bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Wheel-Rail Contact With Pre-Calculated Lookup Tables in Arbitrary-Geometry Tracks With Irregularities
Authors: Escalona José L. , Aceituno Javier F.
Published: January 2016

This paper shows a numerical method for the dynamic simulation of the wheel-rail contact interaction based on pre-calculated lookup tables for its use in railroad multibody dynamics. The multibody railroad model is developed for model-based condition monitoring of railway vehicles that make use of on-board real-time simulation. This application requires a numerically efficient and highly accurate computational model. The new capabilities of the contact model is its ability to be used in the modeling of tracks with arbitrary geometry that may include cross-level, longitudinal level, alignment and gauge variation irregularities using just 2 entries to the lookup table. This fact allows keeping to a minimum the computer memory needed to store the lookup table data. The lookup tables are created assuming constraint (rigid) contact between the wheel and the rail that reduces to 4 the number of degrees of freedom of the wheel. For that reason the wheel-rail normal contact forces are obtained as reaction forces in the multibody dynamic equations. This paper presents the wheelset kinematic description and wheel and rail profiles geometric analysis needed to calculate the contact constraints, the jacobian matrix and the time derivative of the jacobian matrix based on the lookup tables.
Instantaneous-Stiffness Plane Analysis of Underactuated Fingers
Authors: Belzile Bruno , Birglen Lionel
Published: January 2016

The general stiffness of an underactuated finger as seen from the actuator is a function of its internal compliant elements, such as springs, but also depends on its geometry. In this paper, a complete stiffness analysis of a general underactuated finger is presented. The objective is to shed light on important aspects to consider while designing underactuated fingers and how to take advantage of the finger’s stiffness during grasping, for instance in order to estimate information such as contact location and force magnitude. This is done using the instantaneous-stiffness plane of the finger introduced in this paper. This plane shows the relationship between the finger’s geometry and its instantaneous stiffness and how simple changes in geometrical parameters can have significant effects on the finger’s stiffness. This novel tool can be used for a wide range of underactuated finger architectures as will be shown. First, a theoretical framework including numerical simulations is presented. This is then followed by an optimization example of a finger’s geometry and a discussion.
Path Planning and Control for Autonomous Navigation of Single and Multiple Magnetic Mobile Microrobots
Authors: Chowdhury Sagar , Jing Wuming , Jaron Peter , Cappelleri David J.
Published: January 2016

In this paper, we have developed an approach for autonomous navigation of single and multiple microrobots under the influence of magnetic fields generated by electromagnetic coils. Our approach consists of three steps. First, we have developed a heuristics based planning algorithm for generating collision-free trajectories for the microrobots that are suitable to be executed by the available magnetic field. Second, we have modeled the dynamics of the microrobots to develop a controller for determining the forces that need to be generated for the navigation of the robots along the trajectories at a suitable control frequency. Finally, an optimization routine is developed to determine the input currents to the electromagnetic coils that can generate the required forces for the navigation of the robots at the controller frequency. We have validated our approach by simulating two electromagnetic coil systems. The first system has four electromagnetic coils designed for actuating a single microrobot. The second system has an array of sixty-four magnetic microcoils designed for generating local magnetic fields suitable for simultaneous independent actuation of multiple microrobots.
A Systematic Exploration of Wing Size on Flapping Wing Air Vehicle Performance
Authors: Gerdes John , Bruck Hugh A. , Gupta Satyandra K.
Published: January 2016

The design of a flapping wing air vehicle is dependent on the interaction of drive motors and wings. In addition to the wing shape and spar arrangement, sizing and flapping kinematics affect vehicle performance due to wing deformation resulting from flapping motions. To achieve maximum payload and endurance, it is necessary to select a wing size and flapping rate that will ensure strong performance and compatibility with drive motor capabilities. Due to several conflicting trade-offs in system design, this is a challenging problem. We have conducted an experimental study of several wing sizes at multiple flapping rates to build an understanding of the design space and ensure acceptable vehicle performance. To support this study, we have designed a new custom test stand and data post-processing procedure. The results of this study are used to build a design methodology for flapping wing air vehicles with improved performance and to highlight system design challenges and strategies for mitigation. Using the methodology described in this paper, we have developed a new flapping wing air vehicle called the Robo Raven II. This vehicle uses larger wings than Robo Raven and flight tests have confirmed that Robo Raven II has a higher payload capacity.
A Verified and Validated Model for Simulation-Driven Design of Heavy Duty Truck Synchronizers
Authors: Häggström Daniel , Sellgren Ulf , Stenström Wiktor , Björklund Stefan
Published: January 2016

The strong market trend toward lower fuel consumption for heavy road transports requires more frequent gear shifting and increased gear shift performance, i.e. shorter shift time. Increased shift performance means higher loads for the synchronizer which brings component and shifting process optimization more into focus.

