bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multibody Analysis of a Tensegral Servo-Actuated Structure for Civil Applications
Authors: Scoccia Cecilia , Palmieri Giacomo , Callegari Massimo , Rossi Marco , Carbonari Luca , Munafò Placido , Marchione Francesco , Chiappini Gianluca 
Published: November 2021

Abstract
The use of glass elements in civil engineering is spreading in the last years beyond merely aesthetic functions for their ease of installation and production. Nonetheless, the structural performance of such materials in any condition of use is object of investigation. In this scenario, the paper analyses the performance of an innovative concept of tensegrity floor (Patent no 0001426973) characterized by a particular steel-glass adhesive junction that permits a profitable structural cooperation between such basically different materials. As known, at the base of the effectiveness of tensegral structures lies the correct tensioning of metal strands which are devoted at keeping the rigid elements compressed. The tensioning level is then responsible of the actual deformation of the structure, which is of course of uttermost importance while speaking of civil applications. To address this issue with the adequate level of confidence required by construction practice, a mechatronic servo-system is proposed, aimed at maintaining, and modifying when needed, the stress state of the metal cables to adjust the deformation of the upper plane in response to varying loads. Three different actuation schemes, with different levels of realization complexity, are analysed and compared in simulated environment by means of a hybrid multibody-finished elements mode.
Can Gratitude Promote More Creative Engineering Design?
Authors: Sisson Natalie M. , Impett Emily A. , Shu L. H. 
Published: November 2021

Abstract
Urgent societal problems, including climate change, require innovation, and can benefit from interdisciplinary solutions. A small body of research has demonstrated the potential of positive emotions (e.g., gratitude, awe) to promote creativity and prosocial behavior, which may help address these problems.
This study integrates, for the first time, psychology research on a positive and prosocial emotion (i.e., gratitude) with engineering-design creativity research. In a pre-registered study design, engineering students and working engineers (pilot N = 49; full study N = 329) completed gratitude, positive-emotion control, or neutral-control inductions. Design creativity was assessed through rater scores of responses to an Alternate Uses Task (AUT) and a Wind-Turbine-Blade Repurposing Task (WRT).
No significant differences among AUT scores emerged across conditions in either sample. While only the pilot-study manipulation of gratitude was successful, WRT results warrant further studies on the effect of gratitude on engineering-design creativity. The reported work may also inform other strategies to incorporate prosocial emotion to help engineers arrive at more original and effective concepts to tackle environmental sustainability, and in the future, other problems facing society.
Design of a Human-Robot Collaborative System: Methodology and Case Study
Authors: Scoccia Cecilia , Ciccarelli Marianna , Palmieri Giacomo , Callegari Massimo 
Published: November 2021

Abstract
Human-machine collaboration is one of the key drivers of the Industry 4.0 paradigm. The recent advances in collaborative robotics led to the effective implementation of various control strategies able to improve interactions between robots and humans in unstructured environments. This represents an important socio-economic aspect: the robot does not replace the human being, but supports them in carrying out repetitive or dangerous tasks. In this scenario it is necessary to take into account different contrasting issues that derive from the necessity to grant the high performance typical of a robotic installation together with the safety levels required by a manual operation. In this paper we analyse the use case of a famous kitchen industry that decided to test the introduction of collaborative robotics to increase the flexibility and productivity of their production lines. A method, to define the design criteria of the Human-Robot Collaboration system (HRC), is proposed taking into account aspects related to both the safety and the ergonomics of the human operator, using a real-time mapping of the work area and the management of operations. The collaboration between robot and operator can be facilitated thanks to the use of an assistive device which, through the recognition of gestures, allows easy communication. Therefore, this paper aims to combine: operator safety and ergonomics, study of the workstation, sensor technologies, identification and tracing of gestures. Several simulations have been performed to evaluate the proposed collaborative workstation.
A Modified Incremental Harmonic Balance Method for Periodic Forced Oscillations of a Dielectric Elastomer Membrane Undergoing In-Plane Deformation
Authors: Zhang Jian , Zhao Jian , Wang Xuefeng , Wang Hongyu 
Published: November 2021

