bluuebunny/crossref_metadata_2025 huggingface dataset:
Symbolic Linearized Equations for Nonholonomic Multibody Systems With Closed-Loop Kinematics
Authors: Kuslits Márton , Bestle Dieter
Published: November 2018

Multibody systems and associated equations of motion may be distinguished in many ways: holonomic and nonholonomic, linear and nonlinear, tree-structured and closed-loop kinematics, symbolic and numeric equations of motion. The present paper deals with a symbolic derivation of nonlinear equations of motion for nonholonomic multibody systems with closed-loop kinematics, where any generalized coordinates and velocities may be used for describing their kinematics. Loop constraints are taken into account by algebraic equations and Lagrange multipliers. The paper then focuses on the derivation of the corresponding linear equations of motion by eliminating the Lagrange multipliers and applying a computationally efficient symbolic linearization procedure. As demonstration example, a vehicle model with differential steering is used where validity of the approach is shown by comparing the behavior of the linearized equations with their nonlinear counterpart via simulations.
Lower Bounds of the Allowable Motions of One N-Dimensional Ellipsoid Contained in Another
Authors: Ruan Sipu , Chirikjian Gregory S. , Ding Jianzhong
Published: November 2018

This paper studies the representations of a subset of the allowable motions for an N-dimensional ellipsoid inside another slightly larger ellipsoid without collision based on the idea of the Kinematics of Containment. As an extension to the previous work on the closed-form lower bounds, this paper proposes another two lower bounds based on the first-order algebraic condition of containment and the closed-form Minkowski difference between two ellipsoids respectively. Querying processes for a specific configuration of the moving ellipsoid and the calculations of the volume of the proposed lower bounds in configuration space (C-space) are introduced. Examples for the proposed lower bounds in 2D and 3D Euclidean space are implemented and the corresponding motion volumes in C-space are compared with different shapes of the ellipsoids. Finally a case study of the application on automated assembly is introduced.
Gearbox Fault Diagnosis Using Multiscale Sparse Spectrum
Authors: Sun Pan , Shao Yimin , Ding Xiaoxi , Du Minggang
Published: November 2018

Due to its special modulation mechanism with multiple units (eg. shafts, gears, etc.) under various conditions, the related fault information of gear fault would distribute in a broad frequency band. In this manner, it is not easy about accurately detecting the early-stage gear fault by detecting the fault frequency in a limited frequency band. In this paper, a new spectral analysis, called multiscale sparse spectrum (MSS), is proposed to achieve fault frequency detection in a sound way. The overall frequency information about the raw signal is firstly sensed by a series of frequency-window function, which can be reached by short-frequency Fourier transform. Then, according to orthogonal matching pursuit, harmonic atoms are further employed to sparsely mine the modulation components from these multiscale pseudo mono-components. Finally, MSS is proposed to synthesize the existing harmonic-related components. Furthermore, a synthesized sparse spectrum (SSS) is obtained by searching the frequency-frequency ridge from MSS. Compared with EMD and fast-kurtogram analysis, the results show the effectiveness of the proposed method of gear fault detection.
Deriving Information Acquisition Criteria for Sequentially Inferring the Expected Value of a Black-Box Function
Authors: Pandita Piyush , Bilionis Ilias , Panchal Jitesh
Published: November 2018

Acquiring information about noisy expensive black-box functions (computer simulations or physical experiments) is a tremendously challenging problem. Finite computational and financial resources restrict the application of traditional methods for design of experiments. The problem is surmounted by hurdles such as numerical errors and stochastic approximations errors, when the quantity of interest (QoI) in a problem depends on an expensive black-box function. Bayesian optimal design of experiments has been reasonably successful in guiding the designer towards the QoI for problems of the above kind. This is usually achieved by sequentially querying the function at designs selected by an infill-sampling criterion compatible with utility theory. However, most current methods are semantically designed to work only on optimizing or inferring the black-box function itself. We aim to construct a heuristic which can unequivocally deal with the above problems irrespective of the QoI. This paper applies the above mentioned heuristic to infer a specific QoI, namely the expectation (expected value) of the function. The Kullback Leibler (KL) divergence is fairly conspicuous among techniques that used to quantify information gain. In this paper, we derive an expression for the expected KL divergence to sequentially infer our QoI. The analytical tractability provided by the Karhunene Loeve expansion around the Gaussian process (GP) representation of the black-box function allows the circumvention around numerical issues associated with sample averaging. The proposed methodology can be extended to any QoI, with reasonable assumptions. The proposed method is verified and validated on two synthetic functions with varying levels of complexity. We demonstrate the methodology on a steel wire manufacturing problem.
Optimizing Cable Arrangement in Cable-Driven Parallel Robots to Improve the Range of Available Wrenches
Authors: Kamali Kaveh , Joubair Ahmed , Bonev Ilian A.
Published: November 2018

