bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracture Toughness of the Femoral Neck, Femoral Shaft, and Tibial Shaft in Aged Bone
Authors: Brown Christopher U. , Yeni Yener N. , Norman Timothy L.
Published: January 2022

This study investigated the relationship between age and the tension and shear fracture toughness of the femoral neck, femoral shaft, and tibial shaft of aged bone greater than 50 years. Fracture toughness for the different bone locations was shown to be different. Cortical bone of the femoral neck had the highest resistance to crack initiation while the femoral shaft had the lowest. Fracture toughness decreased with age for the femoral shaft and the tibia. The ability of cortical bone of the femoral neck to resist fracture, however, did not decline in bone for this age range.
Dynamic Analysis of the Finger Pulley System Using Joint Torque
Authors: Amirouche F. , Koldoff J. , Gonzalez M.
Published: January 2022

The focus of this study was to introduce the use of localized joint torque as a new approach to analyzing finger dynamics. By using a method of continuous acquisition of all the joints in the finger simultaneously and a rigid body model, the principles of inverse dynamics may be applied to calculate the required joint torque for motion. Though this study presents only torque differences, it paves the way for future computations of joint efficiency. Previous investigators have used the Profundus tendon force and excursion to calculate the work of the system (Greenward, 1994). Using the derived equations of motion and kinematic data, the localized work at the joints may be calculated along with accurate measures of bowstringing effects.
Measurement of Stress Distribution in Various Ankle-Foot Orthoses
Authors: Chu Tai-Ming
Published: January 2022

An Ankle-Foot Orthosis (AFO) is a rehabilitation device that supports and aligns the ankle and the foot to improve the functions of the ankle and foot (Wu, 1990). In today’s orthotic industry, polypropylene (PP, a Colyene™ Co-polymer plus Fleshtones and Colors) is used as a major orthotic plastic due to its high weight-strength ratio, high fatigue resistance, light weight, and excellent molding characteristics (1990). However, earlier failure and improper geometry design bring inconvenience in mobility and discomfort to many patients. A literature search shows several investigations have been conducted. A 3-D Finite Element Model (FEM) was developed by Chu, et al. (1995). The analysis includes the computation of the stress level and the determination of locations of stress concentration. Although the 3-D model provided useful information, limited dynamic results were obtained. Yamamoto, et al. (1993) made a comparative study on the mechanical characteristics of plastic AFOs. Eleven AFOs were tested with the motion of dorsiflexion/plantarflexion and inversion/eversion using a muscle-training machine. The objective of this experimental study is to understand the performance of five AFOs used during walking and the resulting deformation developed while under loads. It is intended that the design parameters of AFOs can be evaluated and modified.
The Effect of PCL Substitution on Patellofemoral Joint Forces and A/P Drawer in the Post-TKA Knee
Authors: Petrella Anthony J. , Karmas Alexandros , Berger Richard C. , Rubash Harry E. , Miller Mark C.
Published: January 2022

The decision to retain the posterior cruciate ligament (PCL) in total knee arthroplasty (TKA) is an issue of some debate. The use of a PCL substituting prosthesis relieves the surgeon of the task of properly tensioning the PCL and allows better surgical exposure (Scuderi and Insall, 1989). Moreover, in vitro studies of post-TKA PCL strain (Incavo et al., 1994) as well as clinical studies of TKA function (Worland et al., 1997) have failed to show a significant difference between PCL retaining and substituting knees. In some cases, however, patellofemoral joint (PFJ) complications such as stress fractures have been observed at a higher rate in the PCL substituting knee (Scuderi and Insall, 1989). The objective of this study was to determine the effect of PCL substitution on PFJ forces and anterior-posterior (A/P) drawer. The study proceeded from the hypothesis that no differences between posterior stabilization and cruciate retention would occur.
Optimization of the Design of a Three-Fingered Gripper Capable of Object Manipulation
Authors: Yates Christian A. , Reisinger Kim D.
Published: January 2022

Robotic assist devices typically consist of a manipulator attached to a robot arm. Often, the assist device must perform the functions of the human hand. Therefore, they should have sufficient dexterity to manipulate an object without putting it down. Four fingered manipulators are by their very nature more complex than then three fingered counterparts. But, with the additional finger, the four fingered hands can manipulate an object without setting it down. We describe a novel design that introduces an additional degree of freedom to one finger, and the design optimization process that insures that the six fundamental grasps (spherical, cylindrical, tip, hook, palmar and lateral) are possible. In addition, we discuss how this one additional degree of freedom increases the manipulability of a three fingered manipulator so that a limited array of object manipulation is possible.
Vertebral Endplate Morphology Predicted via Wolff’s Law
Authors: Grosland Nicole M. , Goel Vijay K. , Grobler Leon J.
Published: January 2022

