bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Approach to Understanding Starling’s Law at the Microstructural Level
Authors: Hu Xiaping , Curry Fitzroy , Weinbaum Sheldon
Published: March 2022

1996 marked the 100th anniversary of Starling’s classic paper proposing that the capillary wall behaves like a semipermeable membrane in which there is net filtration on the arterial side and a net absorption on the venous side due to the colloidal osmotic pressure of plasma proteins. While the validity of the general premise was experimentally demonstrated by Landis in 1930, who showed that in human skin capillaries at heart level that the two competing flows nearly balance one another with the small excess resulting in a lymph flow, recent experiment summarized in [3] have shown that the simple Landis-Starling diagram shown in most textbooks is not true in nearly all other body locations. In nearly all tissues in which detailed measurements of the plasma and interstitial hydrostatic and oncotic pressures have been made along the length of the calillary there is little reabsorption on the venous side since the local interstitial oncotic pressure rises sharply as the flow rate is reduced. This has been beautifully demonstrated by Michel and Philips [3] in individually perfused frog mesentery capillaries, where it is shown that the interstitial colloidal osmotic pressure depends critically on the filtration rate and there is still a small positive net filtration on the venous side. This intriquing paradox has just been reviewed in Michel (1997).

In the proposed paper a new theory is presented to describe the detailed structure of the osmotic gradients and flows across the endothelial surface glycocalyx, the inter-endothelial cleft and the exit region downstream of the cleft exit. The heterogeneity of the flow across the surface of the glycocalyx caused by the local breaks in the junction strand and the non-uniformity of the protein concentration both behind the surface glycocalyx and across the junction strand is considered for the first time. The non-linear coupling of the local fluid flow to the local plasma protein concentration is examined and it is shown that the primary gradient in osmotic force is felt across the surface layer of matrix. The model shows rather remarkably that there there is a heretofore unrecognized large asymmetry in the fluid flow pattern on each side of the junction strand and that the water enters the cleft nearly uniformly along its length despite the widely separated discrete breaks that have been observed in the junction strand [1]. The model provides very good predictions of the experimental measurements in Michel and Philips [3].
Probabilistic Modeling of Rosette Formation
Authors: Long Mian , Zhu Cheng
Published: March 2022

Rosetting is a simple assay for specific cell-cell adhesion [1]. Although routinely used by immunologists to examine the functionality of the interacting receptors and ligands, it has not been regarded as a quantitative method, as the measured rosette fraction has not been quantitatively related to the underlying molecular properties.
Pulsatile Non-Newtonian Flow in a Double Aneurysm
Authors: Guzmán Amador M. , Moraga Nelson O. , Amon Cristina H.
Published: March 2022

An aneurysm is a permanent balloon-like, blood-filled dilatation on an arterial vessel. In an abdominal aortic aneurysm (AAA), the growth and eventual rupture of aneurysmal lesions depends on the interaction between the aneurysm wall and the blood motion along it. Rupture of an aneurysm occurs when the shear stresses exceed the strength of the wall [1]. When an AAA ruptures, 50 percent of patients die before reaching the operating room and 54 percent of the remaining will die within 30 days [2]. Therefore, AAA represents a great danger to the patient [3]. The objective of this study is to investigate the shear stresses in an aneurysm composed by two deforned regions and to examine the effect of the blood non-Newtonian behavior on the flow dynamics.
Numerical Simulation of Korotkoff Sounds
Authors: Hayase Toshiyuki , Hayashi Satoru , Xia Yupeng , Koizumi Tadao
Published: March 2022

Although occurrence of Korotkoff sound is essential in blood pressure measurement with sphygmomanometer, there exist several explanations for its mechanism [1]. The authors have made the study on stability of collapsible tube flow using a Starling register [2]. In this system large deformation of the collapsible tube takes place in the downstream end of the tube and the effect of the rigid pipe is inevitable. In the present report, numerical analysis is performed for a modified system in which external pressure is applied in the limited region of a long collapsible tube to avoid the effect of the rigid pipe. Supply pressure is changed as sinusoidal function of time to model the blood pressure pulsation. Mechanism of the Korotkoff sound generation is examined based on the computational result.
Do Temporal Wall Shear Stress Gradients Promote the Development of Intimal Hyperplasia Within Vascular Bypass Grafts?
Authors: Keynton Robert S. , Evancho Mary M. , Sims Rick L. , Rodway Nancy V. , Rittgers Stanley E.
Published: March 2022

The purpose of this paper is to determine the relationship between the temporal wall shear stress gradient and the development of intimal hyperplasia (IH) within an in vivo animal model of the distal anastomoses of vascular bypass grafts. Tapered Teflon® grafts were placed in the common carotid arteries of adult, mongrel dogs with 30° end-to-side proximal and distal anastomoses and a graft-to-artery diameter ratio of either 1:1 or 1:1.5. Simultaneous axial velocity measurements were obtained using a specially designed 20-MHz ultrasonic wall shear rate transducer. Peak and oscillatory temporal WSSGs were found, at best, to only weakly correlate with IH (r = 0.20 and r = 0.27, respectively). The results from this study suggest that the temporal WSSG parameter, by itself, does not promote the development of IH.
Vein Cuffs May Improve Anastomotic Patency by Reducing Suture-Line Intramural Stresses
Authors: Ballyk Peter D. , Ojha Matadial , Walsh Colin
Published: March 2022