Traditionally, synchronizer development has relied on physical testing of complete synchronizers in general gearbox test rigs or in specialized synchronization test rigs leaving much of the causes of the observed effects unclear. This paper presents a generalized FE-based thermomechanical simulation model to be used for model-based synchronizer analysis and design. The model is targeted for studies of how different external loads and the values of different synchronizer design parameters affect the temperature transient in the friction lining. Recommendations of how major modeling complications should be treated are presented. The developed simulation model is verified and validated with a combination of analytical means and transient temperature measurements of bulk and surface temperatures. The applicability of the presented model, as well as its limitations, are discussed and exemplified with different design cases.
A Stiffness Formulation for Spline Joints
Authors: Hong J. , Talbot D. , Kahraman A.
Published: January 2016

Due to the lack of knowledge in terms of their flexibility and deformation, spline joints are typically assumed to be rigid in dynamic models of gearboxes, transmissions and drive trains. As various dynamic phenomena are associated with the stiffness of a spline joint, any high-fidelity dynamic model of drivetrains must properly capture the stiffness of spline joints. In this study, a general analytical stiffness formulation for spline joints is proposed based on a semi-analytical spline load distribution model. This formulation defines a fully-populated stiffness matrix of a spline joint including radial, tilting and torsional stiffness values as well as off-diagonal coupling terms. A blockwise inversion method is proposed and implemented with this analytical formulation to reduce computational time required. At the end, a detailed parametric study is presented to demonstrate the sensitivity of the spline stiffness matrix to torque level, tooth modifications, misalignments, and tooth indexing errors.
A Simulation-Based CDS Approach: Automated Generation of Simulation Models Based From Generated Concept Model Graphs
Authors: Muenzer Clemens , Shea Kristina
Published: January 2016

Current approaches in Computational Design Synthesis enable the human designer to explore large solution spaces for engineering design problems. To extend this to support designers in embodiment and detail design, not only the generation of solutions spaces is needed, but also the automated evaluation of engineering performance. Here, simulation methods can be used effectively to predict the behavior of a product.

This paper presents a generic approach to automatically generate solution spaces for energy- and signal-based engineering design tasks using first-order logic and Boolean satisfiability. These solution spaces not only include the graph-based product concept topologies but also corresponding bond-graph based simulation models. To do this, guidelines to create partial simulation models for the available building blocks for the synthesis are presented, to assure a valid causality in the final simulation model. Considering the connections in the graph-based product concepts, the simulation models are automatically generated and, simulated. The simulation results are then stored to enable a more informed decision as to which concepts to pursue in detail design. The method is validated using automotive powertrains as a case study. 162 different powertrain concepts are generated and evaluated, showing the advantages of electric powertrains in respect to CO2 emissions and the importance of intelligent control strategies for hybrid ones. This research enables the generation, exploration, and evaluation of solution spaces for energy- and signal-based product concept. Guidelines to define compatible bond-graph based partial simulation models that map to building blocks from an object-oriented graph-based knowledge representation are introduced. Additionally, a generic translation between the graph-based product concepts and simulation models is presented.
Large Scale Needs-Based Open Innovation via Automated Semantic Textual Similarity Analysis
Authors: Schaffhausen Cory R. , Kowalewski Timothy M.
Published: January 2016

Open innovation often enjoys large quantities of submitted content. Yet the need to effectively process such large quantities of content impede the widespread use of open innovation in practice. This article presents an exploration of needs-based open innovation using state-of-the art natural language processing (NLP) algorithms to address existing limitations of exploiting large amounts of incoming data. The Semantic Textual Similarity (STS) algorithms were specifically developed to compare sentence-length text passages and were used to rate the semantic similarity of pairs of text sentences submitted by users of a custom open innovation platform. A total of 341 unique users submitted 1,735 textual problem statements or unmet needs relating to multiple topics: cooking, cleaning, and travel. Scores of equivalence generated by a consensus of ten human evaluators for a subset of the needs provided a benchmark for similarity comparison. The semantic analysis allowed for rapid (1 day per topic), automated screening of redundancy to facilitate identification of quality submissions. In addition, a series of permutation analyses provided critical crowd characteristics for the rates of redundant entries as crowd size increases. The results identify top modern STS algorithms for needfinding. These predicted similarity with Pearson correlations of up to .85 when trained using need-based training data and up to .83 when trained using generalized data. Rates of duplication varied with crowd size and may be approximately linear or appear asymptotic depending on the degree of similarity used as a cutoff. Semantic algorithm performance has shown rapid improvements in recent years. Potential applications to screen duplicates and also to screen highly unique sentences for rapid exploration of a space are discussed.
Automatic Discovery of Design Task Structure Using Deep Belief Nets
Authors: Lan Lijun , Liu Ying , Lu Wen Feng , Alghamdi Awn
Published: January 2016

