bluuebunny/crossref_metadata_2025 huggingface dataset:
Cycloidal Geartrain In-Use Efficiency Study
Authors: Farrell Logan C. , Holley James , Bluethmann William , O’Malley Marcia K.
Published: November 2018

Currently, harmonic drives are the primary speed reducer for robotic applications where a high reduction in a small package is required. Cycloidal drives are an alternative option for high reduction, small package, use-cases with the advantage of a higher specific torque and the ability to customize and integrate the drive for the application. These compact style cycloidal drives have been well studied in theory and simulation for their performance, but very little data is available on their actual performance over time. This paper presents experimental data on performance of a cycloidal drive designed for a Lunar or Martian rover application. Burn-in time efficiency curves and torque/speed efficiency profiles are computed after running the drive through 129k output cycles (7.6M input cycles) over the course of 300+ hours of testing. The study finds that substantial burn-in time may be required for steady-state performance, but peak efficiencies of 81% can be achieved. Also, the efficiency is shown to be dependent on the torque through the actuator. This work demonstrates a customized cycloidal drive in a space application that is comparable to a harmonic drive in efficiency performance, with a 2x increase in specific torque, suggesting the application of cycloidal drives could grow tremendously in robotic designs.
A Bio-Inspired Miniature Climbing Robot With Bilayer Dry Adhesives: Design, Modeling, and Experimentation
Authors: Dharmawan Audelia G. , Xavier Priti , Anderson David , Perez K. Blake , Hariri Hassan H. , Soh Gim Song , Baji Avinash , Bouffanais Roland , Foong Shaohui , Low Hong Yee , Wood Kristin L.
Published: November 2018

This paper presents the design, modeling, and analysis of the force behavior acting on a wheel-legs (whegs) type robot which utilizes bilayer dry adhesives for wall-climbing. The motion of the robot is modeled as a slider-crank mechanism to obtain the dynamic parameters of the robot during movement. The required forces and moment to maintain equilibrium as the robot is in motion is then extensively analyzed and discussed. Following the analysis, fundamental measures to attain an operative climbing robot, such as adhesive requirement and torque specification, are then identified. The outcomes of the analysis are verified through experiments and working prototypes that are in good agreement with the design guidelines.
Efficient Load Sampling for Worst-Case Structural Analysis Under Force Location Uncertainty
Authors: Wang Yining , Ulu Erva , Singh Aarti , Kara Levent Burak
Published: November 2018

An important task in structural design is to quantify the structural performance of an object under the external forces it may experience during its use. The problem proves to be computationally very challenging as the external forces’ contact locations and magnitudes may exhibit significant variations. We present an efficient analysis approach to determine the most critical force contact location in such problems with force location uncertainty. Given an input 3D model and regions on its boundary where arbitrary normal forces may make contact, our algorithm predicts the worst-case force configuration responsible for creating the highest stress within the object. Our approach uses a computationally tractable experimental design method to select number of sample force locations based on geometry only, without inspecting the stress response that requires computationally expensive finite-element analysis. Then, we construct a simple regression model on these samples and corresponding maximum stresses. Combined with a simple ranking based post-processing step, our method provides a practical solution to worst-case structural analysis problem. The results indicate that our approach achieves significant improvements over the existing work and brute force approaches. We demonstrate that further speedup can be obtained when small amount of an error tolerance in maximum stress is allowed.
Towards an Adaptive Control Concept for Unknown Nonlinear MIMO Systems
Authors: Madadi Elmira , Söffker Dirk
Published: November 2018

The design of an accurate model often appears as the most challenging tasks for control engineers especially focusing to the control of nonlinear systems with unknown parameters or effects to be identified in parallel. For this reason, development of model-free control methods is of increasing importance. The class of model-free control approaches is defined by the non-use of any knowledge about the underlying structure and/or related parameters of the dynamical system. Therefore the major criteria to evaluate model-free control performance are aspects regarding robustness against unknown inputs and disturbances to achieve a suitable tracking performance including ensuring stability. Consequently it is assumed that the system plant model to be controlled is unknown, only the inputs and outputs are used as measurements. In this contribution a modified model-free adaptive approach is given as the extended version of existing model-free adaptive control to improve the performance according to the tracking error at each sample time. Using modified model-free adaptive controller, the control goal can be achieved efficiently without an individual control design process for different kinds unknown nonlinear systems. The main contribution of this paper is to extend the modified model-free adaptive control method to unknown nonlinear multi-input multi-output (MIMO) systems. A numerical example is shown to demonstrate the successful application and performance of this method.
Development of a Pedestrian Collision Warning System Integrated Into Windscreen Pillars
Authors: Zeziulin D. V. , Tyugin D. Y. , Tumasov A. V. , Groshev A. M. , Porubov D. M.
Published: November 2018