The thin cortical shell and endplate that surround the trabecular centrum of the vertebral body have yet to be characterized completely. Moreover the optimal thickness values have yet to be predicted. The present investigation coupled an adaptive remodeling algorithm with the FE method to predict the optimal external configuration. Results suggest that the endplate responds to the applied loading conditions, yielding a thinning of the endplate over the nucleus. The predicted thickness values were in agreement with experimental measurements.
An Apparatus for Studying Wear Damage in UHMWPE: Description and Initial Test Results
Authors: Baldini Todd H. , Wright Timothy M. , Estupiñán Jaime A. , Bartel Donald L.
Published: January 2022

Wear of ultra high molecular weight polyethylene (UHMWPE) in total joint arthroplasties causes release of particulate debris that contributes to long term complications such as osteolysis and implant loosening (Wright and Goodman, 1996). Despite the magnitude of this clinical problem, little is known about wear mechanisms in UHMWPE implant components and the factors that control them. Total knee replacement designs, for example, require non-conforming metallic on UHMWPE joint surfaces to assure appropriate kinematics and function. Finite element analysis (FEA) has shown that contact between such surfaces leads to high surface and subsurface stresses (Bartel, et al., 1986). Dynamic FEA has also that shown that femoral rollback on the tibia results in considerable residual stresses in the polyethylene (Estupiñán, et al., 1996). In an effort to complement our analytical studies of stresses associated with wear damage, we have developed a wear apparatus. Our objective is to independently control factors including geometry of the joint surfaces, contact load, the presence (sliding) or absence (rolling) of surface velocity, and the polyethylene material properties, so as to experimentally examine their effects on the creation of damage similar to that observed on retrieved joint implants.
Flow Description in a Gastroesophageal Reflux Episode
Authors: Chen Y.-T. , Boehm R. F. , Little A. G.
Published: January 2022

A numerical simulation is performed on a model of a theoretical gastroesophageal reflux behavior. The process modeled here assumes that the lower esophageal sphincter relaxes and opens, allowing a reflux episode to be initiated by a driving pressure differential in the stomach. At that point the pressure differential is removed and the contents flow back down to the gastric cavity. A typical response of the reflux phenomena is shown.
Alterations in Endothelial Permeability After Intravascular Intervention
Authors: Chesler Naomi C. , Brewton Nathan , Ku David N.
Published: January 2022

Intravascular interventions such as balloon embolectomy are effective in removing arterial and venous thrombi and emboli but lead to endothelial injury. The clinical sequelae of this injury include intimal hyperplasia and renewed clot formation. Changes in endothelial permeability after intravascular intervention may influence the development of intimal hyperplasia. To assess the extent and type of injury engendered by the Fogarty embolectomy catheter, the permeability of the endothelium after sham embolectomy (catheter withdrawal in the absence of a thrombus or thrombus model) was measured in porcine carotid arteries. The maximum shear force required for catheter withdrawal was also measured. The changes in permeability resulting from a prototype textured balloon catheter (Applied Medical, Laguna Hills, CA) were measured for comparison to the Fogarty catheter. While the textured balloon showed a distinct pattern of increased permeability and required significantly more force to withdraw at a set balloon pressure than a Fogarty balloon catheter (p < 0.02), there was no difference in permeability after three balloon inflation and removal cycles. This study demonstrates useful techniques for comparing catheter designs which may be clinically relevant to intimal hyperplasia and rethrombosis after intravascular intervention.
A Simplified Mechanical Model to Predict Motion Restrictions of the Partially Paralyzed Shoulder
Authors: Sarver Joseph J. , Seliktar Rahamim
Published: January 2022

Shoulder motion has been studied by several researchers as a control source for a variety of rehabilitative systems such as functional electrical stimulation for the past 20 years (Mortimer et al., 1973) (Johnson and Peckham, 1990) (Fass et al., 1995). In particular studies involving partial paralysis of the muscles controlling the shoulder (such as with spinal cord injuries at the C5 and C4 level) have produced kinematic results which suggest that elevation and retraction of the shoulder are coupled. With an appropriate model of the partially paralyzed shoulder it might be possible to simulate a variety of motions which evaluate currently employed control algorithms. To that end a simplified mechanical model was developed to investigate the feasibility of developing a more complicated model of the partially paralyzed shoulder. The results of the mechanical model predicted that motion of the paralyzed shoulder would indeed be a coupling of elevation and retraction.
3-Dimensional, Single Marker, Gait Analysis System
Authors: Weir Richard F. ff.
Published: January 2022

There is a wealth of data that can be obtained by recording the 3-D position of a single marker at the approximate level of the body center of mass (BCOM) during walking. Evolving the design of a previous 1-D single marker gait system (Weir & Childress, 1997) we are developing a portable, easy-to-use, real-time system which will measure the position of the BCOM during walking in 3-D. This system will measure instantaneous anterior-posterior, medial-lateral, and vertical displacements of the BCOM. We plan to use these data to measure and estimate gait parameters and symmetry indices.
Development of In-Process Skew and Shift Adjusting Mechanism for Paper Handling
Authors: Shirasawa Satoshi , Otsuki Haruaki
Published: January 2022