Abstract
Dielectric elastomers (DEs) are widely used in soft transducers with mechanical or electrical loads. DE devices are mainly used for applications under dynamic loads, such as, ocean wave generators, loudspeakers, oscillators, and artificial muscles. It is still a challenge to analytically solve the vibration equation of a DE transducer. For example, for a DE membrane undergoing stretching deformation that is studied in this paper, its vibration equation is highly nonlinear with high-order and fractional-order polynomials. Numerical integration (NI) methods or traditional harmonic balance (HB) methods were used in previous works, but the two methods have low efficiency for strong and complex nonlinearities, and it is difficult to improve the accuracy of the solution. In this work, a free-energy model is used to study the dynamic characteristics of a DE membrane undergoing in-plane deformation, which undergoes a combined load excited by mechanical compression and electric fields. To improve the calculation efficiency and accuracy, we employ a modified incremental harmonic balance (IHB) method based on the fast Fourier transform to solve the periodically-excited nonlinear dynamic equation of the DE membrane. Finally, results of the example verify that the modified IHB method is fast and accurate, and has a very good performance in solving a problem with high nonlinearities.
Potential Energy Surfaces for Conceptual Design and Analysis of Mechanical Systems
Authors: Manion Charles A. , Fuge Mark 
Published: November 2021

Abstract
Current computational Design Synthesis approaches have had trouble generating components with higher kinematic pairs and have instead relied on libraries of predefined components. However, higher kinematic pairs are ubiquitous in many mechanical devices such as ratchets, latches, locks, trigger mechanisms, clock escapements, and materials handling systems. In many cases there is a need to synthesize new higher kinematic pair devices. To address this problem, we develop a new representation for mechanical systems that extends the capabilities of configuration spaces to consider arbitrary energy storing mechanical devices. The key idea underlying this representation is the use of potential energy surfaces as a generalization of configuration spaces. This generalization enables modelling of mechanical systems in a physics independent manner and captures behaviors such as dynamics. By modeling a device through the lens of a potential energy surface, we demonstrate that differentiable simulation is possible. Differentiable simulation enables efficient calculation of gradients of potential energy surface parameters with respect to an objective function that depends on trajectories taken on the potential energy surface. This allows synthesis of mechanical devices with desired kinematic and dynamic behavior through gradient descent. We demonstrate this through several synthesis examples including positioning devices (e.g., a funnel) and timing devices (e.g., an oscillator).
Evoked Electromyographic Fatigue Indices During Intermittent Stimulation Towards Dynamic Wrist Contractions
Authors: McKenzie Lachlan R. , Fortune Benjamin C. , Chatfield Logan T. , Pretty Christopher G. 
Published: November 2021

Abstract
Functional electrical stimulation (FES) in stroke rehabilitation is hindered by early patient fatigue. Therefore the study of FES-elicited fatigue is needed to optimise its therapeutic impact. In this study, the reliability of evoked electromyography (EMG) median frequency (MDF) and peak-to-peak (PTP) fatigue indices were investigated during stimulation of the forearm. During isometric constant stimulation the MDF-time and PTP-time waveforms exhibited negative gradients in the ranges (−1.3 to −3.6) Hz · s−1 and (−0.013 to −0.016) V · s−1 respectively, most with coefficients of determination (R2) greater than 0.83. During vEMG-controlled stimulation the MDF-contraction waveforms exhibited negative gradients in the range (−2.4 to −9.0) Hz · Cont−1 while the PTP gradients ranged from (0.0070 to −0.019) V · Cont−1. For these datasets the MDF waveforms’ R2 &gt; 0.62 and most PTP waveforms’ R2 &lt; 0.35. These findings suggest that the MDF and PTP amplitude are suitable fatigue indices during isometric constant stimulation but the PTP-based index becomes unreliable during vEMG-controlled stimulation.
Uncertainty Quantification and Reduction Using Sensitivity Analysis and Hessian Derivatives
Authors: Sánchez Josefina , Otto Kevin 
Published: November 2021

Abstract
We study the use of Hessian interaction terms to quickly identify design variables that reduce variability of system performance. To start we quantify the uncertainty and compute the variance decomposition to determine noise variables that contribute most, all at an initial design. Minimizing the uncertainty is next sought, though probabilistic optimization becomes computationally difficult, whether by including distribution parameters as an objective function or through robust design of experiments. Instead, we consider determining the more easily computed Hessian interaction matrix terms of the variance-contributing noise variables and the variables of any proposed design change. We also relate the Hessian term coefficients to subtractions in Sobol indices and reduction in response variance. Design variable changes that can reduce variability are thereby identified quickly as those with large Hessian terms against noise variables. Furthermore, the Jacobian terms of these design changes can indicate which design variables can shift the mean response, to maintain a desired nominal performance target. Using a combination of easily computed Hessian and Jacobian terms, design changes can be proposed to reduce variability while maintaining a targeted nominal. Lastly, we then recompute the uncertainty and variance decomposition at the more robust design configuration to verify the reduction in variability. This workflow therefore makes use of UQ/SA methods and computes design changes that reduce uncertainty with a minimal 4 runs per design change. An example is shown on a Stirling engine design where the top four variance-contributing tolerances are matched with two design changes identified through Hessian terms, and a new design found with 20% less variance.
Kinematic Modeling of a Novel RR-RP Hybrid Serial-Parallel Mechanism With Variable Topology
Authors: Slaboch Brian J. , Holtzen Peter , Rodriguez Luis A. 
Published: November 2021

