bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Simulation of a Stability Control System for 4 Independent Wheel Drive Electric Vehicle
Authors: Núñez Juan S. , Muñoz Luis E.
Published: December 2016

With the aim of prevent situations of vehicle instability against different driving maneuvers, the vehicle yaw stability becomes crucial for safe operation. This paper presents the design and simulation of a traction and a stability control system algorithms for independent four-wheel-driven electric vehicle. The stability control system consists of a multilevel algorithm divided into a high level controller and a low level controller. First, an analysis of the stability of the vehicle is performed using phase portraits analysis, both in open loop and closed loop. The stability control system is designed to generate a desired yaw moment according to the steady state cornering relationship with the steering angle input. As the test vehicle, a 14 DoF vehicle model is proposed including nonlinear tire models that allow the generation of combined forces. The vehicle model includes the powertrain dynamics. The yaw moment generation is performed using the traction and braking forces between the tires of each side of both front and rear axle. In order to generate the maximum traction forces in each of the wheels, a traction and a braking control is developed via a sliding mode controller scheme. Finally a performance comparison between a controlled and an uncontrolled vehicle is presented. The behavior of both vehicles is simulated using a classical double lane change driving maneuver.
Dynamic Analysis of an Automotive Belt-Drive System With a Noncircular Sprocket by a Modified Incremental Harmonic Balance Method
Authors: Wang X. F. , Zhu W. D.
Published: December 2016

A dynamic model of an automotive belt-drive system with a noncircular sprocket instead of a round sprocket is developed in this work to study the effect of reducing the angular variation of camshafts. There are two sub-models in the belt-drive system, which are an engine model and a belt-drive model, and they are decoupled to simplify the analysis. When the belt-drive system operates at a steady state, it is described by a nonlinear model with forced excitation, which can be approximated by a linear model with combined parametric and forced excitations. Steady-state responses of the engine and belt-drive models are calculated by a modified incremental harmonic balanced method that incorporates fast Fourier transform and Broyden’s method, which is efficient and accurate to obtain a periodic response of a multi-degree-of-freedom system. Steady-state responses of the angular variation of camshafts with different values of sprocket parameters are compared to investigate their optimal values to reduce the angular variation of camshafts. Optimal values of sprocket parameters obtained from the dynamic model of the belt drive differ from those from its kinematic model in some previous studies, which is consistent with published experimental results. This study first shows from a dynamic point of view why use of a noncircular sprocket can reduce the angular variation of camshafts in the operating speed of an engine. Simulation of a speed-up procedure for different sprocket parameters shows results that are consistent with steady-state responses.
An Adaptive Gaussian Mixture Model Approach Based Framework for Solving Fokker-Planck Kolmogorov Equation Related to High Dimensional Dynamical Systems
Authors: Mukherjee Arpan , Rai Rahul , Singla Puneet , Singh Tarunraj , Patra Abani
Published: December 2016

Engineering systems are often modeled as a large dimensional random process with additive noise. The analysis of such system involves a solution to simultaneous system of Stochastic Differential Equations (SDE). The exact solution to the SDE is given by the evolution of the probability density function (pdf) of the state vector through the application of Stochastic Calculus. The Fokker-Planck-Kolmogorov Equation (FPKE) provides approximate solution to the SDE by giving the time evolution equation for the non-Gaussian pdf of the state vector. In this paper, we outline a computational framework that combines linearization, clustering technique and the Adaptive Gaussian Mixture Model (AGMM) methodology for solving the Fokker-Planck-Kolmogorov Equation (FPKE) related to a high dimensional system. The linearization and clustering technique facilitate easier decomposition of the overall high dimensional FPKE system into a finite number of much lower dimension FPKE systems. The decomposition enables the solution method to be faster. Numerical simulations test the efficacy of our developed framework.
Comparison and Extension of Novelty Metrics for Problem-Solving Tasks
Authors: Johnson Tyler A. , Cheeley Avery , Caldwell Benjamin W. , Green Matthew G.
Published: December 2016

Shah’s metrics for measuring ideation effectiveness have been used extensively by the engineering design community to quantify the value of designed concepts. Shah measures novelty as the infrequency of an idea relative to a set of ideas. Vargas-Hernandez extended this novelty metric using partial genealogy trees to consider the frequency of ideas that share the same working principle. These genealogy trees capture differences between individual ideas organized by the following levels of abstraction: physical principle, working principle, and embodiment. Shah’s and Vargas-Hernandez’s metrics both require that all ideas be described at the lowest level (embodiment). This approach excludes ideas that are described at higher levels of abstraction. This paper proposes a new novelty metric that extends Vargas Hernandez’s metrics by including the higher levels of the genealogy trees, allowing abstract ideas to be properly evaluated. This paper compares the newly proposed novelty metric to Shah’s and Vargas Hernandez’s metrics using data from a previous study. The study required participants to perform problem-solving tasks in which they submitted a textual list of ideas for how to solve general day-to-day problems. The proposed novelty metric addresses limitations of the previous metrics when applied to the abstract ideas in the data set and meets established metric requirements. The proposed metric also broadens Shah’s metric in a similar manner as Vargas Hernandez but extends it to capture the entire genealogy tree rather than a subset of the tree.
Fractional Delayed Control Design for Linear Periodic Systems
Authors: Dabiri Arman , Butcher Eric A. , Poursina Mohammad
Published: December 2016