With the arrival of cyber physical world and an extensive support of advanced IT infrastructure, nowadays it is possible to obtain the footprints of design activities through emails, design journals, change logs, and different forms of social data. In order to manage a more effective design process, it is essential to learn from the past and understand, for example, what design tasks are actually carried out, their interactions and how they impact each other. In this paper, a computational approach based on deep belief nets (DBN) is proposed to automatically uncover design tasks and quantify their interactions. A DBN topic modeling with real-valued units is to learn a set of intrinsic topic features from a simple word-frequency based input representation. Evaluated using a design email archive spanning for more than two years, the proposed approach has achieved a much higher accuracy in identifying design tasks compared to a prevailing approach.
Distributed Additive Manufacturing: Concept for the Application of JT (ISO 14306) as Downstream Process Format
Authors: Grimm Marco , Christ Alexander , Anderl Reiner
Published: January 2016

Additive manufacturing is gaining new impetus due to decreasing costs for additive manufacturing machines and materials, and the continuous improvement of additive manufacturing technology itself. The integration of modern internet technologies paves the way for a globally distributed additive manufacturing, but recently used data formats fall short to offer consistent solutions to address current and future requirements for efficient distributed additive manufacturing. The integration of the standardized 3D data format JT (ISO 14306) in distributed additive manufacturing enables the deployment of additive manufacturing processes based on open standards with a suitable integration in established engineering applications. Different geometry representations, integration of meta data, harmonization with other standardized data formats like STEP and the prevalence in industry lead to the usage of one standardized 3D data format for all engineering downstream processes. In this paper, two approaches for the integration of JT based on automated conversion and JT based slicing and tool path generation are introduced and validated. The utilization of web services enables the controlling and monitoring of additive manufacturing processes on mobile devices, independent of the location, for an efficient collaboration on a global scale.
Condition Monitoring of an Electro-Hydrostatic Actuator Using the Dynamic 2nd-Order Smooth Variable Structure Filter
Authors: Afshari Hamed Hossein , Gadsden Stephan Andrew , Habibi Saeid
Published: January 2016

This paper introduces the dynamic 2nd-order Smooth Variable Structure Filter (Dynamic 2nd-order SVSF) method for the purpose of robust state estimation. Thereafter, it presents an application of this method for condition monitoring of an electro-hydrostatic actuator system. The SVSF-type filtering is in general designed based on the sliding mode theory; whereas the sliding mode variable is equal to the innovation (measurement error). In order to formulate the dynamic 2nd-order SVSF, a dynamic sliding mode manifold is defined such that it preserves the first and second order sliding conditions. This causes that the measurement error and its first difference are pushed toward zero until reaching the existence subspace. Hence, this filter benefits from the robustness and chattering suppression properties of the second order sliding mode systems. These help the filter to suppress the undesirable chattering effects without the need for approximation or interpolation that however reduces accuracy and robustness of the SVSF-type filtering. In order to investigate the performance of the dynamic 2nd-order SVSF for state estimation, it applies to an Electro-Hydrostatic Actuator (EHA) system under the normal and uncertain scenarios. Simulation results are then compared with ones obtained by other estimation methods such as the Kalman filter and the 1st-order SVSF method.
The Use of Additive Manufacturing to Fabricate Structural Components for Wearable Robotic Devices
Authors: Churchwell Ray , Hollander Kevin W. , Theisen Connor
Published: January 2016

Our interest is in designing, fabricating and testing wearable robotic devices that assist human gait of able bodied individuals [1, 2]. Recently, we have been experimenting with Additive Manufacturing, 3D printing, using Fused Deposition Modeling technology as a method to fabricate key structural components for these robotic devices.

A key structural component for the JTAR (Joint Torque Augmentation Robot) hip exoskeleton was manufactured using 3D printing and has been destructively tested to validate design requirements, the average force required to destroy the part was 2500 N with a standard deviation of 86 N, and this level of strength provided a safety factor in excess 4 times the expected load. The 3D printed part also has been successfully demonstrated on the JTAR robot for approximately 32 kilometers of hiking with no signs of degradation. The JTAR device has been demonstrated with the 3D printed hip mechanism in various environments, including treadmills and unconstrained outdoor environments.
Energy Stored in Fractional-Order Elements With Constant Inputs
Authors: Hartley Tom T. , Veillette Robert J. , Adams Jay L. , Lorenzo Carl F.
Published: January 2016

The internal efficiency of the energy storage in a general fractional-order circuit element is analyzed. By use of distributed-circuit representations, integral expressions are derived for the energy stored in a fractional-order integrator or a fractional-order differentiator for any given profile of the distributed state. For either constant-current or constant-voltage charging, these expressions for the stored energy are evaluated and compared with the energy supplied at the terminals of the element, so that the efficiency of the charging process is determined. The result is found to verify a published conjecture on the constant-input charging efficiency of the fractional-order elements.
A Three-Dimensional Load Sharing Model of Planetary Gear Sets Having Manufacturing Errors
Authors: Leque Nicholas D. , Kahraman Ahmet
Published: January 2016