Abstract
This paper introduces a new mechanism that will be classified as an RR-RP hybrid serial-parallel mechanism with variable topology. A mechanism with variable topology is a mechanism that can change its topology due to a change it its joints constraint geometric profile. The RR-RP is unique in that it combines the functionality of both an RR and RP serial manipulator without the need for an additional actuator, leading to a lower weight, lower cost, and more efficient mechanism. The new mechanism and its topology are presented, followed by a workspace analysis, derivation of the forward and inverse kinematics, and velocity analysis of the new mechanism.
Visualizing Model-Based Product Definitions in Augmented Reality
Authors: Vernica Teodor , Lipman Robert , Bernstein William Z. 
Published: November 2021

Abstract
Augmented reality (AR) technologies present immense potential for the design and manufacturing communities. However, coordinating traditional engineering data representations into AR systems without loss of context and information remains a challenge. A major barrier is the lack of interoperability between manufacturing-specific data models and AR-capable data representations. In response, we present a pipeline for porting standards-based Product Manufacturing Information (PMI) with three-dimensional (3D) model data into an AR scene. We demonstrate our pipeline by interacting with annotated parts while continuously tracking their pose and orientation. Our work provides insight on how to address fundamental issues related to interoperability between domain-specific models and AR systems.
Optimized Torque Assistance During Walking With an Idealized Hip Exoskeleton
Authors: Ratnakumar Neethan , Zhou Xianlian 
Published: November 2021

Abstract
The hip muscles account for a great percentage of the total human energy expenditure during walking and many wearable devices have been developed in assisting the hip joint to reduce the metabolic Cost Of Transport (COT) for walking. However, the effectiveness of assisting the hip in only one direction (either flexion or extension) or both directions has not been systematically studied and the underlying muscle mechanics and energetics affected by the assistance are not well understood. In this study, human-exoskeleton simulation based optimizations were performed to find optimized hip assistance torque profiles for (1) unidirectional flexion assistance, (2) unidirectional extension assistance, and (3) bidirectional flexion and extension assistance. Our results show that the bidirectional assistance is the most effective in reducing the COT of walking (22.7% reduction) followed by flexion (19.2%) and extension (11.7%). The flexion assistance resulted in more COT saving than the output of its net work by 35.9%, which indicates that the negative work done (42.2% of its positive counterpart) also played an important role in reducing the COT. The bidirectional assistance also reduced the activations of the hip extensors to a great extent and shifted the activation pattern of the hip flexor (ilipsoas). These results can provide valuable information for optimal hip actuation (timing and profiles) and help exoskeleton designers make informed decisions.
A Mixed-Method Analysis of Schedule and Cost Growth in Defense Acquisition Programs
Authors: Hans Atharva , Chaudhari Ashish M. , Bilionis Ilias , Panchal Jitesh H. 
Published: November 2021

Abstract
Cost and schedule overruns are common in the procurement of large-scale defense acquisition programs. Current work focuses on identifying the root causes of cost growth and schedule delays in the defense acquisition programs. There is need for a mix of quantitative and qualitative analysis of cost and schedule overruns which takes into account program factor such as, technology maturity, design maturity, initial acquisition time, and program complexity. Such analysis requires an easy to access database for program-specific data about how an acquisition programs’ technical and financial characteristics vary over the time. To fulfill this need, the objective of this paper is twofold: (i) to develop a database of major US defense weapons programs which includes details of the technical and financial characteristics and how they vary over time, and (ii) to test various hypotheses about the interdependence of such characteristics using the collected data. To achieve the objective, we use a mixed-method analysis on schedule and cost growth data available in the U.S. Government Accountability Office’s (GAO’s) defense acquisitions annual assessments during the period 2003–2017. We extracted both analytical and textual data from original reports into Excel files and further created an easy to access database accessible from a Python environment. The analysis reveals that technology immaturity is the major driver of cost and schedule growth during the early stages of the acquisition programs while technical inefficiencies drive cost overruns and schedule delays during the later stages. Further, we find that the acquisition programs with longer initial length do not necessarily have higher greater cost growth. The dataset and the results provide a useful starting point for the research community for modeling cost and schedule overruns, and for practitioners to inform their systems acquisition processes.
Teleoperation Interface for sAFAM, a Solid Articulated Four Axes Microrobot
Authors: Alqatamin Moath , Ritz Brooke , Sherehiy Andriy , Jackson Douglas , Zhang Ruoshi , Chowdhury Sri S. , Wei Danming , Popa Dan O. 
Published: November 2021

