bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Modelling and Diagnosis of Transverse Crack and Rotor/Stator Rub in a Flexible Rotor System
Authors: Vashisht Rajiv Kumar , Peng Qingjin
Published: November 2019

Due to unbalance present in a rotating machinery, fluctuating stresses are generated leading to the formation of transverse cracks in rotors. The cracks propagate with the passage of time and increase the amplitude of vibration. High vibration amplitudes can give rise to rotor/stator rubs. During the rubbing phase, the crack propagation gets enhanced due to inter-connected nature of these faults. If left unattended, these faults can cause the premature failure of machine components. Hence, there is a need to develop fault detection mechanisms based on the vibration response so that these faults can be diagnosed during initial stages. The effect of gravity and the presence of cracks significantly changes vibration characteristics of the rotor, which is thoroughly investigated in this research for a two-degrees-of-freedom Jeffcott rotor. It has been observed that during rubbing, high harmonics are excited. These harmonics are integer multiple of the rotor spin frequency. Similar type of the response is also observed due to the presence of a transverse rotor crack. It is difficult to distinguish the type of faults based on the steady state dynamic response only. Instead of working only on a steady state vibration response, the transient vibration response during coasting up of the rotor is considered. During coasting up of the rotor, high harmonics are excited for both the crack as well as rotor/stator rubbing. The excitation of higher harmonics starts at much earlier in the spectrogram of the vertical response for the cracked rotor compared to that of rubbing. This fact is used in the development of a fault diagnosis technique based on Short Time Fourier Transform of the vibration response. The proposed technique can efficiently distinguish different types of faults even if multiple faults coexist.
Improving the Stability of a Bulletproofed Vehicle Using Modified Suspension System
Authors: Sharaf A. M. , Yacoub M. I. , Elhefnawy A. A.
Published: November 2019

Bulletproof or high-class protected VIP vehicles are widely produced based on particular types of OEM (Original Equipment Manufacturer) commercial vehicles. The arising implications of increasing the level of protection of such vehicles have reflected several negative consequences on the vehicle directional stability. This is obviously true, since adding extra armored plates will increase both gross vehicle weight and the height of its center of gravity. Additionally, such vehicles are normally driven at higher speeds during critical evasive maneuvers. The proper selection of suitable suspension system in terms of spring, shock absorber and anti-roll bar for front and rear axles will contribute to the overall vehicle stability. This paper presents both theoretical and experimental investigation to upgrade the suspension system of a particular bulletproof vehicle in order to improve its stability during high-speed cornering maneuvers. For this purpose, six kits of nominated suspension systems have been tested in order to measure their stiffness and damping characteristics. Furthermore, for each suspension kit, the considered bulletproofed vehicle is fully assessed in CarSim® simulation environment. In-order to check the gained simulation results, typical field tests of the fully instrumented vehicle along with the modified suspension kit. From both simulation and field tests, a suitable kit for front and rear suspension system as well as braking system has been recommended not only to carry the additional weight of the heavy armored body but also to maintain the vehicle stability within their allowable limits.
Framework for Design From Manufacturing Data Mapping
Authors: Eddy Douglas , Krishnamurty Sundar , Grosse Ian , Steudel Mark , Shimazu Mike
Published: November 2019

Product development can be accelerated by utilizing increasingly available data from manufacturing and service. Despite data availability, few methods can integrate design to qualify product systems and facilitate the design of a product’s next generation. This work introduces a Design from Manufacturing Data Mapping (DfMDM) framework and process to enable development of predictive analytics techniques to learn final system test results. Salient features of the predictive analytics include introduction of an optimal composition of simulation models to more accurately predict system test results from digital twin data while determining which simulation models are most significant. The approach is demonstrated by a case study that accounts for parametric and model uncertainty. These initial results show that this approach to optimally compose simulation models can reduce error in system test result predictions at early product development stages.
Dynamics Analysis of the Deployment of Miura-Origami Sheets
Authors: Xia Yutong , Wang Kon-Well
Published: November 2019

Origami has emerged as a promising tool for the design of mechanical structures that can be folded into small volume and expanded to large structures, which enables the desirable features of compact storage and effective deployment. Most attention to date on origami deployment has been on its geometry, kinematics, and quasi-static mechanics, while the dynamics of deployment has not been systematically studied. On the other hand, deployment dynamics could be important in many applications, especially in high speed operation and low damping conditions. This research investigates the dynamic characteristics of the deploying process of origami structures through investigating a Miura-Ori sheet (Fig. 1(b, c)). In this study, we have utilized the stored energy in pre-deformed spring elements to actuate the deployment. We theoretically model and numerically analyze the deploying process of the origami sheet. Specifically, the sheet is modeled by bar-and-hinge blocks, in which the facet and crease stiffnesses are modeled to be related to the bar axial deformation and torsional motion at the creases. On the other hand, the structural inertia is modelled as mass points assigned at hinges. Numerical simulations show that, apart from axial contraction and expansion, the origami structure can exhibit transverse motion during the deploying process. Further investigation reveals that the transverse motion has close relationship with the controlled deploying rate. This research will pave the way for further analysis and applications of the dynamics of origami-based structures.
To Classify or Combine: The Effects of Idea Generation Mechanisms on the Novelty and Quantity of Ideas
Authors: Kirjavainen Senni , Hölttä-Otto Katja
Published: November 2019