This paper presents a new method for maximizing the range of wrenches that a cable-driven parallel robot (CDPR) can apply on its moving-platform. In this problem, the optimization parameters are the attachment positions of the cables to the moving platform. It is supposed that the attachment points are selected from a set of candidate points. The combinatorial nature of this problem makes it non-trivial and complicated, especially when the whole workspace of the robot is considered in the optimization problem. In this paper, it is shown that this cable arrangement problem can be represented mathematically by a zero-one multi-dimensional knapsack problem. Then, a core concept method is used to find the optimal solution. As an example, the proposed method is applied to a 6-DOF CDPR with eight cables. Experimental results show that the proposed approach can efficiently solves the cable arrangement problem in polynomial time.
Automating the Design of Thick-Origami Mechanisms
Authors: Crampton Erica B. , Sellers Ariana D. , Salmon John L. , Magleby Spencer P.
Published: November 2018

Applying an origami pattern to thick, non-paper-like materials is a challenging task. Though many techniques have been developed to accommodate thickness in origami, creating 3D models of such thick-origami mechanisms is complex. The time and knowledge required to manually model an origami mechanism can impede the exploration of the design space and creation of robust designs. This work presents data structures based on origami that can be used in the automation of thick-origami mechanism design. These structures are described and an example computer program that implements them is investigated. The program automatically generates all the necessary 3D CAD part models and an assembly model for a user-specified origami crease pattern. Models resulting from the program for several crease patterns are demonstrated with a discussion of the advantages and limitations of the system. With further development of the data structures and program, this framework has the potential to help mitigate some of the barriers to more widespread use of origami-based design.
Higher-Order Multiple Scales Analysis of Weakly Nonlinear Lattices With Implications for Directional Stability
Authors: Fronk Matthew D. , Leamy Michael J.
Published: November 2018

Recent focus has been given to nonlinear periodic structures for their ability to filter, guide, and block elastic and acoustic waves as a function of their amplitude. In particular, two-dimensional (2-D) nonlinear structures possess amplitude-dependent directional bandgaps. However, little attention has been given to the stability of plane waves along different directions in these structures. This study analyzes a 2-D monoatomic shear lattice composed of discrete masses, linear springs, quadratic and cubic nonlinear springs, and linear viscous dampers. A local stability analysis informed by perturbation results retained through the second order suggests that different directions become unstable at different amplitudes in an otherwise symmetrical lattice. Simulations of the lattice’s equation of motion subjected to both line and point forcing are consistent with the local stability results: waves with large amplitudes have spectral growth that differs appreciably at different angles. The results of this analysis could have implications for encryption strategies and damage detection.
The Earlier the Better? Investigating the Importance of Timing on Effectiveness of Design for Additive Manufacturing Education
Authors: Prabhu Rohan , Miller Scarlett R. , Simpson Timothy W. , Meisel Nicholas A.
Published: November 2018

Additive Manufacturing (AM) is a novel process that enables the manufacturing of complex geometries through layer-by-layer deposition of material. AM processes provide a stark contrast to traditional, subtractive manufacturing processes, which has resulted in the emergence of design for additive manufacturing (DfAM) to capitalize on AM’s capabilities. In order to support the increasing use of AM in engineering, it is important to shift from the traditional design for manufacturing and assembly mindset, towards integrating DfAM. To facilitate this, DfAM must be included in the engineering design curriculum in a manner that has the highest impact. While previous research has systematically organized DfAM concepts into process capability-based (opportunistic) and limitation-based (restrictive) considerations, limited research has been conducted on the impact of teaching DfAM on the student’s design process. This study investigates this interaction by comparing two DfAM educational interventions conducted at different points in the academic semester. The two versions are compared by evaluating the students’ perceived utility, change in self-efficacy, and the use of DfAM concepts in design. The results show that introducing DfAM early in the semester when students have little previous experience in AM resulted in the largest gains in students perceiving utility in learning about DfAM concepts and DfAM self-efficacy gains. Further, we see that this increase relates to greater application of opportunistic DfAM concepts in student design ideas in a DfAM challenge. However, no difference was seen in the application of restrictive DfAM concepts between the two interventions. These results can be used to guide the design and implementation of DfAM education.
Uncovering Ownership Bias: The Influence of Idea Goodness and Creativity on Design Professionals’ Concept Selection Practices
Authors: Zheng Xuan , Miller Scarlett R.
Published: November 2018