Intimal hyperplasia (IH) is an important complication of arterial bypass surgery which can ultimately lead to graft failure. The pathogenesis of IH involves the migration of smooth muscle cells from the media to the intima where they proliferate and secrete extracellular matrix. This results in a thickened vessel wall which may cause stenosis and/or thrombosis of the distal graft-artery junction. It has been shown that IH is a more significant problem in stiff synthetic grafts than in more compliant vein grafts (Bassiouny et al., 1992), and that synthetic grafts have a higher failure rate (Waiden et al., 1980). Consequently, autogenous vein (or artery) grafts are used clinically whenever possible. In cases where autogenous grafts are not long enough or not available (for e.g. if they have already been harvested or have been obliterated by disease), a vein cuff interposed between the distal end of a synthetic graft and the host artery can improve long term patency by reducing distal anastomotic IH (Miller et al., 1984; Suggs et al., 1988).
Finite Element Modeling of Scleral Creep and Ocular Elongation in Deprivation-Induced Myopia
Authors: Grissom Jerry D. , Siegwart John T. , Eberhardt Alan W.
Published: March 2022

Myopia (nearsightedness) is a condition in which the axial length of the eye is longer than the focal plane and, therefore, images of distant objects are blurred. Discoveries that the environment plays a critical role in ocular development (eg., [1]) suggest that there is a visually guided feedback mechanism by which the axial length is matched to the unaccommodated focal plane (emmetropization). Studies have shown increased scleral creep rates associated with form deprivation myopia [2] suggesting that regulation of creep may be responsible for emmetropization, while excessive unregulated creep may result in myopia.
Measuring the Probability of Receptor Extraction From the Cell Membrane
Authors: Chesla Scott E. , Marshall Bryan T. , Zhu Cheng
Published: March 2022

Recently, there has been an increasing interest in measuring the interaction forces between cell adhesion receptors and their ligands [1–3]. These molecules are either anchored on the membrane of a cell or coated on the surface of a substratum. The two surfaces are joined together as a result of the formation of non-covalent bonds between the receptors and ligands. The forces are measured when the two surfaces are separated. In a theoretical paper published nineteen years ago, George Bell estimated the force required to break a receptor-ligand bond and that required to uproot the receptor from the cell membrane to be of the same order of magnitude [4]. The interpretation of the force data therefore requires the knowledge of detachment mode, i.e., via adhesive mechanism if the receptor-ligand bond is dissociated or via cohesive mechanism if the receptor-membrane anchor is disrupted.
The Large-Deformation Behavior of Mesenchymal Distraction Gap Tissue
Authors: Richards Mark , Hernandez Michael J. , Weiss Jeffrey A. , Wineman Alan S. , Goulet James A. , Goldstein Steven A.
Published: March 2022

A combined experimental and computational approach was adopted to determine a constitutive relationship for mesenchymal gap tissue generated during distraction osteogenesis. Harvested distraction zones were tested to failure in uniaxial tension and 3-D FE models were constructed to simulate mechanical testing. A specific form for the strain energy function was adopted to obtain strain-stiffening behavior. Theoretical uniaxial tension predictions were consistently lower than those from 3-D FEA. By refining the values of the three material parameters, a force-displacement curve in excellent agreement with the experimental results was obtained. This formulation appears capable of capturing the essential elements of the behavior of distraction gap tissue. These results can be implemented to predict strain distributions within this tissue and improve our understanding of how the mechanical environment affects bone regeneration and precursor tissue differentiation during distraction.
Passive Knee Joint Mechanics in A-P Forces: Role of Boundary Conditions, Cruciates, and Menisci
Authors: Bendjaballah M. Z. , Shirazi-Adl A. , Zukor D. J.
Published: March 2022

The ligaments and menisci are the principal stabilizers of the knee joint under various loadings such as anterior-posterior (A-P) horizontal forces. When either of these structures is torn, damaged, or removed, the joint’s stability is compromised resulting in the overload of remaining intact ligaments, menisci, and articular cartilage. The deleterious effects of altered mechanical environment of the joint associated with the ACL deficiency and meniscectomy in generating or accelerating the joint osteoarthritis have been well documented by many clinical studies. Following our earlier investigations [1,2], the purpose of this work is to study the passive biomechanics of the tibiofemoral joint at full extension in A-P loads. Attention is given to the identification of the role of boundary conditions, cruciate ligaments, and menisci on the joint detailed response.
Microindentation of the Individual Layers of Articular Cartilage
Authors: Shin Daehwan , Lin Jian-Hua , Athanasiou Kyriacos
Published: March 2022