In Russia, 36% [1] of all accidents are a collision with a pedestrian. Vehicle structural elements limit visibility to drivers and do not allow fully assessing the traffic situation, forming blind zones. It especially applies to commercial vehicles with large dimensions. The system allowing to expand visibility of the car due to use of displays in windscreen pillars is presented in this article. It is proposed to use the pedestrian recognition system integrated into the windscreen pillars based on neural networks. The system allows to detect and estimate distance to the objects and to give warning signals about possible collision. It consists of an on-board computer, video cameras and output devices. Interior elements of a commercial vehicle were developed and installed. External side mirrors were replaced with video cameras. The exterior elements were designed and installed. Further there were carried out experimental researches of the system.
Casimir Effect on Superharmonic Resonance of Bio-NEMS Circular Plate Resonator Sensors
Authors: Botello Martin , Caruntu Dumitru I.
Published: November 2018

Casimir effect on superharmonic resonance of electrostatically actuated bio-nano-electro-mechanical system (Bio-NEMS) circular plate resonator sensor is investigated. The plate sensor resonator is clamped at the outer end and suspended over a parallel ground plate. The sensor can be used for detecting human viruses. Superharmonic resonance of the second order, frequency near one-fourth the natural frequency of the resonator, is induced using Alternating Current (AC) voltage. The magnitude of the AC voltage is also large enough to be consider hard excitation acting on the resonator. Beside Casimir effect, other external forces (i.e. electrostatic force and viscous air damping) acting on the MEMS resonator create a nonlinear behaviors such as bifurcation and pull-in instability. Hence, numerical models, such as Method of Multiple Scales (MMS) and Reduced Order Model (ROM), are used to predict the frequency-amplitude response for MEMS resonator. MMS transforms the nonlinear partial differential equation of motion into two simpler problems, namely zero-order and first-order. While, ROM, based on the Galerkin procedure which uses the mode shapes of vibration of the resonator as a basis of functions, transforms the nonlinear partial differential equation of motion into a system of ordinary differential equation with respect to dimensionless time. The frequency-amplitude response allows one to observe the behavior of the system for a range of frequencies near the superharmonic resonance. The effects of parameters such as Casimir effect, voltage, and damping on the frequency-amplitude response are reported.
Trajectory Planning of Projectile Catching Maneuvers for Robotic Manipulators
Authors: Charlet Mark , Marcellini Élodie , Gosselin Clément
Published: November 2018

This article introduces a trajectory planning approach for the catching of projectiles with a serial robotic manipulator. A description of the trajectory of the projectiles to be caught is first given. Then, a heuristic approach is introduced in order to determine the interception (catching) point. The planning of the robot trajectory that is required to reach the interception point with the proper velocity is then presented, based on polynomial interpolation. Finally, the trajectory of the robot used to decelerate and stop the projectile is planned. Examples of catching maneuvers are provided in order to illustrate the proposed trajectory planning technique.
Hydraulic Pressure Control and Parameter Optimization of Brake-by-Wire System Based on Driver-Automation Cooperative Driving
Authors: Liu Xiaohui , Yu Liangyao , Zheng Sheng , Chang Jinghu , Li Fei
Published: November 2018

The automatic driving technology of vehicle is being carried out in real road environment, however, the application of unmanned vehicle still needs proof and practice. Autonomous vehicles will be in the stage of co-drive for a long time, that is, driver-control and autonomous system assisting or autonomous system control and driver assisting. The braking system of the intelligent vehicle needs to work in driver driving mode or automatic driving mode during a long stage. Brake-by-Wire system is the development trend of vehicle braking system. The brake modes of the Brake-by-Wire system can be switched easily and it can satisfy the demand for braking system of the intelligent vehicle. However, when the driving mode changes, the characteristic of the braking intention and braking demand will change. In order to improve the braking performance of the intelligent vehicle, hydraulic pressure control and parameter optimization of the Brake-by-Wire system during different driving modes should be different.

Researches are made on hydraulic pressure control and parameter optimization of the Brake-by-Wire system with consideration on differences of braking intensity input and braking requirement between driver driving mode and automatic driving mode through theory analysis, Matlab/Simulink-AMESim simulation and bench test. The study is helpful for improving the braking performance of Brake-by-Wire system in hydraulic pressure control of driver-automation cooperative driving.
A Deep Learning Model for Mining Object-Energy Correlations Using Social Media Image Data
Authors: Dering Matthew , Lee Chonghan , Hopkinson Kenneth M. , Tucker Conrad S.
Published: November 2018