Planet-to-planet load sharing is a major design and manufacturing tolerancing issue in planetary gear sets. Planetary gear sets are advantageous over their countershaft alternatives in many aspects, provided that each planet branch carries a reasonable, preferably equal, share of the torque transmitted. In practice, the load shared among the planets is typically not equal due to the presence of various manufacturing errors. This study aims at enhancing the models for planet load sharing through a three-dimensional formulation of N-planet helical planetary gear sets. Apart from previous models, the proposed model employs a gear mesh load distribution model to capture load and time dependency of the gear meshes iteratively. It includes all three types of manufacturing errors, namely constant errors such as planet pinhole position errors and pinhole diameter errors, constant but assembly dependent errors such as nominal planet tooth thickness errors, planet bore diameter errors, and rotation and assembly dependent errors such as gear eccentricities and run-outs. At the end, the model is used to show combined influence of these errors on planet load sharing to aid designers on how to account for manufacturing tolerances in the design of the gears of a planetary gear set.
Constrained Control for Brushless DC Motors With Fractional Friction Compensation
Authors: Qiu Yanan , Dai Zhiyong , Chen YangQuan , Liang Xiaogeng
Published: January 2016

In this paper, based on the Asymmetric Barrier Lyapunov Function (ABLF), we firstly develop a backstepping Dynamic Surface Control (DSC) scheme for position constraint control of Brushless DC Motors with a new fractional torque observer technique for friction compensation. The fractional compensator is used to estimate the unknown friction torque and guarantees its convergence with zero steady error. The DSC is introduced to eliminate the repeated differentiations involved in ABLF synthesis and to decrease the negative effects from produced disturbance noise in Brushless DC Motors. Finally, we demonstrate that the proposed control scheme could guarantee output constraints within limit ranges and also ensure prescribed tracking error within a neighborhood of 0. A fractional horsepower dynamometer was developed as a Hardware-In-the-Loop platform to emulate the position tracking of Brushless DC motors and Coulomb friction as a mechanical nonlinearity. Comparison experiment studies illustrate that the proposed controller has a favorable performance bounded within constraints and achieves fast convergence. Furthermore, the new method has a better ability of noise rejection.
Prediction and Experimental Correlation of Tooth Root Strains in Spur Gear Pairs
Authors: Dai Xiang , Cooley Christopher G. , Parker Robert G.
Published: January 2016

Spur gear tooth root strains are calculated using a finite element/contact mechanics formulation for varying gear speeds and applied torques. Extensive comparisons with experiments, including those from the literature and new ones, confirm that the finite element/contact mechanics formulation accurately predicts the quasi-static and dynamic tooth root strains. The finite element/contact mechanics model is used to investigate the features of the tooth root strain curves as the gears rotate kinematically and the tooth contact conditions change. Tooth profile modifications are shown to strongly affect the shape of the strain curve. At non-resonant speeds the dynamic tooth root strain curves have similar shapes as the quasi-static strain curves. At resonant speeds, however, the dynamic tooth root strain curves are drastically different because large amplitude vibration causes tooth contact loss.
Tailored Modeling of a Vehicle Power Liftgate Avoiding Explicit Definition of Body-Fixed Reference Frames
Authors: Müller Andreas , Jankowski Krystof P.
Published: January 2016

Contemporary vehicle liftgates are operated by a variety of power actuators. The most typical systems are electrically powered with a computer control system executing driver’s command to open and close the liftgate. The control system has to have enough power to open and close the liftgate in specified time over the range of environmental conditions, on inclined roads and so on. It also has to be able to reverse the direction of motion in a short time when an obstacle is found on the way. In order to develop a reliable controller the dynamic properties of the system have to be modeled first. The dynamic model can be used not only to analyze dynamic properties of the system but also to conceive a model based control strategy based on an inverse dynamics model.

In this paper a tailored modeling approach is reported that avoids the explicit definition of body-fixed frames. This is advantageous since it allows for easy and failsafe manual modeling and model extension. It builds upon a recently proposed modeling approach that uses body-fixed twists. In this paper the approach is first reformulated in terms of spatial twists as this increases the numerical performance.
Quality and Safety Assurance of Railway Tracks by UAV
Authors: Bettemir Önder Halis
Published: January 2016

