Pomo Nation (PPN) of Ukiah, CA, is an example of a Native American government and community that has embarked upon an infrastructure development program to design and build culturally appropriate, sustainable housing for its members. This paper describes the co-design methodology created by the authors to partner with communities that have historical trauma associated with working with outsiders on projects that involved substantial usage of engineering and scientific artifacts, renewable energy technologies for example, that have not integrated their value system or has been historically denied to them. As a case study, we present the lessons learned from a partnership with the Pinoleville Pomo Nation and UC Berkeley’s Community Assessment of Renewable Energy and Sustainability (CARES) team to develop sustainable housing that utilizes sustainability best practices and renewable energy technologies as well as reflect the long-standing culture and traditions of the PPN. We also present the Pomo-inspired housing design created by this partnership and illustrate how Native American nations can partner with universities and other academic organizations to utilize engineering expertise to co-design solutions that address the needs of the tribes. As a result of this partnership, the Pomo-inspired house design was utilized to secure federal funding to create housing that will aid the PPN in their tribal sovereignty, economic self-sufficiency, and environmental harmony goals.
The KCLBOT: A Double Compass Self-Localizing Maneuverable Mobile Robot
Authors: Georgiou Evangelos , Dai Jian S. , Luck Michael
Published: June 2012

The key to autonomous mobile-robot navigation is effective path planning and accurate self-localisation. The lack of self-localisation or inaccurate self-localisation makes any nonholonomic autonomous mobile robot blind in a navigation environment and will deter the robot’s ability to complete path following. In the last several years, many different systems have been considered for self-localisation, from using visual odometry to using a satellite triangulation method, better known as a global position system or GPS. All of these have benefits and detriments, the solution proposed here endeavors to offer more benefits than detriments, utilizing a novel method for self-localisation, employing a dual bearing finder digital compass configuration to resolve the relative location of an autonomous nonholonomic wheeled mobile robot. To facilitate the novel hybrid method, the utilization of the mobile robot’s multiple sensors, dual wheel quadrature shaft encoders and the digital compasses are required. To support the hardware requirements of the novel localisation methodology, the cutting edge technology of a 200 MHz 32-bit ARM 9 processor on a GHI ChipworkX module are employed. The software architecture is based on the Microsoft .NET Micro Framework 4.1 using C# and the Windows Presentation Foundation (WPF). Without the inputs from the dual compass configuration it would not be possible to solve the relative position of the mobile robot analytical. Without the dual compass configuration only a numeric solution is possible, which decelerates the localisation process. The mobile robot’s digital compasses are marked with unnatural markers, for faster identification by an overhead camera. Using the overhead camera tracking results and comparing the telemetry collected by the mobile robot, using the analytical equations, the validation of this method is proven. The most fundamental part of implementing a successful maneuverable nonholonomic mobile robot is accurate self-localisation telemetry. The biggest concern about using a self-localisation technique is the amount of computation it will require to complete the task. Ideally, having an analytical solution to position offers the benefit of a single solution, where the numeric solution has many solutions and requires more time and computation to derive the solution. The benefit of the dual compass configuration is that it offers an analytical solution to the hybrid model that utilizes quadrature shaft encoders and digital compasses. This methodology evidently presents a novel approach where visual odometry is not possible.
Effects of Preloads on Vibration Transmission Through Double Row Angular Contact Ball Bearings
Authors: Gunduz Aydin , Dreyer Jason T. , Singh Rajendra
Published: June 2012

This work investigates the role of double row angular contact ball bearings as a vibration transmitter in shaft-bearing assemblies. In our analyses the double row bearings are represented as five dimensional stiffness elements (with associated damping) through an extension of the stiffness matrix concept described by Lim and Singh (1989) for single row bearings to double row angular contact ball bearings. In particular, the effects of bearing preloads on dynamic characteristics of double row angular contact ball bearings are first numerically explored. The dynamic responses of face-to-face, back-to-back and tandem arrangements are evaluated on a comparative basis under various preloads. The nature and extent of preloads significantly affect the vibration characteristics of the bearing assembly due to major changes in the diagonal and off-diagonal elements of the stiffness matrix, and these effects vary for alternate configurations. The dynamic effects of bearing preloads are then experimentally investigated for a wheel bearing assembly containing double row angular contact ball bearings (with back-to-back arrangement) under two different preloading mechanisms. Experiments show that the mechanism and amount of bearing preloads significantly affect the system natural frequencies, mode shapes and vibration amplitudes, thus altering the vibration behavior of the bearing assembly. Suggestions for further work and applications will be briefly mentioned.
Methodology for Pipeline Route Selection Using the NSGA II and Distance Transform Algorithms
Authors: Kjaernested Sigurjon N. , Jonsson Magnus Th. , Palsson Halldor
Published: June 2012