Idea generation is an integral part of creative problem solving that happens in all businesses developing products — whether they were services or physical products. Idea generation methods have been studied against one another to create an understanding on how to produce most novel and innovative ideas or how to use certain mechanisms such as incubation or analogies in order to promote idea generation.

This paper presents a study comparing two idea generation mechanisms used as interventions during an alternate uses test. A group of 61 participants either classified or combined their ideas from the first round of ideation to come up with more ideas on a second round of idea generation. An outcome-based approach was used to evaluate the data and two metrics, quantity and novelty were used to evaluate the resulting ideas per group and round and unique ideas produced after the intervention.

The results suggest that at least when ideating alone, it is useful to stop and use some time to either classify or stop, observe and start combining the ideas already produced. Both have a positive effect on idea novelty, but classifying ideas results in significantly higher novelty scores over combining ideas. There was no difference in the novelty of unique ideas between the two groups, but both had a positive effect on novelty of unique ideas. Classifying ideas into categories produced significantly more unique ideas than combining ideas.
Dynamics and Control of Self-Standable Motorcycle
Authors: Hara Susumu , Nakagami Koki , Miyata Kikuko , Tsuchiya Mitsuo , Tsujii Eiichirou
Published: November 2019

This study discusses autonomous standing up from the parking mode and ensuring stability for low-speed driving of a novel motorcycle, named “MOTOROiD”. In 2017, Yamaha Motor Co., Ltd. released a motorcycle with a self-stabilizing mechanism, “MOTOROiD.” This prototype has a new rotary axis and can vary the position of the total center of gravity. This axis is called AMCES (Active Mass CEnter control System). This paper shows the modeling of MOTOROiD with parameters uncertainties for the control system design. The modeling is performed based on two different methods for established model verification: Lagrange’s equation method and the multibody dynamics. By using the established model, a unified control method for standing up from the parking mode and ensuring stability is designed by using a two-degree-of-freedom control system structure. The effectiveness of the modeling and control system design to the system with the variable parameter is verified by numerical simulations.
Quadrotor Singularity Free Modeling and Acrobatic Maneuvering
Authors: Liu Haowen , Yang Bingen
Published: November 2019

When an unmanned aerial vehicle (UAV) navigates reactively over an unknown land, it may encounter terrains that require aggressive maneuver to keep the designed coasting speed while staying on the path. During this execution of the aggressive maneuver, the UAV can experience singularity. In this article, a vertical loop aggressive maneuver performed by a quadrotor UAV is investigated. Due to the physical configuration of the quadrotor, the conventional modeling and tracking control method may not be desirable if certain requirements, such as fast coasting speed and sharp turns, are imposed. In this work, a new modeling and maneuver control method, which is called the controlled loop path following (CLPF) method is developed. As shown in numerical examples, the proposed singularity-free model and control method enables a quadrotor to be operated in aggressive maneuverability with features like automatic flipping and precise trajectory following.
Nonlinear Response Identification of an Asymmetric Bistable Harvester Excited at Different Bias Angles by Multiscale Entropy and Recurrence Plot
Authors: Wang Wei , Cao Junyi , Bowen Chris R. , Litak Grzegorz
Published: November 2019

Due to their high sensitivity to excitations with low intensity, bistable energy harvesting systems have received significant attention. In practical applications, it is difficult to achieve a bistable energy harvester (BEH) with a perfectly symmetric potential energy function. Moreover, gravity acts to exert a significant influence on the output response of a BEH oscillator when excited at different bias angles. Therefore, the experimental output voltage time-series of an asymmetric potential BEH are examined in this paper. The BEH studied here is composed of a cantilever beam, two piezoelectric layers at the root and two magnets at the end, and subjected to harmonic excitations at different bias angles. The energy harvesting system exhibited intra-well, periodic and chaotic snap-through vibrational patterns under different excitation frequencies at different bias angles. To better understand the multiple dynamic behaviors of the system corresponding to different power outputs, we identified the output voltage response by the methods of multiscale entropy and recurrence plots. Results indicate that periodic and chaotic vibrational patterns can be readily distinguished by the methods employed. Furthermore, it is demonstrated that the bias angle had a significant influence on the output power of the asymmetric potential BEH.
Kalman Filter Based Sensor Fusion for a Mobile Manipulator
Authors: Ubezio Barnaba , Sharma Shashank , Van der Meer Guglielmo , Taragna Michele
Published: November 2019

