bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Simulation of Robust and Adaptive Controls for a Nonlinear String System
Authors: Jin Weiwei , Qu Zhihua , Lin Kurt
Published: November 2021

In this paper, vibration control of a nonlinear string system is considered. The system consists of a nonlinear string, two boundary supporting mechanisms, and a moving transporter at the base. To suppress the vibration, boundary control designs are carried out. A new robust and adaptive boundary controller is designed using the Lyapunov direct method. The proposed control is implemented at the two ends supporting the string to compensate for vibration induced by the base motion. It is shown that the adaptive/robust boundary control can asymptotically stabilize the nonlinear string. Numerical simulation of the closed loop system demonstrates the effectiveness of the proposed control.
Adaptive Learning Algorithm for Cerebellar Model Articulation Controller: Neural Network Based Hybrid-Type Controller—Part II
Authors: Abdelhameed Magdy Mohamed , Pinson Unat , Cetinkunt Sabri
Published: November 2021

Cerebellar model articulation controller (CMAC) is a useful neural network learning technique. It was developed two decades ago but yet lacks adequate learning algorithm especially when it is used in a hybrid-type controller. Part I of this work was devoted to introduce a new CMAC adaptive learning algorithm. Part II will be directed to experimental application of new learning algorithm of a CMAC based hybrid-type real time controller. The proposed controller is applied for the trajectory tracking of a piezoelectric actuated tool post. It has been proven that the piezoelectric actuated tool post has hysteretic behavior. Extensive experiments have been carried out on the experimental setup to evaluate the proposed adaptive learning algorithm of CMAC. Only few experiments and their results are being presented. In these experiments, the performance of the piezoelectric actuated tool post has been examined and evaluated using different types of control algorithms and applying external load disturbance. The control performance of the proposed controller is compared with those of conventional controllers (PI controller and the conventional CMAC based controller). The experimental results showed that performance of the hybrid-type controller using the proposed learning algorithm is stable and more effective than that of the conventional controllers. Testing and comparing the learning ability of the proposed learning algorithm with that of the conventional CMAC learning algorithm indicated the effectiveness of the learning ability of the proposed algorithm. Finally, the response using the proposed hybrid-type controller is slightly better than using the conventional PI controller under the effect of external load disturbance.
Chatter Synchronization in Vibratory Drilling
Authors: Gouskov Alexander M. , Voronov Sergey A. , Batzer Stephen A.
Published: November 2021

The influence of tool dynamics on the chip formation process during vibratory drilling is analyzed. Regenerative effects and external excitation influences are considered. The mathematical models presented accounts for hole bottom surface formation and the possibility of intermittent cutting. Various technological system configurations are analytically and numerically analyzed.
Second Order Poincaré Map to Study Dynamical Behavior of Nonsymmetrical Gyrostat Satellite
Authors: Shirazi K. H. , Ghaffari-saadat M. H.
Published: November 2021

The second order poincare’ map is described and used for investigation of the dynamical behavior of a gyrostat satellite. The normalized attitudinal equations of motion for a typical non-symmetric gyrostat satellite are considered. For different sets of initial conditions the equations simulated by Runge-Kutta method. The poincare’ section is used to dimension reduction of system phase space. By this map the dimension reduced from six to five. Using secondary map the dimension of phase space can be reduced to four and considering symmetry of phase space the final space has two dimensions that is presentable at the plane. Bifurcation in the attitudinal behavior can be demonstrated easily by the derived map.
The Effects of Indocyanine Green Dye-Enhanced Photocoagulation on the Blood Flow in the Choriocapillaris and the Choroidal Neovascularization (CNV)
Authors: von Kerczek C. , Zhu L. , Ernest A. , Eggleton C. , Topoleski L. D. T. , Flower R. W.
Published: November 2021

Age-related macular degeneration (AMD) is the most common cause of vision loss in patients aged 65 years and older in the United States. In the majority of cases, the loss of central vision is secondary to exudative changes and fibrovascular scarring following choroidal neovascularization (CNV). Prompt laser treatment is recommended [Asrani et al., 1996; Macular Photocoagulation Study Group, 1993; Schneider et al, 1998]. However, direct laser treatment to the entire subfoveal lesion is almost invariably associated with immediate loss of central vision. Loss of central vision may be due to direct damage to foveal photoreceptors and retinal pigment epithelium or from damage to the nerve fiber layer serving foveal function [Han et al., 1988].
Optimization of Organ Freezing Protocols With Specified Allowable Thermal Stress Levels
Authors: Dennis Brian H. , Dulikravich George S. , Rabin Yoed
Published: November 2021

