bluuebunny/crossref_metadata_2025 huggingface dataset:
Different Optimization Criteria for Vehicle Seat Suspension Control: Position Versus Acceleration
Authors: Hashemnia Saeed , Ahmadian Mohammad T.
Published: July 2010

This paper addresses the effect of different optimization criteria for the control purpose of vehicle suspension. In the present study, active vibration control system for a 5 degree-of-freedom (DoF) pitch-plane suspension model with bounce and pitch motions is investigated. In the proposed vehicle model, the impact of the wheel-axle-brake assemblies’ masses is also considered. The developed model is controlled using a fuzzy logic controller (FLC) to minimize the vibration of the driver’s seat. The controller is designed to control the applied force to the seat. Furthermore, in order to determine the optimal value of fuzzy system parameters, genetic algorithm (GA) optimization search is used based on minimizing both vibrations and accelerations of the driver’s seat. In other words, two different criteria are chosen for optimization of the controller: minimizing either absolute displacement or absolute acceleration which is related to ride comfort. In each case, the simulation is implemented and the results are presented. It is shown that optimization according to only one criterion may lead to undesirable results in other system parameters. In addition, it is demonstrated that considering absolute displacement as the only factor to be minimized is ineffective. Finally, another criterion which is a combination of the two previous criteria has been suggested and tested and the obtained results are presented. The combinational criterion can suppress the vibration as well as decreasing the vehicle acceleration.
A Top-Down Concept Selection Integrating Analytical and Optimization Approaches
Authors: Takai Shun , Jikar Vivek K. , Ragsdell Kenneth M.
Published: July 2010

This paper proposes a top-down approach for product concept selection. The proposed approach integrates an analytical approach to define an acceptable part specification range (part range), and an optimization approach to find optimum tolerances of part specifications. In the analytical part of the procedure, an inverse of design matrix is used to identify a part range. In the optimization part of the procedure, a product cost is defined as a function of part specification tolerances, and optimization algorithm is used to find optimum part specification tolerances that minimize the cost of the concept. The concept with the minimum cost is selected as the optimum concept. The usefulness of the proposed approach is demonstrated using an illustrative example.
Neutral Definition and Recognition of Assembly Features for Legacy Systems Reverse Engineering
Authors: Murshed S. M. Mahbub , Dixon Adam , Shah Jami J.
Published: July 2010

Current CAD systems provide utilities to position and orient parts with respect to each other in assemblies through associative relations that include geometric and parametric constraints. However, assembly features are not explicitly defined, nor available in CAD databases for exploitation in downstream applications. This paper examines the attributes of assembly features and proposes a template for their definition in a uniform way. The template can be used in conjunction with an EXPRESS-like language (N-Rep) to define assembly features that are implementation independent. The template includes slots for part features, mating relations, geometric, parametric, kinematic and structural relations. The current application for assembly features being explored is for Reverse Engineering of legacy parts. Assembly features serve as “knowledge containers” in that they allow one to encode form, fit and function in a uniform way so that replacement parts can be redesigned to meet key requirements.
Designing MEMS Disk Resonator Based Biological Mass Sensors Under Fabrication Uncertainty
Authors: Heidari Amir , Choi Hae-Jin
Published: July 2010

A radial-contour mode disk resonator has its own advantages, less energy loss and less airflow damping, over existing counterparts such as surface acoustic wave (SAW) resonators and quartz crystal microbalance (QCM) sensors. Taking these advantages of the disk resonators, we design a biological mass sensor in this paper. One of the important challenges in the design of biological mass sensors is inherent uncertainties of MEMS fabrication processes that may strongly affect to the disk resonator performances. Parameters of main effect on the sensor performance (i.e., mass sensitivity, Sm) are identified among many inputs based on response surface method screening process. The shape of the circular disk deviates from a desired perfect circle due to the fabrication uncertainty. Degree of deviation from perfect circularity significantly affects to the disk frequency. In addition, because of the presence of electrodes in sides, the disk rotation angle must be considered as a parameter that can affect the frequency. In this work, the disk resonator is designed to perform robust to the geometric parameter variations. A series of simulation models is developed to obtain natural frequency and mass sensitivity because analytical solutions cannot predict the resonant frequency variation originated such geometric variances. A non-deterministic metamodeling technique is introduced to replace the time consuming simulation models and used for the efficient local sensitivity analysis which is the main challenge of simulation based robust design. The design problem is to find the mean disk diameter in-between 800 μm and 1400μm to achieve robust maximum Sm. A mathematical construct, Error Margin Index (EMI) combining performance mean and deviation, is employed in the solution search algorithm to find a robust optimum design. Our design solution is the mean disk diameter of 1280 μm. The difference of mean mass sensitivity between traditional optimum design and our robust design is about 0.7μm2/ng. The standard deviation of mass sensitivity at optimal design is high (0.68 μm2/ng) and that of our design is low (0.39 μm2/ng).
Design and Control of the 3 Axes Pneumatic Servo Micromanipulator for the Biological Technology
Authors: Shih Ming-Chang , Chen Hung-Yi
Published: July 2010