End-effector tracking for a mobile manipulator is achieved through Sensor Fusion techniques, implemented with a particular visual-inertial sensor suite and an Extended Kalman Filter algorithm. The suite is composed of an Optitrack motion capture system and a Honeywell HG4930 MEMS IMU, for which a further analysis on the mathematical noise model is reported. The filter is constructed in such a way that its complexity remains constant and independent of the visual algorithm, with the possibility of inserting additional sensors, to further improve the estimation accuracy. Experiments in real-time have been performed with the 12-DOF KUKA VALERI robot, extracting the position and the orientation of the end-effector and comparing their estimates with pure sensor measurements. Along with the physical results, issues related to calibration, working frequency and physical mounting are described.
Theoretical Validation of an Analytical Design Method for Beveloid Gears With Non-Parallel Non-Intersecting Axes
Authors: Marino Daniel , Bachmann Matthias , Binz Hansgeorg
Published: November 2019

An analytical calculation method was developed to determine the main gearing data for beveloid gears with non-parallel non-intersecting axes. To validate the method and identify its limits, a parameter study was to be conducted. A two-stage fractional factorial experimental design was therefore devised to deliberately vary the gearing parameters. For each gearing, an unloaded contact simulation was carried out using the position of the contact pattern, the transmission error and the predefined gear backlash as quality characteristics. The results of the simulation were subsequently classified in three evaluation categories.

Due to the generalizability of the method proposed, it can also be used for the design of other involute gearings. A modification of the equations revealed its applicability for spur gear pairs with no shaft angle and for crossed helical gear pairs with shaft angles up to 90°.

The results for the beveloid gear pairs investigated using a wide range of parameters as well as those for the cylindrical and crossed helical gear pairs proved the validity of the method. In the case of outliers in the evaluation, the causes were identified and corrective actions were presented.
Stress Field Guided Lattice Structure Design Based on Hexahedral Mesh
Authors: Liu Lingyun , Liao Yizhou , Gao Shuming
Published: November 2019

Lattice structures are promising for a wide range of applications. The development of additive manufacturing (AM) technology has made it possible to manufacture complex structures. However, designing the optimal lattices of complex solid models efficiently and automatically remains a challenge. Thus, we propose a novel stress-field-guided lattice design method to improve the mechanical properties of a lattice structure. Stress field is used to make the boundary struts of each cell of a lattice structure aligning to the principal stress direction while remaining conformal. Hierarchical cell templates are designed to reduce the computational burden of the cell optimization of a lattice structure. The proposed method is verified experimentally, and the experimental results prove the efficiency and validity of the proposed method.
Geometric Design of Pure Rolling Rack and Pinion Mechanisms
Authors: Chen Zhen , Zeng Ming , Fuentes-Aznar Alfonso
Published: November 2019

The study of different types of pure rolling rack and pinion mechanisms is presented. They are designed based on the active design of the meshing line to provide pure rolling for the whole cycle of meshing. Parametric equations for contact curves on the rack and pinion are determined by coordinate transformation of the meshing line equations. Moreover, parametric equations for the tooth surfaces of the rack and pinion of three types of meshing, including the convex-to-concave meshing, convex-to-plane meshing, and convex-to-convex meshing are derived according to the motion of generatrices along the calculated contact curves. Then, the basic design parameters are analyzed and formulas for calculation of the geometric size are given. The contact ratio of rack and pinion mechanisms can be designed to be higher than one, which satisfies the condition for the continuous transmission of gears. At last, a numerical simulation is conducted to validate the kinematic performance. This paper lays the foundation for further research of pure rolling rack and pinion mechanisms, their manufacture technology and strength design criterion.
How the Design of a 3D Printer Bridged Engineering Design Processes and the Agile Software Manifesto
Authors: Lindberg Steven , Campbell Matthew I.
Published: November 2019

Individual engineering design projects face different challenges depending on their scale. Instead of dealing with problems of complex multidisciplinary systems, small scale design must overcome issues of limited resources. The philosophy of agile software development has been highly successful in addressing similar issues in the software engineering realm over the past two decades. Through the design and prototyping of a low-budget desktop stereolithography printer, the application of agile principles to engineering design process is explored. The printer’s design is discussed in detail to provide examples of successes and failures when these agile principles are put into practice. The paper concludes with a discussion of how agile principles could be leveraged in engineering design. The approach taken in this paper is more of a longitudinal study of a single design process over a twelve-month period as opposed to rigorous experiments that engage multiple users in short design scenarios. Nonetheless, this case study demonstrates how the application of agile principles can inform, improve, and complement traditional engineering design processes.
Concurrent Topological Optimization of a Wheel and Brake Caliper Assembly
Authors: Gobbi Massimiliano , Previati Giorgio , Ballo Federico
Published: November 2019

The paper deals with the topological optimization of a wheel and brake caliper assembly. In this system, the design of each components is influenced by the actual shape of the other component. In fact, a conflict exists in the room requirements of the two components. In the design process, therefore, not only the material distribution of the two bodies has to be optimized, but also the design space has to be divided in most effective way.