Safety assurance of railway tracks is an important task because defects on the railway track may cause trains to be derailed. Unfortunately, there are many fatal train crashes reported in Turkey, Spain and India caused by derailment of the trains. Besides the fatalities, derailment of the trains causes significant economic losses, delay of the timetables and discomfort. Manually investigating the railway tracks are substantially time consuming and expensive. In addition to this, it is human dependent so that the task is prone to error, which may end up without noticing important defects. In this study, a robust and economical method, which automates the investigation of railway tracks, is proposed. The proposed method scans the railway track by a high-resolution optic camera mounted on an UAV. Obtained optic images of the railway track are georeferenced by automatically extracting the Ground Control Points (GCP). The railway track is extracted from the optic image by edge detection. Afterward, any defect on the railway track such as missing bolt or damage on the sleepers and any impropriety of ballasts can be detected by performing image analysis techniques. Advantages of the optic system are its lightweight, higher georeferencing accuracy, and low power consumption. Sony HX300 DSLR camera with 20.4 MP resolution is calibrated on the ground and optical images are obtained at similar imaging geometry. For this reason, flight altitude is fixed as 12 foot above the railway track. The optical camera is mounted on quadcopter, which has 6 kg of maximum take-off weight. The system is tested in Pittsburgh and satisfactory initial test results are obtained. Consequently, site tests showed that the proposed robust and economic system is a good candidate to be implemented for monitoring the railway tracks.
Ecological Robustness as a Design Principle for Sustainable Industrial Systems
Authors: Layton Astrid , Bras Bert , Weissburg Marc
Published: January 2016

Ecology has acted as a source for sound design principles and studies have examined how ecological principles can enhance sustainability in human industrial networks. Engineered systems are often designed for maximum performance, but in many cases robustness is sought with respect to unwanted variations in input or other parameters. Taguchi’s signal to noise ratio and other quality engineering principles are well known fundamentals in the field of robust design. In this paper, we will introduce flow-based equations from ecological network analysis (ENA) to determine how to modify the flows and connections in industrial systems to balance efficiency and robustness against disturbances. In ENA, the robustness of a system is given by the relationship of flow path diversity to system efficiency. Systems with diverse flows are more resilient to a disturbance since there are redundant pathways, but are inefficient precisely because they contain many flow paths with the same endpoints. Efficient systems have increased capacity to transfer material and energy, but this is at the cost of fewer pathways so the system is brittle. Thus, given a disturbance, a robust system balances redundancy with efficiency/capacity. Ecological systems seem to occupy a narrow range of states that balance efficiency and resilience to confer robustness. Human networks, like trade networks, water reclamation facilities, etc. have been analyzed using these robustness principles and methods for flow based ecological network analysis. These analyses show that human networks may be more brittle than their ecological counterparts because of insufficient flow path diversity.
A Pilot Study of Customer Requirement Derivation Methods Among Engineering Students
Authors: Renz Julian Steffen , Olewnik Andrew
Published: January 2016

It is desirable for designers to use formal representations when interpreting customer need statements. However, to date there is no methodology that systematically evaluates the quality of information generated by a specific customer requirement derivation (CRD) method. This work develops and applies an evaluation framework that compares a traditional method rooted in work from Pahl and Beitz, and Ulrich and Eppinger, with approaches derived from affordance modeling literature. The framework is based on eight metrics derived from extant literature. Results of a pilot study involving sophomore engineering students suggest that no method is dominant but there are differences among methods on most metrics. The framework lays the basis for further research on CRD methods and offers insights for engineering education and engineers in practice.
Polymeric Micro-Filter Fabrication Using a Micro Injection Moulding Process
Authors: Surace Rossella , Bellantone Vincenzo , Fassi Irene
Published: January 2016

This paper reports on fabrication and characterization of a micro-filter for hearing aid, dialysis media and inhaler. The micro-feature specifications consist in a diameter of 2.3 mm, a thickness of 0.2 mm and it is composed by a mesh with grid of 80 μm and ribs with width of 70 μm.

The proposed micro-filter is fabricated by micro injection moulding process adopting a steel mould manufactured by micro Electrical Discharge Machining process (micro EDM). Different polymeric materials (POM, HDPE, LCP), particularly indicated for the injection moulding applications due to their flowability and stability, are tested and evaluated in relation to the process replication capability. Since the polymer micro-filter is made of a complex grid of micro-ribs, the injection moulding process must ensure complete filling of the micro-parts, preventing any defects (i.e. premature solidification, incomplete filling, flash and air traps). To this aim, different system parameters configurations (melt and mould temperature, injection velocity, holding time and pressure, cooling time, pressure limit) are tested for obtaining acceptable part in all polymers grade. Finally, the component is dimensionally characterized by confocal microscopy and its filtration capacity is then verified. Although the feature complexity was high, the results showed that the object could be successfully replicated by filling completely the micro cavities with two of them: POM and HDPE. The most significant parameters influencing the part filling were the mould temperature and the injection velocity. These findings allow to further optimize the micro-injection process parameters to obtain a high quality product.
Injection Force Effects on Propidium Iodide Uptake in Nanoinjected HeLa Cells
Authors: Lewis Tyler E. , Jensen Brian D. , Burnett Sandra H.
Published: January 2016

