bluuebunny/crossref_metadata_2025_split huggingface dataset:
Explicit Time Integration of Multibody Systems Modelled With Three Rotation Parameters
Authors: Holzinger Stefan , Gerstmayr Johannes 
Published: November 2020

Abstract
Rigid bodies are an essential part of multibody systems. As there are six degrees of freedom in rigid bodies, it is natural but also precarious to use three parameters for the displacement and three parameters for the rotation parameters — since there is no singularity-free description of spatial rotations based on three rotation parameters. Standard formulations based on three rotation parameters avoid singularities, e.g. by applying reparameterization strategies during the time integration of the rotational kinematic equations. Alternatively, Euler parameters are commonly used to avoid singularities. State of the art approaches use Lie group methods, specifically integrators, to model rigid body motion without the need for the above mentioned solutions. However, the methods so far have been based on additional information, e.g., the rotation matrix, which has to been computed in each step. The latter procedure is thus difficult to be implemented in existing codes that are based on three rotation parameters. In this paper, we use the rotation vector to model large rotations. Whereby Lie group integration methods are used to compute consistent updates for the rotation vector in every time step. The resulting rotation vector update is finite, while the derivative of the rotation vector in the singularity becomes unbounded. The advantages of this method are shown in an example of a gyro. Additionally, the method is applied to a multibody system and the effects of crossing singularities are presented.
Damage Identification Using Static and Dynamic Responses Based on Topology Optimization and Lasso Regularization
Authors: Sugai Ryo , Saito Akira , Saomoto Hidetaka 
Published: November 2020

Abstract
This paper presents a damage identification method based on topology optimization and Lasso regularization. The method uses static displacements or dynamic responses to identify damages of structures. The method has the potential to identify damages with high fidelity, in comparison with ordinary damage identification method based on optimization with parameterized geometry of the damages. However, it is difficult to precisely detect damage using topology optimization due mostly to the large number of design variables. Therefore, supposing that the damage is sufficiently small, we propose a method adding Lasso regularization to the objective functions to suppress active design variables during topology optimization process. To verify the effectiveness of the proposed method, we conducted a set of numerical experiments for static and dynamic problems. We have succeeded in suppressing active design variables and delete artificially generated damages and the location and shape of damage have been precisely identified.
Complete, Minimal and Continuous Kinematic Error Models of Perfect Multi-DOF Joints for Parallel Manipulators
Authors: Kong Lingyu , Chen Genliang , Zhang Zhuang , Xie Anhuan , Wang Hao , Zhang Dan 
Published: November 2020

Abstract
Kinematic error model plays an important role in improving the positioning accuracy of robot manipulators by kinematic calibration. In order to get a better calibration result, the error model should satisfy complete, minimal and continuous criteria. In order to meet the complete requirement, the multi degree-of-freedom (DOF) joints, such as universal or spherical joint in parallel robots, have to be regarded as serial chains formed by multiple independent single DOF joints, such that the manufacturing errors of these joints can be considered. However, several previous work found that these manufacturing errors for some parallel manipulators have little effect on the accuracy improvement. Besides, considering these kind of errors will cause the kinematics to be much more complicated. Therefore, under the assumptions of perfectly manufactured universal, spherical and cylinder joints, a complete, minimal and continuous (CMC) error model is presented in this paper. The identifiability of the kinematic errors of these multi-DOF joints are analytically analyzed. In order to verify the correctness and effectiveness of the proposed method, a numerical simulation of kinematic calibration is conducted on a 6-UPS parallel manipulator. The calibration result is also compared to the one derived from the error model with 138 error parameters. Since the error model and calibration methods are described uniformly, it can be applied to most parallel manipulators.
DynManto: A Matlab Toolbox for the Simulation and Analysis of Multibody Systems
Authors: Held Alexander , Moghadasi Ali , Seifried Robert 
Published: November 2020