Articular cartilage is known to have three distinct layers (superficial, middle, and deep) along its depth. Each layer has different biochemical, structural, and cellular characteristics. In the superficial layer, collagen fibrils are densely arranged along a tangential direction to the articular surface. Collagen fibrils are randomly oriented in the middle layer and vertically toward the subchondral bone in the deep layer. The superficial layer has a relatively low concentration of proteoglycans while the matrix in the middle and deep zones contains higher concentrations. The chondrocytes are flattened and most densely populated in the superficial layer, are rounded in the middle zone, and are larger, elongated, and arranged vertically between extracellular matrix in the deep layer [1, 2]. Based on the depth-related differences in the structural, biochemical, and cellular compositions, it is reasonable to assume that intrinsic mechanical properties of articular cartilage vary with depth. However, little information is available on the variation of the biomechanical properties in different layers of articular cartilage. The objectives of this study were 1) to test the applicability of the microindenter for testing cartilage at the microscopic level and 2) to obtain the intrinsic biomechanical properties of rabbit articular cartilage as a function of depth.
Compression-Induced Intervertebral Disc Degeneration in a Mouse Model
Authors: Colliou Olivier K. , Liebenberg Ellen , Duncan Neil A. , Lotz Jeffrey C.
Published: March 2022

While the cause of low-back pain is unknown in many patients, a significant percentage is thought to be due to degeneration of the intervertebral disc1. Because of the severe structural demands placed on the spine, and the epidemiological association between physical activity and disc degeneration, mechanical forces are thought to be a central etiologic factor. Therefore, precise knowledge of the cascade of biologic events associated with disc degeneration, and the means by which they are coupled to physical loading, would be invaluable for developing improved guidelines for maintaining disc health and for directing tissue repair. The aim of this study was to develop an in vivo mouse model in which disc degeneration is induced through the application of a precisely controlled and quantified mechanical load.
Formulation of a Continuum Anisotropic Model for the Anulus Fibrosus in Tension
Authors: Elliott Dawn M. , LeRoux Michelle A. , Laursen Tod A. , Setton Lori A.
Published: March 2022

The anulus fibrosus (AF) of the intervertebral disc is a highly structured material made up of alternating tissue layers (lamella) with collagen fibers oriented +30° and −30° to the circumferential axis (Figure 1). Collagen confers a high tensile stiffness to the AF which contributes to the load-bearing function of the intervertebral disc in vivo. In addition, the specialized organization of the AF gives rise to strongly anisotropic behaviors which may contribute to its mechanical function. Numerous models have been proposed for the material behavior of the AF including a fiber-reinforced composite or membrane, a layered transversely isotropic material, an orthotropic material, and a poroelastic isotropic material [6,8,9,12]. Fiber-reinforced models are complicated by the need to quantify the collagen content, the collagen and ground substance material properties, and associated fiber-matrix interactions. Continuum models of the AF are complicated by the need to determine a unique set of material properties which can require as many as 9 independent constants for a linear orthotropic material.
The Role of Mechanical Stimulation on Ligament Fibroblast Gene Expression of Extracellular Matrix and Adhesion Proteins
Authors: Hsieh Adam H. , Shi Yan , Sung K.-L. Paul
Published: March 2022

This study investigates mechanical stretch induced gene expression of anterior cruciate ligament (ACL) and medial collateral ligament (MCL) fibroblasts, in particular the gene expression of extracellular matrix (ECM) proteins. While the ACL does not exhibit a functional healing response after injury, the MCL does heal post-traumatically [1]. Intrinsic differences between ACL and MCL fibroblasts are hypothesized to be partially responsible for the healing differential. The objective of this study is to examine the effects of stretch on gene expression in ACL and MCL fibroblasts to understand how physical forces can influence tissue healing and remodeling.
Dissociation of Individual Molecular Bonds Under Force
Authors: Zhu Cheng , Chesla Scott E.
Published: March 2022

Specific interactions between receptors on cell surfaces are essential for living organisms to sense and adapt to their environment. For example, CD16A (Feγ receptor IIIA) signals a variety of immune functions upon binding of immunoglobulin (Ig) G. While receptor-ligand binding has been extensively studied in chemical terms, only until very recently has direct measurement of individual bond forces become possible. Evans et al. [1] pioneered the use of the micropipet technique to measure detachment forces between two red blood cells (RBC) crosslinked by antibodies. While these authors achieved the sensitivity necessary to detect individual bonds (in piconewton range), the forces they measured appeared to be those of uprooting the molecules from the cell membrane (cohesive detachment mode) instead of dissociating the antibody-antigen bonds (adhesive detachment mode).
A Finite Deformation Theory and Finite Element Formulation for Coupled Electrokinetic and Fluid Flow in Soft Tissues: Application to Electroosmotic Flow
Authors: Levenston Marc E. , Frank Eliot H. , Grodzinsky Alan J.
Published: March 2022