This paper describes the servo pneumatic control technique, which is applied to the biomedical and biological technology. A cell micromanipulator is built by a 3-axes servo pneumatic micromanipulator system, which is set horizontally or vertically and driven by pneumatic cylinders. Due to the nonlinear characteristic of the air flow and the compressibility of air, the system is highly nonlinear system. Therefore, the compensators must be designed to reject those nonlinear effects and to improve the positioning precision. The dead-zone of the 3 axes pneumatic servo micromanipulator is measured, and the relation of velocity and voltage is plotted. Finally, a hybrid fuzzy controller, with dead zone, and velocity compensation, is designed to control the positioning precision of the 3 axes pneumatic servo micromanipulator. From the experimental results, the pneumatic servo micromanipulator has the positioning accuracy of 40 nm with different displacements. The system can be potentially used for the cell extraction, puncture, cutting and microinjection of the biological technology.
Robotics in Nuclear Materials Processing at LANL: Capabilities and Needs
Authors: Turner Cameron J. , Harden Troy A. , Lloyd Jane A.
Published: July 2010

Nuclear material processing operations present numerous challenges for effective automation. Confined spaces, hazardous materials and processes, particulate contamination, radiation sources, and corrosive chemical operations are but a few of the significant hazards. However, automated systems represent a significant safety advance when deployed in place of manual tasks performed by human workers. The replacement of manual operations with automated systems has been desirable for nearly 40 years, yet only recently are automated systems becoming increasingly common for nuclear materials handling applications. This paper reviews several automation systems which are deployed or about to be deployed at Los Alamos National Laboratory for nuclear material handling operations. The needs that resulted in the development of these systems can be found throughout the nuclear industry. Highlighted are the current social and technological challenges faced in deploying automated systems into hazardous material handling environments and the opportunities for future innovations.
Metrics for Evaluating and Optimizing the Barrier and Time to Reverse Engineer a Product
Authors: Harston Stephen P. , Mattson Christopher A.
Published: July 2010

Reverse engineering, defined as extracting information about a product from the product itself, is a common industry practice for gaining insight into innovative products. Both the original designer and those reverse engineering the original design can benefit from estimating the time and barrier to reverse engineer a product. This paper presents a set of metrics and parameters that can be used to calculate the barrier to reverse engineer any product as well as the time required to do so. To the original designer, these numerical representations of the barrier and time can be used to strategically identify and improve product characteristics so as to increase the difficulty and time to reverse engineer them. As the metrics and parameters developed in this paper are quantitative in nature, they can also be used in conjunction with numerical optimization techniques, thereby enabling products to be developed with a maximum reverse engineering barrier and time — at a minimum development cost. On the other hand, these quantitative measures enable competitors who reverse engineer original designs to focus their efforts on products that will result in the greatest return on investment.
Integrated Optimization for Supporting Functional and Layout Designs During Conceptual Design Phase
Authors: Kobayashi Masakazu , Suzuki Yuya , Higashi Masatake
Published: July 2010

This paper proposes a new integrated optimization of a functional structure and a components layout for supporting a conceptual design. A conceptual design is the second phase of a product development, where designers build up the functional structure and the components layout of the target design object as the design concept. However, a functional design and a layout design are very different tasks, there is a lot of flexibility for decision makings during them and its solution space is vast. Therefore, it is extremely difficult for designers to build up an optimal design concept by considering various design requirements themselves. To overcome this limitation, this paper develops a new design method based on optimization techniques. This method consists of two optimizations, a functional optimization and a layout optimization, and obtains the optimal solutions by cooperatively executing two optimizations. Specifically, a functional optimization based on a GA is the main part of the proposed method and executed just one time whereas a layout optimization is executed to calculate the layout with minimum area (or volume) for each design solution for each iteration during the process of the functional optimization and the result is used as one of its valuation characteristics. Using the proposed method, designers can simultaneously obtain both the functional structure and the components layout of the target design object that satisfies performance, cost and area at a high level. To demonstrate the flow of the proposed method and confirm its effectiveness, this paper describes the case study, where internal devices of a personal computer are designed using the proposed method.
Sustainable Product Design by a Simultaneous Consideration of Pre-Life and End-of-Life of Products
Authors: Kwak Minjung , Kim Harrison M.
Published: July 2010