A novel concept of determining optimized cooling protocols for freezing three-dimensional organs has been developed and its feasibility examined computationally. The concept is based on determining correct spatial variation of temperature distribution on the walls of a freezing container at every instant of time during the cooling process so that local thermal stresses in the heterogeneous organ are always kept below a specified level while maximizing the local cooling rates. The cryo-preservation medium must be gelatin which prevents thermal convection. The optimized cooling protocol was simulated by developing a time-accurate finite element computer program to predict unsteady heat conduction with phase change and thermal stresses within a realistically shaped and sized organ made of tissues with temperature-dependent physical properties. A micro-genetic optimization algorithm was then used to achieve nonlinear constrained optimization of parameterized time-varying container wall temperature distribution so that the prescribed maximum allowable thermal stresses are never exceeded in the organ.
Modeling of the Local Heating of Non-Perfused Tissue With Directionally Dependent Thermal Diffusivity and Heat-Induced Damage
Authors: Davis Sean E. , Thamire Chandrasekhar , Wright Neil T.
Published: November 2021

Minimally invasive heat therapies are of continued clinical interest to alter the functional attributes of tissue in the treatment of a number of pathologies. The extent of heating and tissue alteration is governed by the physics of the mode of heating, the geometry of the heater, and the properties of the tissue. Analytical models are needed to optimize the design of protocols and predict clinical outcomes. Presented here are the results of a finite difference model of the heating and alteration of a hypothetical non-perfused artery adjacent to a joule-heated, catheter-mounted balloon as might be used to enhance coronary angioplasty. The calculations suggest that shorter heating times (∼20 s) at greater balloon lumen temperatures (95 °C) better localize heating-induced changes to tissue than longer heating at lower temperatures (470 s at 60 °C) for the same alteration of the target arterial tissue.
A New Thermal-Fatigue Life Prediction Model for Wafer Level Chip Scale Package (WLCSP) Solder Joints
Authors: Lau John H. , Pan Stephen H. , Chang Chris
Published: November 2021

A new empirical equation for predicting the thermal-fatigue life of wafer level chip scale package (WLCSP) solder joints on printed circuit board (PCB) is presented. The solder joints are subjected to thermal cycling and their crack lengths at different thermal cycles are measured. Also, the average strain energy density around the crack tip of different crack lengths in the corner solder joint is determined by a time-dependent nonlinear fracture mechanics with finite element method. The solder is assumed to be a temperature-dependent elastic-plastic and a time-dependent creep material.
Interfacial Delamination Propagation in Multi-Layered High-Density Wiring Electronic Packaging Structures
Authors: Hu Hurang , Xie Weidong , Sitaraman Suresh
Published: November 2021

One of the most common failure modes in multi-layered electronic packaging structures is interfacial delamination. The objective of this research is to examine the possibilities of interfacial delamination in a next-generation electronic packaging structure under thermal loading. A sophisticated analytical model has been developed to determine energy release rate and stress intensity factor for delamination propagation. The model takes into consideration the temperature-dependent material properties as well as direction-dependent material properties. Although delamination between two adjacent layers is studied, the model takes into consideration the effect of all dielectric, metallization, and substrate layers in the multi-layered structure.

Assuming that an initial delamination exists between the base layer and the Copper metallization layer, the present work studies the propagation of delamination. In the analytical model, the base layer is modeled as an orthotropic thermo-elastic material. Copper and the polymer dielectric materials are modeled as isotropic thermo-elastic material. For the Copper/base layer interface, the variation of bimaterial constant (ε) with temperature is obtained through the analytical model. The effect of some key parameters, such as materials Young’s modulus, coefficient of thermal expansion, and the base layer thickness on energy release rate is presented. Design recommendations for improved thermo-mechanical reliability are proposed.
Thermomechanical Durability of High I/O BGA Packages
Authors: Davuluri Pavan , Dasgupta Abhijit , Young Steven
Published: November 2021

Efficient modeling strategies are developed to study thermomechanical durability of high I/O Ball Grid Array (BGA) packages, in order to facilitate virtual qualification and accelerated testing of component designs. A viscoplastic stress analysis technique is developed where the critical solder joint(s) (joint(s) at which failure first occurs) are modeled in detail with a multi-domain Rayleigh-Ritz (MDRR) methodology (Ling and Dasgupta, 1996; Ling and Dasgupta 1997; Ling 1997; and Rassian and Lee, 1998) while the load-sharing offered by non-critical joints is modeled with a simplified compact model. This hybrid technique is used to study the behavior of solder interconnects in selected Ball Grid Array (BGA) package under thermal cycling environments. Parametric studies are conducted to determine the optimal scheme for allocating a critical number of solder joints to the MDRR model, and the remaining non-critical joints to the compact models. Damage calculations are made with the Energy Partitioning Solder Durability model (Dasgupta et al., 1992) and cycles-to-failure predictions are compared with both finite element model predictions as well as experimental failure data provided by CALCE EPSC sponsors. Parametric studies on change in solder joint durability with interconnect volume are also discussed in this paper.
Damage Mechanics Based Fatigue Life Prediction for 63Sn-37Pb Solder Material
Authors: Wei Y. , Chow C. L. , Neilsen M. K. , Fang H. E.
Published: November 2021