We have developed a new type of paper handling mechanism to adjust skew and shift which may cause paper jam. The developed mechanism is compact, highspeed, highly robust, and capable of in-process adjustment of large skew and shift. Until now, in order to adjust skew and shift in-process, the conventional adjusting mechanism is able to adjust either skew or shift and even if it is able to adjust both, it does not have sufficient reliability. To solve this problem, the proposed mechanism uses a ball-actuator as an adjusting mechanism. By clipping paper by two free rotating balls and controlling the ball rotation, the developed mechanism is able to control skew and shift of clipped paper. We estimated performance of the developed mechanism and concluded that it is possible to construct an adjusting mechanism to meet the skew and shift requirements.
Free Vibration and Stability of a Rotating Disk-Spindle System
Authors: Sathe Pushkaraj J. , Parker Robert G.
Published: January 2022

This work examines the free vibration and stability of a rotating flexible disk-spindle system. The extended operator formulation (Parker, 1997) is exploited to discretize the system using Galerkin’s method. The coupled vibration modes of the system consist of disk modes, in which the disk dominates the system deformation, and spindle modes, in which the spindle dominates the system deformation. Both the natural frequencies and vibration modes are strongly affected by disk flexibility. If the membrane stresses associated with disk rotation are neglected then the system exhibits flutter instabilities, but these instabilities are not present when membrane stresses are included. Natural frequency veering between disk and spindle frequencies is prominent at low speeds and substantially affects the spectrum and stability. No veering is observed at high speeds where rotational stress stiffening diminishes disk-spindle coupling and causes the natural frequencies to converge to those of a rotating spindle carrying a rigid disk. Changes to the vibration modes are examined in terms of a strain energy ratio measuring the contribution of the disk strain energy to the total modal strain energy.
Trends and Mechanical Issues in Optical Disk Drives
Authors: Lee Seung-Yop , Kim Sookyung
Published: January 2022

Recent trends and the effect of mechanical vibrations in optical disk drives are reviewed in this paper. The transition from CD drives to high density DVD drives and the development of writable optical disk drives require tighter mechanical tolerance. The demand for faster access time and higher data transfer rate also leads to critical mechanical problems to limit the tracking and focusing servo performances. The current mechanical issues in the optical disk drives and various technologies to overcome the mechanical problems are introduced. Vibrations of disk-spindle system, actuator and suspension designs of the optical pick-up, and general mechanical designs for the fast and stable access mechanism are considered.
Simultaneous Determination of Temperatures, Heat Fluxes, Deformations, and Tractions on Inaccessible Boundaries
Authors: Dennis Brian H. , Dulikravich George S.
Published: January 2022

A finite element method (FEM) formulation for the detection of unknown steady boundary conditions in heat conduction and linear elasticity and thermoelasticity continuum problems is presented. The present FEM formulation is capable of determining displacements, surface stresses, temperatures, and heat fluxes on the boundaries where such quantities are unknown or inaccessible, provided such quantities are sufficiently over-specified on other boundaries. Details of the discretization, linear system solution techniques, and sample results for 2-D problems are presented.
A Method for Defining Gaussian Probability Densities for Forward Modeling in Finite Dimensions Using the Method of Tarantola
Authors: Clutz Christopher J. R. , Maniatty Antoinette M.
Published: January 2022

The inverse problem of recovering an unknown boundary function given some information about the (interior) solution is considered. It is assumed that the forward problem is governed by a linear partial differential equation (PDE) and that homogeneous boundary conditions exist on the rest of the boundary. A method developed by Tarantola (Tar87) is used which is based upon statistical inference on finite dimensional random vectors. Within this framework, a method for constructing Gaussian probability density functions which model the forward problem is proposed.
Identification of the Friction Coefficient for Steady and Unsteady Shallow-Water Flows
Authors: Soulaimani Azzeddine
Published: January 2022

This work presents some recent results on the solution of shallow-water flows using the finite element method and the optimal control method for distributed systems. The objective is to identify the friction coefficient for steady and unsteady flows, such as the numerical solution is close to the measurement data. We investigate the following aspects: the finite element discretization, the regularization of the cost function and the solution algorithms. Several benchmark tests are presented.
A Singular Perturbation Approach for Modeling Differential-Algebraic Systems
Authors: Gordon Brandon W. , Liu Sheng , Asada Haruhiko
Published: January 2022