Abstract
The Dynamic Modeling and Analysis Toolbox DynManto is an acedemic Matlab code which allows the modeling, simulation and sensitivity analysis of spatial multibody systems. The kinematics of rigid and flexible bodies is described by the floating frame of reference formulation and the body properties are provided by standard input data files. In this way the evaluation of the equations of motion is computationally efficient and an arbitrary parameterization of the system can be achieved. The latter is important in the automated adjoint sensitivity analysis of multibody systems, which yields gradient information for system analyses, parameter identifications or gradient-based optimizations. The capabilities of DynManto are demonstrated by the application examples of a flexible two-arm manipulator and Chebyshev’s Lambda Mechanism.
Collocated Position Control of Oscillatory System in Presence of Delay
Authors: Szaksz Bence , Stepan Gabor 
Published: November 2020

Abstract
The stability of the collocated position control of a mass is studied when a pendulum is attached to it. The simplest proportional-derivative (PD) controller is applied, but the relevant constant time delay is taken into account. The linearized governing equations of the system are investigated. Stability charts are constructed for different pendulum parameters. Closed form expression is derived for the critical time delay; for delay values larger than the critical one, the PD controller cannot stabilize the desired position of the mass. The frequencies of the self-excited vibrations at the stability boundaries have essential role in identifying the types of loss of stability.
Assessment of Conceptual Design Problems Comprising Design Rationale and Sketches
Authors: Khan Sumbul , Maheshwary Khushbu , Arlitt Ryan , Blessing Lucienne 
Published: November 2020

Abstract
Conventional forms of design assessment are time consuming for instructors. Crowdsourced assessment of students’ design concepts raises the need of efficient rubrics that facilitate novices to score similar to experts, in reduced time. We investigate rubrics in the context of conceptual design problems, that comprise open-ended questions, requiring students to express their design concepts and supporting rationale using text and sketches. We conducted exploratory post-hoc analysis on assessment data collected by instructors of a Design program at a Singaporean secondary school. Our results suggest that integrated rubrics — that consider both text and sketch component together — are better suited for the assessment of conceptual design problems, than task-specific rubrics, that consider textual and sketch components separately. Evidence from both novice assessors as well as experts suggests that the articulation of design rationale using text is crucial for the assessment of conceptual design problems as it provides assessors input into why design decisions were taken, thus aiding in the evaluation process. Our insights are relevant for developing frameworks that employ crowdsourcing for the assessment of conceptual design problems.
A Two-Stage Extension of the Generalized-α Method for Constrained Systems in Mechanics
Authors: Jay Laurent O. , Merwine Brice Ch. , Sugiyama Hiroyuki , Yamashita Hiroki 
Published: November 2020

Abstract
We present a new two-stage second order extension of the generalized-α method of Chung and Hulbert for systems in mechanics having nonconstant mass matrix and holonomic constraints. Both the position and velocity level constraints are preserved. The extension lends itself to efficient implementation.
Multi-Objective Optimization of the Impeller Geometry for an Automotive Torque Converter Using RBF and NSGA-II Methods
Authors: Chen Jie , Wu Guangqiang 
Published: November 2020

Abstract
Since impeller shape has great influence on hydraulic performance of a torque converter, a multi-objective optimization method based on non-dominated sorting genetic algorithm II (NSGA-II) has been used to redesign the impeller geometry. Radial basis function (RBF) is attempted to establish the surrogate models for performance responses in impeller design. A sophisticated automotive torque converter case is exemplified, which demonstrates that RBF provides a better surrogate accuracy and NSGA-II is more effective than the other methods studied. To verify the optimization results, the complete numerical characteristic curves of the torque converter with the optimized impeller are compared to the validated numerical characteristic curves of the initial torque converter. The numerical results show that the stall torque ratio and peak efficiency are increased by 3.18% and 1.4%, respectively. The results indicate a reasonable improvement in the optimal design of torque converter impeller and a higher performance using the NSGA-II method.
A Heterogeneous Model for Gait Analysis of the Lower-Limb and the Prosthesis Coupled System
Authors: Lv Yang , Fang Hongbin , Xu Jian , Wang Qining , Zhang Xiaoxu 
Published: November 2020