Due to the fixed charge density (FCD) in the solid matrix and the ionic nature of the interstitial fluid, cartilage and other soft tissues exhibit coupling between mechanical (deformation, fluid flow, fluid pressurization) and electrical (current, streaming potential) phenomena (Maroudas et al., 1969; Frank and Grodzinsky, 1987). Similar behavior has long been recognized in soil mechanics, and linear finite element formulations have been developed (Lewis and Garner, 1972). Soft tissues, however, typically undergo large deformations and have material properties that strongly vary with deformation. To date, no finite element formulations have been introduced that are capable of representing the nonlinear, electromechanically coupled behavior of soft tissues.
Analysis of Transient Swelling and Electrical Responses of an Isolated Cell to Sudden Osmotic Loading
Authors: Gu W. Y. , Lai W. M. , Hung C. T. , Liu Z. P. , Mow V. C.
Published: March 2022

The cell volume changes in response to changes in the osmolality of an extracellular medium. When the medium osmolality decreases, extracellular water will move into the cell so that the cell volume increases (swelling). The rate of change in cell volume depends on the material properties of the cell, such as the tensile stiffness and hydraulic permeability. During cell swelling, the cell membrane is stretched, possibly affecting membrane permeability to various ions (i.e., stretch-activated ion-channels). The transport of ions and water will result in a change in membrane potential [e.g., 1] as well as a change in intracellular ion concentrations. Therefore, mechanical, chemical and electrical events are coupled within a cell. It is important to understand these coupled events in order to separate mechanical and chemical signals and to begin to elucidate the biophysical signal transduction pathways. As a first step to model a cell, we have begun to study mechanical, chemical and electrical phenomena across a cell membrane using recently developed theories [1–3]. In this study, we report our analysis of transient swelling and electrical responses of an isolated cell to an osmotic load, which has been studied experimentally [e.g., 4]. The objective of this study was to relate the changes in cell volume, intracellular ion concentration and electrical potential (which can be readily measured) to the cell material properties (e.g., stiffness, hydraulic permeability and ion-channels).
A Material Characterization of Human Medial Collateral Ligament
Authors: Quapp Krista M. , Weiss Jeffrey A.
Published: March 2022

Despite the vast amount of research on mechanical properties of the knee ligaments, the material properties of human medial collateral ligament (MCL) have never been characterized. The material properties of knee ligaments have only been determined in the longitudinal direction of the ligament. The transverse properties are also necessary for development of 3-d constitutive models. This study determined the longitudinal and transverse material properties of the MCL and evaluated the ability of three material models to describe the material behavior.
Finite Element Study of the Human Cervical Spine
Authors: Kumaresan Srirangam , Yoganandan Narayan , Pintar Frank A.
Published: March 2022

Finite element studies have proliferated in the lumbar spine. Similar modeling efforts to understand the biomechanical behavior of the cervical spine are lacking [3]. The purpose of this study is to report the advancements made in the finite element analysis of the human cervical spine by our group. Details specific to this presentation include the validation studies and the stress analysis of the intervertebral components under complex loading.
Facet Joint Local Component Kinetics in Whiplash Trauma
Authors: Yoganandan Narayan , Pintar Frank A.
Published: March 2022

The term whiplash was introduced in 1928. Since its introduction, it has been primarily dedicated to refer to the sequela of events stemming from vehicular rear-end crashes wherein the human body is initially accelerated from back to front through dynamic impact. Other terminologies have included cantilever injury, hyperextension injuries, cervical sprain/strain, and acceleration-deceleration syndrome. It is estimated that 86% of all clinically seen neck injuries result from motor vehicle crashes and that 85% of these injuries occur due to rear-end impact. Precise estimates for the actual incidence and the associated economics of the injury are not easily available. This is primarily due to the multitude of variables involved in the production and assessment of trauma. Vehicular factors, occupant demographics and positioning at the time of crash, and collision variables together with the human tolerance constitute a significant body of parameters responsible for the injury sequela; symptoms may be acute or chronic. A generally reported incidence rate of whiplash injury is about one in 1000 in Western countries and approximately 25% of the patients become chronic with 10% suffering serious pain [1].
Loads on Neck and Head Joints due to G-Y Acceleration
Authors: Sadegh Ali M. , Perry Chris , Knox Francis
Published: March 2022

During an emergency ejection from aircraft, pilots are subjected to a high acceleration that could cause injuries. To determine the forces and torques at the head, neck and upper-torso joints, an ATB model was developed. The model was validated with test results for G-y accelerations of human subjects. The sled test results of human subjects were used and the loads and torques were determined. The results indicated that the maximum forces and torques increas with the increase in the amplitude and duration of the input acceleration; however, the maximum compressive force at the head pin has a minimum value of 150 lb at 5.5 G.
Biodynamics of Cervical Spine Hyperflexion Injuries
Authors: Voo Liming M. , Pintar Frank A. , Yoganandan Narayan , Maiman Dennis J.
Published: March 2022

Hyperflexion injuries of the human cervical spine occur in the vehicular crash environment, contact sports, and accidental falls. Hyperflexion of the head-neck is a violent movement when head-neck is forced to bend forward into extremely position. It often causes injuries to the posterior ligamentous tissues and instability of the lower cervical spine. Cervical spine injuries are frequently associated with head impact. Our previous experimental studies have demonstrated that alignment variation of the head-neck complex with respect to a similar external load vector significantly alters the injury mechanisms and biomechanical response variables (3, 4). Determining the correlation among the alignment condition, spinal column configuration, biomechanical responses, and injury mechanisms can assist the evaluation of injury risks and preventive measures. The present in vitro experimental study was conducted to delineate the biodynamic parameters associated with hyperflexion injury of the cervical spine.
Use of Calf Lumbar Spine Models for the Test of Spinal Instrumentation
Authors: Lim Tae-Hong , Eck Jason C. , Riley Lee H. , Yoshida Hyroyuki
Published: March 2022