This paper presents a method of TMF analysis based on the theory of damage mechanics to examine the fatigue damage accumulation in 63Sn-37Pb solder. The method is developed by extending a viscoplastic damage model proposed earlier by the authors (Wei, et al 1999, 2000). A computer simulation is carried out to calculate hysteresis loops at three different strain ranges. The damage-coupled fatigue damage model is applied to predict the cyclic softening behavior of the material and the prediction is found to agree well with the experiment. With a proposed failure criterion based on the concept of damage accumulation, the TMF model is also found to predict successfully the fatigue life of 63Sn-37Pb solder.
Thermal Fatigue Analysis of PBGA Solder Joints With the Consideration of Damage Evolution
Authors: Lee Shi-Wei Ricky , Newman Keith , Hu Livia
Published: November 2021

This paper presents a computational thermal fatigue analysis for the life prediction of solder joints in a plastic ball grid array-printed circuit board (PBGA-PCB) assembly. The PBGA has a full grid array of 256 solder balls with 1.0 mm ball pitch. The PCB is a 4-layer FR-4 laminate with a thickness of 1.57 mm (62 mils). The assembly is subjected to −40∼125°C thermal cycling (one-hour cycle). Finite element analysis is performed to obtain the creep hysteresis loops. Based on a previously developed model, the evolution of damage is considered in the life prediction of solder joints. Besides, PCBs with various thicknesses (40 mils and 20 mils) are investigated. The results from different cases are compared and discussed.
Optimizing a Lithium Niobate Slicing Process Using ID Saw in Wafer Manufacturing
Authors: Fang Tong , Jundt Dieter H. , Lambropoulos John C.
Published: November 2021

The paper summarizes a systematic study of the lithium niobate wafer slicing process using inner diameter (ID) diamond blade. The dynamometer is used for the measurement of cutting forces in ID slicing when changing various process parameters. Experimental observations regarding the radial and axial dressing effect, removal rate effect, and contact geometry effect are reported. The normal and tangential cutting forces under typical ID slicing conditions with fixed abrasive diamond blade correlate to the feed rate, geometrical contact length, and diamond sharpness. The axial cutting forces are related to blade deflections. An interpretation of slicing of lithium niobate in terms of a micromechanics model of material removal by inclined cracking along cleavage planes is presented.
Simulating Motion of an Operator-Controlled Gantry Crane in a Cluttered Work Environment
Authors: Frakes David , Grosser Karen , Fortgang Joel , Singhose William
Published: November 2021

Manipulating payloads with overhead gantry cranes can be challenging due to the oscillations induced by the crane motion and by external disturbances. The problem gets increasingly difficult when the work environment is cluttered with obstacles that must be avoided. This paper examines this problem and investigates the role of the operator actions. To do this, simple mathematical models of the operator behavior and crane dynamics are developed. Furthermore, the effect of adding an input shaping controller to reduce oscillations is examined.
Imaging and Motion Prediction for an Automated Live-Bird Transfer Process
Authors: Lee Kok-Meng , Joni Jeffry , Yin Xuecheng
Published: November 2021

This paper presents the illumination design of a real-time live-bird imaging system for determining the size and initial presentation of a bird on a moving conveyor. A real-time live-bird imaging system presents a challenging design problem, for it must minimize the variability of the birds’ visual reflexes to mechanical processes, it must account for variations in bird size/shape/color, it must meet the cycle-time requirement, and yet provide an adequately illuminated environment to ease human supervision. In this paper, we first identify the variables needed for motion prediction. Second, by analyzing the bird visual perception we have developed a two-stage structured illumination that has the potential to minimize the demand on the control efforts of the transfer system, and to improve birds’ welfare and the ultimate product quality. Finally, we present the image algorithms and experimental results of the design evaluation using live birds. It is expected that the design principles presented in this paper provide essential bases for motion analysis, prediction, and control of an automated live-bird transfer process.
The Modeling and Control of the Hydraulic Servo System by Using On-Off Valve
Authors: Wang Xuanyin
Published: November 2021

This paper researches on the hydraulic servo system by using ordinary on-off valves. The mathematic model of an asymmetric hydraulic cylinder servo control system is built, and its characteristic is analysed here. To reduce the static and dynamic characteristic differences between forward and reverse motion of asymmetric cylinder, and improve system’s performance, a self-tuning linear quadratic gaussian optimum controller (SLQG) is designed successful. In the end, an asymmetric hydraulic cylinder servo system of paint robot is researched. The result shows that the above method is effective.
Modeling the Internal Leakage of Hydraulic Servovalves
Authors: Eryilmaz Bora , Wilson Bruce H.
Published: November 2021