Ownership bias is a type of decision making bias that leads to an individual’s tendency to prefer their own ideas over the ideas of others during the design process. While prior work has identified the existence of this effect in design professionals, this prior research failed to take into account the social effects of working in a team environment or to identifying the underlying impact of the characteristics of the idea set that impact the effects. Therefore, the purpose of this study was to identify the existence of ownership bias and the factors underlying its existence through two design workshops with 45 design professionals from two engineering companies. Through the study, design professionals individually generated and selected ideas as part of a 2-hour team design challenge. The ideas were rated for their perceived future value through team consensus and for their creativity by expert ratings. The results suggest that design professionals only exhibited ownership bias for ideas that were assessed to have little to no future value in the design process by their team members (low in idea goodness) and the creativity of the ideas did not effect this relationship. However, professionals did show a preference for ideas with high usefulness and low uniqueness, demonstrating a potential bias against creative concepts regardless of ownership.
A Fuzzy Based Propulsion Selection for Fuel Efficiency in Hybrid Electric Vehicle
Authors: Bhattacharjee Debraj , Bhola Prabha , Dan Pranab K.
Published: November 2018

This article proposes a fuzzy based fuel-efficient propulsion selection logic for a hybrid electric vehicle (HEV) in ‘Highway Fuel Economy Test (HWFET)’ driving cycle. Optimal utilisation of combustion engine, in HEV, reduces the fossil fuel consumption. This can be realized through an electronic control unit, embedded with effective propulsion selection logic that governs the power split device in series-parallel HEV. A propulsion control logic, based on the road gradeability, velocity, torque demand and vehicle battery state of charge (SOC) is presented in this article. A comparison with conventional propulsion selection logic based system shows that the HEV modelled with proposed fuzzy based one, results in better speed tracking with steep road grades, as it provides better torque supply at desired speed points. The analysis indicates a reduction in consumption of both the fossil fuel as well as the electrical fuel (SOC).
Human Face Reconstruction in Biomedical Applications
Authors: Barone Sandro , Bordegoni Monica , Cucinotta Filippo , Graziosi Serena , Razionale Armando V. , Sfravara Felice
Published: November 2018

3D virtual reconstruction of human body parts is nowadays a common practice in many research fields such as the medical one, the manufacturing of customized products or the creation of personal avatar for gaming purpose. The acquisition can be performed with the use of an active stereo system (i.e., laser scanner, structured light sensors) or with the use of a passive image-based approach. While the former represents a consolidated approach in human modeling, the second is still an active research field. Usually, the reconstruction of a body part through a scanning system is expensive and requests to project light on the patient’s body. On the other hand, the image-based approach could use multi-photo technique to reconstruct a real scene and provides some advantages: low equipment costs (only one camera) and rapid acquisition process of the photo set. In this work, the use of the photogrammetry approach for the reconstruction of humans’ face has been investigated as an alternative to active scanning systems. Two different photogrammetric approaches have been tested to verify their potentiality and their sensitivity to configuration parameters. An initial comparison among them has been performed, considering the overall number of points detected (sparse point cloud reconstruction, dense point cloud reconstruction). Besides, to evaluate the accuracy of the reconstruction, a set of measures used in the design of wearable head-related products has been assessed.
Three-Position Rigid Body Guidance Using Specified Moving Pivots for a Four-Bar Mechanism With Variable Topology
Authors: Slaboch Brian J.
Published: November 2018

This paper provides an algorithm allowing a designer to perform three position rigid body guidance with specified moving pivots for a 4R-RRRP mechanism with variable topology (MVT). A mechanism with variable topology is a mechanism that changes from one topological state to another due to a change in joint geometry. Both a graphical approach and an algebraic solution are presented. An example is provided in which a circuit defect in a 4R mechanism can be avoided using a 4R-RRRP mechanism. Two additional examples are provided that show the results of this new theory. Practical applications for this theory are found in many industries including manufacturing, aerospace, and healthcare.
A New Efficient Stiffness Evaluation Method to Improve Accuracy of Hexapods
Authors: Kalas Vinayak J. , Vissière Alain , Roux Thierry , Company Olivier , Krut Sébastien , Pierrot François
Published: November 2018

Structural compliance of hexapods limits their positioning accuracy. Taking a step towards solving this problem, this paper proposes a new efficient method to evaluate the stiffness of hexapods in order to predict and correct their positioning error due to compliance. The proposed method can be used to predict the six degree of freedom deflection of the platform under load. This method uses a simple lumped stiffness parameter model whose parameters can be estimated using the identification technique presented in this paper. An experimental study with micrometer level measurements performed on a hexapod based micro-positioning system is used to assess the efficiency of the presented method.
Study on the Dynamics Response of Ultra-Precision Single-Point Diamond Fly-Cutting Machine Tool As Multi-Rigid-Flexible-Body System Based on Transfer Matrix Method for Multibody Systems
Authors: Lu Hanjing , Rui Xiaoting , Chen Gangli
Published: November 2018