The design of the wheel and brake caliper assembly can be seen as a special class of topological optimization problem. Such problem of concurrent topological optimization of two components sharing part of the design space has been already addressed by the authors in previous papers under the restriction that the two bodies have the same mesh in the shared part of the domain. In this paper, a novel development of the presented optimization algorithm is described. The algorithm is modified in order to allow the concurrent optimization of two bodies with different meshes in the common part of the domain. This new development allows the methodology to be applied to any real problem with arbitrarily complex geometry. The application to the case of the wheel and brake assembly is shown.
Evaluating Crowdsourced Design Concepts With Machine Learning
Authors: Camburn Bradley , He Yuejun , Raviselvam Sujithra , Luo Jianxi , Wood Kristin
Published: November 2019

Automation has enabled design of increasingly complex products, services, and systems. Advanced technology enables designers to automate repetitive tasks in earlier design phases, even high level conceptual ideation. One particularly repetitive task in ideation is to process the large concept sets that can be developed through crowdsourcing. This paper introduces a method for filtering, categorizing, and rating large sets of design concepts. It leverages unsupervised machine learning (ML) trained on open source databases. Input design concepts are written in natural language. The concepts are not pre-tagged, structured or processed in any way which requires human intervention. Nor does the approach require dedicated training on a sample set of designs. Concepts are assessed at the sentence level via a mixture of named entity tagging (keywords) through contextual sense recognition and topic tagging (sentence topic) through probabilistic mapping to a knowledge graph. The method also includes a filtering strategy, the introduction of two metrics, and a selection strategy for assessing design concepts. The metrics are analogous to the design creativity metrics novelty, level of detail, and a selection strategy. To test the method, four ideation cases were studied; over 4,000 concepts were generated and evaluated. Analyses include: asymptotic convergence analysis; a predictive industry case study; and a dominance test between several approaches to selection of high ranking concepts. Notably, in a series of binary comparisons between concepts that were selected from the entire set by a time limited human versus those with the highest ML metric scores, the ML selected concepts were dominant.
Automated Tradeoff Analysis of Cost Versus Machinability for Design Feedback
Authors: Grier Alan T. , Campbell Matthew I.
Published: November 2019

As CAD tools become more sophisticated, engineers are able to more easily create complex part geometries with minimal mass given strength and stiffness requirements. However, these complex part geometries can be difficult to subtractively manufacture, which consequently increases manufacturing cost and production time. This paper presents a method independent of CAD kernels for use early in the design process to automatically evaluate a given part’s machinability and to provide visual geometric additions that decrease manufacturing cost while maintaining the part’s strength and stiffness requirements. Using tessellated and voxelized representations of a part geometry, potential machining orientations are identified and selectively combined to form a set of candidate solutions. The resulting part geometry for each candidate is determined by intersecting the machinable geometries for each individual machine setup, and may have some amount of added volume over the as-designed part. Manufacturing costs for each candidate are estimated based on the volume to be machined and number of required machining setups. Evaluating and culling candidates based on these two objectives (added volume and cost) provides the design engineer with a set of Pareto-optimal solutions that show where material can be added to reduce manufacturing costs. The method is implemented and is tested on three example parts to demonstrate its capability and utility.
Towards Dynamic Simulation Guided Optimal Design of Tumbling Microrobots
Authors: Xie Jiayin , Bi Chenghao , Cappelleri David J. , Chakraborty Nilanjan
Published: November 2019

Design of robots at the small scale is a trial-and-error based process, which is costly and time-consuming. There are no good dynamic simulation tools to predict the motion or performance of a microrobot as it moves against a substrate. At smaller length scales, the influence of adhesion and friction, which scales with surface area, becomes more pronounced. Thus, rigid body dynamic simulators, which implicitly assume that contact between two bodies can be modeled as point contact are not suitable. In this paper, we present techniques for simulating the motion of microrobots where there can be intermittent and non-point contact between the robot and the substrate. We use this simulator to study the motion of microrobots of different shapes and select shapes that are most promising for performing a given task.
Study on Transfer Matrix of Single-Ended Input and Single-Ended Output Plate With Large Motion and Small Deformation
Authors: He Zihao , Rui Xiaoting , Zhang Jianshu , Zhang Lina , Hu Shaoheng
Published: November 2019