This paper considers flow, in particular, leakage flow, between a servovalve spool and valve body. Although often ignored, experimentation and analysis indicate that at small spool displacements this flow is much larger than orifice flow. In precision positioning applications, where the servovalve operates within the null region, leakage flow may severely degrade the performance of conventional servohydraulic designs based on ideal orifice relation. Hence, servovalve models for such applications should include leakage flow. We have developed a model for leakage flow in a servovalve. This has been achieved by reviewing experimental leakage flow data and identifying a simple mathematical form that (1) makes physical sense and (2) can replicate experimental data. The resulting model accurately captures leakage behavior, which is modeled as turbulent flow with a flow area inversely proportional to the overlap between the spool land and valve orifices. When combined with orifice relations, the model extends the accuracy and region of applicability of existing servovalve models. Furthermore, the leakage model is easily parameterized, an important feature for controller design and adaptive methods.
Control-Oriented Modeling of an Injection Molding Machine Including the Fill-to-Pack Transition
Authors: Zheng Danian , Alleyne Andrew , Havlicsek Heather
Published: November 2021

In this paper the modeling of a typical injection cycle for an injection molding machine (IMM) is examined. Both the mold filling and mold packing phases of the cycle are examined along with a critical fill-to-pack transition. The novelty in this modeling work is that the non-linear model considers both the machine hydraulic actuator and polymer flow characteristics in extensive detail. The resulting model will provide simulation capabilities to facilitate machine controller design; however the actual controller is not the focus of the current work. The modeling is based on (a) the characteristics of digitally controlled electrohydraulic valves, (b) the dynamics of the hydraulic actuator ram system, and (c) the gross polymer melt behavior determined from simple polymer engineering models. The simulation model is validated against experimental data and demonstrates the availability of a relatively accurate system model for full cycle control of this electrohydraulic system.
Comparison of Two Distributed Fuzzy Logic Controllers for Flexible-Link Manipulators
Authors: Shi Linda Z. , Trabia Mohamed B.
Published: November 2021

Fuzzy logic control presents a computationally efficient and robust alternative to conventional controllers. An expert in a particular system can usually design a fuzzy logic controller for it easily as can be seen in many applications where fuzzy logic has been already successfully implemented. On the other hand, fuzzy logic controllers are not readily available for flexible-link manipulators. This paper presents two different approaches to design distributed controllers for flexible-link manipulators. The first approach, which is based on observing the performance of flexible manipulators, uses a distributed controller composed of two PD-like fuzzy logic controllers; one controller controls the joint angle while the other controls the tip vibration. The second distributed controller is based on evaluating the importance of the parameters of the system. The most two important parameters, joint and tip point velocities, are grouped together in the same fuzzy logic controller. The other parameters, joint angle and tip point displacement, are used in the second fuzzy logic controller. Both approaches are tuned using nonlinear programming. The paper compares these two approaches with tracking using a linear Quadratic Regulator (LQR).
A Behavior-Based Autonomous Agent Possessing System Detectable Error
Authors: Bearden Keith L. , Nowack Mark L. , Troxell Wade O.
Published: November 2021

A great deal of recent research is devoted to increasing the robustness and capability of behavior-based robotic systems. Behavior-based systems are extremely susceptible to sensor errors. To overcome this, most researchers have added processors to the basic system to compare multiple redundant sensors. This is an effective error detection approach, but it costs processor time, increases complexity, and can actually reduce reliability. Most importantly such systems lack the ability to self-detect error. All other forms of representation are unable to determine system level functional failures without the use of an external observer. This paper proposes a divergence from detecting sensor error to detecting functional error. By looking at the functional error space, the system can determine an error and move away from the error. This method will not determine a sensory failure as the cause of the functional failure; rather, this method determines that the system is not performing its main function and then tries something else. This leads to a system that can function with the loss of forty percent of its sensory capability for either the case of a disconnected sensor or a stuck sensor.
Bounded-Input-Bounded-Output Stability of Nonlinear Feedback Systems in a Volterra Representation
Authors: Glass John W. , Franchek Matthew A.
Published: November 2021

Presented in this paper is a stability condition for a class of nonlinear feedback systems where the plant dynamics can be represented by a finite series of Volterra kernels. The class of Volterra kernels are limited to p-linear stable operators and may contain pure delays. The stability condition requires that the linear kernel is nonzero and that the closed loop characteristic equation associated with the linearized system is stable. Next, a sufficient condition is developed to upper bound the infinity-norm of an external disturbance signal thereby guaranteeing that the internal and output signals of the closed loop nonlinear system are contained in L∞. These results are then demonstrated on a design example. A frequency domain controller design procedure is also developed using these results where the trade-off between performance and stability are considered for this class of nonlinear feedback systems.
An Integrated Environment for Vehicle Dynamics Controls and Integration
Authors: Deng Weiwen , Lee Yong , Nisonger Robert , Chin Yuen-kwok
Published: November 2021