Calf lumbar spines have been widely used for the biomechanical tests of various spinal fixation devices as a substitute for human cadaveric lumber spines. While similar size, loss cost, and less inter-specimen variations are positive attributes, little effort has been made to determine if the use of calf spines is biomechanically justifiable. Wilke et al.[1] investigated the range of motion, neutral zone, and stiffness of thoracolumbar calf spines. It was determined that these values were similar to those previously reported for the human spine. In this study, however, the test was limited to the intact calf spine, and no statistical analysis was made since the results were compared to the results of various studies reported in the literature. Direct comparison of biomechanical testing results of calf and human models has not been presented yet. The purpose of this study was to perform flexibility tests on calf and human lumbar spines using identical methods in order to determine if the anatomical and mechanical differences in the two models affect the results of flexibility tests.
Determining Inertial Properties of Female Adolescents
Authors: Todd Beth A. , Buckner Tina K. , Owens Jonathan M. , Horne Stephanie M. , Bennett M. Virginia
Published: March 2022

There are many instances where inertial properties of the human body or its segments are needed for analysis of human motion. Some of the most critical of these are the design of safety devices to protect a seated person during a vehicular collision, such as an automotive seat belt system or a pilot ejection system. [1] Since many studies have dealt with military combat situations, they have primarily dealt with young adult males. [2] However, a few studies have included adult females and individuals of other ages. [3]-[6] Automotive restraints, for instance, have been designed using this data under the assumption that a system able to restrain a 50% male could restrain the 95% female and all children. However, as automotive safety systems have become more complex than passive restraints, this assumption may no longer be adequate. Therefore, it is more critical than ever before to determine the inertial properties of children.
Biomechanical Comparison of a New Soft Composite Functional ACL Knee Brace vs. Hard Shell Designs
Authors: Han Gayle , Mazza Steven B. , Holt Lisa J. , Billotti Joseph , Langrana Noshir A. , Zimmerman Mark C.
Published: March 2022

The anterior cruciate ligament is the most commonly injured ligament in the knee [1]. Functional knee braces have been widely used to protect the ACL deficient patient. Research suggests that the hard shell design, although cumbersome, is the most resistant to anterior tibial displacement in the ACL deficient knee [1]. The purpose of this study is to compare the mechanical test performance of an off-the-shelf soft composite brace to custom-fit hard shell braces using a clinically relevant testing protocol.
Small Punch Testing for Characterization of Ultra-High Molecular Weight Polyethylene Used in Total Joint Replacements
Authors: Kurtz Steven M. , Jewett Charles W. , Foulds Jude R. , Srivastav Sanjeev , Edidin Avram A.
Published: March 2022

Gamma sterilization results in temporally and spatially inhomogeneous density distributions through the thickness of ultra-high molecular weight polyethylene (UHMWPE) components for total joint replacement [1]. Conventional approaches to estimate the through-thickness distribution of mechanical properties in total joint replacement components have relied on empirical correlations between local measurements of density and these properties [2].
A Fracture Toughness Test of Bone-Biomaterial Interfaces Under Mixed Mode Loading Conditions
Authors: Wang X. D. , Agrawal C. M.
Published: March 2022

Bone-biomaterial interfaces in orthopaedic and dental prosthetic systems are often exposed to a complex loading environment1–4. However, current testing of interfacial strength of orthopaedic and dental material systems is mainly performed under isolated tensile or shear mode and there are no effective methodologies for assessing the interfacial bonding strength under mixed-mode loading conditions. To address this issue, the present study was performed to develop a fracture mechanics based technique for estimating the mixed-mode fracture toughness of bone-biomaterial interfaces. A sandwich specimen comprising the bone-biomaterial interface was used in this study, and both analytical and numerical analyses were performed in conjunction with an empirical validation using bone to bone and dental cement interfaces.
Fatigue Properties of Acrylic Bone Cement as Improved by Processing Technique: A Review of Concepts
Authors: Furman Benjamin R. , Saha Subrata
Published: March 2022

The fatigue properties of bone cement are a critical factor in the long-term aseptic loosening of total hip arthroplasties. The objective of this paper is to provide a condensed review of recent findings related to the effect of porosity reduction and fiber reinforcement on the fatigue properties of bone cement. Individual treatments are discussed.
Material Tissue Interfaces of New Biostable Polymers
Authors: Greenbaum S. R. , Zambo S. J.
Published: March 2022