Abstract
By considering the coupling effect between the healthy lower-limb and the passive prosthesis, this paper builds a heterogeneous dynamic model for gait analysis, where the motions of the healthy limb and the prosthesis are driven by the central pattern generator (CPG) and the hip joint swing, respectively. The foot-ground contact is modelled as the process of unilateral force reaction rather than the constraint to get a refined representation of the gait motion. The response of the heterogeneous model, solved by numerical calculation, is then analyzed by comparison with a real gait test. Preliminary results show that the heterogeneous model not only describes the amputee’s gait well but also reveals a new gait feature of period-doubling. Parameter analysis further indicates that the period-doubling gait will return to the single-period pattern by amplifying the vertical motion of the hip joint at the amputated side. This dynamic bifurcation, which mimics the process of hip swing adaption, provides new insight into the compensatory mechanism for lamely walking.
A Topology Optimization Method for the Design of Orthotropic Plate Structures
Authors: Smith Hollis , Norato Julian 
Published: November 2020

Abstract
This work introduces a topology optimization method for the design of structures composed of rectangular plates each of which is made of a predetermined anisotropic material. This work builds upon the geometry projection method with two notable additions. First, a novel geometric parameterization of plates represented by offset surfaces is formulated that is simpler than the one used in previous works. Second, the formulation presented herein adds support to the geometry projection method for geometric components with general anisotropic material properties. A design-generation framework is formulated that produces optimal designs composed exclusively of rectangular plates that may be made of a predetermined, generally anisotropic material. The efficacy of the proposed method is demonstrated with a numerical example comparing optimal cantilever beam designs obtained using isotropic- and orthotropic-material plates. For this example, we maximize the stiffness of the structure for a fixed amount of material. The example reveals the importance of considering material anisotropy in the design of plate structures. Moreover, it is demonstrated that an optimally stiff design for plates made of an isotropic material can exhibit detrimental performance if the plates are naively replaced with an anisotropic material. Although the example given in this work is in the context of orthotropic plates, since the formulation presented in this work supports arbitrary anisotropic materials, it may be readily extended to support the design of each component’s material anisotropy as a part of the optimization routine.
Estimation of Reaction Time During Human Balancing on Rolling Balance Board Based on Mechanical Models
Authors: Molnar Csenge A. , Insperger Tamas 
Published: November 2020

Abstract
Human balancing on rolling balance board in the sagittal plane is analyzed such that the geometry of the balance board can be adjusted: the radius R of the wheels and the elevation h between the top of the wheels and the board can be changed. These two parameters have a significant influence on the stability of standing on the board as shown by preliminary experiments. The human body was modeled by a single inverted pendulum, while the balance board was considered by the geometry of the mechanical model. Based on literature, it was assumed that the central nervous system (CNS) controls by signals proportional to the angle and angular velocity of the human body and the balance board and is able to tune the feedback gains with 40% accuracy during the balancing process. To take the reaction time into consideration, operation of the CNS was modeled as a delayed proportional-derivative feedback. The critical time delay for the stabilization process is defined such that if the delay is larger than the critical one then no control gains could stabilize the system. Four balance board configurations were chosen with different wheel radius and the corresponding critical time delays were computed based on the mechanical model. Eight young healthy individuals participated in the experiments. Their task was to perform 60 s long balancing trials on each balance board. The reaction time of the participants was estimated by comparing the numerical results obtained for the critical time delay and their successful and unsuccessful balancing trials. The reaction times were found to be in the range of 0.10–0.15 s which are in good agreement with the literature.
Generative Design of Origami-Inspired Mechanisms With a Variational Level Set Approach
Authors: Ye Qian , Gu Xianfeng David , Chen Shikui 
Published: November 2020