This paper provides an overview of VehSim, a PC Windows-based vehicle simulation software for vehicle dynamics, controls and integration. The function and features of VehSim are discussed in general. With its high fidelity, flexibility, portability and user-friendly interfaces, VehSim provides an integrated development environment for engineers to conduct vehicle, especially chassis/driveline modeling, simulation and control algorithm design and to build quick software prototypes to accelerate chassis/driveline controls and integration development. VehSim’s structure, which includes file system, database structure and user graphic interfaces are described. Through its modularized and hierarchical structure, VehSim features great flexibility for engineers to customize their own project needs by developing their own control algorithms or incorporating supplier provided subsystem models and control modules into vehicle dynamics. With the compatibility of VehSim to real-time environment, engineers are able to perform both quick off-line simulation and on-line in-vehicle validation for algorithm development. VehSim also provides built-in user-friendly model preprocessors and postprocessors for engineers to easily build vehicle and/or subsystem models, adjust numerical computation parameters and process the simulation results on line. A 3D solid model based motion animator is also integrated in VehSim for on-line visual processing of simulation results.
A New Mechanism Explaining High Frequency Chatter Vibration Involving Tool Tip X-Y Looping in Fine Boring
Authors: Edhi Evita , Hoshi Tetsutaro
Published: November 2021

The study deals with boring tool, which was found to exhibit chatter in fine boring operation occurring at high frequencies, more than 10,000 Hz, and causing reduced tool life. The boring tool was operated in a stage of a transfer-type machining equipment and used for making small diameter hole, 15mm (0.59in), in a hardened alloy steel of motorcycle engine component.

The objective of the research is to identify the mechanism responsible for the onset of the high frequency chatter.

To study the mechanism, cutting tests have been performed in analogous machining operation, as well as structural dynamics examination of boring tool using experimental modal analysis by sinusoidal excitation.

The experimental study has revealed that the traditional knowledge of regenerative chatter can not fully explain the chatter mechanism, but the effect of regeneration, the imaginary part effect of inner modulation, and the X-Y looping of the tool tip are three relevant characteristics in the onset of the chatter.

Those findings are included in a new theoretical chatter model of which validity is evaluated principally by computational analysis of energy supplied and dissipated in the cutting process-boring tool structure system per vibration cycle.
Real-Time Force Control of a Grinding Process Using Unfalsification and Learning Concept
Authors: Razavi H. Ali , Kurfess Thomas R.
Published: November 2021

Conventional controller synthesis relies on a plant model that is not falsified by the open-loop experiments. Alternatively, without any plant model or prejudicial assumptions it is possible to find a set of controllers that are not falsified by the performance specification or the measured data (Safanov and Tsao, 1997). This approach is used to implement a real-time force controller on a reciprocating surface grinder.
Model-Based Machining Force Control
Authors: Landers Robert G. , Ulsoy A. Galip
Published: November 2021

Regulating machining forces provides significant economic benefits by increasing operation productivity and improving part quality. Machining force regulation is a challenging problem since the force process varies significantly under normal operating conditions. Since fixed-gain controllers cannot guarantee system performance and stability as the force process varies, a substantial research effort has been invested in the development of adaptive force controllers. However, adaptive controllers can be difficult to develop, analyze, implement, and maintain due to their inherent complexity. Consequently, adaptive machining force controllers have found little application in industry. In this paper, a model-based machining force control approach, which incorporates detailed force process models, is introduced. The proposed design has a simple structure and explicitly accounts for the changes in the force process to maintain system performance and stability. Two model-based machining force controllers are implemented in face milling operations. The stability robustness of the closed-loop system with respect to model parameter uncertainties is analyzed, and the analysis is verified via simulation and experimental studies.
Improving the Performance of Process Controllers Using a New Clustered Neural Network
Authors: Solemani Mohammad R. , Guillot Michel
Published: November 2021

This paper presents first a newly developed clustered neural network, which incorporates self-organization capacity into the well-known common multilayer perceptron (MLP) architecture. With this addition, it is possible to reduce significantly overall memory degradation of the neuro-controller during on-line training.

In the second part of the paper, this clustered multilayer perceptron (CMLP) network is applied and compared to the MLP through modeling and simulations of machining processes. Simulation results presented using machining data demonstrate that the CMLP possesses more powerful modeling capacity than the standard MLP, offers better adaptability to new operating conditions, and finally performs more reliably. During on-line training with machining data about 65% degradation of previously learned information can be observed in the MLP as opposed to only 11% for the CMLP.