Dynamic systems described by an implicit mixed set of Differential and Algebraic Equations (DAEs) are often encountered in control system modeling and analysis due to inherent constraints in the system. A key difficulty in control and simulation of DAE systems is that they are not expressed in an explicit state space representation. This paper describes a general approach based on singular perturbation analysis for adding fast dynamics to a system of DAEs so that they can be expressed in an explicit state space form. Conditions for asymptotic convergence and approximation methods are investigated. The approach is illustrated for a model of a two-phase flow heat exchanger.
“Soft” Real-Time Applications Under Windows NT™
Authors: Mattern Duane
Published: January 2022

The Microsoft® Windows NT™ operating system is inappropriate for “hard” real-time applications that require a deterministic response as might be required in a closed-loop control system where safety is an issue. There are third party development packages that extend NT so that it can be used in a “hard” real-time system. These tools cost several times more than the cost of the PC hardware and this is too expensive for most educational purposes. An example of how “soft” real-time applications can be run under Windows NT using only the Visual C compiler is presented in this article. The multimedia timer and the high performance counter are used in the example to provide a user mode “pseudo-interrupt”. The example is an animated, second order, spring-mass-damper system with a frame time of 25 milliseconds. A circular buffer is used for data storage. The example program can be modified for other “soft” real-time applications and access to the source code is provided.
Magnetic Levitation Testbed for Controls Education
Authors: Craig Kevin , Kurfess Thomas , Nagurka Mark
Published: January 2022

This paper describes a magnetically levitated testbed for use in undergraduate and graduate controls education. Key components of the testbed include an electromagnetic coil to create the magnetic field, a ferrous object for levitation, a position sensor for height determination, and a controller for feedback adjustment of the coil current. In this paper the unit’s design, development, and use in educational arenas are discussed.
Display of Friction in Virtual Environments Based on Human Finger Pad Characteristics
Authors: Nahvi A. , Hollerbach J. M. , Freier R. , Nelson D. D.
Published: January 2022

A friction display system is proposed for virtual environments. Since a user’s fingertip is often placed inside a ring or thimble of a haptic interface, the finger pad cannot move relative to the finger structure as freely as it would move in the real world. Thus, it is necessary to imitate the real world movement of the human finger pad in the virtual environment. This paper quantifies the frictional properties of the human finger pad on 9 subjects by simultaneously recording force and movement of the finger pad when it rubs against a rigid plate. Results of such tests and implementation in a virtual environment are reported.
Resolution of Virtual Grating Orientation With 2-DOF and 3-DOF Force Feedback Systems
Authors: Weisenberger Janet M. , Krier Michael J. , Rinker Martha A.
Published: January 2022

The present study describes experiments comparing human observers’ ability to resolve the orientation of grating stimuli presented on a 3-DOF haptic interface (PHANToM) and a 2-DOF haptic interface (Immersion IE2000 joystick). Although the force renderings for the two devices are of necessity quite distinct, both yield surprisingly credible percepts of surface texture. Accordingly, resolution for sinusoidal gratings (3-DOF device) and “square-wave” gratings (2-DOF device) was measured as the minimum spatial period required to determine which of two grating orientations had been presented. For the 3-DOF device, this ability was tested for a range of grating amplitudes. For the 2-DOF device, a range of damping constants was employed. Pilot results showed better performance for the 2-DOF device, most likely attributable to the sharp delineation of “edges” for the gratings presented, as compared to the “edgeless” sinusoidal gratings presented on the 3-DOF device. In addition, observers reported a number of interesting perceptual phenomena when stimuli were close to threshold.
The Future of Robust Control Engineering
Authors: Nwokah O. D. I.
Published: January 2022

The field of mechanical systems is viewed within and as a subset of general mechanical and electromechanical systems design. Thus, it should address issues of modeling, analysis, measurement and control of complex mechanical systems. Mechanical engineers in particular are comfortable with design theories only if they can validate them experimentally. Furthermore, any newly suggested methodologies must seek to close some technological deficiency gap between what engineers currently do, and what they would like to do, otherwise engineers would not be inclined to buy into the new methodologies. This calls for a metric to measure such a gap. Although control theory is a very mature field, only a relatively small subset of this theory has been found most useful by design engineers. On the other hand it is often the case that some methodologies are discovered by design engineers and in general use before a complete scientific justification for all of its aspects are delineated. While most of the available theory is linear, almost all mechanical systems are nonlinear.

In this paper, we examine the future impact of modeling as well as information technology on the design and control of mechanical systems. It is argued that developments in computer technology and in modeling will have more influence on the future of mechanical systems than corresponding developments in control theory. However, domain specific control theories will emerge, and should prove more significant than control theories of “everything.” The future lies in the smart integration of modeling, computer technology, engineering design and targeted control theory.
Mechatronics in University and Professional Education: Is There Anything Really New Here?
Authors: Craig Kevin
Published: January 2022

Mechatronics is the synergistic combination of mechanical engineering, electronics, control systems and computers. The key element in mechatronics is the integration of these areas through the design process. The essential characteristic of a mechatronics engineer and the key to success in mechatronics is a balance between two sets of skills: modeling / analysis skills and experimentation / hardware implementation skills. Synergism and integration in design set a mechatronic system apart from a traditional, multidisciplinary system. So the answer is YES! There is something new here — in the way mechanical engineers are expected to design and in the way professors must now teach design!