The objective of this study is to develop a methodology for use in geothermal pipeline route selection. Special emphasis is placed on finding the shortest route and minimizing the visual affects of the pipeline. Two different approaches are taken to solving the problem. In the first method a distance transform algorithm is used both for visual effects ranking and to obtain the optimal path. Subsequently a genetic algorithm is used to modify the route with regards to necessary expansion units. Included in the tool is site selection for separators and pipeline gathering points based on visual effects, incline, inaccessible areas and total distance to boreholes. The second method uses the Non-dominated sorting genetic algorithm II (NSGA II) to obtain the optimal path with regards visual effects, route length and pipeline gradient. This method uses the distance transform ranking method along with constraints on route length to generate the initial population for the genetic algorithm. The methods are implemented for the Hverahlið geothermal area.
Identifying Fractional Viscoelastic Models Based on Surface Wave Motion
Authors: Iannitto Marco , Royston Thomas J. , Magin Richard L.
Published: June 2012

In previous studies of the second author mechanical wave motion on a viscoelastic material representative of biological tissue was analyzed. Compression, shear and surface wave motion in and on a viscoelastic halfspace excited by surface and subsurface sources were considered. It was shown that a fractional order Voigt model, in which the damping component, dependent on the first derivative of time, is replaced with a fractional element dependent on a derivative of time of fractional order between 0 and 1, resulted in closer agreement with experiment as compared with the conventional (integer order) models of Voigt and Zener. In the present study different materials and a wider range of viscoelastic models are considered. An algorithm to evaluate the frequency-dependent shear moduli of viscoelastic materials measuring the propagation of Rayleigh waves on the surface of the media is presented and viscoelastic models (both of integer and fractional order) are compared to experimental results. It is shown that, in the frequency range of interest (100–600 Hz), the use of the fractional order assumption improves the match of theory to experiment.
A Meshfree B-Spline Finite Element Formulation for Unilateral Contact Problems
Authors: Grishin Alex , Shah Jami J.
Published: June 2012

The integrated, accurate and robust analysis of unilateral structural contact problems at all scales is a prerequisite for a comprehensive CAE process which accommodates the design of assemblies. In addition, such an integration must reduce any manual intervention to a bare minimum. The current reliance on legacy mesh-based finite element software for such analysis instead leads to excessive manual mesh construction and modification. Although the adoption of a meshfree formulation would seem to hold the answer, the current state-of-the-art in node-based formulations suffers from a lack of stability and/or consistency for such applications. This investigation demonstrates that there exists a meshfree B-Spline formulation which is consistent, stable, and demonstrates accuracy comparable to that of mesh-based approaches for simple frictionless Hertzian problems in two dimensions. Together with the Solution Structure Method (SSM) of boundary condition enforcement, it is argued that this approach may provide a more robust finite element framework within existing CAE pipelines.
Complete High Dimensional Inverse Characterization of Fractal Surfaces
Authors: Michopoulos John G. , Iliopoulos Athanasios
Published: June 2012

The present paper describes a methodology for the inverse identification of the complete set of parameters associated with the Weirstrass-Mandelbrot (W-M) function that can describe any rough surface known by its profilometric or topographic data. Our effort is motivated by the need to determine the mechanical, electrical and thermal properties of contact surfaces between deformable materials that conduct electricity and heat and require an analytical representation of the surfaces involved. Our method involves utilizing a refactoring of the W-M function that permits defining the characterization problem as a high dimensional singular value decomposition problem for the determination of the so-called phases of the function. Coupled with this process is a second level exhaustive search that enables the determination of the density of the frequencies involved in defining the trigonometric functions involved in the definition of the W-M function. Our approach proves that this is the only additional parameter that needs to be determined for full characterization of the W-M function as the rest can be selected arbitrarily. Numerical applications of the proposed method on both synthetic and actual elevation data, validate the efficiency and the accuracy of the proposed approach. This approach constitutes a radical departure from the traditional fractal dimension characterization studies and opens the road for a very large number of applications.
Deformation, Stress and Natural Frequency Analysis of the Fullerene by Finite Super Element Method
Authors: Sarvi Masoud Nasiri , Ahmadian M. T.
Published: June 2012

Accurate prediction of static and dynamic response of nano structures is one of the important interests of scientists in the last decade. Nano bearing as an important part of nano machines has been extensively implemented in recognizing and disassembling cancerous cells and building molecular support structures for strengthening bones. For this reason, Molecular Dynamic Method and some experimental methods are implemented in this area. As nano ball bearing is one of the most important components of nano machines, a large number of studies are concentrated to analyze it statically and dynamically. In this paper, a Fullerene is simulated by a spherical super element whose stress, deformation and natural frequency are calculated. The Fullerene is considered to be the C60 which is properly similar with a 66 surface-node spherical super element. In this study the mechanical properties of the fullerene and boundary conditions of the nano ball bearing under loading are introduced and stress and natural frequency of a fullerene under concentrated load is presented with two different strategies, super element and conventional elements. Compatible findings of these two methods validate and confirm the results. Findings indicate that applying 1 super element for the simulation of the fullerene leads to same results as implementing 154764 conventional elements.