In this paper, the fractional Chebyshev collocation (FCC) method is proposed to design fractional delay controllers for linear systems with periodic coefficients. In our previous study, it was shown that this method can be successfully used to stabilize fractional periodic time-delay systems with the delay terms being of integer orders. In the current paper, it is shown that this method can be extended successfully to design fractional delay controllers for fractional periodic systems. For this propose, the solution of linear periodic systems with fractional delay terms is expressed in a Banach space. The short memory principle is used to show that the actual response of the system can be approximated by an approximated monodromy operator. The approximated monodromy operator yields the solution of a fixed length interval by mapping the solution of the previous interval with the same length. Usually obtaining the approximated monodromy operator is complicated or even impossible. The spectral radius of the approximated monodromy matrix indicates the asymptotic stability of the system. The efficiency of the proposed fractional delayed control is illustrated in the case of a second order system with periodic coefficients.
Optimal Planning of the Bike Change Strategy for Hilly Time-Trials on Cycling
Authors: Roa Sergio D. , Muñoz Luis E.
Published: December 2016

During the individual time-trial competitions in cycling, the cyclist’s skills are essential, but it is also important the race strategy. The race strategy includes the manner in which the cyclist competes and the selection and set-up of the cycling equipment. For hilly time-trials, part of the race strategy consists of the right selection of the bike type. Depending on the characteristics of the road such as total distance and altitude profile, a time-trial bike or a traditional road bike could be used. Additionally, in some races it is possible to change bike type as a part of the strategy. This strategy seeks to take advantage of time-trial bikes during low gradient sections and to take advantage of road bikes during high gradient sections. The purpose of this work is to plan an optimal bike change strategy to determine if it is advantageous to change the bike type, and if so, to find the point of the route where the change minimizes race time. The optimal planning methodology is based on a bike model, a simplified altitude profile and an optimization problem. A model parameters identification process is performed based on experimental tests in a hilly route. This route is used as a case study for the optimal planning of the bike change strategy.
In-Plane Blade-Hub Dynamics in Horizontal-Axis Wind-Turbines
Authors: Acar Gizem , Acar Mustafa A. , Feeny Brian F.
Published: December 2016

Blade-hub dynamics of a horizontal-axis wind turbine is studied. Blade equations are coupled through the hub equation, and have parametric terms due to cyclic aerodynamic forces, centrifugal effects and gravitational forces. Blade inertia is usually small compared to the rotor inertia, which enables us to treat the effect of blade motion as a perturbation on the rotor motion. The rotor speed is not constant, and the cyclic variations cannot be expressed as explicit functions of time. Therefore, it is more convenient to use the rotor angle as the independent variable. By doing so, and assuming small variations in rotor speed, the blade equations are decoupled from the rotor equation. The inter-dependent blade equations constitute a three-degree-of-freedom system with periodic parametric and direct excitation. The response is analyzed by using method of multiple scales. The system has a superharmonic and a subharmonic resonances due to direct and parametric effects introduced by gravity. Amplitude frequency relations and stabilities of these resonances are studied.
Force Optimization Approaches for Common Anthropomorphic Grasps
Authors: Cloutier Aimee , Yang James
Published: December 2016

A smart choice of contact forces between robotic grasping devices and objects is important for achieving a balanced grasp. Too little applied force may cause an object to slip or be dropped, and too much applied force may cause damage to delicate objects. Prior methods of grasping force optimization in literature have mostly assumed grasp only at the fingertips but have rarely considered how the whole hand grasps more common to anthropomorphic hands affect the optimization of grasping forces. Further, although numerical examples of grasping force optimization methods are routinely provided, it is often difficult to compare the performance of separate methods when they are evaluated using different parameters, such as the type of grasping device, the object grasped, and the contact model, among other factors. This paper presents three optimization approaches (linear, nonlinear, and nonlinear with linear matrix inequality (LMI) friction constraints) which are compared for an anthropomorphic hand. Numerical examples are provided for three types of grasp commonly performed by the human hand (cylindrical grasp, tip grasp, and tripod grasp) using both soft finger contact and point contact with friction models. Contact points between the hand and the object are predetermined. Results are compared based on their accuracy, computational efficiency, and other various benefits and drawbacks unique to each method. Future work will extend the problem of grasping force optimization to include consideration for variable forces and object manipulation.
Creating a Concept Inventory Set of a Kinematics and Dynamics Machinery Course to Support Lectures in a Flipped Classroom Environment
Authors: Canfield Stephen L. , Hill Tristan W. , Zuccaro Stephen G.
Published: December 2016