Product recovery has become a field of rapidly growing interest for product manufacturers as a promising solution for product stewardship as well as economic viability. As product recovery is a process highly dependent upon the way a product is designed, it should be considered early at the design stage so that the product may be designed to facilitate efficient and effective recovery at its end-of-life stage. To make a product easy to recover, manufacturing companies first need to understand the links between product design and recovery profit. They should be able to evaluate which design is better than others and why that is so. To accommodate such companies that seek for a design-for-recovery method, in this paper, a comparative study is conducted to analyze how design differences affect product recovery and what architecture characteristics are desirable from the end-of-life perspective. Three cell phone handset designs sharing the same design concept but entailing different architecture are created, for which the individual designs and the recovery potential of each design are evaluated under three different scenarios. The results highlight preferred design alternatives with their design implications for sustainable product design.
Computational Development of Single- and Dual-Frequency Modulation Atomic Force Spectroscopy for Ambient Air Applications
Authors: Chawla Gaurav , Solares Santiago D.
Published: July 2010

The ability of atomic force microscopy (AFM) to acquire tip-sample interaction force curves has allowed researchers to understand the mechanical behavior of numerous materials at the nanoscale. However, AFM force spectroscopy with the most commonly used techniques can be a slow process for non-uniform samples, as it often requires the measurement to be performed at one fixed surface point at a time. In this paper we present two dynamic AFM based spectroscopy methods, one requiring operation in single-frequency-modulation mode and another using dual-frequency-modulation, which could allow a more rapid acquisition of topography and tip-sample interaction force curves. Numerical simulation results are provided along with discussions on the benefits and limitations of both.
Design of a Tunable Stiffness Composite Leg for Dynamic Locomotion
Authors: Galloway Kevin C. , Clark Jonathan E. , Koditschek Daniel E.
Published: July 2010

Passively compliant legs have been instrumental in the development of dynamically running legged robots. Having properly tuned leg springs is essential for stable, robust and energetically efficient running at high speeds. Recent simulation studies indicate that having variable stiffness legs, as animals do, can significantly improve the speed and stability of these robots in changing environmental conditions. However, to date, the mechanical complexities of designing usefully robust tunable passive compliance into legs has precluded their implementation on practical running robots. This paper describes a new design of a “structurally controlled variable stiffness” leg for a hexapedal running robot. This new leg improves on previous designs’ performance and enables runtime modification of leg stiffness in a small, lightweight, and rugged package. Modeling and leg test experiments are presented that characterize the improvement in stiffness range, energy storage, and dynamic coupling properties of these legs. We conclude that this variable stiffness leg design is now ready for implementation and testing on a dynamical running robot.
Unified Synthesis of Compact Planar Path-Generating Linkages With Rigid and Deformable Members
Authors: Rai Ashok Kumar , Saxena A. , Mankame Nilesh D.
Published: July 2010

A unified procedure for the synthesis of planar linkages that may take the form of rigid body, fully compliant or partially compliant mechanisms is presented. The procedure automates the selection of mechanism topology as characterized by the number and connectivity of the links as well as the nature of the connections between the links, the mechanism shape as characterized by the shapes of the individual links, and the mechanism dimensions which include the locations of the joints and the cross-sectional dimensions of the links. The synthesis task is posed as an optimization problem and is solved by a hybrid, elite-preserving genetic algorithm. Three examples of compact mechanisms that trace different non-smooth paths in response to a single, monotonic and bounded force input are used to illustrate the synthesis capability of the procedure. Prototypes of the designs are built and tested to verify their performance.
A Framework for Computational Design Synthesis Based on Graph-Grammars and Function-Behavior-Structure
Authors: Helms Bergen , Shea Kristina , Hoisl Frank
Published: July 2010

Computational design synthesis supports the knowledge-intensive process of developing new products. However, most approaches to date are often limited to a narrow domain and viewpoint of a synthesis task. The framework introduced in this paper aims to respond to the need for a method that integrates a richer product representation for computational synthesis within a framework that includes simulation, performance evaluation, and search. A computational and parameterized product model is presented that combines the Function-Behavior-Structure levels of abstraction. Graph-grammars are then used to create a formal definition of vocabulary and valid graph transformation rules. This approach offers the possibility to harness the large knowledge source of design catalogues in order to formulate vocabulary in a viewpoint-independent and thus, flexible way. In addition to manually entered and problem-specific rules, a class of generic rules is introduced that is instantiated computationally based on the defined vocabulary and has the advantage of being problem independent and re-usable. Finally, validation of the method is given through the synthesis of electric power-trains. This research goes beyond prior work in the field as it allows for synthesis and reasoning on different layers of abstraction, including function, behavior and structure, and introduces methods to alleviate the encapsulation of engineering knowledge for synthesis methods.
Process Optimization of Sheet Metal Forming Using Operating Window
Authors: Kim Kyungmo , Yin Jeong Je , Suh Yong S.
Published: July 2010