The dynamics response optimization of an ultra-precision machine tool system is the key to improve machining accuracy. Based on the transfer matrix method for multibody systems (MSTMM), the dynamics model as multi-rigid-flexible-body system is established. The overall transfer equation, overall transfer matrix, eigenfrequency equation and dynamics equation with respect to generalized coordinates are derived in this paper. Considering the environmental micro-vibration, cutting force and spindle centrifugal force during the machining process as external excitations, the vibration characteristics and dynamics response are simulated by using MSTMM. The computational results are in good agreement with test results, which validates the proposed method and dynamics model used in this paper.
Static and Stability Analysis of a Planar Compliant Tensegrity Mechanism
Authors: Tanouye Miranda M. , Vikas Vishesh
Published: November 2018

Traditional tensegrity mechanisms are comprised of compressive (rigid rods) and tensile members (strings). Compliant tensegrity mechanisms (CoTM) introduce springs alongside strings and rods, allowing these structures to be more adaptable and robust. The kinematic and stability analyses of such mechanisms will facilitate better behavioral understanding for control of such structures. Generally, the kinematic analysis assumes zero-free length (ZFL) springs which facilitates simplification of equations of motion. However, a general ZFL does not exist and the relaxation of ZFL assumption for a CoTM introduces computational complexities resulting from their non-linear nature. The research considers equilibrium and stability analysis of a planar CoTM mechanism consisting of two triangular platforms connected by a compressive member and two spring elements. For an assumed numerical example, the analysis illustrates the increase in computation complexity, and non-linear behavior of equilibrium and stable solutions as assumption is relaxed from 1) both spring ZFL, to 2) one spring ZFL, and 3) no spring ZFL.
Applying Path Planning to the Design of Additively Manufactured Functionally Graded Materials
Authors: Kirk Tanner , Malak Richard , Arroyave Raymundo
Published: November 2018

Additive manufacturing has enabled the creation of a near infinite set of functionally gradient materials. One limitation on the manufacturability and usefulness of these materials is the presence of undesirable phases along the gradient path. For example, such phases may increase brittleness, diminish corrosion resistance, or severely compromise the printability of the part altogether. In the current work, a design methodology is proposed to plan an FGM gradient path for any number of elements that avoids undesirable phases at a range of temperatures. Gradient paths can also be optimized for a cost function. A case study is shown to demonstrate the effectiveness of the methodology in the Fe-Ni-Cr system. Paths were successfully planned from 316L SS to pure Cr that either minimize path length or maximize separation from undesirable phases. Examinations on the stochastic variability, parameter dependency, and computational efficiency of the method are also presented. Several avenues of future research are proposed that could improve the manufacturability, utility, and performance of FGMs through gradient path design.
Development and Pilot Study of an Integrated Sensor System to Measure Fuel Consumption and Cookstove Use
Authors: Ventrella Jennifer , MacCarty Nordica
Published: November 2018

Accurate, accessible methods for monitoring and evaluation of improved cookstoves are necessary to optimize designs, quantify impacts, and ensure programmatic success. Despite recent advances in cookstove monitoring technologies, there are no existing devices that autonomously measure fuel use in a household over time and this important metric continues to rely on in-person visits to conduct measurements by hand. To address this need, researchers at Oregon State University and Waltech Systems have developed the Fuel, Usage, and Emissions Logger (FUEL), an integrated sensor platform that quantifies fuel consumption and cookstove use by monitoring the mass of the household’s fuel supply with a load cell and the cookstove body temperature with a thermocouple. Following a proof-of-concept study of five prototypes in Honduras, a pilot study of one hundred prototypes was conducted in the Apac District of northern Uganda for one month. The results were used to evaluate user engagement with the system, verify technical performance, and develop algorithms to quantify fuel consumption and stove usage over time. Due to external hardware malfunctions, 31% of the deployed FUEL sensors did not record data. However, results from the remaining 69% of sensors indicated that 82% of households used the sensor consistently for a cumulative 2188 days. Preliminary results report an average daily fuel consumption of 6.3 ± 1.9 kg across households. Detailed analysis algorithms are still under development. With higher quality external hardware, it is expected that FUEL will perform as anticipated, providing long-term, quantitative data on cookstove adoption, fuel consumption, and emissions.
Exploring System Architecture Attributes and Dynamic Change Propagation
Authors: Long Daniel , Ferguson Scott
Published: November 2018

Long-lived systems will experience many successive changes during their lifecycle as they are adapted to meet new system requirements. Existing change propagation tools predict how changes to a system’s design at a fixed point in its life are likely to spread, but have not been extended to consider a series of successive modifications where the change probabilities update. This change in propagation probabilities in response to successive changes is introduced as Dynamic Change Propagation (DCP). This paper integrates research from change propagation, network theory, and excess to achieve the following objectives: 1) describe how a DCP model predicts system propagation change trajectories, 2) use a new synthetic test case generator to correlate network parameters like degree distribution with DCP, and 3) determine the correlations between a measure of DCP and a selection of existing change propagation metrics. Results indicate that DCP is limited by reducing the number of dependencies between components (affirming the usefulness of adding modularity to a system) and including high degree component ‘hubs’ between components.
Sensitivity of Balancing in Legged Systems Under Torque Constraint Variations
Authors: Gonzalez Carlos , Mummolo Carlotta , Kim Joo H.
Published: November 2018