Dynamics of Machinery is a traditional engineering course based on long-standing kinematic theory and proven practices. Given the established nature of the class, Dynamic of Machinery could be considered for a flipped classroom model in which students watch a prerecorded lecture prior to class, and then spend class time practicing the theory through examples. One of the limitations to the flipped model is the concern that students have not fully grasped the material from the recorded lecture. This paper suggests the use of a concept quiz associated with each pre-recorded lecture as a required component to meet prior to attending the class. The concept quizzes are associated with each unit lecture and collectively should form a concept inventory for the class that defines the fundamental range of knowledge for successful students. This paper will present the format the concept quizzes and how they are used in the flipped class environment for a traditional, junior level kinematics of machinery course. The paper will present the concepts according to topics and divided among 39 lectures associated with each class.
Vibration Analysis of Vertical-Axis Wind-Turbine Blades
Authors: Afzali Fatemeh , Kapucu Onur , Feeny Brian F.
Published: December 2016

In this work the derivation of a vibration model for an H-rotor/Giromill blade is investigated. The blade is treated as a uniform straight elastic Euler-Bernoulli beam under transverse bending and twisting deformation. The derivation of the energy equations for the bending and twisting blade and a simplified aerodynamic model is issued. Lagrange’s equations are applied to assumed modal coordinates to obtain nonlinear equations of motion for bend and twist. A single quasi-steady airfoil theory is applied to obtain the aeroelastic loads. The behavior of the linearized equation for bend only is examined.
Cognitive Empathy in Design Course for a More Inclusive Mechanical Engineering
Authors: Wong (Lau) Kathleen , Norris Rebecca L. , Siddique Zahed , Altan M. Cengiz , Baldwin James , Merchan-Merchan Wilson
Published: December 2016

Cognitive Empathy, often referred to as perspective taking, refers to the ability to identify and understand details about another’s experience so that one can understand why people may think and feel the way that they do. In recent years the need for designers to develop Cognitive Empathy skills has been recognized and has given rise to human-centered design and empathic design. Many mechanical engineering and design departments offer courses and have programs in these emerging topics. Mechanical engineers need to have basic understanding of Cognitive Empathy to function in today’s workplace. In addition, most mechanical engineering undergraduate programs do not have a diverse student body representative of the general population. Although there are many reasons, we believe that having a welcoming, inclusive environment is a precursor to improving diversity and thus should be an important consideration in mechanical engineering education. We propose that introducing carefully designed training on Cognitive Empathy in design courses could result in (i) a more welcoming and inclusive environment and (ii) a new generation of designers better equipped to consider the users. In this paper we present an “Intercultural Cognitive Empathy” training that was given to all mechanical engineering seniors at the University of Oklahoma to create a more inclusive environment. The students in a senior design course received the training at the beginning of the semester, before forming their design teams, so that they could use the skills to better communicate with each other. Cognitive Empathy research provided the foundation for the training and intercultural active learning components were also integrated. A student survey, done at the end of the semester, showed that students retained and used different components of the training throughout the semester. The assessment strongly suggests that this training should be part of the regular curriculum.
On Nonlinear Dynamics of Nanotweezers
Authors: Caruntu Dumitru I. , Liu Bin
Published: December 2016

This paper deals with amplitude-frequency response of electrostatic nanotube nanotweezer device system. Soft alternating current (AC) of frequency near natural frequency actuates the nanotubes. This leads the system into parametric resonance. The Method of Multiple Scales (MMS) in which the nonlinear electrostatic and van der Waals forces are expanded in Taylor series is used to compare two expansions, one up to third power and the other up to fifth power. The frequency response of the system is reported and the effects of van der Waals forces, electrostatic forces, and damping forces on the frequency response are investigated.
The Preferences for Creativity Scale (PCS): Identifying the Underlying Constructs of Creative Concept Selection
Authors: Toh Christine A. , Miller Scarlett R.
Published: December 2016

Creativity is highly emphasized during the engineering design process, but prior research has shown that decision-making biases and individual attributes can affect perceptions and preferences for creativity. However, there is a lack of knowledge of how to measure creativity during concept selection, or about the factors that affect designers’ preferences for creative concepts in an engineering design context. As a first step in understanding what factors contribute to the promotion or filtering of creative concepts during concept selection, this study investigates the factors that can affect preferences for creativity through the development of a psychometric survey that assesses student designers’ preferences for creativity through Exploratory Factor Analysis and Confirmatory Factor Analysis. The result of these analyses is the 23-item Preferences for Creativity Scale (PCS) that assesses an individual’s preference for creativity in engineering design on 4 major dimensions: (1) Team Centrality, (2) Risk Tolerance, (3) Creative Confidence/ Preference, and (4) Motivation. The results of these analyses provide a foundation for studying creativity in the design process and allow for future research that investigates the factors that influence creative concept selection in engineering design.
Sample-Based Design of Functionally Graded Material Structures
Authors: Liu Xingchen , Shapiro Vadim
Published: December 2016