The ability to deliver DNA sequences and molecular loads into the nucleus of a cell is a large area of interest in the medical community, and has numerous applications including gene therapy. Different methods of gene delivery each have their own advantages and disadvantages. Experimentation was performed using a new technique called nanoinjection to determine how force affects the efficiency and viability of the injection process. Nanoinjection, which utilizes an array of millions of solid microlances made on a 2 cm square silicon chip to inject cells, allows us to inject hundreds of thousands of cells at a time with high efficiencies. The solid nature of the lances allows them to be smaller, increasing cell viability. HeLa cells were used for testing in conjunction with an injection device that allowed for precise control of the injection force. Propidium iodide (PI), a dye that fluoresces when bound to DNA and doesn’t penetrate the membrane of living cells, was injected to monitor the efficiencies of transporting molecular loads across the cell membrane. The data was normalized to the controls for both efficiency (PI uptake) and viability to make it easier to see and determine trends. Results indicate a slow rise in injection efficiency from 0 to 1.8 Newtons of force where it reaches a maximum efficiency of 4.11 when normalized to the PI uptake of the positive controls. The data then levels, averaging an efficiency of approximately 3.1. The slow rise is likely due to more of the cells being punctured as the force increases until most have been punctured and the efficiency levels off. Viability had no clear trend, only varying between 0.97 and 1.04 when normalized to the viability of the negative controls.
Non-Intuitive Dependent Decision Making: Sub-Optimal Design Selection
Authors: Cooksey K. Daniel , Mavris Dimitri
Published: January 2016

This paper explores a flaw in traditional design decision making (including optimization) when uncertainty is present. It introduces the concept of the Non-Intuitive Dependent Decision Making (NIDDM) problem, where the assumption that each of the design alternatives is independent can be false due to a common underlying uncertainty. In this situation, the implicit assumption that design alternatives are independent can lead to a sub-optimal selection. This paper provides a simplified example of the NIDDM problem, and uses this to define the conditions where the NIDDM problem arises. An aerospace design toolset is then used to explore the NIDDM problem in realistic conditions, and a discussion is presented about when traditional robust design processes are appropriate or an alternative design methodology is needed.
Modeling and Dynamic Parameter Identification of the SCHUNK Powerball Robotic Arm
Authors: Memar Amirhossein H. , Esfahani Ehsan T.
Published: January 2016

This paper presents the modeling and dynamic parameter identification of the 6-DoF SCHUNK Powerball LWA 4P robotic arm. Precise positioning, zero backlash and compact design of the joints which integrate two perpendicular axes, make this robot ideal for service robotics applications and human-robot interaction. Due to the significant effect of the lubricant temperature on the behavior of viscous friction in the harmonic drives, a systematic procedure is developed to overcome this problem. A series of experiments have been conducted to model the friction at each joint, then the procedure of identification has been applied based on an inverse dynamic model and linear least-square techniques. Finally, a verification trajectory is executed by the robot to validate the estimated parameters of the system.
Orderly Perforation of Polyester Films by Excimer Laser
Authors: Li Wenqi , Sancaktar Erol
Published: January 2016

The effects of 248 nm KrF excimer laser irradiation on combinations of different thickness PET films and different stainless steel mask mesh opening sizes were considered as a possible method to achieve different size perforations on different thickness PET films, in order to provide an effective and controllable perforation technology. Therefore, ablation behavior of PET films has been investigated for different laser energy fluence and number of laser pulses. Morphology of irradiated samples was observed by optical microscopy, and atomic forced microscopy to study topography and microstructures after laser ablation. An attempt has been made of correlate these findings with the orientation, strength and mechanical properties of the polymer.

The experimental results reveal that the percentage of perforation and the average perforated area increase with increasing number of pulses for all film thicknesses. The affected area, defined as the perforated area plus the heat affected zone (a black-char-region around the perforated area) decrease with increasing number of pulses. Due to the heat conducted from the steel mash wire, especially at cell corners, the perforation process seems to start initially at the cell corners. High laser fluence seems to lead to surface depressions due to thermal shock and surface stress waves along the process directions confirmed by tensile testing and x-ray analyses. The presence and the geometry of surface depressions were confirmed by atomic forced microscopy.
Decentralized Algorithm for Force Distribution With Applications to Cooperative Transport
Authors: Kennedy Monroe D. , Guerrero Luis , Kumar Vijay
Published: January 2016