Polymers have been used in the human body for the last 25 years for things such as vascular grafts, pacemaker leads and joint replacement. Until recently, these polymers have been polyesters or polyethers. The newest polymers, developed by Corvita Corporation, are polycarbonates. These polymers have shown better resistance to biodegredation than their predecessors1. These newer polyurethanes are now being used in applications, such as stent grafts, where they were not before. The new polymer structure, method of manufacture and characteristics allow the material to be used in arterial vascular graft applications.
A Survey of Multibody Dynamics for Virtual Environments
Authors: Gillespie R. Brent , Colgate J. Edward
Published: March 2022

The field of computational dynamics is surveyed, focusing on issues relevant to the construction of a general purpose simulator with haptic display. The various formalisms available for generating dynamical models will be examined with regard to the form of the equations of motion which they produce. To render the effects of intermittent contact and other transient phenomena as driven by a human haptic explorer, a model is needed which is computationally efficient yet can handle changing kinematic constraints neatly. Models in dependent and independent coordinates produced with the Newton-Euler, Lagrangian and Kane formalisms will each be examined in order to provide a vantage point from which an informed selection may be made from among the many tools now available in computational dynamics.
Passive Implementation of Multibody Simulations for Haptic Display
Authors: Brown J. Michael , Colgate J. Edward
Published: March 2022

This paper addresses the issue of providing stability guarantees during the implementation of multibody simulations for haptic display. It introduces the concept of a virtual coupling between the multibody simulation and haptic display hardware. This coupling separates the simulation design process from the sampled-data stability issues that arise during its implementation with a haptic display. Necessary conditions for passivity of a 1-DOF haptic display with a discrete-time passive simulation and an arbitrary virtual coupling are given. The implications of discrete-time passivity on numerical integration and collision response algorithms are also addressed.
Temporal Bandwidth Requirements for Tactile Shape Displays
Authors: Peine William J. , Wellman Parris S. , Howe Robert D.
Published: March 2022

Haptic interfaces that include tactile shape displays must correlate small-scale shape information with finger position. High temporal bandwidth of the display actuators is required to provide realistic sensation during rapid finger motions. To characterize finger speeds during surgical palpation, we performed an experiment where subjects used the tip of the index finger to search for 4 mm lumps embedded in flat rubber models. The models were 15 to 25 mm thick soft silicone rubber with mechanical characteristics approximating lung or breast tissue. Average fingertip speed while in contact with the rubber was approximately 38±16 mm/s (mean ± standard deviation), and average maximum speed was 90±31 mm/s. While moving between contact intervals, the average finger tip speed was approximately 76±18mm/s, and average maximum speed was 146±37 mm/s. There were no significant speed differences between experienced surgeons and subjects who had no medical training. The results indicate that a 30 Hz bandwidth is necessary for shape displays used in haptic interfaces for lump localization in surgery. A shape display design meeting this specification is also presented.
Achieving a Massless Haptic Interface
Authors: Stoianovici Dan , Richer Edmond , Ephanov Anton , Hurmuzlu Yildirim
Published: March 2022

Transparency is an important characteristic that has to be achieved in a haptic interface. In an exoskeletal device, this requirement translates into an active compensation scheme that renders a massless mechanism. Specifically, one has to balance gravitational, Coriolis, and inertia forces/torques of the mechanical structure. The success of such compensation methods strictly relies on an effective identification of the system parameters that appear in the dynamic equations of the interface. In this paper we apply a novel parameter identification method that achieves this task. We conduct a set of experiments to evaluate the transparency of the Pneumatic Haptic Interface (Φ) developed in the Systems Laboratory at Southern Methodist University.
6-DOF Desk-Top Voice-Coil Joystick
Authors: Salcudean S. E. , Parker N. R.
Published: March 2022

This paper presents the design of a 6-DOF desk-top magnetically levitated force-feedback joystick utilizing voice-coil actuation. Relative to prior designs (Hollis et. al., 1991), (Salcudean et. al.. 1995), (Berkelman et. al., 1996), this haptic interface features a novel geometry, a novel optical sensor and optimized actuation. These allow for all the electronics including the control microprocessor to be integrated in its base, with the device tapering from a handle 5.5” high to a footprint of 10.5″ × 5.5″. The device has a maximum translational motion range of ±3mm limited by the actuation gap, and a predicted maximum rotational motion range of ±5° limited by the sensor motion range. The moving mass of 260 grams will have maximum accelerations exceeding 10 g’s, and will be able to exert continuous forces as large as 16N.
Real-Time Impulse-Based Simulation of Rigid Body Systems for Haptic Display
Authors: Chang Beeling , Colgate J. Edward
Published: March 2022

To date, haptic interfaces have rarely been used to display complex virtual environments such as those involving 3D mechanical assembly operations, or the use of hand tools. Of the limitations which have been encountered, one is the absence of suitable simulation techniques which provide a general, user-defined virtual environment. This paper discusses the use of an impulse-based simulation as a general purpose multibody simulator for haptic display. This technique uses Poisson’s hypothesis in conjunction with Coulomb friction as the basis of the contact model. Since haptic displays are required to run in real time with a constant step size and high update rate, changes to the algorithm are required. We identify the “impact state” as a critical feature of the contact model, and outline the various ways it can be chosen. Finally, we describe the implementation of a planar multibody simulator on one and two-axis haptic displays.
Contact Force Perception With an Ungrounded Haptic Interface
Authors: Richard Christopher , Cutkosky Mark R.
Published: March 2022

Two haptic interfaces, each able to provide either grounded or ungrounded haptic feedback, were constructed. Tests were conducted to compare a subject’s ability to perform boundary detection and object size discrimination tasks with grounded or ungrounded haptic feedback, with or without vision. Not surprisingly, grounded feedback is better than ungrounded feedback in displaying forces that stem from grounded sources. However, ungrounded haptic feedback can give comparable results in boundary detection tests.