Finally, an adaptive control scheme intended for on-line optimization of the machining processes is presented. This scheme uses a feedforward CMLP inverse neuro-controller which learns off-line and on-line the relationships between process inputs and output under simulated perturbations (i.e., tool wear and non-homogeneous workpiece material properties). The first results using the CMLP inverse neuro-controller are promising.
Modular Modeling Using Lagrangian DAEs
Authors: Piché Robert , Palmroth Mikko
Published: November 2021

Layton’s Analytical System Dynamics theory for modeling multidisciplinary physical systems with Lagrangian differential algebraic equations (DAEs) is extended by introducing a technique for using hierarchical reusable modules. Connections between submodels are represented in a systematic manner using kinematic constraints and Lagrange multipliers. Simulation software design issues are discussed: data structures, consistent initial conditions, index reduction, and DAE solvers. An example of an electromechanical feedback control system is presented in detail.
Contribution to Eigenvalues of LTI System by Physical Subsystems
Authors: Ye Yong , Youcef-Toumi Kamal
Published: November 2021

This paper presents some results on the relation between the dynamic properties of a subsystem and the eigenvalues of the overall system. Since the eigenvalues corresponding to the unreachable/unobservable modes of a subsystem is not affected by the dynamic properties of other subsystems, one can expect useful information from a measurement of the reachability/observability of a mode of a subsystem. In this paper, it is proven that when such a measurement is in a certain range, the position of the corresponding eigenvalue of the overall system is within certain boundary. The results can contribute to model assembly, model reduction and system synthesis. An example is presented to illustrate the application.
Modeling Flexible Segments With Force and Moment End Loads via the Pseudo-Rigid-Body Model
Authors: Lyon Scott M. , Howell Larry L. , Roach Gregory M.
Published: November 2021

This paper presents the development of a new pseudo-rigid-body model to model the deflection path of flexible segments with force and moment loads. Three separate loading cases are presented including: a cantilever beam with applied end-force and moment in the same direction, a cantilever beam with the applied end-force and moment in opposite directions with no inflection point being produced in the beam, and a cantilever beam with the applied end-force and moment in opposite directions which produces an inflection point in the beam. These types of segments are common in compliant mechanisms so it is important to have a method for their design and analysis.
DECAFF: Experimental Study on Human Haptic Perception
Authors: Springer Scott L. , Ferrier Nicola J.
Published: November 2021

DECAFF is a method for design and control of haptic interfaces that utilizes a DE-Coupled Actuator and Feed-Forward control. In this paper results of an experimental investigation are presented that quantify improved human haptic perception while using the DECAFF system, compared to the traditional haptic interface design and control systems. Perception improvements include the increased stability for rigid surfaces and increased ability of subjects to accurately identify initial contact with virtual surface boundaries. Traditional haptic interfaces employ an actuator directly coupled to the human operator that provides a force proportional to wall penetration distance and velocity. The DECAFF paradigm for design and control of haptic displays utilizes a de-coupled actuator and pre-contact distance sensing as a feed forward control term to improve stability and response performance. A human perception experiment has been performed that compares the touch sensation of the subjects for both the DECAFF system and traditional approaches to haptic display. In the human factors study the quality of rigid body display is evaluated in addition to the sensitivity of touch experienced by the subjects while making initial contact with virtual surfaces.
A Real-Time Static Posture Classification System
Authors: Slivovsky Lynne A. , Tan Hong Z.
Published: November 2021

As computing becomes more ubiquitous, there is a need for distributed intelligent human-computer interfaces that can perceive and interpret a user’s actions through sensors that see, hear and feel. A perceptually intelligent interface enables a more natural interaction between a user and a machine in the sense that the user can look at, talk to or touch an object instead of using a machine language. The goal of the present work on a Sensing Chair is to enable a computer to track, in real time, the sitting postures of a user through contact sensors that act like a layer of artificial skin. This is accomplished with surface-mounted pressure distribution sensors placed on the backrest and the seatpan of an office chair. Given the similarity between a pressure distribution map from the contact sensors and a greyscale image, computer vision and pattern recognition algorithms, such as Principal Components Analysis, are applied to the problem of classifying steady-state sitting postures. A real-time multi-user sitting posture classification system has been implemented in our laboratory. The system is trained on pressure distribution data from subjects with varying anthropometrics, and performs at an overall accuracy of 96%. Future work will focus on the modeling of transient postures when a user moves from one steady-state posture to the next. A robust, real-time sitting posture tracking system can lead to many exciting applications such as automatic control of airbag deployment forces, ergonomics of furniture design, and biometric authentication for computer security.
A Psychophysical Study of Sensory Saltation With an Open Response Paradigm
Authors: Tan Hong , Lim Adrian , Traylor Ryan
Published: November 2021

As we develop new haptic interfaces, it is desirable to present haptic information in an intuitive and effective manner. The sensory saltation phenomenon is a haptic spatiotemporal illusion that, with the appropriate spatial and timing parameters, evoke a powerful perception of directional lines. Efforts are underway to develop a general-purpose haptic display based on sensory saltation that can find application in many areas including a haptic driving navigation guidance system. The current study is designed to test the hypothesis that saltatory signals can be readily perceived by human observers without training. Using a 3-by-3 tactor array, horizontal, vertical and diagonal saltatory lines are generated. An open response paradigm is used to permit subjects to describe saltatory signals with their own imagination. Results show that the saltatory signals used in this study share unique and consistent interpretations among the group of observers tested. Future work include a follow up study of the same saltatory signals using a standard absolute identification paradigm.
Calibration and Mapping of a Human Hand for Dexterous Telemanipulation
Authors: Griffin Weston B. , Findley Ryan P. , Turner Michael L. , Cutkosky Mark R.
Published: November 2021