The authors of this work present a method that mines big media data streams from large Social Media Networks in order to discover novel correlations between objects appearing in images and electricity utilization patterns. The hypothesis of this work is that there exist correlations between what users take pictures of, and electricity utilization patterns. This work employs a Convolutional Neural Network to detect objects in 578,232 images gathered from over 15,000,000 tweets sent in the San Diego area. These objects were considered in the context of concurrent power use, on a monthly and hourly basis. The results reveal both positive and negative correlations between power use and specific objects, such as lamps (.053 hourly), dogs (−.011 hourly), horses (.422 monthly) and motorcycles (−.415, monthly).
Follower Forces in Pre-Stressed Fixed-Fixed Rods to Mimic Oscillatory Beating of Active Filaments
Authors: Fatehiboroujeni Soheil , Gopinath Arvind , Goyal Sachin
Published: November 2018

Flagella and cilia are examples of actively oscillating, whiplike biological filaments that are crucial to processes as diverse as locomotion, mucus clearance, embryogenesis and cell motility. Elastic driven rod-like filaments subjected to compressive follower forces provide a way to mimic oscillatory beating in synthetic settings. In the continuum limit, this spatiotemporal response is an emergent phenomenon resulting from the interplay between the structural elastic instability of the slender rods subjected to the non-conservative follower forces, geometric constraints that control the onset of this instability, and viscous dissipation due to fluid drag by ambient media. In this paper, we use an elastic rod model to characterize beating frequencies, the critical follower forces and the non-linear rod shapes, for pre-stressed, clamped rods subject to two types of fluid drag forces, namely, linear Stokes drag and non-linear Morrison drag. We find that the critical follower force depends strongly on the initial slack and weakly on the nature of the drag force. The emergent frequencies however, depend strongly on both the extent of pre-stress as well as the nature of the fluid drag.
Toward a Generative Human-in-the-Loop Approach for Conceptual Design Exploration Using Flow Failure Frequency in Functional Models
Authors: Arlitt Ryan M. , Van Bossuyt Douglas L.
Published: November 2018

A challenge systems engineers and designers face when applying system failure risk assessment methods such as Probabilistic Risk Assessment (PRA) during conceptual design is their reliance on historical data and behavioral models. This paper presents a framework for exploring a space of functional models using graph rewriting rules and a qualitative failure simulation framework that presents information in an intuitive manner for human-in-the-loop decision-making and human-guided design. An example is presented wherein a functional model of an electrical power system is iteratively perturbed to generate alternatives. The alternative functional models suggest different approaches to mitigating an emergent system failure vulnerability in the electrical power system’s the heat extraction capability. A preferred functional model configuration that has a desirable failure flow distribution can then be identified. The method presented here helps systems designers to better understand where failures propagate through systems and guides modification of systems functional models to adjust the way in which systems fail to have more desirable characteristics.
Local Symmetry Based Hint Extraction of B-Rep Model for Machining Feature Recognition
Authors: Li Zhi , Lin Jie , Zhou Danchen , Zhang Bo , Li Hai
Published: November 2018

Machining feature recognition is a key technology in design for manufacturing, inter-operation of neutral format solid models, and reuse of design models in down-streaming applications. Although many approaches have been proposed, the detection and processing of intersection features are still challenging. In this paper, we studied the local property of B-rep model and usage in intersection feature detection. To support hint based reasoning and processing, we proposed a symmetry property definition with relation to edges of solid models. This symmetry property is based on conventional edge convexity, which is an extension of the feature hint theory. The Transformation of global or partial graph matching to local property matching would reduce the complexity in feature matching stages. We implemented a prototype module to evaluate the feasibility of the proposed approach.
An Attempt of Error Tracing and Compensation Method of the Linkage Error of Five-Axis CNC Machine Tool
Authors: Jiang Zhong , Ding Jiexiong , Ding Qicheng , Du Li , Wang Wei
Published: November 2018

Nowadays the five-axis machine tool is one of the most important foundations of manufacturing industry. To guarantee the accuracy of the complex surface machining, multi-axis linkage performance detection and compensation of five-axis machine tools is necessary. RTCP (Rotation Tool Center Point) is one of the basic essential functions for the five-axis machine tools, which can keep the tool center with the machining trajectory when five axes move synchronously. On the basis of RTCP function, a way to detect multi-axes linkage performance of five-axis machine tools is briefly introduced, and linkage error model is built in accordance with the topological structure of machine tool. Based on the feature of the linkage errors of the five-axis machine tool, the error tracing and compensation method is proposed. Some simulations and experiments that verify the error tracing method could locate the linkage error category are established. Therefore, a new attempt to detect and compensate the linkage error of the five-axis machine tool is provided in this paper.
Dynamic Performance Optimization of the Dual Clutch Transmission Based on Genetic Algorithm
Authors: He Dongwei , Wu Guangqiang , Shi Yimin , Yang Wenbin
Published: November 2018