Sheet metal forming process may yield unexpected defective products due to many uncontrollable factors such as irregular material properties, lubricants, and variations of other forming conditions. Traditional design methods based on deterministic optimization theory have limited capability of including such factors. In this paper, we propose a method in determining the optimal condition of a sheet metal forming process with conflicting failure modes. A robust design method is used with computer simulations and optimization techniques. A new SN ratio is proposed based on the operating window method, to improve the problems of traditional SN ratio. The robust design process is applied to a sheet metal forming process for an automobile component, and the effectiveness of the proposed method is verified.
Optimal Design of an Electrothermal Microfluidic Pump
Authors: Du E. , Manoochehri Souran
Published: July 2010

AC electrokinetics in microfluidic systems has been extensively investigated for its great potential in microfluidic pumping applications. The oscillating flow pattern in a microchannel with planar floor configuration restricts the pumping capacity due to the fast recirculating vortices over the electrode surface positioned in the microchannel floor. Patterned microgrooved floor in a fluidic microchannel can be employed to modify the flow pattern and make it uniaxial thus increase the net flow rate. Silicon KOH wet etching can be utilized to fabricate the microgrooved floor of the channel for its highly smooth surface quality and precise and reproducible configuration. We have developed an optimization methodology for the design of microgrooved configuration for a microfluidic pump using alternating current electrothermal (AC ET) actuation mechanism. The flow rate for the AC ET pumping system with optimized microgrooved floor can be higher as compared to the planar case without any significant increases of the temperature profile. In this paper, we are presenting the results of an optimum microgrooved floor configuration for an effective pumping application.
Creating Polytope Representation of Design Spaces for Visual Exploration Using Consistency Technique
Authors: Devanathan Srikanth , Ramani Karthik
Published: July 2010

A polytope-based representation is presented to approximate the feasible space of a design concept that is described mathematically using constraints. A method for constructing such design spaces is also introduced. Constraints include equality and inequality relationships between design variables and performance parameters. The design space is represented as a finite set of (at most) 3-dimensional (possibly non-convex) polytopes, i.e., points, intervals, polygons (both open and closed) and polyhedra (both open and closed). These polytopes approximate the locally connected design space around an initial feasible point. The algorithm for constructing the design space is developed by adapting consistency algorithm for polytope representations.
Modular Product Design Using Cyberinfrastructure for Global Manufacturing
Authors: Yoo John Jung-Woon , Kumara Soundar R. T. , Simpson Timothy W.
Published: July 2010

Modularization of parts — a fairly recent trend in product development — facilitates part definitions in a standardized, machine-readable form, so that we can define a part based on its input(s), output(s), features, and geometric information. Standardizing part definitions will enable manufacturing companies to more easily identify part suppliers in global, virtual environments. This standard representation of parts also facilitates modular product design during parametric design. We will show that this problem of modular product design can be formulated as an AI Planning problem, and we propose a solution framework to support modular product design. Using part specification information for personal computers, we demonstrate the proposed framework and discuss its implications for global manufacturing.
Optimization of Machine Product Designs From Deeper Level Characteristics Using Collaboration Theory Concepts
Authors: Yoshimura Masataka , Kikuchi Shin
Published: July 2010

Successfully optimization of product designs calls for the continuous evolution of optimized design solutions, which is best achieved by collaboration among a group of experts who understand the intricacies of the product’s characteristics. The achievement of successful collaborations depends on optimization methodologies that focus on design characteristics located at deeper levels of hierarchically decomposed design problems, and the construction of optimization scenarios that have an explicit goal of maximizing the expected profits that result from the collaboration. This paper proposes methodologies and procedures based on hierarchical optimizations that aim to effectively conduct collaborative product design optimizations. The proposed methodologies are applied to a machine product design, and their effectiveness is demonstrated.
Robust Optimization of the Loaded Contact Pattern in Hypoid Gears With Uncertain Misalignments
Authors: Gabiccini M. , Bracci A. , Guiggiani M.
Published: July 2010

This paper presents an automatic procedure to optimize the loaded tooth contact pattern of face-milled hypoid gears with misalignments varying within prescribed ranges. A two-step approach is proposed to solve the problem: in the first step, the pinion tooth micro-topography is automatically modified to bring the perturbed contact patterns (as the assembly errors are varied within the tolerance limits) match a target area of the tooth, while keeping them off the edges; in the second step, a subset of the machine-tool settings is identified to obtain the required topography modifications. Both steps are formulated and solved as unconstrained nonlinear optimization problems. While the general methodology is similar to the one recently proposed by the same authors for the optimization at nominal conditions, here the robustness issues with respect to misalignment variations are considered and directly included in the optimization procedure: no a posteriori check for robustness is therefore required. Numerical tests show that nominally satisfactory and globally robust hypoid pairs can be designed by a direct process and within a unified framework, thus avoiding tiresome trial-and-error loops.
Redundancy Resolution Using Tractrix: Simulations and Experiments
Authors: Ravi V. C. , Rakshit Subrata , Ghosal Ashitava
Published: July 2010