This paper presents a calibration scheme and kinematic mapping to support dexterous telemanipulation. The calibration scheme is intended for use with an instrumented glove and permits an accurate determination of the intended motions of a virtual object grasped between a human operator’s thumb and index finger. The motions of the virtual object are then mapped to analogous motions of a scaled virtual object held in a two-fingered robot hand. A non-linear mapping scheme allows better utilization of the human and robot hand workspaces.
Haptic Simulation of Assembly Operation in Virtual Environment
Authors: Yoshikawa Tsuneo , Yoshimoto Kouki
Published: November 2021

This paper presents a haptic simulator of 2-dimensional peg-in-hole assembly operations in a virtual environment, considering the dynamics and the surface friction characteristics of the peg and the hole. An operator can operate the virtual peg by inserting his fingers into rings at the tips of link mechanisms which display the operating feeling to the operator. By using this simulator, we can measure the force between fingers and the peg, the contact states between the peg and hole, and the position of the peg during the operation. To examine the validity of the simulator, comparison between the peg-in-hole task using the simulator and that in the real world has been performed. It is hoped that this simulator will help in gathering data of human skill in assembly tasks and analyzing the human skill.
Aluminum Space Frame Behavior in Frontal Crash
Authors: Baccouche Mohamed Ridha , Wagner David A. , Mahmood Hikmat F. , Jawad Saad A.
Published: November 2021

Developing crashworthy aluminum structural systems presents a dual challenge. The challenge lies first in the material and second in the design approach. The objective of this paper is to examine both the material and design elements and to validate the design methodology using CAE analysis and components experimental data from an aluminum space frame partial front end structural buck design & development project. The CAE analysis examines the static and dynamic load carrying capacity and crash energy management of the components and partial front end systems under full frontal rigid barrier impact. The experimental validation uses static and dynamic data from several components and one partial front end structural buck designed and manufactured during the undertaking of this design project. The components were tested while the design is being carried out. The testing of the partial front end buck was carried out at a later date. The objective of this paper is not to correlate CAE results with the test data, but rather to demonstrate the benefit and effectiveness of applying low resolution fast CAE tools, such as nonlinear collapsible beam finite element and stability codes, along with limited components static and dynamic testing to the early stage of a program to guide the structural crashworthiness and energy management design process and achieve design objectives.
Characterization of Frontal Crash Pulses
Authors: Mahmood Hikmat F. , Aouadi Fadhel
Published: November 2021

This paper presents test data of more than 30 vehicles of different manufacturer, weight and front-end length. The relationships between the vehicle frontal NCAP pulse, the dummy response and the vehicle characteristics are shown in many figures. Vehicle frontal pulses were characterized and analyzed by considering different time zones within the pulse duration: bumper effect zone (0 ms. to 5 ms.), engine effect zone (18 ms. to 35 ms.), dummy engagement zone (48 ms. to 68 ms.). Also, ratios and delays between rocker pulse and the dummy chest and head pulses are computed and analyzed. The purpose of this study is not to develop a crash pulse but to generate design information that can assist in the design of front-end structure to meet injury criteria.
Tissue Engineering: Interdisciplinary, Multi-Disciplinary Technology
Authors: Parenteau Nancy L. , Sullivan Susan , Cosman Maury D.
Published: November 2021

Tissue engineering is the use of engineering and biology for the repair, replacement or regeneration of tissues. It often requires multiple disciplines within engineering and the biological sciences. Each problem is unique in its requirements. While the intent may differ, e.g. structural repair, physiological correction, chemical delivery, or a combination, most applications will require multi-disciplinary input.
Genzyme Tissue Repair
Authors: Hefernan John
Published: November 2021

Genzyme Tissue Repair (GTR) is a leading developer of cell therapies for the treatment of knee injuries and severe burns. GTR has pioneered the field of autologous cell therapy, in which a patient’s own cells are used to replace those that have been lost to injury or disease. With two major products on the market, GTR continues to be one of the leading companies in the field of tissue engineering. This portion of the presentation will focus on the process controls and specifications to produce these two products detailed below.
Regulation of Neointimal Morphogenesis by Blood Shear Stress
Authors: Liu Shu Q.
Published: November 2021

Blood vessels are subject to blood shear stress, which influences vascular biological processes [1]. Here the author investigates how blood shear stress regulates neointimal morphogenesis in blood vessels.
Axial Stretch Increases Cell Proliferation in Arteries in Organ Culture
Authors: Han Hai-Chao , Vito Raymond P. , Michael Kristin , Ku David N.
Published: November 2021