Gear shift law is determined, and shifting control logic, clutch pressure control strategy are developed, Simulation models of the continuous up-shift and down-shift process of DCT are established. Comparison of simulation results by the indicators of friction work, friction power and jerk, Influence on shifting performance about clutch pressure rate and circulates pressure are analyzed qualitatively. According to the fitness function of overall performance of shifting quality, the pressure optimal control objectives of DCT are proposed, and based on genetic algorithm for present control method in engagement process of DCT, the parameter optimization is studied.
Kinematic Synthesis Using Reinforcement Learning
Authors: Vermeer Kaz , Kuppens Reinier , Herder Justus
Published: November 2018

The presented research demonstrates the synthesis of two-dimensional kinematic mechanisms using feature-based reinforcement learning. As a running example the classic challenge of designing a straight-line mechanism is adopted: a mechanism capable of tracing a straight line as part of its trajectory. This paper presents a basic framework, consisting of elements such as mechanism representations, kinematic simulations and learning algorithms, as well as some of the resulting mechanisms and a comparison to prior art. Series of successful mechanisms have been synthesized for path generation of a straight line and figure-eight.
Crowdfunding Campaign As a Design-Based Pedagogical Approach for Experiential Learning of Technology Entrepreneurship
Authors: Luo Jianxi , Pey Kin Leong , Wood Kristin
Published: November 2018

Engineers are increasingly expected to master the knowledge and skills for entrepreneurship. Academic courses on entrepreneurship have been adopted in engineering schools around the world. However, the experiential learning of technology entrepreneurship remains challenging because it requires not only the experiences of ideation, design and prototyping in classrooms and fab labs but also broader engagement with users, manufacturers, marketers, and investors in business contexts. To conquer this challenge, we developed an approach to use an online crowdfunding campaign as a pedagogical approach to intensify the experiential learning of students in a technology entrepreneurship course. This approach, as part of a course module, provides a real-world context of uncertainty and resource constraints that characterize the entrepreneurship process, and it allows university students to discover and interact with actual users, investors, manufacturers and other stakeholders of their products around the world. We experimented with the use of a crowdfunding campaign as a pedagogical approach for experiential learning in the Entrepreneurship course at Singapore University of Technology and Design (SUTD). We found evidence of increased prototyping quality; learning intensity; empathy toward users, manufacturers, marketers and other stakeholders; and an increased interest in pursuing an entrepreneurial career.
Uncertainty Quantification of Reliability Analysis Under Surrogate Model Uncertainty Using Gaussian Process
Authors: Bae Sangjune , Park Chanyoung , Kim Nam H.
Published: November 2018

The main objective of this paper is to quantify the effect of surrogate model uncertainty on reliability in addition to the aleatory randomness of the input variables, especially when Kriging surrogate model is utilized where the prediction uncertainty is modeled with a normal distribution. A novel approach is presented which requires only a single set of Monte Carlo Simulation (MCS) to precisely estimate the variance of reliability that is used as an uncertainty measure. It is found that the method only requires the bivariate cumulative distribution function, and the result shows that the uncertainty is well quantified without going through multiple numbers of MCS.
Current-Aided Time-Frequency Analysis of Vibration Signals for Gearbox Fault Diagnosis
Authors: Tu Xiaotong , Hu Yue , Li Fucai
Published: November 2018

Vibration monitoring is an effective method for mechanical fault diagnosis. Wind turbines usually operated under varying-speed condition. Time-frequency analysis (TFA) is a reliable technique to handle such kind of nonstationary signal. In this paper, a new scheme, called current-aided TFA, is proposed to diagnose the planetary gearbox. This new technique acquires necessary information required by TFA from a current signal. The current signal is firstly used to estimate the rotating speed of the shaft. These parameters are applied to the demodulation transform to obtain a rough time-frequency distribution (TFD). Finally, the synchrosqueezing method further enhances the concentration of the obtained TFD. The validation and application of the proposed method are presented by a simulated signal and a vibration signal captured from a test rig.
Optimal Non-Uniform Parametrization for Fourier Descriptor Based Path Synthesis of Four Bar Mechanisms
Authors: Sharma Shashank , Purwar Anurag , Ge Q. Jeffrey
Published: November 2018

Fourier descriptor based path synthesis algorithms rely on harmonic decomposition of four-bar loop closure equation to split the design space into smaller subsets. The core of the methodology depends on calculation and fitting of Fourier descriptors. However, a uniform time parametrization is assumed in existing literature. This paper aims to explore the use of non-uniform time parametrization of input data and calculation of an optimal parametrization. Additionally, design-centric constraints have been proposed to give user enhanced control over coupler speed. As a result, this work improves the existing algorithm tremendously.
Persistent Target Detection and Tracking by an Autonomous Swarm
Authors: Gainer John J. , DeVries Levi D. , Kutzer Michael D.
Published: November 2018