Abstract
Origami has inspired the engineering design of self-assemble and re-configurable devices. Under particular crease patterns, a 2D flatten object can be transformed into a complex 3D structure. This work intends to find out a systematic solution for topology optimization of origami structures. The origami mechanism is simulated using shell models where the in-plane membrane, out of plane bending, and shear deformation can be well captured. Moreover, the pattern of the folds is represented implicitly by the boundaries of the level set function. The topology of the folds is optimized by minimizing a new multiobjective function, aiming to balance the kinematic performance with the structural stiffness as well as the geometric requirements. Besides regular straight folds, our proposed model can mimic crease patterns with curved folds. With the folding curves implicitly represented, the curvature flow are utilized to control the complexity of the generated folds. The effectiveness of the proposed method is demonstrated through the computational generation and physical validation of a thin-shell origami gripper.
Virtual Reality to Improve the User Experience of Traditional Museums
Authors: Spadoni Elena , Carulli Marina , Bordegoni Monica 
Published: November 2020

Abstract
Museums have been subjected to important changes in the approach they use to involve visitors. Among the other trends, storytelling and interactive exhibitions are two of the most used approaches used to make exhibitions more interesting for users. Virtual Reality and Augmented Reality methods can be effectively used in the context of a museum exhibition to support both storytelling and interaction. The primary objective of the use of these technologies is to make the visit of museums much more engaging, and suitable for different types of visitors.
Among the several museums that are moving in this direction, there is the Museo Astronomico di Brera. The museum mainly consists of a corridor, hosting instruments used by astronomers, and the Cupola Schiaparelli, which is an observatory dome.
The aim of the research presented in this paper is to develop an interactive Virtual Reality application to be used for improving the users’ experience of visits to the Museo Astronomico di Brera. Specifically, the paper presents a VR application to virtually visit the Dome. Preliminary tests have been carried out for evaluating the users’ sense of presence in the VR environment. An analysis of the collected data is presented in the paper.
On the Design of an Innovative Eight-Bar Linkage Walking Machine
Authors: Lin Bo-Hong , Chen Yu-Hsun 
Published: November 2020

Abstract
A walking machine is equipped with leg mechanisms so that it can move across uneven ground. In this study, feasible leg mechanisms for walking machines are generated through the Creative Mechanism Design Methodology, including the steps of existing designs analysis, generalization, specialization, and particularization. One design of a linkage mechanism with eight links and ten joints is selected at the first step. Then, according to the concepts of generalization and specialization, one of the kinematic generalized chains with the same number of links and joints is chosen, and five feasible specialized chains are generated by assigning the frame, thigh link, calf link, and the crank, sequentially. Moreover, by applying feature encoding, two of the feasible designs are obtained by removing the results that cannot fit the motion characteristics, and the corresponding mechanism sketches are presented through particularization. One of the innovation designs is selected, and the dimensional synthesis is made through the techniques in geometric constraint programming. Finally, the motion characteristics are determined to verify its feasibility through theorical determination and computer simulation. The analysis results can be used to explore kinetics and mechanism advantage.
Development of a Multi-DOF Tuned Dynamic Absorber for Reducing Hand Vibrations on an Off-Highway Vehicle
Authors: Xu Hongan , Clark David , Zeis Marlin , Hill Mike , Zambito Tony 
Published: November 2020