This paper describes the undergraduate program in mechatronics at Rensselaer, i e, two senior-elective courses, Mechatronics (fall semester) and Mechatronic System Design (spring semester), and in particular, the integration of the theory covered in lectures with the laboratory exercises. The hardware systems used in both courses are described. Also discussed are observations from conducting professional training in mechatronics both in industry and for the ASME Professional Development Program.
Controllers or Components: Deciding What (and What Not) to Teach in Mechatronics Courses
Authors: Carryer J. Edward
Published: January 2022

This paper examines the breadth of the field of Mechatronics in the context of determining appropriate content and processes for Mechatronics courses. Issues addressed include the aspects of a uniquely Mechatronics course and the impact of student background, sub-domain of focus and curricular integration on the content of Mechatronics courses. It will be useful for those seeking guidance on appropriate content and the design of new Mechatronics courses. The paper should also prove useful to those involved in evaluating the structure and content of existing courses for the purpose of their improvement.
Meeting Industrial Needs in Mechatronics and Control
Authors: Auslander David M.
Published: January 2022

Widespread use of embedded computing in mechanical and other physical systems has lead to a need for new skills and attitudes on the part of engineers who are leaders and central participants in projects that lead to such products. In this essay I attempt to delineate that skill set, thereby identifying many of the subfields associated with mechatronics. The intent is to provide background for use both in design of curricula for educational institutions interested in mechatronics and control and to focus on research areas that will lead to advances in the art of mechatronics.
A Finite Element Model of Thermally Induced Angular Contact Spindle Bearing Loads
Authors: Gibson Alex O. , Stein Jeffrey L.
Published: January 2022

Thermally induced bearing loads have long been recognized as a key factor impacting the reliability and performance of machine tool spindle systems. This is particularly true for reconfigurable machine tool spindles which may experience a wide range of external loads, processes and spindle speeds. The models of thermally induced bearing load which have been developed thus far have calculated the thermal expansion of the spindle’s components using a classical solution that assumes the spindle is a circular cylinder of infinite length and that the temperature within the cylinder only varies in the radial direction. While this approach to calculating the thermal expansion provides reasonably accurate predictions of the bearing load if the thermal gradients in the axial and radial directions are small, it can result in large errors in the calculated bearing load if the thermal gradients within the spindle become large. The purpose of this paper is to present a new model of thermally induced spindle bearing load that uses a finite element model to calculate the thermal expansion of the spindle components. The model includes the thermally and mechanically induced spindle bearing loads in a back to back angular contact bearing pair that are due to radial and axial thermal expansion as well as the centrifugal forces and moments within the bearings. Simulation results are used to compare and contrast bearing load predictions that are based upon both a finite element and a classical thermal expansion calculation. The results demonstrate that the bearing load predictions based upon the classical thermal expansion calculation substantially under predict the bearing load as the heat load, due to increasing spindle speeds, is increased. As these errors in the predicted bearing load may be high enough to alter important design decisions, it is concluded that a finite element, or equivalent, thermal expansion calculation be used in future thermally induced bearing load models unless the thermal gradients within the spindle are known to be small.
Intelligent Agile Line Boring Station
Authors: Pasek Zbigniew J. , Szuba Phil
Published: January 2022

This paper describes efforts leading to the development of a precision, agile line boring station for machining of long bores in automotive applications. A new concept of a “smart” line boring tool is described. The tool is equipped with an on-line compensation mechanism, relying on sensing and intelligence built into the tool itself, for real-time correction of the boring process yielding increased precision. The tool body contains a number of sensors (e.g., laser with multiple detectors and strain gages) and the necessary instrumentation. Using sensor signals, an onboard computer controls the motions of the tool-tip actuated by a mechanism powered by a piezoelectric actuator. To supplement the advantages provided by the “smart” tool, a prototype agile line boring machine was developed. The design integrates multiple new concepts of mechanical structure of the machine with an intelligent controller. Open structure of the controller enabled integration of several error compensation functions enhancing machining precision.
Optimal Velocity Estimation of Slowly Moving Systems With Quantized Position Output
Authors: Jacobsen Michael P. , Tsao Tsu-Chin
Published: January 2022

Feedback control systems and many manufacturing processes can benefit from precise velocity information, although direct measurement of linear velocity is often impractical and/or costly. The accepted procedure of inferring velocity from quantized position measurements can in some instances yield noisy and inaccurate estimates. This paper proposes an optimal velocity estimation scheme incorporating measured acceleration data for use in slowly moving systems. Simulation and experimental results demonstrate improved low speed velocity estimation compared to traditional methods. The optimal velocity feedback is also shown to decrease overshoot in a closed-loop implementation.
Frequency Based Nonlinear Controller Design for Regulating Systems Subjected to Time Domain Constraints
Authors: Glass John W. , Franchek Matthew A.
Published: January 2022