The balancing capabilities of a legged system can be influenced by several properties of the system itself, for instance, the strength of joint motors in a robot or muscle strength in living systems. In this work, the changes in the balancing capabilities of a legged system are evaluated as the joint actuator torque limits of the system change. The legged system is modeled with an inverted pendulum model with an actuated ankle and a finite foot size. The effect of variations of the ankle torque limits on the system balance stability is quantified through the local properties of Lagrange multipliers in optimization theory and are validated through numerical experiments. With the proposed method, the information on the balance stability boundary of a legged system is used to predict the balance stability characteristics of the system with altered joint torque limits, hence providing quantifiable guidelines to the design of such systems.
Dynamic Modeling and Electrical Characterization of a Heaving Hybrid Triboelectric-Electromagnetic Energy Harvester
Authors: Saadatnia Zia , Esmailzadeh Ebrahim , Naguib Hani E.
Published: November 2018

In this study the dynamic and electrical performance of a novel hybrid Electromagnetic-Triboelectric energy harvester is studied. The mechanism incorporates a linear tubular electromagnetic (EMG) transducer as well as a free-standing grating triboelectric (TENG) transducer. The heaving of the slider inside the stator triggers both EMG and TENG which results in electricity generation. The dynamic model of the system is firstly developed and the system response under external excitation is carried out. Then, the electrical output characteristics of each harvesting unit are developed based on the dynamic response. Then, the effects of various parameters such as frequency of excitation and external electrical load on the output performance of the harvester including voltage, current, and power density of the EMG and TENG units are investigated. This study provides a guideline toward the design and analysis of novel mechanical energy harvesters.
Dynamic Analysis of High-Speed Rotating Shafts Using the Flexible Multibody Approach
Authors: Hurskainen Vesa-Ville , Bozorgmehri Babak , Matikainen Marko K. , Mikkola Aki
Published: November 2018

In this study, a higher-order finite element based on the absolute nodal coordinate formulation (ANCF) is applied in the dynamic analysis of high-speed rotating shafts. Static and modal tests are carried out to analyze the performance and accuracy of the introduced ANCF element. Also, via a transient dynamic benchmark test involving a rotating flexible shaft, the accuracy of the examined beam element in high-speed applications is analyzed. According to the results, the introduced beam element can adequately capture cross-section deformationin high-speed rotating shaft analysis.
Coupled Bending, Torsion and Axial Vibrations of a Cable-Harnessed Beam With Periodic Wrapping Pattern
Authors: Yerrapragada Karthik , Salehian Armaghan
Published: November 2018

This paper presents an equivalent continuum model to study the bending-torsion-axial coupled vibrations of a cable-harnessed beam. The pre-tensioned cable is wrapped periodically around the beam in a diagonal manner. The host structure is assumed to behave as a Euler-Bernoulli beam. The system is modeled using energy methods. The diagonal wrapping pattern results in variable coefficient strain and kinetic energies. Homogenization technique is used to convert spatially varying coefficients into a constant coefficient one. Coupled partial differential equations representing the bending, torsion and the axial modes are derived using Hamilton’s principle. The free vibration characteristics such as the natural frequencies and the mode shapes of the coupled system are analyzed for a fixed-fixed boundary condition and compared to results from the uncoupled and finite element analysis models.
Short-Term Load Forecasting With Different Aggregation Strategies
Authors: Feng Cong , Zhang Jie
Published: November 2018

Effective short-term load forecasting (STLF) plays an important role in demand-side management and power system operations. In this paper, STLF with three aggregation strategies are developed, which are information aggregation (IA), model aggregation (MA), and hierarchy aggregation (HA). The IA, MA, and HA strategies aggregate inputs, models, and forecasts, respectively, at different stages in the forecasting process. To verify the effectiveness of the three aggregation STLF, a set of 10 models based on 4 machine learning algorithms, i.e., artificial neural network, support vector machine, gradient boosting machine, and random forest, are developed in each aggregation group to predict 1-hour-ahead load. Case studies based on 2-year of university campus data with 13 individual buildings showed that: (a) STLF with three aggregation strategies improves forecasting accuracy, compared with benchmarks without aggregation; (b) STLF-IA consistently presents superior behavior than STLF based on weather data and STLF based on individual load data; (c) MA reduces the occurrence of unsatisfactory single-algorithm STLF models, therefore enhancing the STLF robustness; (d) STLF-HA produces the most accurate forecasts in distinctive load pattern scenarios due to calendar effects.
Divergence in Problems Rather Than Solutions: Design Processes of Microfluidic Engineers in Academia
Authors: Lee Jin Woo , Daly Shanna R. , Huang-Saad Aileen Y. , Seifert Colleen M.
Published: November 2018