This paper presents an autonomous multivehicle control algorithm capable of persistently searching and tracking targets in a defined search area subject to operational endurance constraints of individual agents. The algorithm development is modular to allow scalability and a control architecture that can be modified to any type of autonomous vehicle, search area, or target. In practical application, a target can be anything from heat signatures to radioactive material; therefore, this work employs a generic emitter-detector pair as a placeholder relationship for real world applications. The control strategy accounts for the appearance, motion, and disappearance of multiple targets in the search space constituting the utility of creating a team of multiple search agents. When agent battery level drops below a predetermined threshold, the agent returns to a base station to recharge and be relaunched into the mission. Remaining agents must account for this loss and gain of other team members as they exit the search environment. The contributions of this work are 1) the design of search trajectories for autonomous vehicles with limited endurance, 2) incorporation of return-to-base and recharge time requirements, and 3) coordination of multiple vehicles by developing a decision-making model to and assign agents to operational modes. We have run an extensive number of experimental trials to collect and analyze performance data for further development and testing.
Surrogate Based Multi-Objective Optimization of J-Type Battery Thermal Management System
Authors: Liu Yuanzhi , Ghassemi Payam , Chowdhury Souma , Zhang Jie
Published: November 2018

This paper proposes a novel and flexible J-type air-based battery thermal management system (BTMS), by integrating conventional Z-type and U-type BTMS. With two controlling valves, the J-type BTMS can be adaptively controlled in real time to help balance the temperature uniformity and energy efficiency under various charging/discharging situations (especially extreme fast changing). Results of computational fluid dynamics simulations show that the J-type system performs better than the U-type and Z-type systems. To further improve the thermal performance of the proposed J-type BTMS, a surrogate-based multi-objective optimization is performed, with the consideration of the two major objectives, i.e., uniformity and energy efficiency. The concurrent surrogate selection (COSMOS) framework is adopted in this paper to determine the most suitable surrogate models. Optimization results show that: (i) the uniformity of the temperature distribution is improved by 38.6% compared to the benchmark, (ii) the maximum temperature is reduced by 19.1%, and (iii) the pressure drop is decreased by 14.5%.
A Simple Total-Lagrangian Finite-Element Formulation for Nonlinear Behavior of Planar Beams
Authors: Babilio Enrico , Lenci Stefano
Published: November 2018

The present contribution reports some preliminary results obtained applying a simple finite element formulation, developed for discretizing the partial differential equations of motion of a novel beam model. The theoretical model we are dealing with is geometrically exact, with some peculiarities in comparison with other existing models. In order to study its behavior, some numerical investigations have already been performed through finite difference schemes and other methods and are reported in previous contributions. Those computations have enlightened that the model under analysis turns out to be quite hard to handle numerically, especially in dynamics. Hence, we developed ad hoc the total-lagrangian finite-element formulation we report here. The main differences between the theoretical model and its numerical formulation rely on the fact that in the latter the absolute value of the shear angle is assumed to remain much smaller than unity, and strains are piecewise constant along the beam. The first assumption, which actually simplifies equations, has been taken on the basis of results from previous integrations, mainly through finite difference schemes, which clearly showed that, while other strains can achieve large values in their range of admissibility, shear angle actually remains small. The second assumption led us to define a two-nodes constant-strain finite element, with a fast convergence, in terms of number of elements versus solution accuracy. Although, at the present stage of this ongoing research, we have only early results from finite elements, they appear encouraging and start to shed new light on the behavior of the beam model under analysis.
Hybrid-Bistable Vibration Energy Harvester With Adaptive Potential Well
Authors: Kim Jinki , Dorin Patrick , Wang K. W.
Published: November 2018

Many common environmental vibration sources exhibit low and broad frequency spectra. In order to exploit such excitations, energy harvesting architectures utilizing nonlinearity, especially bistability, have been widely studied since the energetic interwell oscillations between their stable equilibria can provide enhanced power harvesting capability over a wider bandwidth compared to the linear counterpart. However, one of the limitations of these nonlinear architectures is that the interwell oscillation regime may not be activated for a low excitation level that is not strong enough to overcome the potential energy barrier, thus resulting in low amplitude intrawell response which provides poor energy harvesting performance. While the strategic integration of bistability and additional dynamic elements has shown potential to improve broadband energy harvesting performance by lowering the potential barrier, there is a clear opportunity to further improve the energy harvesting performance by extracting electrical power from the kinetic energy in the additional element that is induced when the potential barrier is lowered. To explore this opportunity and advance the state of the art, this research develops a novel hybrid bistable vibration energy harvesting system with a passive mechanism that not only adaptively lowers the potential energy barrier level to improve broadband performance but also exploits additional means to capture more usable electrical power. The proposed harvester is comprised of a cantilever beam with repulsive magnets, one attached at the free end and the other attached to a linear spring that is axially aligned with the cantilever (a spring-loaded magnet oscillator). This new approach capitalizes on the adaptive bistable potential that is passively realized by the spring-loaded magnet oscillator, which lowers the double-well potential energy barrier thereby facilitating the interwell oscillations of the cantilever across a broad range of excitation conditions, especially for low excitation amplitudes and frequencies. The interwell oscillation of the cantilever beam enhances not only the piezoelectric energy harvesting from the beam but also the electromagnetic energy harvesting from the spring-loaded magnet oscillator by inducing large amplitude vibrations of the magnet oscillator. Numerical investigations found that the proposed architecture yields significantly enhanced energy harvesting performance compared to the conventional bistable harvester with fixed magnet.
Manufacturability Constraint Formulation for Design Under Hybrid Additive-Subtractive Manufacturing
Authors: Patterson Albert E. , Allison James T.
Published: November 2018