Hyper-redundant robots are characterized by the presence of a large number of actuated joints, many more than the number required to perform a given task. These robots have been proposed and used for many application involving avoiding obstacles or, in general, to provide enhanced dexterity in performing tasks. Making effective use of the extra degrees of freedom or resolution of redundancy have been an extensive topic of research and several methods have been proposed in literature. In this paper, we compare three known methods and show that an algorithm based on a classical curve called the tractrix leads to a more ‘natural’ motion of the hyper-redundant robot with the displacements diminishing from the end-effector to the fixed base. In addition, since the actuators at the base ‘see’ the inertia of all links, smaller motion of the actuators nearer to the base results in a smoother motion of the end-effector as compared to other two approaches. We present simulation and experimental results performed on a prototype eight link planar hyper-redundant manipulator.
Topology Optimization of Piezoelectric Energy Harvesting Strap Buckle
Authors: Zheng Bin , Huang Hong-Zhong , Gea Hae Chang
Published: July 2010

In the past decades, the stagnant growth of battery technology becomes the bottle-neck of new generation of portable and wearable electronics which ask for longer work time and higher power consumption. Energy harvesting device based on the direct piezoelectric effect that converts ambient mechanical energy to usable electric energy is a very attractive energy source for portable and wearable electronics. This paper discusses the design of piezoelectric energy harvesting strap buckle that can generate as much as possible electric energy from the differential forces applying on the buckle. Topology optimization method is employed to improve the efficiency of piezoelectric energy harvesting strap buckle in a limited design space. A stiffness or displacement constraint is introduced to substitute material volume constraint in this problem formulation to avoid useless optimum result with nearly zero material volume. The sensitivities of both objective function and design constraint are derived from the adjoint method. A design example of piezoelectric energy harvesting strap buckle using the proposed topology optimization method is presented and the result is discussed.
Thesaurus for Natural-Language-Based Conceptual Design
Authors: Yamamoto Eiko , Taura Toshiharu , Ohashi Shota , Yamamoto Masaki
Published: July 2010

Conceptual design is a process wherein new functions are created through engineering design. In conceptual design, we use natural language since it plays an important role in the expression and operation of a function. Moreover, natural language is used in our day-to-day thinking processes and is expected to keep a fine interface with the designer. However, it is at a disadvantage with regard to the expression of a function, since physical phenomena, which are the essence of a function, are better expressed in the form of mathematical equations than natural languages. In this study, we attempt to develop a method for using natural language for operating a function by harnessing its advantages and overcoming its disadvantage. We focus on the vital process in conceptual design, that is, the function dividing process wherein the required function is decomposed into sub functions that satisfy the required function. We construct a thesaurus by semiautomatic extraction of the hierarchical structures of words from a document by using natural language processing. We show that the constructed thesaurus can be useful in supporting the function dividing process.
Evaluation and Optimization of Industrial Robot Families Using Different Kinematic Measures
Authors: Feng Xiaolong , Holmgren Bo , O¨lvander Johan
Published: July 2010

In this paper, overall manipulability measure and stroke of workspace are proposed and evaluated as design criteria for optimal kinematics design of a family of industrial robots. The object of study is a 6 degree of freedom serial robot manipulator where individual family members (robots) share arms from a common platform. The paper presents a formal mathematical framework where the product family design problem is stated as an optimization problem and where optimization is used to find an optimal product family. The paper illustrates how the proposed kinematic design criteria may be used to support the optimal kinematics design of a family of industrial robots, and it also visualizes the tradeoff between the size of the common platform and the kinematics performance of individual robots.
A Framework for Engineering Dissection Exercise Creation and Implementation
Authors: Hart Kathleen M. , Shooter Steven B. , Kim Charles J.
Published: July 2010

Hands-on product dissection and reverse engineering exercises have been shown to have a positive impact on engineering education, and many universities have incorporated such exercises in their curriculum. The CIBER-U project seeks to examine the potential to utilize cyberinfrastructure to enhance these active-learning exercises. We have formulated a framework for product dissection and reverse engineering activity creation to support a more rigorous approach to assessing other exercises for satisfaction of the CIBER-U project goals and adapting the best practices. This framework is driven by the fulfillment of learning outcomes and considers the maturity of students at different levels. Prototype exercises developed with the framework are presented. The approach is sufficiently general that it can be applied to the consideration and adaption of other types of exercises while ensuring satisfaction of the established goals.
Inertial Sensing of Dummy Kinematics
Authors: Redkar Sangram , Sugar Tom , Dillard Bill , Narayanan Karthik
Published: July 2010