Front-end design processes including problem definition and idea generation set a course for the ultimate success of a design. Many design process models emphasize the importance of divergence — considering alternative options — in promoting creativity. Depending on the circumstances of the design environment, design strategies to support divergence may be different as design processes are impacted by various contextual factors, such as available resources and expertise. To investigate how engineers explore alternatives during front-end design, we interviewed 10 academic engineers working in the discipline of microfluidics. Typically, a design process is described as identifying a problem and then generating potential solutions. In our sample, we found these engineers began their design processes with an existing solution and then searched for problems that fit. This qualitative study provided rich descriptions of design processes that show little to no evidence of divergence in generating possible solutions, and instead provide evidence of significant divergence in exploring possible problems. These data suggest traditional models of the design process are inadequate to capture the inverted solution-to-problem design process evident in designs of microfluidic devices created by academics. Understanding how design processes are altered in practice based on contextual factors such as setting and discipline can lead to strategies to better support innovation.
Kinesthetically Augmented Mid-Air Sketching of Multi-Planar 3D Curve-Soups
Authors: Mohanty Ronak R. , Bohari Umema H. , Vinayak  , Ragan Eric
Published: November 2018

We present haptics-enabled mid-air interactions for sketching collections of three-dimensional planar curves — 3D curve-soups — as a means for 3D design conceptualization. Haptics-based mid-air interactions have been extensively studied for modeling of surfaces and solids. The same is not true for modeling curves; there is little work that explores spatiality, tangibility, and kinesthetics for curve modeling, as seen from the perspective of 3D sketching for conceptualization. We study pen-based mid air interactions for free-form curve input from the perspective of manual labor, controllability, and kinesthetic feedback. For this, we implemented a simple haptics-enabled workflow for users to draw and compose collections of planar curves on a force-enabled virtual canvas. We introduce a novel force-feedback metaphor for curve drawing, and investigate three novel rotation techniques within our workflow for both controlled and free-form sketching tasks.
Design of Structures With Multiple Equilibrium Configurations
Authors: Li Yang , Pellegrino Sergio
Published: November 2018

Being able to design structures with multiple equilibrium configurations is the basis for the design of multi-stable structures, which are of interest for future research on multi-configuration structures that require ‘simple’ actuation schemes. It is already known that adding elastic springs to a rigid mechanism can create structures with multiple equilibrium configurations. The spring properties, such as their rest positions, can be taken as design parameters that can be used to achieve specific equilibrium configurations of the structure. This paper provides a linearized formulation for the equilibrium constraints that can be solved for the rest positions of the springs. This method allows the design of specific equilibrium configurations. It can also handle more complex problems and is easier to solve in comparison to existent techniques. An example design of a four-bar linkage that has 5 equilibrium configurations is presented.
The Influence of Partial Force Balancing on the Shaking Moments, Contact Forces, and Precision of a Delta Robot-Like Manipulator in a Compliant Frame
Authors: de Jong Jan J. , Meijaard J. P. , van der Wijk Volkert
Published: November 2018

For the Delta robot, a high-speed parallel pick-and-place manipulator, base vibrations are a significant problem. Especially since the Delta robot is suspended above its workpiece, it requires a large, stiff, and heavy base frame for fast and accurate motions. Dynamic balancing of the shaking forces and the shaking moments is a known technique to reduce the dynamic loads on the base frame and to the surroundings. In this paper it is investigated how solely with partial force balancing, dynamic loads and pick-and-place accuracy of a Delta robot-like manipulator can be improved, considering also the compliance of the base frame. This is done since partial force balance solutions can be implemented relatively simply in the current Delta robot designs, whereas full force and moment balance solutions are complex to apply in practice. Numerical simulations with a representative planar model of a Delta robot-like manipulator with a compliant base frame show that with an increasing amount of force balance the shaking moments increase up to 16% for full force balance. The floor contact forces first reduce and then increase with increasing force balance. With 43% force balance the floor contact forces are minimal, giving a 63% reduction. The end-effector accuracy slightly improves with increasing force balance until full force balance yields a 31% accuracy improvement. A further increase of the force (over) balance shows a 59% improvement of end-effector accuracy for 350% force balance. These effects are mainly due to the typical design of the Delta robot base frame and the way the robot is mounted to it.
Modeling and Machine Learning Aided Analysis of a Claw-Less Magnetically Coupled Ball-Drive Design
Authors: Gebre Biruk A. , Pochiraju Kishore
Published: November 2018