Subjects also reported that the application of forces to the fingertips by a moving paddle, as employed in the ungrounded tests and in some of the grounded tests, enhanced the realism of the virtual boundary contacts. Additional results concerning the synchronization of different feedback mechanisms and the use of a brake for grounded feedback are discussed in terms of their implications for the design of haptic interfaces.
Identification of Sphere Size Using the PHANToM™: Towards a Set of Building Blocks for Rendering Haptic Environment
Authors: Tan Hong Z.
Published: March 2022

This paper presents an approach to developing building blocks for rendering synthetic haptic environments using force-reflective haptic interfaces. The task of sphere size identification is used to explore an accurate and efficient way of estimating human performance using the absolute identification paradigm. The results show that subjects can reliably identify 3 to 4 sphere sizes with a set of spheres ranging from 10 to 80 mm in radius. Subjects with prior experience with force-reflective haptic interfaces exhibit higher performance levels. The results also indicate that gradually increasing stimulus complexity yields more accurate measurements of information transmission at little additional cost in terms of total number of experimental trials. Subsequent studies will utilize the new experimental protocol developed in this study.
A New Approach to Estimation of Nonlinear Parametrization in Dynamic Systems
Authors: Annaswamy A. M. , Thanomsat C. , Mehta N. R. , Loh A. P.
Published: March 2022

Nonlinear parametrizations occur in dynamic models of several complex engineering problems. The theory of adaptive estimation and control has been applicable, by and large, to problems where parameters appear linearly. We have recently developed an adaptive controller that is capable of estimating parameters that appear nonlinearly in dynamic systems in a stable manner. In this paper, we present this algorithm and its applicability to the problem of temperature regulation in chemical reactors. It is shown in that the proposed controller leads to a significantly better performance than those based on linear parametrizations.
A Nonlinear Parametrization for Stable Neural Network-Based Identification and Control
Authors: Bošković Jovan D.
Published: March 2022

In this paper a stable neural network-based identification and control method for a class of first-order nonlinear plants is suggested. The method is based on neural networks built using a rational activation function. The paper discusses a method for stable adjustment of the network parameters and robustness issues in the resulting closed-loop system. The overall control scheme also includes a robust global controller that guarantees that the state of the system is confined to a region in the state space. The combination of robust global and neural network-based controllers appears to be well suited for performance improvement in complex nonlinear systems.
Partial State Feedback Based Real Time Neural Controller: Theory and Experiments
Authors: Shukla Deepak , Dawson Darren M. , Paul Frank W.
Published: March 2022

A partial state feedback based direct adaptive control scheme is developed using Orthonormal Activation Function based Neural Networks (OAFNN), for real time trajectory tracking control of a class of nonlinear systems. The OAFNNs are employed in the controller for feed-forward compensation of unknown system dynamics. The network weights are tuned on-line, in real time using Desired Compensation based Adaptive Laws (DCAL). The overall stability of the system and the neural networks is guaranteed using Lyapunov analysis and a modified integral version of projection algorithm. The developed neural controllers are evaluated experimentally and the experimental results support theoretical analysis.
Recurrent Neural Networks for Fault Diagnosis and Severity Assessment of a Screw Compressor
Authors: Li C. James , Fan Yimin
Published: March 2022

This paper describes a method to diagnose the most frequent faults of a screw compressor and assess the magnitude of these faults. To determine the condition of the compressor, a feedforward neural network model is first identified from the compressor’s operating data. A recurrent neural network is then used to classify the model into one of three conditions including baseline, gaterotor wear and excessive friction. Finally, another recurrent neural network estimates the magnitude of fault from the model. The method’s ability to generalize was evaluated. Experimental validation of the method was also performed. The results show significant improvement over the previous method which used only feedforward neural networks.
Observer-Based Control of a Gas Furnace via Fuzzy Modeling
Authors: Kiriakidis Kiriakos
Published: March 2022

The paper addresses the control problem of complex plants, using state space realizations derived from Takagi-Sugeno fuzzy models. In particular, a state feedback controller, based on estimated state information, is proposed for the regulation of gas furnaces. The method comprises procedures to design a converging state estimator and a stabilizing controller separately. It is shown that if the estimator and controller gains satisfy an additional sufficient condition the observer-based closed loop is stable. Simulation studies on the fuzzy model of the gas furnace process verify the result.
Adaptive Fuzzy Control of Vehicle Semi-Active Suspensions
Authors: Lieh Junghsen , Li Wei-Jie
Published: March 2022

The optimization of passive and controllable suspensions is subject to the constraint that conflicts the car body and tire modes. The application of control systems for improving ride quality has been studied for many years. The control force for an active suspension is derived from either full-state or partial-state signals, which requires extensive hardware, consumes higher energy, and has a low reliability. On-off and variable semiactive suspensions have been used for their simplicity, however they are lack of adaptive capability for nonlinear damping modulation.