Motor vehicle crashes claim over 40,000 lives and injure over two million people each year in the United States. To reduce the number of injuries and fatalities through vehicle design improvements, it is important to study occupant kinematics and related injury mechanisms during crashes. Occupant motion in crash tests is typically measured with high speed video, spatial scanning, direct field sensing, and inertial sensing. In this work, we present simulation and testing results on inertial sensing of dummy kinematics based on a novel algorithm known as Quaternion Fuzzy Logic Adaptive Signal Processing for Biomechanics (QFLASP-B). This approach uses three angular rates and three accelerations (one gyroscope-accelerometer pair about each axis) per rigid body to compute orientations (roll, pitch and yaw), positions and velocities in the inertial (fixed) reference frame. In QFLASP-B, quaternion errors and gyro biases are calculated and used in an adaptive loop to remove their effects. The Fuzzy Estimator at the core of the algorithm consists of a fuzzification process, an inference mechanism, a Rule Base and a defuzzification process. In this paper, we examine those aspects of the QFLASP-B Fuzzy Estimator critical to accurate kinematics sensing, hardware and software implementations and experimental results compared with traditional approaches.
Kinematic Analysis and Experimental Verification on the Steering Characteristics of a Two Actuated Spoke Wheel Robot With a Tail
Authors: Ren Ping , Jeans J. Blake , Hong Dennis
Published: July 2010

Intelligent Mobility Platform with Active Spoke System (IMPASS) is a novel wheel-leg hybrid robot that can walk in unstructured environments by stretching in or out three independently actuated spokes of each wheel. This paper firstly introduces the latest prototype of the robot that has two actuated spoke wheels and one tail. Due to its metamorphic configurations, this robot can be considered as a mechanism with variable topologies (MVTs). The mobility analysis in previous work is briefly summarized and then the transformation relationships between different configurations are addressed. Thus, the motions of the robot on the ground, such as steering, straight-line walking and other combinations can be uniformly interpreted as series of configuration transformations. In order to maintain the coherence between the coordinate setups in different configurations, previous rigid body kinematic models are modified. Two types of turning, steady state turning and turning gait transition, are revisited with the characteristics being refined. Finally, the hardware design of the prototype is demonstrated, followed by the experimental verifications of the characteristic motions. The work presented in this paper lays the kinematics foundation for the future research on the motion planning algorithms of IMPASS.
Level Set Based Robust Shape and Topology Optimization Under Random Field Uncertainties
Authors: Chen Shikui , Lee Sanghoon , Chen Wei
Published: July 2010

A level-set-based method for robust shape and topology optimization (RSTO) is proposed in this work with consideration of uncertainties that can be represented by random variables or random fields. Uncertainty, such as those associated with loading and material, is introduced into shape and topology optimization as a new dimension in addition to space and time, and the optimal geometry is sought in this extended space. The level-set-based RSTO problem is mathematically formulated by expressing the statistical moments of a response as functionals of geometric shapes and loading/material uncertainties. Spectral methods are employed for reducing the dimensionality in uncertainty representation and the Gauss-type quadrature formulae is used for uncertainty propagation. The latter strategy also helps transform the RSTO problem into a weighted summation of a series of deterministic topology optimization subproblems. The above-mentioned techniques are seamlessly integrated with level set methods for solving RSTO problems. The method proposed in this paper is generic, which is not limited to problems with random variable uncertainties, as usually reported in other existing work, but is applicable to general RSTO problems considering uncertainties with field variabilities. This characteristic uniquely distinguishes the proposed method from other existing approaches. Preliminary 2D and 3D results show that RSTO can lead to designs with different shapes and topologies and superior robustness compared to their deterministic counterparts.
Response Surface Method Using Sequential Sampling for Reliability-Based Design Optimization
Authors: Zhao Liang , Choi K. K. , Lee Ikjin , Du Liu
Published: July 2010