We consider a system of cooperating robots transporting an object in which each individual robot is small and resource constrained and the number of robots is large precluding architectures that support a centralized coordination and control system. In nature, a swarm of ants can transport large payloads that are beyond the capability of individual organisms by using simple strategies that only require coordination with their immediate neighbors. We adopt a similar paradigm in which robots communicate with their immediate neighbors although the wireless communication links that are typical in small robots can be noisy and therefore not robust. We derive decentralized coordination algorithms that allow robots to converge to a load distribution system that is optimal in the sense of minimizing interaction forces while achieving the desired resultant wrench to allow manipulation and transport. We demonstrate the key ideas using simulations for 100 robots.
Efficiently Handling Process Overruns and Underruns in Real-Time Embedded Systems
Authors: Xu Jia
Published: January 2016

Methods for handling process underruns and overruns when scheduling a set of real-time processes increase both system utilization and robustness in the presence of inaccurate estimates of the worst-case computations of real-time processes. In this paper, we present a method that efficiently re-computes latest start times for real time processes during run-time in the event that a real-time process is preempted or has completed (or overrun). The method effectively identifies which process latest start times will be affected by the preemption or completion of a process. Hence the method is able to effectively reduce real-time system overhead by selectively re-computing latest start times for the specific processes whose latest start times are changed by a process preemption or completion, as opposed to indiscriminately re-computing latest start times for all the processes.
Designing Projection Patterns for 3D Structured-Light Sensors
Authors: Marin Veronica , Nejat Goldie
Published: January 2016

Structured-light (SL) sensing techniques have been emerging as a popular non-contact optical method for 3D surface profiling of complex objects in manufacturing inspection applications. The measured object is illuminated with sinusoidal phase-shifted projection patterns that are deformed based on the 3D surface profile of the object. To-date, no methodology exists to determine the number of multiple fringe patterns needed in order to improve the measurement accuracy of an SL sensory system. In this paper, we present a novel design methodology that encompasses a detailed procedure for designing the projection patterns in order to minimize system noise and provide accurate 3D measurements. Experiments are presented to demonstrate the effectiveness of the proposed methodology.
Visual Target-Tracking Using a Formation of Unmanned Aerial Vehicles
Authors: Mas Ignacio , Curi Sebastian , Kitts Christopher , Giribet Juan I.
Published: January 2016

We present a method to visually track and follow a target using a platoon of three unmanned aerial vehicles for the purpose of surveillance, monitoring or escorting. A coordination control technique that enhances specification and monitoring of high level formation parameters such as position, orientation and size is used as a basis for the coordination. A model of a video camera is employed to obtain relative positions with respect to the target of interest. An open-source simulator of Parrot Ar.Drone quadrotors running on the Robot Operating System environment is used to demonstrate the system functionality. Two test cases are presented to illustrate the validity of the approach.
Programming Arduino Boards With the C/C++ Interpreter Ch
Authors: Turley Curtis , Montironi Maria Alessandra , Cheng Harry H.
Published: January 2016

This paper presents the ChArduino package which is designed to control the Atmel AVR microcontroller based Arduino boards through the C/C++ interpreter Ch. Traditionally, Arduino boards are programmed using the official Arduino IDE or lower-level AVR C libraries. These methods require specific cross-compilation tools to compile the code and upload it onto the board. Whenever a change is made to the source code, it needs to be recompiled and uploaded, making application development cumbersome, especially for beginners and as the size of the application grows. The approach presented in this paper is aimed at reducing the effort associated with code compilation, especially in classroom environments where microcontroller programming is first introduced. In fact, when using this method, code is executed in an interpreted manner and every function call is processed separately by the interpreter, thus compilation and uploading are not required to make changes effective. The ChArduino package consists of a library of functions running on a computer and a specialized firmware loaded onto the Arduino board. The firmware on the Arduino board is pre-compiled and the latest version is automatically uploaded at run time, if not already. At power-up, the firmware initializes the board and then waits for a command from the computer. The use of the C/C++ interpreter Ch also makes available line-by-line debugging, numerical analysis, and plotting capabilities. The supported communication protocols between the Arduino board and the computer are serial and Bluetooth. The application code written using this package is completely compatible with the entire spectrum of Arduino boards and can be ported to the Arduino IDE with minimal changes. The applications of the method described in this paper are general but apply especially to the K-12 education field in that the package creates a simple, user-friendly, environment for the absolute beginner to learn the basic principles of mechatronic systems including programming, microcontrollers, and electrical circuits. Lesson plans are being developed to use the ChArduino package in microcontroller introductory courses and the package is currently being introduced for preliminary testing in schools through the UC Davis C-STEM Center.
A Theoretical Investigation of the Critical Timescales Needed for Digging in Dry Soil Using a Biomimetic Burrowing Robot
Authors: Isava Monica , Winter Amos G.
Published: January 2016