Spatial variation of material structures is a principal mechanism for creating and controlling spatially varying material properties in nature and engineering. While the spatially varying homogenized properties can be represented by scalar and vector fields on the macroscopic scale, explicit microscopic structures of constituent phases are required to facilitate the visualization, analysis and manufacturing of functionally graded material (FGM). The challenge of FGM structure modeling lies in the integration of these two scales. We propose to represent and control material properties of FGM at macroscale using the notion of material descriptors which include common geometric, statistical, and topological measures, such as volume fraction, correlation functions and Minkowski functionals. At microscale, the material structures are modeled as Markov random fields: we formulate the problem of design and (re)construction of FGM structure as a process of selecting neighborhoods from a reference FGM, based on target material descriptors fields. The effectiveness of the proposed method in generating a spatially varying structure of FGM with target properties is demonstrated by two examples: design of a graded bone structure and generating functionally graded lattice structures with target volume fraction fields.
Hybrid Simulation of a Dynamic Multibody Vehicle Suspension System Using Neural Network Modeling Fit of Tire Data
Authors: Dye John , Lankarani Hamid
Published: December 2016

Multibody models of vehicle suspension systems are a useful tool for investigating road handling performance and passenger harshness of a vehicle under varying conditions. The multibody model describes the nonlinear interactions between the vehicle chassis and the wheel through its suspension kinematic connections. It can be a challenge to model the wheel and road interaction due to the highly nonlinear nature of the tire dynamics. Early tire models in programs such as MSC Adams attempted to fit and interpolate empirical tire data. Interpolation of such a large dataset can be numerically inefficient leading to empirical formulations or utilization of advanced finite element (F.E.) models. Empirical formulations, such as the Magic Formula Tire model and Fiala model, utilize parameters to generalize a tire under pure slip or combined slip conditions. Advanced tire models, such as FTire or RMOD-K, use parametrized nonlinear FE approaches and tread models to represent the tire dynamics. Similar to the empirical models, a neural network is used in this study for function fitting from previously measured data can represent the steady state tire dynamics without the need of manual parametrization. A neural network is used to fit tire test data provided by the Tire Testing Consortium (TTC), which has been utilized by many Formula SAE (FSAE) competition vehicles. A network is created to generate the lateral forces of a tire that will act upon the multibody simulation. Each network has been trained utilizing the gradient descent method with adaptive learning on over 100,000 data points generated from the TTC data. The data is condensed into the weights of a network with 13 hidden neurons. The neural network representing lateral force use a range of slip angles, tire pressures, normal forces, and inclination angles as inputs to generate the lateral force output, which achieve an RMSE of 19.62 lbf (87.18 N) during training. All tire data was generalized under combined slip conditions. A half vehicle model is then constructed in this study with the rigid body components representing a double A-arm suspension typically found in performance vehicles. Ideal dynamic elements has been used to represent the spring, dampers and tire vertical stiffness. A rigid body element for the tire is used to represent the wheel and tire inertias and to apply the tire forces generated by the neural networks. The simulation is then ran under varying tire pressures and steady state conditions, and compared to similar fits using parameterized empirical models. These models show that the nonlinear dynamics of a tire can be incorporated from measured data utilizing neural network models in an efficient and effective way.
Analysis of Brain Activity Influenced by Replication Accuracy in Imitation Learning in Manufacturing Industries
Authors: Asaka Yusuke , Watanuki Keiichi , Fukuda Shuichi , Muramatsu Keiichi , Hou Lei
Published: December 2016

Here, we investigate and discuss the effect of accuracy of imitation for improvement of skills on brain activity. In order to improve the skills, learners combine and accumulate information of the skills through practice. Thus, we used near-infrared spectroscopy (NIRS) to investigate brain activity during the process of improvement. Evaluation of the level of knowledge acquisition with monitoring of brain activity can be an indicator of the learner’s degree of skill progression.