A new version of the transfer matrix method for multibody system, where the translational and angular accelerations as well as the internal forces and torques are taken as new state variables, is used to study the dynamics of plate with large motion and small deformation. Modal synthesis method is used to describe the deformation of the plate. The transfer matrix of plate with large motion and small deformation is derived. A continuously accelerating rotating plate subjected to constant torque and a rigid-flexible coupling pendulum containing a plate with large motion and small deformation are studied respectively, their overall transfer equations are established. Dynamic simulation of two examples is carried out and the result is compared with other methods.
Topology Optimization of Cable-Actuated, Shape-Changing, Tensegrity Systems for Path Generation
Authors: Myszka David H. , Joo James J. , Woods Daniel C. , Murray Andrew P.
Published: November 2019

This paper presents a topology optimization methodology to synthesize cable-actuated, shape-changing, tensegrity systems specified through path generation requirements. Estabished tensegrity topology optimization procedures exist for static structures. For active tensegrity systems, motion characteristics are typically explored after the structural topology is determined. The work presented in this paper extends the established procedure to introduce prescribed motion into the topology optimization. A ground structure approach is used in conjunction with the design space. The topology optimization problem is formulated into a mixed integer linear programming problem. Desired motion is prescribed by identifying trace points in the design space and corresponding paths. The result of this methodology is the creation of a tensegrity system that can achieve shape-change as specified with prescribed paths.
A Computational Framework to Support Social Entrepreneurs in Creating Value for Rural Communities in India
Authors: Yadav Abhishek , Das Ashok K. , Allen Janet K. , Mistree Farrokh
Published: November 2019

Over 250 million people in India currently lack access to basic services needed to live a rudimentary lifestyle. Most of these people reside in rural parts of the country. Lack of employment, economic opportunities, and development in rural areas are foundational to low socio-economic levels in these communities. Added to this are environmental issues such as natural resource depletion, yearlong droughts, climate change. We hypothesize that social enterprises developed at the community level can improve the quality of life of people in rural India.

The lack of access to investment and resources to identify and develop social enterprises are major challenges for the creation of social enterprises. We hypothesize that a successful partnership between two major stakeholders, namely, social entrepreneurs and corporate social responsibility (CSR) investors is the key in developing multiple social enterprises to foster rural development. However, CSR and other investors require quantitative information along with impact evaluation of the value proposition before investing. Social entrepreneurs lack tools to develop and present value propositions for the village in a quantitative form. In this paper, we propose a computational framework to fill this gap and to facilitate dialog between CSR investors and social entrepreneurs that may result in a mutually favorable investment.
Design Optimization of a Three-Stage Planetary Gear Reducer Using Genetic Algorithm
Authors: Feng Yanbiao , Zhang Wenming , Yang Jue , Dong Zuomin
Published: November 2019

The multi-stage reducer, especially the planetary gear reducer, usually serves in heavy-duty machinery such as shield tunneling machine, tracked excavator, mining truck and crusher. Those application areas require great load capacity, long life, and high geometrical mechanical performance, and the high ratio so on. This paper first presents a novel architecture of three-stage reducer. To achieve those objectives collectively, this paper presents an optimization methodology based on genetic algorithm (GA). The geometrical volume is set as objective function. The gear module, teeth number, and gear face width are chosen as design variables, taking the life, geometrical spacing, efficiency and load capacity, etc. as constraints. The optimization results are satisfactory and can help designer to employ novel architecture by fulfilling requirements.
Effects of Head Supported Mass on Predicted Neck Musculoskeletal Loadings During Walking and Running
Authors: Zhou Xianlian , Chen Xinyu , Roos Paulien E. , Whitley Phillip
Published: November 2019

This study aimed to investigate how muscle activation and intervertebral compressive forces during walking and running are altered with different head supported mass (HSM) types. A detailed neck musculoskeletal model was adapted and simulations were performed using existing motion data. It was found HSM wear required increased muscle activations, with the highest increase in running. Extensor activation increased particularly for the HSM with its center of mass (COM) in front of the head’s COM and flexor activation was significantly higher in running than in walking. Intervertebral compressive forces increased with HSM wear and the heaviest HSM caused the highest increase. During walking, the computed maximum compressive force at C7 was 129.7N without an HSM, and 163.6N and 208.5N with HSMs with a mass of 1.43 kg and 3.12 kg respectively. For running, it was 275.7N without an HSM, and 349.1N and 451.2N with the two HSM types. Overall muscle contributions to the compressive force varied over the gait cycle and were higher in running (26–110%) than in walking (18–58%). It was concluded that neck musculoskeletal loading increases with HSM wear, which is affected by HSM mass and mass distribution.
Learning to Design From Humans: Imitating Human Designers Through Deep Learning
Authors: Raina Ayush , McComb Christopher , Cagan Jonathan
Published: November 2019