Presented is a nonlinear controller design methodology for a class of regulating systems subjected to quantitative time domain constraints. The output performance specification is an allowable time domain tolerance and the system experiences actuator saturation. The controller design is executed in the frequency domain and is applicable when the frequency response of a linear design cannot satisfy the gain and phase characteristics required by quantitative time domain specifications. A describing function (DF) approach, automated by the Volterra Series, facilitates the nonlinear controller design. The resulting gain and phase distortions associated with the DF of the dynamic nonlinear element are used to achieve the desirable open loop gain and phase characteristics identified by the time domain constraints. The design methodology is illustrated on the idle speed control of a Ford 4.6L V-8 fuel injected engine. The engine input is the by-pass air valve and the regulated output is engine speed. The power steering pump generates the nonmeasureable external torque load.
Desired Compensation Adaptive Robust Control
Authors: Yao Bin
Published: January 2022

A desired compensation adaptive robust control (DCARC) approach is proposed for nonlinear systems having both parametric uncertainties and uncertain nonlinearities. DCARC of nonlinear systems transformable to a normal form is first solved. A DCARC backstepping design is then developed to overcome the design difficulties associated with unmatched model uncertainties. The proposed DCARC has the unique feature that the adaptive model compensation part depends on the reference trajectory and parameter estimates only. Such a structure has several implementation advantages. First, the regressor in the model compensation part can be calculated off-line and on-line computation time may be reduced. Second, the interaction between the parameter adaptation and the robust control law is minimized, which may facilitate the controller gain tuning process considerably. Third, the effect of measurement noise is minimized since the regressor does not depend on actual measurements. As a result, a fast adaptation rate may be chosen in implementation to speed up the transient response and to improve overall tracking performance. These claims have been verified in the comparative experimental studies for the control of robot manipulators.
An Active, Surface Wave Bed for Transporting Humans and Elastic Bodies
Authors: Spano Joseph , Asada Haruhiko H.
Published: January 2022

Bedridden patients and elastic bodies are transported by generating surface waves on an active bed. The motion of each node on the bed surface is coordinated such that it follows a circular trajectory with a certain phase lag from its adjacent nodes. This surface wave actuation allows a bedridden patient to move freely while lying comfortably upon the bed. First, the basic properties of surface waves are investigated. Technical requirements for transporting humans and elastic bodies are obtained. To assure comfort during transport, the stress distribution at the contact area is analyzed based on elasticity theory. Transport speed and efficiency are analyzed as well. A proof-of-concept prototype is designed, built and tested. It is demonstrated that a human is moved along the bed surface while lying on the bed.
Design and Control of a Wheelchair With a Continuously Variable Transmission (CVT)
Authors: Wada Masayoshi , Asada Haruhiko H.
Published: January 2022

A novel vehicle design for holonomic omnidirectional wheelchairs is presented in this paper. The new design allows the vehicle to change the shape of its footprint as well as to continuously vary the gear ratio of the drive mechanism. The variable footprint mechanism consists of a pair of beams intersecting at a pivotal point in the middle. Two pairs of ball wheels at the diagonal positions of the vehicle chassis are mounted, respectively, on the two beams. The angle between the two beams varies actively so that the ratio of the wheel base to the tread may change. Four independent servomotors driving the four ball wheels allow the vehicle to move in an arbitrary direction from an arbitrary configuration as well as to change the angle between the two beams and thereby change the footprint configuration. The objective of controlling the beam angle is threefold. One is to augment the static stability of the vehicle by varying the footprint so that the mass centroid of the vehicle may be kept within the footprint at all times. The second is to reduce the width of the vehicle when going through a narrow doorway. The third is to apparently change the transmission ratio relating the vehicle speed to individual actuator speeds. Required vehicle tasks are coordinated by the hierarchical control architecture. First the concept of the varying footprint mechanism is described briefly, then three control algorithms for varying the footprint are presented followed by the hierarchical control architecture for coordinating the different tasks. A proof of concept prototype wheelchair is designed, built, and tested.
A Procedure for the Synthesis of Simple Spring Realizable Spatial Stiffnesses
Authors: Huang Shuguang , Schimmels Joseph M.
Published: January 2022

In this paper, the synthesis of the stiffness matrices that can be realized with “simple springs” connected in parallel to a single rigid body is presented. The expression “simple spring” is used to refer to the set of elastic relations associated with passive translational springs and rotational springs.