Ball-driven mobility platforms have shown that spherical wheels can enable substantial freedom of mobility for ground vehicles. Accurate and robust actuation of spherical wheels for high acceleration maneuvers and graded terrains can, however, be challenging. In this paper, a novel design for a magnetically coupled ball drive is presented. The proposed design utilizes an internal support structure and magnetic coupling to eliminate the need for an external claw-like support structure. A model of the proposed design is developed and used to evaluate the slip/no-slip operational window. Due to the high-dimensional nature of the model, the design space is sampled using randomly generated design instances and the data is used to train a support vector classification machine. Principal component analysis and feature importance detection are used to identify critical parameters that control the slip behavior and the feasible (no-slip) design space. The classification shows an increase in the feasible design space with the addition of, and increase in, the magnetic coupling force. Based on the results of the machine learning algorithm, FEA design tools and experimental testing are used to design a spherical magnetic coupler array configuration that can realize the desired magnetic coupling force for the ball drive.
Analytical Modelling of the Dynamics of the Four-Bar Mechanism: A Comparison of Some Methods
Authors: Meijaard J. P. , van der Wijk V.
Published: November 2018

Some thoughts about different ways of formulating the equations of motion of a four-bar mechanism are communicated. Four analytic methods to derive the equations of motion are compared. In the first method, Lagrange’s equations in the traditional form are used, and in a second method, the principle of virtual work is used, which leads to equivalent equations. In the third method, the loop is opened, principal points and a principal vector linkage are introduced, and the equations are formulated in terms of these principal vectors, which leads, with the introduced reaction forces, to a system of differential-algebraic equations. In the fourth method, equivalent masses are introduced, which leads to a simpler system of principal points and principal vectors. By considering the links as pseudorigid bodies that can have a uniform planar dilatation, a compact form of the equations of motion is obtained. The conditions for dynamic force balance become almost trivial. Also the equations for the resulting reaction moment are considered for all four methods.
Evaluation of i-Pod App to Assess Whole-Body Vibration and Seat Transmissibility on Mobile Mining Equipment
Authors: Mayton Alan G. , Kim Brian Y.
Published: November 2018

Researchers at the National Institute for Occupational Safety and Health (NIOSH) performed a pilot study focusing on the measurement accuracy of a mobile iOS application (app) to assess whole-body vibration (WBV) and seat performance on mobile mining equipment. The major objectives of this study were to assess the accuracy of an iPod app and determine if a pair of iPods running the iPod app were suitable to measure SEAT (Seat Effective Amplitude Transmissibility) value. The goal is to recommend a simple method to determine when a vehicle seat may need to be repaired, replaced, or adjusted. The study showed that the iPod app has the potential to serve as a low-cost tool to estimate WBV exposures to operators of mobile mining equipment. The study results were similar to those obtained by Burgess-Limerick et al. for operator WBV exposures on mining equipment. In contrast, an effort to examine seat performance using the mobile app showed greater variation between the app and the precision Siemens/LMS system selected as the “gold standard.” When comparing the Siemens/LMS and iPod pair systems, SEAT values calculated using weighted-root-mean-square acceleration (aw) resulted in a mean percent difference of 8.5±7.9%, whereas those calculated using vibration dose value (VDV) resulted in a mean percent difference of 5.5±4.4%. Additional data collection is necessary to determine what factors may be associated with this variance.
Hysteresis Identification of Carbon Nanotube Composite Beams
Authors: Taló Michela , Lacarbonara Walter , Formica Giovanni , Lanzara Giulia
Published: November 2018

Nanocomposites made of a hosting polymer matrix integrated with carbon nanotubes as nanofillers exhibit an inherent hysteretic behavior arising from the CNT/matrix frictional sliding. Such stick-slip mechanism is responsible for the high damping capacity of CNT nanocomposites. A full 3D nonlinear constitutive model, framed in the context of the Eshelby-Mori-Tanaka theory, reduced to a 1D phenomenological model is shown to describe accurately the CNT/polymer stick-slip hysteresis. The nonlinear hysteretic response of CNT nanocomposite beams is experimentally characterized via displacement-driven tests in bending mode. The force-displacement cycles are identified via the phenomenological model featuring five independent constitutive parameters. A preliminary parametric study highlights the importance of some key parameters in determining the shape of the hysteresis loops. The parameter identification is performed via one of the variants of a genetic-type differential evolution algorithm. The nanocomposites hysteresis loops are identified with reasonably low mean square errors. Such outcome confirms that the 1D phenomenological model may serve as an effective tool to describe and predict the nanocomposite nonlinear hysteretic behavior towards unprecedented material optimization and design.
Shape-Morphing Using Bistable Triangles With Dwell-Enhanced Stability
Authors: Alfattani Rami , Lusk Craig
Published: November 2018