Humans as designers have quite versatile problem-solving strategies. Computer agents on the other hand can access large scale computational resources to solve certain design problems. Hence, if agents can learn from human behavior, a synergetic human-agent problem solving team can be created. This paper presents an approach to extract human design strategies and implicit rules, purely from historical human data, and use that for design generation. A two-step framework that learns to imitate human design strategies from observation is proposed and implemented. This framework makes use of deep learning constructs to learn to generate designs without any explicit information about objective and performance metrics. The framework is designed to interact with the problem through a visual interface as humans did when solving the problem. It is trained to imitate a set of human designers by observing their design state sequences without inducing problem-specific modelling bias or extra information about the problem. Furthermore, an end-to-end agent is developed that uses this deep learning framework as its core in conjunction with image processing to map pixel-to-design moves as a mechanism to generate designs. Finally, the designs generated by a computational team of these agents are then compared to actual human data for teams solving a truss design problem. Results demonstrates that these agents are able to create feasible and efficient truss designs without guidance, showing that this methodology allows agents to learn effective design strategies.
Design and Analysis of an Auto-Parametrically Excited Platform for Active Vibration Control
Authors: Le Thao , Bhat Sandesh G. , Subramanian Susheelkumar C. , Waswa Peter M. B. , Redkar Sangram
Published: November 2019

Many researchers have proved the potential of autoparametric system in controlling stability and parametric resonance. In this paper, two different designs for auto-parametrically excited mass-spring-damper systems were studied: one system was controlled by rotational motion of the spring, and the other system was controlled by sliding motion of the spring. The theoretical models were developed to predict the behavior of the systems and also generated stability charts to analyze the systems. For each system, the numerical results from both the nonlinear equation and linearized equation were analyzed and compared. Simulation models were constructed to validate the analytical results. The error between simulation and theoretical results was within 2%. Both theoretical and simulation results displayed that the implementation of autoparametric system could help reduce the resonance by up to 33% and amplify the resonance by up to 34%.
Smart Agricultural In-Field Service Robot: From Toy to Tool
Authors: Wang Peng , Tian Junwei , Niu Haoyu , Chen YangQuan
Published: November 2019

A low-cost and multi-functional ground mobile robot is presented for precision agricultural application. A modified toy car is used as the hardware platform, and robotic operating system (ROS) as the software platform. By adding sensors and end effector, the robot can be controlled remotely. Our vision is to build an autonomous in-field service robot to realize some specific tasks instead of farmers.
Investigating the Impact of Component Uncertainty on Autonomous Vehicle Overtaking Maneuvers
Authors: Tsai Hsin-Ting , Chan Kuei-Yuan
Published: November 2019

Autonomous vehicles sense the environment and act accordingly using modern electronic and mechanical components. Although these subsystems and components are delicately designed and manufactured, uncertainties in real-world vehicle operations could cause various undesirable performance deviations or even failure. In this work, we study the impact of component uncertainties on vehicle overtaking maneuver, one of the most common actions in traffic. A model is built to simulate the flow of information and the actions of each component in the control strategy of overtaking. Possible variations of major components are investigated. The impact of uncertainties on the overtaking maneuver are first analyzed. Based on the results, we see that the angle resolution of the distance-detecting device has the biggest impact while the angular velocity-detecting device has relatively small influence. While the control strategy changes, we also observe the impact swifts. Therefore, one could systematically use the existing uncertainty to see how output performance changes by using the proposed model; alternatively, one could also study the robustness of the control strategy under uncertainties.
Improvement of Thermal Performance of Pin Fin Heat Sink Using Different Types of Perforations: A Study Under Natural Convection
Authors: Kumar Aashish , Mondal Manoj Kumar
Published: November 2019

Improvement of thermal management can significantly enhance the coefficient of performance (COP) of the thermoelectric (TE) system which is one of the potential solutions for cooling electronic components. Since heat sinks are an integral part of all the electronic equipment, therefore, great consideration is given towards meticulous selection of heat sink for improving its reliability and performance. Various methods are being studied to improve heat transfer rates of heat sink such as microchannel, liquid cooling, nano-fluids, fin topology optimization, anodization of pins, and changing heat sink materials. Recent studies have demonstrated that perforations in pins increase the heat transfer rate of pin fin heat sink, though, the results are inadequate to infer the best geometry. Further research is hence necessary to establish the best possible combination of geometry, size, and number of perforations. The present work aims to numerically identify a heat sink configuration with maximum heat transfer rate among several configuration possibilities under laminar flow condition using ANSYS Fluent 18.2. The simulation results demonstrate that lateral perforation in fins enable higher heat transfer rate than the unmodified heat sink geometry, due to higher Nusselt number and reduced pressure drop. The parametric study also reveals that heat sink with three elliptical perforations boost heat transfer rates (about 21% higher) when compared to heat sink with solid and other perforated geometries. Furthermore, perforations reduce weight and greater effectiveness, making it more desirable for its wide-scale applications.
Muscle Force Prediction in OpenSim Using Skeleton Motion Optimization Results As Input Data
Authors: Zaman Rahid , Xiang Yujiang , Rakshit Ritwik , Yang James
Published: November 2019