Therefore, our final goal is constructing a new learning model based on brain activity monitoring and improving learning efficiency. We experimented on the assembly operation by imitation learning that assumed work in the manufacturing industries from a previous example. As a result, we showed the possibility of brain activity shift with improvement of the skill. In this article, we targeted task accuracy and investigated whether the brain activity shift is caused by a progress in the task accuracy, act of practice, or some other factor. As a result, we showed a possibility that the trend shift in the right and left dorsolateral prefrontal area and frontal pole was not caused by the simple task accuracy improvement but by the action of practice, which helped subjects store the information.
An Investigation on Resonant Characteristics of Micro/Nano-Beams Based on Nonlocal Elasticity Theory
Authors: Bakhtiari-Nejad Firooz , Nazemizadeh Mostafa
Published: December 2016

In present paper, resonant characteristics of vibrating micro/nano-beams are investigated based on the nonlocal elasticity theory. The natural frequency and quality factor of the micro/nano-beams are known as important resonant characteristics which play crucial roles in resonant vibration of the beams in air environments. To determine the resonant characterizes of the micro/nano-beams, the governing vibration equation of the nonlocal beam with fixed end supports is derived considering the air damping force. As the beam is modeled the beam as a string of vibrating adjacent spheres in interaction with the ambient air environment, the air damping force is obtained as a function of the resonant frequency. Furthermore, to calculate the quality factor of the size-dependent micro/nano-beams, the time-dependent vibration equation is presented in modal space based on the orthogonality conditions. Therefore, the quality factor obtained as a function of the natural frequencies and size-dependent nonlocal parameter at various resonant modes of vibration. Then, a parametric study investigates the nonlocal effects on the quality factor of the resonant micro/nano-beam. The obtained results indicate that the nonlocal size effects decreases the quality factor. In addition, the size effects play more prominent role at the higher resonant modes of vibration.
Standardized Vocabularies for Assembly Systems Modelling and Automation Alternatives Description
Authors: Salmi Anas , David Pierre , Blanco Eric , Summers Joshua D.
Published: December 2016

The aim of this research is to support assembly lines designers in conceiving new processes with optimal automation levels selection. Several alternatives with various automation options may exist. Graphic representations and analyses of the different designs are needed. The finality is to offer a quick, exhaustive, and reliable way of modelling alternatives based on a given product design. In this sense we propose a new assembly tasks vocabulary to be combined to an existing lower layer vocabulary of elementary motions and a graphic modelling language. These developments deal with an existing automation decision approach as an extension allowing to overcome identified gaps and to ease its implementation and computerization. The proposal facilitates assembly systems alternatives generation with automation options consideration based on an initial representation. The generated alternatives are then subject to further analyses with regard to automation criteria and performance indicators considering planned production targets.
Topology Optimization of Compliant Mechanisms Explicitly Considering Desired Kinematics and Stiffness Constraints
Authors: Hasse Alexander
Published: December 2016

A mechanism is designed to transform forces and/or displacements from an input to one or multiple outputs. This transformation is essentially ruled by the kinematics, i.e. the defined ratio between input and output displacements. Although the kinematics forms the basis for the design of conventional mechanisms, approaches for the topology and shape optimization of compliant mechanisms do not normally explicitly include the kinematics in their optimization formulation. The kinematics is more or less an outcome of the optimization process. A defined kinematics can only be realized by iteratively adjusting process-specific optimization parameters within the optimization formulation. Moreover, existing approaches normally minimize the strain energy that is stored in the compliant mechanisms according to a defined input and output displacement — although in some applications a certain amount of strain energy is required. This paper presents a new optimization formulation that solves the aforementioned problems. It is based on the principles of designing compliant mechanisms with selective compliance formerly presented by the author. The formulation is derived by means of an intensive workup of the design problem of compliant mechanisms. The method is validated for different design examples ranging from standard single-input/single-output mechanisms (force inverters) to multi-output mechanisms (shape-adaptive structures).
MotionGen: An iOS and Android App for Planar Four-Bar Motion Generation
Authors: Purwar Anurag , Deshpande Shrinath , Ge Q. J.
Published: December 2016

MotionGen is an indigenously developed app for Apple iOS and Google Android platforms to help mechanism designers solve planar four-bar motion generation problem. The app is a computer implementation of authors’ recent work in developing a unified framework for the synthesis and simulation of planar four-bar mechanisms for the motion generation problem.

Simplicity, high-utility, and wide-spread adoption of planar four-bar linkages have made them one of the most studied topics in Kinematics leading to development of algorithms and theories that deal with path-, function-, and motion generation-problems. Yet to date, there have been no attempts to develop efficient computational algorithms amenable to real-time computation of both type and dimensions of planar four-bar mechanisms for a given motion. MotionGen solves this problem effectively by extracting the geometric constraints of a given motion to provide the best dyad-types as well as dimensions of a total of up to six four-bar linkages. The unified algorithm also admits additional practical constraints, such as imposition of fixed- and moving-pivot and -line locations along with mixed exact- and approximate-synthesis scenarios. In that regard, its synthesis capabilities set it apart from other softwares of its ilk. However, its simulation approach also departs from more traditional methods, which typically involves assembling four rigid bodies and then designating fixed and moving links. Instead, the MotionGen requires users to assemble only two of the geometric constraints of mechanical dyads for quick prototyping of planar four-bar linkages. The app is equipped with an intuitive graphical user interface that allows a fluid dialog with the user to facilitate rapid manipulation and visualization of linkages.
Automated Finite Element Analysis on Tree Branches
Authors: Keane Devon , Avanzi Domenick , Evans Lance , Shahbazi Zahra
Published: December 2016