This article addresses the generation and use of manufacturability constraints for design under hybrid additive/subtractive processes. A method for discovering the natural constraints inherent in both additive and subtractive processes is developed; once identified, these guidelines can be converted into mathematical manufacturability constraints to be used in the formulation of design problems. This ability may prove to be useful by enhancing the practicality of designs under realistic hybrid manufacturing conditions, and supporting better integration of classic design-for-manufacturability principles with design and solution methods. A trade-off between design manufacturability and elegance has been noted by many scholars. It is posited that using realistic manufacturing conditions to drive design generation may help manage this trade-off more effectively, focusing exploration efforts on designs that satisfy more comprehensive manufacturability considerations. While this study focuses on two-step AM-SM hybrid processes, the technique extends to other processes, including single-process fabrication. Two case studies are presented here to demonstrate the new constraint generation concept, including formulation of shape and topology optimization problems, comparison of results, and the physical fabrication of hybrid-manufactured products. Ongoing work is aimed at rigorous comparison between candidate constraint generation strategies and the properties of the constraint mapping.
A Study on the Influence of Planar Mechanism Design on Energy Use During Controlled Movements
Authors: Myszka David H. , Fischer Austin M. , Murray Andrew P.
Published: November 2018

This paper presents a study on the energy utilization of planar automation mechanisms that operate with controlled moves. Designers of factory automation for pick & place tasks often select multiple degree-of-freedom robotic devices. With multiple degrees-of-freedom, task flexibility is available, but many operations require little or no flexibility. The majority of research on the energy usage of these robot devices for pick & place tasks focuses on path planning.

The study presented in this paper explores the energy savings in using low degree-of-freedom devices and the influence of design parameter selection. Energy predictor equations are developed and confirmed through experimentation. Various positioning mechanisms of differing dimensions are studied for trends in energy utilization. Lastly, an actuator control strategy is proposed for further reducing energy requirements. The study concludes that energy usage can be substantially decreased in pick & place applications by reducing the degrees of freedom of the device, implementing a prudent mechanism architecture, ideally selecting mechanism dimensions and optimally controlling the actuator(s).
Modal Analysis of Magnetic Resonance Imaging (MRI) Scanner Support Structure
Authors: Rodrigue Geneviève , Mechefske Chris K.
Published: November 2018

Experimental and computational modal analysis has been completed as part of a larger project with the ultimate goal of understanding MRI vibration and implementing passive vibration isolation in the MRI machine support structure. The specific purpose of the modal analysis is to extract natural frequencies (eigenvalues) and mode shapes (eigenvectors) of the MRI support structure in order to validate the computational model of the base against the experimental results so that the former may be used as an analysis and design tool. From the model, the resonance points of the MRI support structure are determined within the expected frequency ranges of excitation.
Evaluation of the Algorithmic Error of New Specification Tools for an ISO 14405-1:2016 Size
Authors: Jbira Ibtissem , Tahan Antoine , Mahjoub Mohamed Ali , Louhichi Borhen
Published: November 2018

Due to machine tool imprecisions during manufacturing, the actual product cannot be the same as the nominal model. The product’s geometric variations influence the geometrical requirements of functionality and assembly [6, 8]; this remains a problem of industrial performance and plays a major role in the quality and cost of products; hence the need for a reliable strategy to evaluate errors in the final inspection of part quality. Among all the geometric characteristics, the circular characteristic is very common on most parts. Therefore, the measurement and evaluation of circularity with a high degree of accuracy is of utmost importance. Size, form and orientation are the basic descriptors of the geometric quality of the objects. The recent publication of ISO 14405-1: 2016 defines the size as the fundamental geometric descriptor; it described a new set of specification tools for the size of part characteristics that directly apply to the ideal geometry of the component [13]. These tools present new challenges for an inspector using a coordinate metrology system. The study of the influence of form defects on the identification of dimensional and geometrical requirements seems necessary. This paper studies four modifiers ISO 14405-1:2016 (Minimum circumscribed size (GN), Maximum recorded size (GX), least squares size Minimum (GG) and Minimum area (MZ)) will be studied. This paper presents simple and effective algorithms for evaluating the circularity error of a large number of points using four specification modifiers of ISO 14405-1:2016, and a study on the influence of measurement system strategies on different algorithms for the evaluation of these new specifications. An analysis software was developed to compare the sensitivity of different parameters (number of points, noise amplitude and circularity defect) on ISO 14405-1:2016 modifiers.
Message Framing to Reduce Automobile Idling
Authors: Paniccia Christian , Shu L. H.
Published: November 2018