To study the effect of axial stretch on vascular function and wall remodeling, porcine carotid arteries were cultured under conditions of physiological flow and elevated axial stretch in an ex vivo organ culture system. Smooth muscle cell proliferation was measured by bromodeoxyuridine index. Results showed that cell proliferation was significantly increased in the highly stretched arteries when compared to the normally stretched arteries. This may indicate the feasibility of stimulating new arterial growth by stretching natural arteries.
Early Stabilizing Effects of HAC vs PMMA for Vertebroplasty in Compression Burst Fractures
Authors: Hitchon Patrick W. , Taggard Derek A. , Rogge Thomas N. , Goel Vijay K. , Drake John S.
Published: November 2021

Multiple strategies exist for the management of thoracolumbar burst fractures. Particularly in osteoporotic bone and elderly patients, minimally invasive techniques for stabilization are desirable. PMMA has been used to enhance structural support during spinal stabilization as well as for percutaneous vertebroplasty. As an inert substance, PMMA is associated with an exothermic reaction making it less than ideal for use in close proximity to neural elements. As an alternative we are studying HAC vs. PMMA. HAC has the advantages of being osteoconductive, biocompatible, and non-exothermic. The purpose of the current study was to test the early stabilizing effect of HAC as compared to PMMA using an experimentally produced burst fracture and a subsequent percutaneous vertebroplasty for stabilization.
Characterization of In Situ Elongation in the Interosseous Ligament of the Forearm
Authors: Gabriel Mary , Stabile Kathryne , Pfaeffle Jamie , Tomaino Matthew , Fischer Kenneth
Published: November 2021

For most ligaments, the strains vary spatially and depend upon joint position. Quantifying the distribution of strain in ligaments is necessary to understand their normal function and their injury mechanisms. In addition, the strain distribution is important data for developing functional reconstruction techniques.
A Finite Element Model of a Rotating Platform Total Knee Employing a Nonlinear, Dual-Surface-Contact Formulation
Authors: Otto Jason K. , Brown Thomas D. , Callaghan John J.
Published: November 2021

Mobile bearing total knees avoid the conformity/constraint tradeoff of fixed bearing total knees. However, a recent in vivo fluoroscopic study of the most popular mobile bearing total knee in the U.S. showed that bearing motion failed to occur in half of the patients observed. A nonlinear, multiple-surface contact finite element model of a rotating platform total knee was therefore developed to investigate the interaction at the “mobile” interface (contact between the tibial tray and the polyethylene insert) under physiologically relevant loads (1–4 BW) and rotations (10° endorotation). The data showed that there was a linear relationship between axial load and the torque resisting endorotation. Peak contact stresses were located on the medial and lateral peripheral edges of the polyethylene insert. All relative rotation occurred at the “mobile” interface. The same trends were seen in a complementary experimental study of the same components, suggesting that the finite element model is valid under these loading conditions.
A Comparison of the Viscoelastic Behavior of the Lumbar Intervertebral Disc Before and After the Implantation of a Prosthetic Disc Nucleus
Authors: Bain Allison C. , Sherman Tara , Norton Britt K. , Hutton William C.
Published: November 2021

A prosthetic disc nucleus device has been designed to replace the degenerated lumbar intervertebral disc (IVD) nucleus. In this study, we measured the creep response of a lumbar motion segment in the intact condition, after a nucleotomy, and after implantation with the device. The creep behavior was modeled with a three parameter standard linear solid to determine the elastic (E1, E2) and viscous (η) constants that describe the behavior of the disc. The average elastic damping constant (E1), and the viscous constant (η) were significantly lower after the nucleotomy than in the intact state. There were no significant differences between the intact motion segment and the device-implanted motion segment. This study demonstrates that the prosthetic disc nucleus device restores the viscoelastic behavior of the intact spine after nucleotomy.
Probabilistic Finite Element Analysis of the Human Lower Cervical Spine
Authors: Thacker Ben H. , Nicolella Daniel P. , Kumaresan Srirangam , Yoganandan Narayan , Pintar Frank A.
Published: November 2021

The probabilistic response of an anatomically accurate, three-dimensional, non-linear and experimentally validated finite element model of the human lower cervical spine is presented. Biological variability of the model input variables is accounted for by modeling these parameters as random variables. Efficient probabilistic methods are used to determine the effect of biological variability on the computed response of the non-linear finite element model. Probabilistic sensitivity factors are determined to assess the relative importance of each of the random variables on the probabilistic response.
Head Injury and Improved Padding in Infant Seats
Authors: Sances Anthony , Carlin Fred H. , Harcourt John
Published: November 2021

Head injury is a common finding for infants and young children who are involved in automobile accidents and are restrained in infant seats. A source of injury is the shell of the safety seat itself since it may offer little reduction in head acceleration to the infant that contacts the interior of the seat. Door panel intrusion during a side collision may also introduce external forces on the infant seat. By the introduction of effective and sufficient padding, and protecting the infant seat shell from external intrusion, a reduction in head injury potential may be obtained. This dynamic study shows that a marked reduction in HIC, angular velocity and angular acceleration occurs with improved padding in the shell of an infant seat.