Traditional RBDO requires the sensitivity for both the most probable point (MPP) search in inverse reliability analysis and design optimization. However, the sensitivity is often unavailable or difficult to compute in complex multi-physics or multidisciplinary engineering applications. Hence, the response surface method (RSM) is often used to calculate both function evaluations and sensitivity effectively. Researchers have been developing the RSM for decades, and yet are still searching for an approach with an efficient sampling method for fast convergence while meeting the accuracy criteria. This paper proposes a new adaptive sequential sampling method to be integrated with the Kriging method for RBDO. By using the bandwidth of the prediction interval from the Kriging method, a new sampling strategy and a new local response surface accuracy criteria are proposed. In this sequential sampling method, the response surface is initiated using very few samples. An additional sampling point will then be determined by finding the point that has the largest absolute ratio between the bandwidth of the prediction interval and the predicted response within a neighboring area of current point of interest. The insertion of additional sampling will continue until the accuracy criterion of the response surface in the neighborhood of the current point of interest is achieved. Case studies show this proposed adaptive sequential sampling technique yields better result in terms of convergence speed compared with other sampling methods, such as the Latin hypercube sampling and the grid sampling, when the same sample size is used. Both a highly nonlinear mathematical example and a vehicle durability engineering example show that the proposed RSM yields accurate RBDO results that are comparable to the sensitivity-based RBDO results, as well as significant savings in computational time for function evaluation and sensitivity computation.
Robust Design Method for Diverse Conditions
Authors: Watai Atsuki , Nakatsuka Satoshi , Kato Takeo , Ujiie Yoshiki , Matsuoka Yoshiyuki
Published: July 2010

This study demonstrates a robust design method for diverse conditions that are diverse design object, user features, and the environments that the object will be used in. In diverse conditions, two design problems are conceivable. One of the two problems occurs when an objective characteristic is in a non-normal distribution due to strong non-linear, discontinuous or stochastically fluctuant objective functions. We focus on the probability density function of the objective characteristic and propose an index to estimate the feasibility of an objective characteristic within a tolerance. The other problem is when a control factor has an adjustable range that enables users to adjust to meet their needs. To derive the optimum adjustable range of the control factor, we propose an index to estimate the ratio of the sum of sets of the probability of the objective characteristic within the tolerance. The proposed method using these indices is applied to an example where the appropriate cushion angle of a public vehicle seat is determined. As a result, the solutions using the indices are more robust than the conventional one.
Optimization of Twin Tensioner Performance in a Belt-Driven Integrated Starter-Generator System for Micro-Hybrids
Authors: Olatunde Adebukola , Zu J. W.
Published: July 2010

The objective of this paper is to optimize the belt tensioning mechanism, known as the Twin Tensioner. The optimized tensioner achieves the minimum magnitude of belt tension in a Belt-driven Integrated Starter-generator (B-ISG) system. The B-ISG is an emerging hybrid transmission that closely resembles conventional serpentine belt drives. The system contains an integrated starter-generator (ISG) unit that performs a start-stop function on the engine. A derivation of the system’s equation of motion is simulated in this paper. A parametric study evaluates the Twin Tensioner’s parameters with respect to their impact on static tensions. Design variables are selected from these parameters for optimization. The optimization uses the genetic algorithm (GA) and the sequential quadratic programming (SQP) searches. Computations for belt tension based on the optimized design variables indicate the optimal system contains spans with static tensions that are significantly lower in magnitude than in the original design.
Analysis of Product Flexibility for Future Evolution Based on Design Guidelines and a High-Definition Design Structure Matrix
Authors: Tilstra Andrew H. , Seepersad Carolyn C. , Wood Kristin L.
Published: July 2010

The design of a product determines the flexibility of that product for future evolutions, which may arise from a variety of change modes such as new market needs or technological change. The energy, material, and information exchanged between components of a product along with the spatial relationships and movement between those components all influence the ability of that product’s design to be evolved to meet the new requirements of a future generation. Previous work has produced a set of guidelines for product flexibility for future evolution that have been shown to improve the ability of a design to be adapted when new needs arise. Although these guidelines are conceptually easy to understand, it is difficult to assess the extent to which a product follows the guidelines. This paper presents a systematic method to analyze the flexibility for future evolution of products based on selected guidelines. The High-Definition Design Structure Matrix is presented as a product representation model which captures sufficient interaction information to highlight potential design improvements based on the aforementioned guidelines. An interaction basis is used to facilitate the consistency and comparison of HD-DSM models created by different examiners and/or for different systems. The selected guidelines are interpreted in terms of the HD-DSM by creating analysis processes that relate to the characteristics described by the guideline. Two similar power screwdrivers are compared for flexibility for future evolution based on a quantitative analysis of their respective HD-DSMs.
A Hybrid Sensitivity Analysis for Use in Early Design
Authors: Hutcheson Ryan S. , McAdams Daniel A.
Published: July 2010