This work aims to develop interventions to reduce automobile idling, where a driver runs the engine unnecessarily while not moving. Idling is a serious problem that wastes fuel, pollutes the air, and releases greenhouse gas emissions. Drivers idle for different reasons, including misconceptions about the time needed to warm up their engines and how much additional fuel is expended by turning the engine off and back on. Information-based interventions, i.e., messages to address idling, may therefore work more effectively to change behavior by correcting such misconceptions than for other types of pro-environmental behaviors where corresponding misconceptions may not exist.

This work incorporates Regulatory Focus Theory, a social-psychological framework which differentiates between promotion- and prevention-focused individuals. Furthermore, messages are framed with respect to idling-relevant concerns that participants identify — finance, health, or the environment.

Participants were asked to express behavioral intention and engagement in response to messages tailored for their regulatory focus and domain of concern. Results revealed that 1) participants prioritized finance and health much more often than the environment; 2) most participant categories responded well to their targeted messages; 3) Promotion/Finance participants seemed especially challenging to motivate, but modifications to their targeted messages led to improved results.
Finite Element Thermal Analysis of Melt Pool in Selective Laser Melting Process
Authors: Luo Zhibo , Zhao Yaoyao Fiona
Published: November 2018

Selective laser melting is one of the powder bed fusion processes which fabricates a part through layer-wised method. Due to the ability to build a customized and complex part, selective laser melting process has been broadly studied in academic and applied in industry. However, rapidly changed thermal cycles and extremely high-temperature gradients among the melt pool induce a periodically changed thermal stress in solidified layers and finally result in a distorted part. Therefore, the temperature distribution in the melt pool and the size and shape of the melt pool directly determine the mechanical and geometrical property of final part. As experimental trial-and-error method takes a huge amount of cost, different numerical methods have been adopted to estimate the transient temperature and thermal stress distribution in the melt pool and powder bed. The most existing research utilizes the moving Gaussian point heat source to model the profile of the melt pool, which consumes a significant amount of computational cost and cannot be used to implement the part-level simulation. This research proposes a new line heat source to replace the moving point heat source. Some efforts are applied to reduce the computational cost. Specifically, a relatively large step size is used for the line heat source to reduce the number of time steps. In addition, a mesh refinement scheme is adopted to reduce the number of cells in each time step by refining the mesh close to the heat source and coarsening the mesh far away from it. On the other hand, efforts are implemented to increase the accuracy of the simulation result. Temperature-dependent material properties are considered in this FE framework. In addition, material transition among powder, liquid, and solid are incorporated in the developed FE framework. In this study, temperature simulation of one scanning track based on self-developed FE code is applied for Stainless Steel 316L. The simulation results show that the temperature distribution and history of melt pool within line heat source are comparable to that of the moving Gaussian point heat source. While the simulation time is reduced by more than two times depending on the length of line heat input. Therefore, this FE model can be used to numerically investigate the process parameters and help to control the quality of the final part.
Time-Dependent Reliability-Based Robust Design Optimization via Extreme Value Moment Method
Authors: Yu Shui , Wang Zhonglai
Published: November 2018

During the product design and development stage, design engineers often encounter reliability and robustness of dynamic uncertain structures. Meanwhile, time-varying and high nonlinear performance are the basic characteristics of reliability analysis and design. Hence, the time-dependent reliability analysis and integrating reliability-based design with robust design become a primary challenge in reliability-based robust design optimization. This paper proposes a multi-objective integrated framework for time-dependent reliability-based robust design optimization and the corresponding algorithms. The multi-objective integrated framework, which minimizes the mean value and coefficient of variation for the objective function at the same time subject to time-dependent probabilistic constraints, is first established. The time-dependent probabilistic constraints are then converted into deterministic constraints using a combination of moment method and the sparse grid based stochastic collocation method. The evolutionary multi-objective optimization algorithm is finally employed for the deterministic multi-objective optimization problem. Several examples are investigated to demonstrate the effectiveness of the proposed method.
Experimental Studies on Attenuation of Rotor-Stator Dynamics: Effects of High-Frequency Inclusion and Annular Fluid
Authors: Kanzari Meryem , AlQaradawi Mohammed , Balachandran Balakumar
Published: November 2018