There are many instances where creating finite element analysis (FEA) requires extensive time and effort. Such instances include finite element analysis of tree branches with complex geometries and varying mechanical properties. In this paper, we discuss the development of Immediate-TREE, a program and its associated Guided User Interface (GUI) that provides researchers a fast and efficient finite elemental analysis of tree branches. This process was discussed in which finite element analysis were automated with the use of computer generated Python files. Immediate-TREE uses tree branch’s data (geometry, mechanical properties and etc.) provided through experiment and generates Python files, which were then run in finite element analysis software (Abaqus) to complete the analysis. Immediate-TREE is approximately 240 times faster than creating the model directly in the FEA software (Abaqus). The process used to develop Immediate-TREE can be applied to other finite element analysis of biological systems such as bone and tooth.
Power Generation From Mastication Forces Using a Smart Tooth
Authors: Bani-Hani Muath , Karami M. Amin
Published: December 2016

The batteries of the current pacing devices are relatively large and occupy over 60 percent of the size of pulse generators. Therefore, they cannot be placed in the subtle areas of human body. In this paper, the mastication force and the resulting tooth pressure are converted to electricity. The pressure energy can be converted to electricity by using the piezoelectric effect. The tooth crown is used as a power autonomous pulse generator. We refer to this envisioned pulse generator as the smart tooth. The smart tooth is in the form of a dental implant. A piezoelectric vibration energy harvester is designed and modeled for this purpose. The Piezoelectric based energy harvesters investigated and analyzed in this paper initially includes a single degree of freedom piezoelectric based stack energy harvester which utilizes a harvesting circuit employing the case of a purely resistive circuit. The next step is utilizing and investigating a bimorph piezoelectric beam which is integrated/embedded in the smart tooth implant. Mastication process causes the bimorph beam to buckle or return to unbuckled condition. The transitions result in vibration of the piezoelectric beam and thus generate energy. The power estimated by the two mechanisms is in the order of hundreds of microwatts. Both scenarios of the energy harvesters are analytically modeled. The exact analytical solution of the piezoelectric beam energy harvester with Euler-Bernoulli beam assumptions is presented. The electro-mechanical coupling and the geometric nonlinearities have been included in the model for the piezoelectric beam.
A New Friction Model for Mechanical Transmissions Considering Joint Temperature
Authors: Legnani Giovanni , Simoni Luca , Beschi Manuel , Visioli Antonio
Published: December 2016

This article illustrates a model that describes the behaviour of power loss (friction) in mechanical transmissions. The model is applied to joints of an industrial manipulator, it is justified on the bases of preliminary observations of some robot behaviour and it is validated with an extensive experimentation on a commercial 6 degrees of freedom anthropomorphic manipulator. The paper shows that friction decreases with increasing temperature which in turn depends on the working cycle of the manipulator. The proposed model permits a prediction of the variation of the friction contribution during extensive working operations and it is suitable for industrial applications to improve the control performance or to predict the energy consumption.
Merging Digital and Physical-Based Design
Authors: Bordegoni Monica , Cugini Umberto
Published: December 2016

Product designers are more and more addressing the design of product experience, in addition to the more traditional product design, where the focus of the design practice is on the interaction between the product and its users. Traditional methods and tools used so far for the design of products are not suitable to the design of experience. Among the emerging methods, experience prototyping seems effective and well addressing the new requirements of experience design. The paper describes the emerging technologies enabling experience prototyping, and provides some examples where this new methodology for experience design has been applied.
A Discussion on Specifications and Prototyping in Designing for Sustainable Behavior
Authors: Filippi Stefano , Barattin Daniela , Graziosi Serena , Ferrise Francesco , Bordegoni Monica
Published: December 2016

Today’s world is facing numerous problems due to an un-controlled waste of energy and of primary resources in general. To manage this, on one side designers are asked to improve the efficiency of products; on the other side, users must be trained toward a more sustainable lifestyle. Some researchers are exploring the idea of trying to change users’ behavior while interacting with products in order to make it more sustainable. This trend is known as “design for sustainable behavior” applied to energy/resources consumption issues. Our idea is to stimulate users in changing their behavior by introducing a multisensory communication with the product. This communication is not meant as warning messages informing the users about wrong habits/actions or something like; instead, it should consist of sensorial stimuli able to naturally drive users in performing the right actions. However, before designing these stimuli, it is fundamental to highlight the aspects and conditions that do not allow users behaving in a sustainable way when interacting with products. In this paper we discuss about the aspects that could be useful to explore in order to retrieve the specifications to drive both the design and prototyping phases, so as to faithfully test the effectiveness of the feedback with final users.
Optimal Task Planning of Humanoid in Cluttered Environment
Authors: Teja Hari , Balachandran Abhilash , Shah Suril V.
Published: December 2016