This paper describes an integrated approach to predict human leg and spine muscle forces during lifting by integration of a predictive skeletal model with OpenSim. The two-dimensional (2D) skeletal lifting motion is first predicted by using an inverse dynamics optimization method. Then, the prediction outputs, including joint angle profiles, ground reaction forces, and center of pressure, are incorporated in OpenSim biomechanics software to analyze muscle forces for lifting. Therefore, the integrated approach has predictive capability on musculoskeletal level. By using this method, we can predict and analyze muscles forces for heavy weight lifting motion which is difficult to simulate directly using a 3D musculoskeletal model.
Image-Based Motion Analysis for Self-Reconfigurable Mobile Robot With Integrated Docking
Authors: Sohal Shubhdildeep S. , Ben-Tzvi Pinhas
Published: November 2019

This paper presents the design integration and experimental results of target-based autonomous locomotion of a Self-Reconfigurable Mobile Robot. Uncertainties in the sensory data can accumulate the misalignments in locomotion behavior of the robot. Such misalignments can result in a poor coupling performance resulting in the failure of the overall docked system. Therefore, it is desirable for a robot to be capable of mechanically tolerating such misalignments. As a result, a Hybrid-Wheeled mobile robot, interfaced with a 2-DOF, high misalignment tolerant coupling (GHEFT) mechanism is presented in this paper. This combined assembly is used as a source of locomotion for autonomous docking in a multi-robot assembly using Image-Based Visual Servoing (IBVS). The resulting output is then implemented in a simulated environment for the autonomous locomotion of the robot. Experimental results demonstrate the feature motion and trajectory followed under the hybrid locomotion of the robot.
Design, Analysis, and Optimization of a New Two-DOF Articulated Multi-Link Robotic Tail
Authors: Liu Yujiong , Ben-Tzvi Pinhas
Published: November 2019

Based on observations from nature, tails are believed to help animals achieve highly agile motions. Traditional single-link robotic tails serve as a good simplification for both modeling and implementation purposes. However, this approach cannot explain the complicated tail behaviors exhibited in nature where multi-link structures are more commonly observed. Unlike its single-link counterpart, articulated multi-link tails essentially belong to the serial manipulator family which possesses special transmission design challenges. To address this challenge, a cable driven hyper-redundant design becomes the most used approach. Limited by cable strength and elastic components, this approach suffers from low frequency responses, inadequate generated inertial loading, and fragile hardware, which are all critical drawbacks for robotic tails design. To solve these structure related shortcomings, a multi-link robotic tail made up of rigid links is proposed in this paper. The new structure takes advantage of the traditional hybrid mechanism architecture, but utilizes rigid mechanisms to couple the motions between ith link and i + 1th link rather than using cable actuation. By doing so, the overall tail becomes a rigid mechanism which achieves quasi-uniform spatial bending for each segment and allows performing highly dynamic motions. The mechanism and detailed design for this new tail are synthesized. The kinematic model was developed and an optimization process was conducted to minimize the bending non-uniformity for the rigid tail.
Mathematical Modeling of a Two Degree of Freedom Vibration Energy Harvester for Low Speed Rotary Structure Application
Authors: Nezami Saman , Lee Soobum
Published: November 2019

This paper presents mathematical modeling of a two degree of freedom energy harvester which converts slow mechanical rotation into piezoelectric vibration using gravity force and magnetic repelling force, for large-scale machinery monitoring such as wind turbine blades. The harvester consists of a disk with an unbalanced mass, a piezoelectric cantilevered beam, and two magnets attached to both the beam and the disk. Three coupled equations that describe the motion of the disk, vibration of the beam, and the harvester voltage output are derived using the energy method. Then ODE45 in MATLAB software is used to solve the equations. The result shows that the energy harvester’s performance varied by blade rotational speed. At low blade speed (less than 15 rpm), the harvester generates power by regularized magnetic excitation per blade revolution. The power output of the harvester increases by increasing the blade speed. At high blade speed, however, the disk behavior and the power generation mechanism changes due to the increased centrifugal force. The results show that the model can predict the power peak as a function of blade speed, and the proposed harvester can generate a considerable amount of power for self-sustainable sensing and structural health monitoring.
Self-Starting Cogging-Torque-Assisted Motor Drive for Use in a Heavy-Duty Diesel Engine
Authors: Reinholz Devin K. , Reinholz Bradley A. , Seethaler Rudolf J.
Published: November 2019

This paper describes the design process and simulation results of a variable valve actuation system modeled after the cogging-torque-assisted motor drive (CTAMD) found in literature. Unlike the CTAMD, the new design is capable of handling large exhaust pressures. Furthermore, the new design incorporates damper windings to improve upon the CTAMD by enabling self-starting. The new variable valve actuator is designed for the 6-cylinder Westport 15L diesel engine. The simulated results suggest that the new variation of the CTAMD can be effectively applied to a turbocharged heavy-duty diesel engine.