RoboClam is a bio-inspired robot that digs into underwater soil efficiently by expanding and contracting its valves to fluidize the substrate around it, thus reducing drag. This technology has potential applications in fields such as anchoring, sensor placement, and cable installation. Though there are similar potential applications in dry soil, the lack of water to advect the soil particles prevents fluidization from occurring. However, theoretically, if the RoboClam contracts quickly enough, it will achieve a zero-stress state that will allow it to dig into dry soil with very little drag, independent of depth. This paper presents a theoretical model of the two modes of soil collapse to determine how quickly a device would need to contract to achieve this zero-stress state. It was found that a contraction time of 0.02 seconds would suffice for most soils, which is an achievable timescale for a RoboClam-like device.
Flexure Design for Eight-Bar Rectilinear Motion Mechanism
Authors: Liu Yang , McCarthy J. Michael
Published: January 2016

This paper replaces the hinged pivots of an eight-bar linkage with flexure joints in order to achieve a flexure-connected linkage system that guides rectilinear movement of its end-effector. The goal is a linkage design that can be reduced in size to provide a suspension for the proof masses of a MEMS gyroscope. The symmetric design of the linkage and its long travel relative to other MEMS suspensions has the potential to provide a number of advantages, such as the reduction of quadrature error. The design presented yields 0.1% deviation over its range of movement. An example also presents the driving linkage of the MEMS gyroscope, which is also designed as flexure connected linkage.
Force Transfer Characterization of a Soft Exosuit for Gait Assistance
Authors: Quinlivan Brendan , Asbeck Alan , Wagner Diana , Ranzani Tommaso , Russo Sheila , Walsh Conor
Published: January 2016

Recently, there has been a growing interest in moving away from traditional rigid exoskeletons towards soft exosuits that can provide a variety of advantages including a reduction in both the weight carried by the wearer and the inertia experienced as the wearer flexes and extends their joints. These advantages are achieved by using structured functional textiles in combination with a flexible actuation scheme that enables assistive torques to be applied to the biological joints. Understanding the human-suit interface in these systems is important, as one of the key challenges with this approach is applying force to the human body in a manner that is safe, comfortable, and effective. This paper outlines a methodology for characterizing the structured functional textile of soft exosuits and then uses that methodology to evaluate several factors that lead to different suit-human series stiffnesses and pressure distributions over the body. These factors include the size of the force distribution area and the composition of the structured functional textile. Following the test results, design guidelines are suggested to maximize the safety, comfort, and efficiency of the exosuit.
Creativity Predictors: Findings From Design-by-Analogy Ideation Methods’ Learning and Performance
Authors: Moreno Diana , Blessing Luciënne , Wood Kristin , Vögele Claus , Hernández Alberto
Published: January 2016

There is still much to learn about the mechanisms and interactions by which psychological and cognitive factors influence creative performance in design, and more explicitly in design’s ideation stage. The present study aims to explore such influences for Design by Analogy (DbA) ideation methods. 69 participants from 52 companies in Mexico and Singapore executed two ideation sessions (phase I and phase II) to generate solution ideas for a service design problem (same design problem was used for both phases). Between the two phases participants were assigned and trained with one of three selected ideation conditions: Control, WordTree and SCAMPER. Finally, they were asked to self-evaluate 11 factors that may influence their creative performance. The explored factors comprised individual, performance self-perception and contextual factors. Individual factors are considered with respect to the ideation activity and the design problem. In the case of the ideation activity evaluated factors are: entertainment (boring-fun), motivation, inspiration and easiness (difficult-easy). For the design problem, interest, easiness and inspiration are considered. Performance self-perception factors are: commitment (minimal effort-hard work), concentration (unfocused-focused) and level of success (unsuccessful-successful). Lastly, the Contextual factor considered is the self-perceived relation of time with respect to ideas. Two main analyses are presented and discussed in this article: the effect of learning and applying DbA ideation methods on participants’ factor self-evaluation, and; the relationship between the 11 self-evaluated factors and creative performance using the metrics of Fluency, Novelty and Fixation.
A Novel Algorithm for Solving Design Equations for Synthesizing Platform Linkages
Authors: Ge Xin , Ge Q. J. , Gao Feng
Published: January 2016

This paper revisits the problem of geometric design of platform linkages such that one or more of its points of the platform stays on a sphere or a plane. We develop a novel algorithm taking advantage of linear structure in the design constraint equations. The new algorithm reduces the problem of synthesizing platform linkages with spherical and plane constraints to a two-stepped process: null space analysis followed by a generalized eigenvalue problem. An example is provided to show the effectiveness of the algorithm.
Development of a Quadruped Tracked Mobile Robot
Authors: Fujita Toyomi , Tsuchiya Yuichi
Published: January 2016

We have developed a tracked mobile robot which is equipped with four legs at its body. This robot is able to not only move on rough terrain robustly, but also perform handing tasks such as carrying an object and removing small obstacles in its movement by using the legs as manipulation arms. This paper describes mechanisms and characteristics of the robot. Several experimental results showed the validity on basic movements by legs and tracks and handling tasks of this robot.