Due to high degrees of freedom of humanoids and induced redundancy, there are multiple ways of performing a given manipulation task. Finding optimal ways of performing tasks is one desirable property of any motion planning framework. This includes optimizing the path with respect to a certain objective function. Additionally, a variety of constraints need to be satisfied such as stability, self-collision and collision with objects in the environment and also kinematic closed-loop chains formed during the task. Time requirements of the planner is another important aspect that drives us to use sampling based methods. In this paper, we present an asymptotically optimal sampling based approach for generating statically stable motion plans. We use RRT*-connect algorithm which we obtained by modifying RRT-Connect. Moreover, we use a gradient based inverse kinematics solver to generate goal configurations. We evaluate the efficacy of our approach in the results section in a simulation environment on Hubo+ robot model. The results show a significant improvement in path costs as well as overall optimality of the given task.
Self-Foldability of Rigid Origami
Authors: Tachi Tomohiro , Hull Thomas C.
Published: December 2016

When actuating a rigid origami mechanism by applying a driving force (moment) at their crease lines, we often confront the bifurcation problem where it is not possible to predict the way the model will fold when it is in a flat state. In this paper, we develop a mathematical model of self-folding and propose the concept of self-foldability of rigid origami when a set of driving forces are given. In particular, we desire to design a driving force such that a given crease pattern can uniquely self-fold to a desired mode without bifurcation. We provide necessary conditions for self-foldability that serve as tools to analyze and design self-foldable crease patterns. Using these tools, we analyze unique self-foldability of several fundamental patterns and demonstrate the usefulness of the proposed model for mechanical design.
Design and Preliminary Testing of a Prototype for Evaluating Lower Leg Trajectory Error as an Optimization Metric for Prosthetic Feet
Authors: Olesnavage Kathryn M. , Winter Amos G.
Published: December 2016

This work presents the design and preliminary testing of a prosthetic foot prototype intended for evaluating a novel design objective for passive prosthetic feet, the Lower Leg Trajectory Error (LLTE). Thus far, all work regarding LLTE has been purely theoretical. The next step is to perform extensive clinical testing. An initial prototype consisting of rotational ankle and metatarsal joints with constant rotational stiffness was optimized and built, but at 2 kg it proved too heavy to use in clinical testing. A new conceptual foot architecture intended to reduce the weight of the final prototype is presented and optimized for LLTE. This foot consists of a rotational ankle joint with constant stiffness of 6.1 N·m/deg, a rigid structure extending 0.08 m from the ankle-knee axis, and a cantilever beam forefoot with bending stiffness 5.4 N·m2. A prototype was built using machined delrin for the rigid structure, three parallel extension springs offset along a constant radius cam from a pin joint ankle, and machined nylon as the beam forefoot. In preliminary testing, it was determined that, despite efforts to minimize weight and size, this particular design was still too heavy and bulky as a result of the extension springs to be used in extensive clinical testing. Future work will focus on reducing the weight further by replacing linear extension springs with flexural elements before commencing with the clinical study.
Parametric Study of the Swimming Performance of a Novel Robot Fish With Active Compliant Propulsion Mechanism
Authors: Zhong Yong , Du Ruxu
Published: December 2016

This paper presents a novel robot fish propelled by an active and compliant propulsion mechanism. The key innovation of this robot fish is the combination of an active wire-driven mechanism with a soft compliant tail to construct the active compliant propulsion mechanism, which can accomplish multi-modal swimming motions. First, the design method was proposed, the wire-driven mechanism and the compliant tail could be well designed. Second, using this robot fish experimental platform, numerous experiments were conducted to investigate the effect of different controllable parameters on cruising speed, descending speed and turning performance. These parameters include flapping frequency and amplitude of the propulsion mechanism, attack angle of the pectoral fins. A more detailed parametric study was conducted with these significant parameters to study and understand the relationship between swimming performance and various parameters. This process can help to optimize controllable parameters for superior swimming performance. Based on the parametric study, we obtained the best experimental swimming performance under optimized parameters; the maximum speed reached 2.15 BL/s (body length per second), the maximum turning speed is 269°/s the descending speed is 42 cm/s (when attack angle is 60 degree). Compared with existing robot, the new robot fish has several advantages: it is simple in structure, easy to control, and capable of high speed swimming and maneuverable swimming.
Finite Element Approximation of the Extended Fluid-Structure Interaction (eXFSI) Problem
Authors: Ebna Hai Bhuiyan Shameem Mahmood , Bause Markus , Kuberry Paul
Published: December 2016