Sensitivity analyses are frequently used during the design process of engineering systems to qualify and quantify the effect of parametric variation on the performance of a system. Two primary types of sensitivity analyses are generally used: local and global. Local analyses, generally involving derivative-based measures, have a significantly lower computational burden than global analyses but only provide measures of sensitivity around a nominal point. Global analyses, generally performed with a Monte Carlo sampling approach and variation-based measures, provide a complete description of a concept’s sensitivity but incur a large computational burden and require significantly more information regarding the distributions of the design parameters in a concept. Local analyses are generally suited to the early stages of design when parametric information is limited and a large number of concepts must be considered (necessitating a light computational burden). Global analyses are more suited towards the later stages of design when more information regarding parametric distributions is available and fewer concepts are being considered. Current derivative-based local approaches provide a significantly different set of measures than a global variation-based analysis. This makes a direct comparison of local to global measures impossible. To reconcile local and global sensitivity analyses, a hybrid local variation based sensitivity (HyVar) approach is presented. This approach has a similar computational burden to a local approach but produces measures in the same format as a global variation-based approach (contribution percentages). This HyVar sensitivity analysis is developed in the context of a functionality-based design and behavioral modeling framework. An example application of the method is presented along with a summary of results produced from a more comprehensive example.
Product Modular Design Using Atomic Theory
Authors: Yen Chao-Ching , Smith Shana
Published: July 2010

In this paper, an innovative method is presented which uses the properties of atomic theory to solve design modularization problems for product design. With the developed method, products can be modularized based upon different given constraints, e.g., material compatibility, part recyclability, and part disassemblability. The developed method can help engineers effectively create modular designs in the initial design stage, based upon different design requirements. With design considerations incorporated into new modules, a new design can be created which improves upon an original design, with respect to design requirements.
Electromagnetic Valve Actuation System With Two Configurations
Authors: Seethaler Rudolf , Duerr Konrad
Published: July 2010

Electromagnetic valve actuation systems for automotive combustion engines must provide extremely fast valve motion when the engine speed is high, but they also need to ensure low valve seating velocities during engine idle. These two constraints are difficult to combine in conventional spring assisted electromagnetic valve actuation devices that operate at a fixed resonance frequency. This paper focuses on a mechanism with two distinct configurations for low and high speed engine operations respectively. The mechanism is based on two pivoting cams. The synthesis of the cam profile ultimately determines the performance of the actuation system. An algorithm is presented that provides a time optimum cam profile for the high speed cam. The low speed cam is designed to allow for servo control of the valve system. A control scheme that aims to minimize electric losses in the drive system is also introduced. Both the cam synthesis algorithms and the control algorithm are applied to a typical automotive valve train and a digital simulation is used to validate the effectiveness of the mechanical cam design and control scheme.
Simplified Calculation Method for the Efficiency of Involute Spur Gears
Authors: Pedrero Jose´ I. , Pleguezuelos Miguel , Mun˜oz Marta
Published: July 2010

The traditional methods for computation of the efficiency of cylindrical gear transmissions are based on the hypotheses of constant friction coefficient and uniform load distribution along the line of contact. However, the changing rigidity of the pair of teeth along the path of contact produces a non–uniform load distribution, which has significant influence on the friction losses, due to the different relative sliding at any point of the line of contact. In previous works, the authors obtained a non-uniform model of load distribution based on the minimum elastic potential criterion. This load distribution was applied to compute the efficiency of spur and helical gears, resulting in slightly greater values of the efficiency than those obtained if the load distribution along the line of contact is assumed to be uniform. In this work, this non-uniform model of load distribution is applied to study the efficiency of involute spur gears with transverse contact ratio between 1 and 2 (i.e., the load is shared among one or two pairs of teeth), assuming the friction coefficient to be constant along the path of contact. Analytical expressions for the power losses due to friction, for the transmitted power and for the efficiency are presented. A study of the influence of some transmission parameters (as gear ratio, pressure angle, etc.) on the efficiency is also presented.
On the Topological Representation and Compatibility of Variable Topology Mechanisms
Authors: Shieh Win-Bin , Sun Frederick , Chen Dar-Zen
Published: July 2010

Variable topology mechanisms can serve many design functions with only one mechanism through changing their topology, these mechanisms have raised broad interest and attracted many studies in recent years, yet few have consolidated the different types of these mechanisms, nor discussed them in the light of the space they operate in. This work classified the variable topology mechanisms, and presented an expression of the mechanism’s working space. Variable topology mechanisms are classified into three types, topology changed by intrinsic constraints, topology changed by joint geometry change, and topology changed by external constraints. The causes and effects of various constraints inducing a topology change are described with the operating space, compatibility characteristics of joints, loops, and working stages with the operating space are established, verifying whether joints will constraint and lock up each other. The admissible operating space for a loop interface pairs so that loops are compatible, and the requisites of different working stages being workable with each other are identified. As a result, some basic requirements for admissible variable topology mechanisms are unveiled, laying a foundation stone for systematical synthesis of variable topology mechanisms.