This paper presents a new design concept for a morphing triangle-shaped compliant mechanism. The novel design is a bistable mechanism that has one changeable side. These morphing triangles may be arrayed to create shapemorphing structures. The mechanism was based on a six-bar dwell mechanism that can fit in a triangle shape and has stable positions at the motion-limit (dead-center) positions. An example of the triangle-shaped compliant mechanism was designed and prototyped: an isosceles triangle with a vertex that changes from 120 degrees to 90 degrees and vice versa. Three of these in the 120-degree configuration lie flat and when actuated to the 90-degree configuration become a cube corner. This design may be of use for folding and packaging assistance. The force analysis and the potential energy analysis were completed to verify the stability of the triangle-shaped compliant mechanism. Because of its dead-center motion limits the vertex angle cannot be extended past the range of 90 degrees to 120 degrees in spite of the mechanism’s compliant joints. Furthermore, because it is a dwell mechanism, the vertex angle is almost immobile near its stable configurations, although other links in the mechanism move. This makes the stable positions of the vertex angle robust against stress relaxation and manufacturing errors. We believe this is the first demonstration of this kind of robustness in bistable mechanisms.
“A Makerspace Is More Than Just a Room Full of Tools”: What Learning Looks Like for Female Students in Makerspaces
Authors: Tomko Megan , Schwartz Amanda , Newstetter Wendy , Alemán Melissa , Nagel Robert , Linsey Julie
Published: November 2018

Postulating that the act of making stimulates learning, a widespread effort prompted the integration of makerspaces on college campuses. From community colleges to research-based higher education institutions, large investments were and still are being made to advance the making spirit and encourage non-traditional learning in academic settings. While optimistic that students are taking advantage of the makerspace resources and are in fact learning from their experiences, there needs to be a more direct effort to understand the learning, if any, that is occurring in the makerspace. The makerspace is labeled as an open, learning environment where students are able to design, create, innovate, and collaborate [1, 2]. In response, we investigate the claims of this statement through the research question: how is learning experienced by female students in an academic makerspace? Female students in STEM, especially those engaged in makerspaces, have unique and uncharacteristic experiences that can lend way to various learning and pedagogical implications. The purpose of this paper is to highlight our methodological process for incorporating in-depth phenomenologically based interviewing and for utilizing open and axial coding methods to establish grounded theory. We interview five female students through purposeful maximum variation sampling and snowball sampling. Through a rigorous and iterative data analysis process of the ten-percent of the overall, we created a preliminary coding scheme that articulates how learning is occurring, what design skills are being learned, and what life skills are being learned. These preliminary findings show that not only are these female students learning by doing and learning how to problem solve in design, but they are also overcoming fears, developing patience, and communicating ideas in these design-oriented makerspaces.
Automatic Clustering of Sequential Design Behaviors
Authors: Rahman Molla Hafizur , Gashler Michael , Xie Charles , Sha Zhenghui
Published: November 2018

Design is essentially a decision-making process, and systems design decisions are sequentially made. In-depth understanding on human sequential decision-making patterns in design helps discover useful design heuristics to improve existing algorithms of computational design. In this paper, we develop a framework for clustering designers with similar sequential design patterns. We adopt the Function-Behavior-Structure based design process model to characterize designers’ action sequence logged by computer-aided design (CAD) software as a sequence of design process stages. Such a sequence reflects designers’ thinking and sequential decision making during the design process. Then, the Markov chain is used to quantify the transitions between design stages from which various clustering methods can be applied. Three different clustering methods are tested, including the K-means clustering, the hierarchical clustering and the network-based clustering. A verification approach based on variation of information is developed to evaluate the effectiveness of each method and to identify the clusters of designers who show strong behavioral similarities. The framework is applied in a solar energy systems design problem — energy-plus home design. The case study shows that the proposed framework can successfully cluster designers and identify their sequential decision-making similarities and dissimilarities. Our framework can support the studies on the correlation between potential factors (e.g., designers’ demographics) and certain design behavioral patterns, as well as the correlation between behavioral patterns and design quality to identify beneficial design heuristics.
Analysis of Consumer Response and Pricing of Smart and Connected Products
Authors: Patel Deep N. , Yadav Darshan , Morkos Beshoy
Published: November 2018

The emergence of Internet of Things (IoT) has created an unanticipated rise of smart and connected products in the consumer market. While, smart and connected products have become a fundamental part of our day to day life, consumer’s perspective regarding these smart and connected products still remains an uncharted territory. This paper tries to explore how these “smart” and “connected” products are perceived in the consumer market and what are the key driving factors behind the unparalleled success of these products. In order to answer these questions, the authors first determined the “smartness” and “connectivity” criteria to judge all the products based on the most commonly used rating systems for such products. Followed by a case study analysis to determine if there is a correlation between “smartness”, “connectivity” and other product parameters. It is discovered that “smartness” as defined in the paper, is a resource intensive component of a product and therefore, directly affects the price of a product. On the other hand, consumers are more receptive to “connectivity” aspect of a product. The correlations found in the paper could help fill the gaps between areas of focus for technology development in the industry and user demands.