Abstract
A variety of off-highway vehicles are subject to significant steering wheel vibrations during operation. Typical examples of such machines are vibratory asphalt and soil compactors. Large compacting forces, while essential for the proper compacting operation, will inevitably cause undesired effects such as severe vibrations of steering wheels. Traditional vibration control measures are often found either impractical or less effective in reducing the level of hand vibrations which is considered an important quality and safety issue in compacter design and sales. In this paper, an advanced concept of reducing hand vibrations is presented in the context of Multi-degree-of-freedom Tuned Dynamic Absorbers (MTDA). The MTDA essentially represents an assembly of simple dynamic absorbers individually tuned to different targeted vibration modes in different degree of freedoms. While the design concept and associated parameters are numerically determined by FEA, the prototype is fine tuned to the desired vibration modes through a bench test. The effectiveness of the MTDA is experimentally verified in-situ through a sequence of tests which are carefully designed to adequately reflect its performance under field conditions.
Inverse Identification of Non-Linear ODEs for the Dynamic Control of Material Testing Systems
Authors: Lunasin Evelyn M. , Iliopoulos Athanasios P. , Michopoulos John G. , Steuben John C. 
Published: November 2020

Abstract
The development of advanced robotic systems for material testing by the U.S. Naval Research laboratory has expanded the set of requirements for mechatronic system control. This expansion lies beyond the limits of readily available control system capabilities because of the high control rate requirements. To establish this capability, a control mechanism based on the online identification of the ordinary differential equation governing the coupled equations of motion and deformation is proposed in the present work. The part of the proposed approach involving the inverse identification of the ODEs at hand is described in its general form first. Subsequently, the numerical verification is demonstrated via synthetic tests for a compliant actuation system with varying levels of noise injected in the system.
Excimer Laser Treatment of Nylon Fibers for Improved Adhesion to Vulcanized Natural Rubber
Authors: Sancaktar Erol , Basan Satilmis 
Published: November 2020

Abstract
Cords made of steel, nylon or polyester are important reinforcement components used in tire industry. The bond strength between the cords and the rubber matrix is closely related to the surface properties of the cord fibers. Previous research revealed Ultraviolet (UV) laser-induced characteristic topography on synthetic fibers after irradiation, which is considered by us as an advantageous factor in developing bonding strength between fiber-rubber composites. We applied various UV laser treatments on the surfaces of nylon fibers in order to obtain similar topographic features. Adhesion is affected by the valleys and peaks that form on the surface of the fibers by laser radiation. In this study, nylon cords were irradiated with different number of UV pulses using an excimer laser to understand the effect of the laser beam on nylon fiber-rubber adhesion. A fiber pull-out test method developed by our research group for bonding strength of nylon cord fibers to carbon black filled and vulcanized natural rubber was utilized in pull-out configuration. The results showed that the maximum pull-out load was reached at 300 laser pulses and then decreased.
Favoring Complexity: A Mixed Methods Exploration of Factors That Influence Concept Selection in Design for Additive Manufacturing
Authors: Prabhu Rohan , Leguarda Rainmar L. , Miller Scarlett R. , Simpson Timothy W. , Meisel Nicholas A. 
Published: November 2020

Abstract
The capabilities of additive manufacturing (AM) open up designers’ solution space and enable them to build designs previously impossible through traditional manufacturing. To leverage AM, designers must not only generate creative ideas, but also propagate these ideas without discarding them in the early design stages. This emphasis on selecting creative ideas is particularly important in design for AM (DfAM), as ideas perceived as infeasible through the traditional design for manufacturing lens could now be feasible with AM. Several studies have discussed the role of DfAM in encouraging creative idea generation; however, there is a need to understand concept selection in DfAM. In this paper, we investigated the effect of two variations in DfAM education: 1) restrictive DfAM and 2) dual DfAM (opportunistic and restrictive) on students’ concept selection process. Specifically, we compared the creativity of the concepts generated by the students to the creativity of the concepts selected by them. Further, we performed qualitative analyses to explore the rationale provided by the students in making these design decisions. From the results, we see that teams from both educational groups select ideas of greater usefulness; however, only teams from the restrictive DfAM group select ideas of higher uniqueness and overall creativity. Further, we see that introducing students to opportunistic DfAM increases their emphasis on the complexity of designs when evaluating and selecting them. These results highlight the need for DfAM education to encourage AM designers to not just generate but also select creative ideas.