Abstract
The sAFAM is a novel mm-size microrobot built using MicroElectroMechanical Systems (MEMS) technology. It consists of a monolithically fabricated microrobotic arm assembled onto four in-plane actuators, capable of moving along four degrees of freedom, including translational movement in X and Y axes as well as pitch and yaw. In this paper, several design modifications were proposed to increase movement precision, stability, and controllability to the sAFAM tip. An interface is developed to assist a human operator accurately position the microrobot tip during nano-object handling. A Python-based graphical user interface (GUI) was programmed to make it intuitive for an operator to use and obtain required tip precision under a microscope. Experimental results demonstrate the functionality of the proposed control solution, and the tip motion resolution using microscope images of the microrobot tip under 20x magnification during operation. The hardware and software requirements for the proposed experimental setup and control platform are discussed in detail.
Robot Motion Planner for Under-Constrained Trajectories With Part-Specific Geometric Variances
Authors: Oridate Ademola , Pryor Mitchell , Seepersad Carolyn 
Published: November 2021

Abstract
Industrial manipulators often interact with large and complex objects for a variety of automation tasks. Finding a feasible path for the robot end-effector that ensures task success is often non-trivial due to considerations such as reachability, singularity avoidance, and collision avoidance. This paper proposes an approach to expand the search space for feasible robot trajectories (and search for an optimal solution) by taking advantage of task redundancy for certain tasks while ensuring task completion. The effort builds on previous work enabling virtual fixture generation for complex shapes given CAD or scan data. The proposed method has been developed into a trajectory planning library on the ROS (Robot Operating System) framework and tested by simulating an interaction of a six-axis industrial robot with an aircraft fuselage. Results show increased coverage of task area with minimal robot base placements.
Calibration of Parallel Kinematic Machine Based on Stewart Platform – A Literature Review
Authors: Karmakar Sourabh , Patel Apurva , Turner Cameron J. 
Published: November 2021

Abstract
Stewart platform-based Parallel Kinematic Machines (PKM) have been extensively studied by researchers due to their inherent finer control characteristics. This has opened its potential deployment opportunities in versatile critical applications like the medical field, engineering machines, space research, electronic chip manufacturing, automobile manufacturing, etc. All these precise, complicated, and repeatable motion applications require micro and nano-scale movement control in 3D space; a 6-DOF PKM can take this challenge smartly. For this, the PKM must be more accurate than the desired application accuracy level and thus proper calibration for a PKM robot is essential. Forward kinematics-based calibration for such hexapod machines becomes unnecessarily complex and inverse kinematics complete this task with much ease. To analyze different techniques, an external instrument-based, constraint-based, and auto or self-calibration-based approaches have been used for calibration. This survey has been done by reviewing these key methodologies, their outcome, and important points related to inverse kinematic-based PKM calibrations in general. It is observed in this study that the researchers focused on improving the accuracy of the platform position and orientation considering the errors contributed by a single source or multiple sources. The error sources considered are mainly structural, in some cases, environmental factors are also considered, however, these calibrations are done under no-load conditions. This study aims to understand the current state of the art in this field and to expand the scope for other researchers in further exploration in a specific area.
Informed Latent Space Exploration for Image-Based Path Synthesis of Linkages
Authors: Deshpande Shrinath , Lyu Zhijie , Purwar Anurag 
Published: November 2021

Abstract
This paper brings together rigid body kinematics and machine learning to create a novel approach to path synthesis of linkage mechanisms under practical constraints, such as location of pivots. We model the coupler curve and constraints as probability distributions of image pixels and employ a Convolutional Neural Network (CNN) based Variational AutoEncoder (VAE) architecture to capture and predict the features of the mechanism. Plausible solutions are found by performing informed latent space exploration so as to minimize the changes to the input coupler curve while seeking to find user-defined pivot locations. Traditionally, kinematic synthesis problems are solved using precision point approach, wherein the input path is represented as a set of points and a set of equations in terms of design parameters are formulated. Generally, this problem is solved via optimization, wherein a measure of error between the given path and the coupler curve is minimized. A limitation of this approach is that the existing formulations depend on the type of mechanism, do not admit practical constraints in a unified way, and provide a limited number of solutions. However, in the machine design pipeline, kinematic synthesis problems are concept generation problems, where designers care more about a large number of plausible and practical solutions rather than the precision of input or the solutions. The image-based approach proposed in this paper alleviates the difficulty associated with inherently uncertain inputs and constraints.