Flexible, rotating structures can experience complex dynamics, when torsional and lateral motions are involved. Oilwell drill strings form one example of such structures. In the present study, the authors investigate the influence of sinusoidal drive speed modulation on whirling motions of flexible rotors with contact interactions. For two types of drilling-like operations, one with drill mud and another without drill mud, the stability of motions is studied. A laboratory-scale drill rig is used to study the dynamics of a flexible rotor, which is driven at one end and housed within a stator at the other end. Experimental results are presented and discussed for different drive speeds. The findings suggest that the addition of drill mud in the annular space between the rotor and stator along with high-frequency modulation in the drive input helps attenuate lateral motions. The torsional motions appear to be influenced more by the high-frequency drive speed modulation. A three-degree-of-freedom model has been constructed to study lateraltorsional dynamics of a rotor-stator system. The model predictions are compared with the experimental data. The findings of this work have relevance for constructing practical solutions to control whirl dynamics of flexible rotors such as drill strings.
Toward a Model-Based Experimental Approach to Assessing Collective Systems Design
Authors: Valencia-Romero Ambrosio , Grogan Paul T.
Published: November 2018

This work presents a conceptual model of collective decision-making processes in engineering systems design to understand the tradeoffs, risks, and dynamics between autonomous but interacting design actors. The proposed approach combines value-driven design, game theory, and simulation experimentation to study how technical and social factors of a design decision-making process facilitate or inhibit collective action. The collective systems design model considers two levels of decision-making: 1) lower-level design value exploration; and 2) upper-level design strategy selection. At the first level, the actors concurrently explore two strategy-specific value spaces with coupled design decision variables. Each collective decision is mapped to an individual scalar measure of preference (design value) that each actor seeks to maximize. At the second level, each of the actor’s design values from the two lower-level design exploration tasks is assigned to one diagonal entry of a normalform game, with off-diagonal elements calculated in function of the “sucker’s” and “temptation-to-defect” payoffs in a classical strategy game scenario. The model helps generate synthetic design problems with specific strategy dynamics between autonomous actors. Results from a preliminary multi-agent simulation study assess the validity of proposed design spaces and generate hypotheses for subsequent studies using human subjects.
On the Solution of Multi-Precision-Point Path Synthesis of Planar Four-Bar Mechanisms Based on Solution Region Methodology
Authors: Han Jianyou , Liu Wupeng
Published: November 2018

In this paper, the solution region synthesis method for multi-precision-point path synthesis of planar four-bar mechanisms is presented. The solution region method is to represent an infinite number of mechanism solutions in a plane, in which the x-coordinate and the y-coordinate of the plane are both taken as the concerned parameters of the mechanisms. Then the feature curves of the mechanisms can be expressed in the plane. Firstly, the synthesis equations for the multi-precision-point path synthesis of planar four-bar mechanisms are established. Then according to the proposed defect judgment method, the defective solutions are eliminated, and an infinite number of solutions without defects are obtained. After considering and imposing design requirements, the linkages of different types and different curve types are represented in the solution region. Finally, Taking the path generation of eight points as the example, the methodology of establishing the solution region and the feasible solution region are presented, and the synthesis results are illustrated.
Energy Transfer in a Linear Turbulence Model
Authors: Bak Bendegúz Dezső , Kalmár-Nagy Tamás
Published: November 2018

Energy transfer is present in many natural and engineering systems which include different scales. It is important to study the energy cascade (which refers to the energy transfer among the different scales) of such systems. A well-known example is turbulent flow in which the kinetic energy of large vortices is transferred to smaller ones. Below a threshold vortex scale the energy is dissipated due to viscous friction. We introduce a mechanistic model of turbulence which consists of masses connected by springs arranged in a binary tree structure. To represent the various scales, the masses are gradually decreased in lower levels. The bottom level of the model contains dampers to provide dissipation. We define the energy spectrum of the model as the fraction of the total energy stored in each level. A simple method is provided to calculate this spectrum in the asymptotic limit, and the spectra of systems having different stiffness distributions are calculated. We find the stiffness distribution for which the energy spectrum has the same scaling exponent (−5/3) as the Kolmogorov spectrum of 3D homogeneous, isotropic turbulence.
New Insights Into Shape Memory Alloy Bimorph Actuators Formed by Electron Beam Evaporation
Authors: Sun Hao , Luo Jianjun , Lu Ming , Nykypanchuk Dmytro , Shi Yong
Published: November 2018

In order to create shape memory alloy (SMA) bimorph microactuators with high-precision features, a novel fabrication process combined with electron beam (E-beam) evaporation, lift-off resist and isotropic XeF2 dry etching method was developed. To examine the effect of E-beam deposition and annealing process on nitinol (NiTi) characteristics, the NiTi thin film samples with different deposition rate and overflow conditions during annealing process were investigated. With the characterizations using scanning electron microscope and x-ray diffraction, the results indicated that low E-beam deposition rate and argon employed annealing process could benefit the formation of NiTi crystalline structure. Besides, SMA bimorph microactuators with high-precision features as small as 5 microns were successfully fabricated. Furthermore, the thermomechanical performance was experimentally verified and compared with finite element analysis simulation results.