We have previously identified the realizable sub-space of stiffnesses achieved with simple springs and provided a procedure to synthesize an arbitrary full-rank stiffness matrix within this realizable subspace. In this paper, an optimization routine is used in conjunction with the synthesis procedure to obtain alternate sets of springs that better satisfy practical design considerations. The procedure presented here requires no more than 7 simple springs to realize any simple spring realizable stiffness.
An Evolutionary Algorithm for the Reduction of DOFs in Modular Reconfigurable Robots
Authors: Chen I-Ming , Yang Guilin
Published: January 2022

The Reduced Degree-of-freedom (RDOF) concept is introduced in optimizing the modular reconfigurable robot configurations for specific task requirement. With fewer modules and degrees of freedom (DOFs), a modular robot would have a simple configuration, high loading capacity, and low power consumption rate, so that it can perform the task effectively. In this article, we formulate RDOF problem as a design optimization problem. A weighted sum of the number and types of modules is chosen as the objective function. Several task-related kinematic performance measures are considered as design constraints. Based on the problem specific coding scheme, the evolutionary algorithm (EA) approach is employed to search the optimal solutions. A virtual module concept is also introduced in the coding scheme to guarantee the operation of EA. The effectiveness of this approach is demonstrated by an example.
Fuzzy Basis Function Networks of Hierarchical Structure for Modeling Manufacturing Processes
Authors: Lee Cheol W. , Shin Yung C.
Published: January 2022

A framework for modeling complex manufacturing processes using fuzzy neural networks is presented with a novel training algorithm. In this study, fuzzy basis function networks (FBFN) which are similar in structure to radial basis function networks are adopted. A hierarchical structure which consists of FBFNs is proposed to construct comprehensive models of the complex processes. The modeling scheme provides valuable advantages over the conventional approaches. A new adaptive least-squares (ALS) algorithm, based on the least-squares method and genetic algorithm (GA), is proposed for autonomous learning and construction of FBFNs. It adds significant fuzzy basis functions (FBF) at each iteration depending on error reduction measures while searching for the best nonlinear parameters of the networks using GA. The ALS algorithm realizes a hybrid structure-parameter learning without any human intervention. Simulation studies with grinding processes are shown to demonstrate that the proposed modeling framework with the training algorithm is a promising approach to modeling complex manufacturing processes.
Application of Intelligent Monitoring and Control in Automated Industrial Processes
Authors: de Silva Clarence W.
Published: January 2022

This paper will consider an intelligent supervisory control system for industrial processes. Evaluation of the performance of the process and assessment of the quality of the product are two important responsibilities of this control system. A suitable structure for the control system will be presented and some design issues will be addressed using, as illustrative examples, several practical systems which we have developed in the Industrial Automation Laboratory.
A Model for Controlled Planning of Object Manipulation Using Multiple Agents: An Overview
Authors: Payandeh Shahram
Published: January 2022

In implementation of intelligent mechanisms such as dexterous mechanical hands, reconfigurable fixtures or part feeders, it is always required to plan to manipulate object in order to gain its proper configuration within the work-space of the manipulating agents. Most of the proposed planners for coordinated control have been based on ad-hoc approaches using search strategies embedded within various search trees. What has been lacking in these algorithms is a formal framework for analysis, synthesis and evaluation of their performances. This paper presents an overview of application of such possible controlled planner architecture for manipulating objects using multiple agents. The controller is based on discrete-event control theory. The paper extends the application of such theory to the case of multiple agents manipulating a common object. Here for example, a set of events for lifting and rotating an object is described as labeled alphabets. Then it is shown how the manipulation of object can be described as finite-state automaton. The set of uncontrollable events is constructed. The supervisor (planner) can then be constructed by first defining the details of its legal behaviors.
Evaluation of Service-Induced Residual Stresses in Railroad Commuter Car Wheels
Authors: Gordon Jeff , Jones Jerrel A. , Perlman A. Benjamin
Published: January 2022

Analyses of the effects of service conditions on the distribution of residual stresses in railroad commuter car wheels are presented. Novel software has been applied to estimate the effects of service conditions on the as-manufactured state of these wheels. Contact loads resulting from wheel and rail interaction and thermal loads from on-tread braking are considered. Results indicate that contact stresses acting alone result in increased net rim hoop compression. However, thermal stresses due to frictional heating reverse the as-manufactured residual compressive state. In particular, high-performance stop braking may result in large net hoop tension in the rim. When contact and thermal loads interact, the effects of braking dominate the process. The presence of tensile residual hoop stress at the wheel tread has been shown to favor the formation and growth of fatigue cracks, threatening the safety of train operations. The paper provides a description of the analytical methodology and results of its application to a representative class of commuter service. Comparisons of the predicted depth of rim stress reversal with the thermal cracking observed in the wheels of this fleet provides confidence in the ability of the technique to assess the likelihood of thermal crack development in other types of commuter operations and in railroad freight service.
Application of Impedance Methods for Predicting Vibrations of a Locomotive Cab
Authors: Ahmadian Mehdi , Dhruna Chetran J.
Published: January 2022