Simulation results show that the designed motor is capable of self-starting, and infinitely variable lifts. The damper windings are shown to be more beneficial at enabling self-starting and infinitely variable lifts than a spring, since they do not impose additional energy requirements during a valve transition. Furthermore, the new design is also shown to be capable of actuating exhaust valves in the presence of cylinder pressures up to 16 bar with similar efficiency to that of a standard camshaft valve train.
Lifetime Prediction Considering Nonlinearity in Degradation Progression
Authors: Jihin Rosmawati , Söffker Dirk
Published: November 2019

In this paper, the establishment of a prognostic approach based on a nonlinear degradation model for reliability assessment focusing on health state and remaining useful life estimation is considered. A model able to describe the non-linearity of degradation to predict future damage progression for real-time application has to be defined. Real-time data are generated during operation, so incomplete data about failure and usage up to the end of life are expected. For the accurate prediction of system lifetime, estimation of future degradation from the point of assessment is required. At this point, the unavailable data are numerically calculated by integrating linearized gradients adaptively by considering nonlinearity in current degradation. The coefficients used to define future degradation gradients are identified according to different states assuming future linear degradation increments. These coefficients are determined using an optimization-based algorithm simultaneously with the calculation of consumed lifetime by extending the previously established state machine lifetime model. For performance evaluation of the approach, the effectiveness of predicting remaining useful life using tribological experiments data is investigated. The results show the potential of this approach to deal with nonlinearity in the degradation progression.
Research on Instability Principle of Virtual Tracks Train When Braking on Curve
Authors: Zuo Jianyong , Gu Yihao , Lu Haiying , Yu Jie , Liu Cheng
Published: November 2019

Virtual tracks train is a new type of rail transit, which combines traditional rail vehicles and road vehicles. In order to study the effect of braking on the stability of virtual tracks train on curve, a four-axle model with train body model, steering model, braking model and tire model was built in Matlab/Simulink to research the change of yaw velocity, lateral acceleration and vehicle speed when it brakes on curve. Through step steering test of the vehicle, the model was verified to analyze the braking stability on steady steering condition.

Simulation result shows that when virtual tracks train brakes after 8s of turning with an individual axle locking up, different instability phenomena such as loss of guidance capacity, folding and drifting, would occur, which leads to instability of braking on curve. Using ABS can help improve the stability of it. With the instability principle put forward through the simulation, brake system and brake force distribution law could be designed to meet the need of virtual tracks train.
A Gear-Slider Gravity Compensation Mechanism: Design and Experimental Study
Authors: Vu Linh Nguyen , Kuo Chin-Hsing
Published: November 2019

This paper presents the design and experimental study of a geared five-bar module for the gravity compensation of a rotating mass. In this design, a compression spring is installed on the rotating link and a pair of spur gears are used to transmit the elastic force to counterbalance the gravitational force. The design problem is first formulated as an optimization model for minimizing the actuation torque and then simplified to an analytical equation for approximating the perfect compensation design. One unique feature of the study is that the friction effect of the meshing gears is considered in the design of the spring stiffness. A prototype of the proposed mechanism was built and experimentally investigated via the manual and motor-driven tests. In the manual test, the measured peak static motor torque due to gravity was reduced up to 84.3% with the spring attachment. On the other hand, in the motor-driven test, the measured peak motor torque was reduced up to 90% and 72.8% during the downward and upward motions, respectively, and the power reduction rate of the driving motor could achieve up to 86.5% within the overall range of motion.
A New Robustness Metric for Robust Design Optimization Under Time- and Space-Dependent Uncertainty Through Metamodeling
Authors: Wei Xinpeng , Du Xiaoping
Published: November 2019

Product performance varies with respect to time and space in many engineering applications. This work discusses how to measure and evaluate the robustness of a product or component when its quality characteristics are functions of random variables, random fields, temporal variables, and spatial variables. At first, the existing time-dependent robustness metric is extended to the present time- and space-dependent problem. The robustness metric is derived using the extreme value of the quality characteristics with respect to temporal and spatial variables for the nominal-the-better type quality characteristics. Then a metamodel-based numerical procedure is developed to evaluate the new robustness metric. The procedure employs a Gaussian Process regression method to estimate the expected quality loss that involves the extreme quality characteristics. The expected quality loss is obtained directly during the regression model building process. Three examples are used to demonstrate the robustness analysis method. The proposed method can be used for robustness assessment during robust design optimization under time- and space-dependent uncertainty.