The intent of this paper is to apply a fuzzy logic concept for control of semiactive damping that is normally nonlinear with stochastic disturbances. The nonlinear damping coefficient is adjustable in order to control the bounce acceleration, suspension travel and tire deflection. A quarter-car model is used to examine the fuzzy control rule. Results from simulation are presented.
New Laser-Based Optical Position Sensor With Applications to Robot End-Effector Motion
Authors: White W. N. , Beck B. T. , Garimella V.
Published: March 2022

This paper examines the characteristics of a new laser-based optical position sensing technique that has been under development in the Department of Mechanical Engineering at Kansas State University. Previous investigations with the technique focused on quasi-static single degree of freedom position measurements using a single laser-generated light sheet. The present paper extends the basic concept by utilizing two intersecting laser light sheets to sense spatial position in two dimensions. The image of the intersecting light sheets is viewed on a flat reflective screen. It is detected by a high resolution video camera, with associated frame grabbing hardware/software, and subsequently related to body position by processing the video image of the intersecting light sheets.
In Vitro Measurement of the Six Degree-of-Freedom Kinematics of the Human Knee During Simulated Gait
Authors: Sheshadri Vikram B. , Rullkoetter Paul J. , Hillberry Ben M.
Published: March 2022

This paper describes a method to determine the six degree-of-freedom kinematics of the human knee. A complete description of knee motion requires information on both the patellofemoral and the tibiofemoral joints. Six degree-of-freedom spatial linkages are used to determine the relative motion of each of the joints. One linkage is connected across the tibiofemoral joint and a second is connected across the patellofemoral joint. A three cylindric open chain model is then used to describe the motion of each of the joints. Sample kinematic data were developed using the Purdue Knee Simulator with natural knee specimens. The simulator is able to recreate anatomical loading of the knee during various activities. The natural specimens were mounted in the simulator with the linkages attached. Data were recorded for level walking and six degree-of-freedom kinematics were determined for the tibiofemoral as well as the patellofemoral joints.
Computer Modeling of Knee Simulator Tibio-Femoral and Patello-Femoral Loading
Authors: Maletsky Lorin P. , Hillberry Ben M.
Published: March 2022

With the continuing need to evaluate prosthetic wear and kinematics of the knee joint, a number of in vitro dynamic test machines, termed knee simulators, have been built. The objective of this work was to develop a model to predict the tibio-femoral and patello-femoral forces generated for a variety of different knee simulator designs and loading configurations. Moving contact areas determined from experimental kinematics were used to determine moment arms for the forces about the knee. The model was validated using data experimentally obtained using the Purdue Knee Simulator.
On the Spatial Compliance Control of Parallel Manipulators and Levitated Platforms
Authors: Fasse Ernest D.
Published: March 2022

This paper looks at the control of mechanical compliance of manipulators and platforms capable of complex spatial motion. The family of compliances used has spatial transformation properties that make it easier to select compliance parameters to perform useful tasks. Control laws were previously derived for serial manipulators; this is a first investigation into the control of other mechanisms. In particular, this paper presents control laws for (1) the so-called Stewart-Gough class of six degree-of-freedom, parallel manipulators, and (2) a six degree-of-freedom, electrodynamically levitated platform, assuming small motions. Simulation results are given.
The Realizable Space of Spatial Stiffnesses Achieved With a Parallel Connection of Simple Springs
Authors: Huang Shuguang , Schimmels Joseph M.
Published: March 2022

In this paper, we identify the space of spatial compliant behavior that can be achieved through the use of simple springs connected in parallel to a single rigid body. Here, the expression “simple spring” refers to the set of compliant relations associated with purely translational springs and purely rotational springs.

We show that, regardless of the number of springs used, there exists a subspace within the 21 dimensional symmetric spatial stiffness matrix space that cannot be reached by a parallel simple spring system. The subspace of “realizable” spatial stiffness matrices achieved with parallel simple springs is 20 dimensional and is defined by a linear necessary and sufficient condition on the positive semidefinite stiffness matrix. We show that any full-rank spatial stiffness matrix satisfying the condition can be realized using only line springs.
A Robust Universal Controller
Authors: Lam S. H.
Published: March 2022

The present paper advocates the use of ODE-based (instead of algebra-based) constraints on the output variables of a controlled system, and the use of dynamic control laws (instead of static control laws) — when finite but small errors in honoring the constraints are considered acceptable. It is assumed that the sensor signals are reliable and have good signal-to-noise ratios, that the controller has ample computational power, and that the hardware/software “sampling time” ts is much smaller than the system characteristic time tg. A universal dynamic control law is proposed which does not require detailed knowledge of the system itself — and is therefore completely robust with respect to uncertainties of the system — provided the control problem to be solved is reasonable. The meaning of the equivocal word “reasonable” will be explained.