This study evaluates the vibration isolation effect of various mounting systems in a heavy freight locomotive cab, and provides an analytical method for the prediction of structural vibration. The cab is set up in a controlled laboratory environment in a manner similar to the installation on a locomotive. Field measurements are used to emulate actual vibration input to the cab structure. A 16-channel data acquisition system is used to collect vibration data at various points on and inside the cab structure. Upon establishing the baseline for laboratory vibration measurements and correlating them with field data, acceleration data was collected at discrete locations, both inside and outside of the cab. The data was used in conjunction with an analytical formulation to generate vibration approximations of the discrete locations. To validate the analytical approximations, experimental results were compared with the analytical predictions using simulated field input to the cab. The test results from the analytical model approximations proved to have a strong correlation with experimental results. Vibration approximations of locations outside the cab had a higher correlation to the experimental data than the points on the inside. Although the model did not yield exact results for several positions inside the cab, it resulted in several recommendations for future work.
Progress in Railway Mechanical Engineering: 1997–1998 Report of Survey Committee — Passenger and Commuter Rail Vehicles and Components
Authors: Hesser Kenneth R.
Published: January 2022

This annual ASME committee report covers major worldwide developments in rail passenger and commuter vehicle equipment. The information contained herein was obtained from responses to survey letters sent to the manufacturers of passenger rail vehicles and components, and from a review of trade and technical publications.
Durability of Ceramic Matrix Composites
Authors: Pastor Michael S. , Case Scott W. , Reifsnider Ken L.
Published: January 2022

Continuous fiber reinforced ceramic composites are currently being developed as potential retrofit and replacement materials for non-structural hot section components in turbine engines. These materials display many of the beneficial high temperature characteristics of monolithic ceramics while displaying material pseudo ductility resembling durable metals. At present, however, they are very expensive to produce and test. Therefor, the development of reliable analytical techniques to augment the development and testing of these materials would be very beneficial.

A damage evolution model for composite materials is presented here as well as the its specialization to a Nicalon™ reinforced SiC composite system. Application of the model to high temperature tensile fatigue and rupture life predictions are also presented. A comparison of predicted to experimental behavior is then finally made.
Plastic and Viscoplastic Effects on Residual Strength of a Titanium Matrix Composite After Thermomechanical Fatigue
Authors: Kroupa Joseph L.
Published: January 2022

Using a simple fiber failure criterion, the influence of plasticity and visco-plasticity on the residual strength of a unidirectional titanium matrix composite is investigated. Solely, by the redistribution of thermally induced residual stresses, the residual strength is found to reduce after thermomechanical cycling. During in-phase thermomechanical fatigue (TMF) the strains within the fibers at high temperatures and loads are retained in the composite after cooling to room temperature. The fiber stresses, initially compressive after processing, are found to be significantly different after in-phase TMF. This shift in residual stresses reduces the predicted residual strength. Elastic and bilinear plasticity models are used to show the potential errors one may expect from simple/incomplete analysis. Using two viscoplastic models, the influence of loading frequency on residual strength demonstrates the importance of complete matrix characterization. The two viscoplastic models are Bodner-Partom and GVIPS. (Generalized viscoplastic potential structure). The influence of waveform can be observed by comparing the results of TMF using triangular, sinusoidal and square waveforms. The key feature that reduces residual strength is amount of time spent at high load and temperature.
Durability of Woven Polymer Matrix Composites
Authors: Patel Sneha R. , Case Scott W. , Reifsnider Ken L.
Published: January 2022

The authors of this paper obtained residual strength and damage accumulation data on an unaged composite material system consisting of a graphite reinforced polymer [[0/90]2w]s five harness satin weave. Tests were conducted under ambient conditions as well as typical aircraft temperature (120°C). The data was intended to be used to develop models of damage and failure modes to predict remaining strength and life of the material as a function of material properties and environmental factors. The models are based on damage tolerance concepts where remaining strength is used as a measure of damage accumulated in the composite and failure is assumed to occur when the remaining strength equals the applied strength.

Initial mechanical properties appeared unchanged from room temperature to elevated temperature (120°C). Matrix cracking, however, was markedly lower at elevated temperature. The major fatigue damage modes observed were matrix cracking and delamination. Residual strength for specimens fatigued at room temperature was only minimally affected while a stiffness reduction of approximately 7% was seen for specimens tested at 85 and 74 percent UTS and 50 and 75% life. At room temperature, the saturation crack density as a result of fatigue was the same as the crack saturation density found from tensile failure. At elevated temperature, the strength was again unaffected but the stiffness reduction was greater at about 12%. In addition, the crack saturation density for specimens fatigued at elevated temperature was the same as the saturation crack density for specimens fatigued at room temperature.

Because no changes in remaining strength were found, the model originally considered in this study for life prediction could not be used. Further consideration will be given to using or developing a more suitable model after more data at elevated temperature and with moisture are obtained.