This contribution is the second part of three papers on Adaptive Multigrid Methods for the eXtended Fluid-Structure Interaction (eXFSI) Problem, where we introduce a monolithic variational formulation and solution techniques. To the best of our knowledge, such a model is new in the literature. This model is used to design an on-line structural health monitoring (SHM) system in order to determine the coupled acoustic and elastic wave propagation in moving domains and optimum locations for SHM sensors. In a monolithic nonlinear fluid-structure interaction (FSI), the fluid and structure models are formulated in different coordinate systems. This makes the FSI setup of a common variational description difficult and challenging. This article presents the state-of-the-art in the finite element approximation of FSI problem based on monolithic variational formulation in the well-established arbitrary Lagrangian Eulerian (ALE) framework. This research focuses on the newly developed mathematical model of a new FSI problem, which is referred to as extended Fluid-Structure Interaction (eXFSI) problem in the ALE framework. The eXFSI is a strongly coupled problem of typical FSI with a coupled wave propagation problem on the fluid-solid interface (WpFSI). The WpFSI is a strongly coupled problem of acoustic and elastic wave equations, where wave propagation problems automatically adopts the boundary conditions from the FSI problem at each time step. The ALE approach provides a simple but powerful procedure to couple solid deformations with fluid flows by a monolithic solution algorithm. In such a setting, the fluid problems are transformed to a fixed reference configuration by the ALE mapping. The goal of this work is the development of concepts for the efficient numerical solution of eXFSI problem, the analysis of various fluid-solid mesh motion techniques and comparison of different second-order time-stepping schemes. This work consists of the investigation of different time stepping scheme formulations for a nonlinear FSI problem coupling the acoustic/elastic wave propagation on the fluid-structure interface. Temporal discretization is based on finite differences and is formulated as a one step-θ scheme, from which we can consider the following particular cases: the implicit Euler, Crank-Nicolson, shifted Crank-Nicolson and the Fractional-Step-θ schemes. The nonlinear problem is solved with a Newton-like method where the discretization is done with a Galerkin finite element scheme. The implementation is accomplished via the software library package DOpElib based on the deal.II finite element library for the computation of different eXFSI configurations.
Active Flow Control of Dynamic Stall by Means of Jet Flow at Reynolds Number 106
Authors: Asgari Ehsan , Tadjfar Mehran
Published: December 2016

In this study, we have examined slot location and velocity ratio of a tangential co-flow jet in dynamic stall motion of an airfoil at Reynolds number 1×106, for active flow control (AFC) purposes. The airfoil is the symmetrical NACA 0012 with a pitching motion between AOAs 5 deg. and 25 deg. about its quarter-chord with a sinusoidal motion. We have utilized Computational Fluid Dynamics (CFD) tool to numerically investigate the impact of jet location and jet velocity ratio on the aerodynamic coefficients. We have placed the jet location upstream the counter clock-wise (CCW) vortex which is formed during the upstroke motion near the leading-edge. We have also selected several other locations nearby to perform sensitivity analysis. Our results showed that placing the jet slot within a very small range upstream the CCW vortex has tremendous effects on both lift and drag, such that maximum drag which occurs at maximum incidences reduced by 80%. There was another unique observation: putting jet at separation point leads to an inverse behavior of drag hysteresis curve in upstroke and downstroke motions. Drag in downstroke motion is significantly lower than upstroke motion, whereas in uncontrolled case the converse is true. In addition, by implementing jet flow lift is significantly enhanced during both upstroke and downstroke motions. Finally, it should be indicated that this study provides initial steps in investigations of applying synthetic jet actuator (SJA) on a pitching airfoil at high Reynolds number 106 with effects of changing momentum ratio and SJA frequency, which will be presented in the near future.
Modeling Transition on Smooth and Rough Blades
Authors: Wei Liang , Ge Xuan , George Jacob , Durbin Paul
Published: December 2016

Laminar to turbulent transition occurs in a broad range of industrial applications, and in nature. There are many mechanisms (natural or bypass) that lead to transition. Accurately predicting both the onset location and length of transition has been persistently difficult. A new, local, intermittency-function-based transition model for both low (< 1%) and high freestream turbulence intensity flows, over smooth and rough surfaces, is introduced and formulated. It is coupled with the k-ω RANS model.

The intermittency model was validated on the ERCOFTAC experimental zero-pressure-gradient smooth flat plate boundary layer cases T3A-, T3A, T3B with leading-edge freestream turbulence intensity 0.9%, 3.5%, 6%, respectively. Skin friction profiles agree well with the experimental data. The model was then tested on periodic wakes, and flows over Stripf’s turbine blades with a broad range of roughnesses, from hydraulically smooth to fully rough. The predicted skin friction and heat transfer properties by the current model agree well with the published experimental and numerical data.