bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assembly Configurations and Branches of Planar Single-Input Dyadic Mechanisms
Authors: Foster David E. , Cipra Raymond J. 
Published: February 2021

Abstract
This paper examines the problem of enumerating the assembly configurations (ACs), also called circuits, of planar single-input dyadic (SID) mechanisms which have links with pin joints and sliding joints. An SID mechanism is a multi-loop mechanism which can be defined by adding one loop at a time such that the mechanism has one degree of freedom after each loop is added. A method is given to find the ACs of such a mechanism. The emphasis is on using graphical interpretation to determine the mobility regions of the mechanism which are preserved when each new loop is added to the mechanism. This method of interpretation is readily automated. Each AC can be represented as a set of instructions for the input link to follow, along with a list of dyad configurations for each instruction. Each instruction corresponds to a branch of the mechanism. Examples are given to demonstrate the use of this method.
Assembly Configurations of Single-Loop Mechanisms With Pin Joints and Sliding Joints
Authors: Foster David E. , Cipra Raymond J. 
Published: February 2021

Abstract
This paper examines the problem of enumerating the assembly configurations (ACs), also called circuits, of planar mechanisms which can be described as a single loop. An algorithm is given which allows the user to find and distinguish the ACs of such a mechanism, by determining if each pair of adjacent links can line up. If each pair can line up, then the mechanism has one AC; otherwise, it has two ACs. It is shown that a single-loop mechanism can have no more than 2 ACs. The algorithm is demonstrated with two examples.
On Force and Motion Control of Serial-Parallel Robots
Authors: Wang Shih-Liang 
Published: February 2021

Abstract
A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.
Design of Tactile Fixtures for Robotics and Manufacturing
Authors: Nederbragt Walter W. , Ravani Bahram 
Published: February 2021

Abstract
This paper presents a theoretical framework for the design of tactile sensing fixtures for robotics and manufacturing. The framework presented uses group theory to analyze the symmetry of contact conditions on a fixture to determine if a fixture design is appropriate to determine the relative location of the sensor frame with respect to the fixture frame. Mechanical fixtures consisting of planar, spherical, and cylindrical surfaces are studied for their usefulness as part of referencing fixtures. The theory developed is used in guiding the design of a simple yet novel touch sensing fixture for part referencing and calibration in manufacturing and robotics.
Velocity Analysis of Truss-Type Manipulators
Authors: Canfield Stephen L. , Soper R. Randall , Hendricks Scott L. , Reinholtz Charles F. 
Published: February 2021

Abstract
A generalized method for the velocity analysis of truss-type manipulators is presented. This analysis relies on a priori knowledge of the position analysis for the manipulator. The approach uses a connectivity chart to define the equations required to determine the velocities of the nodal points of the truss. The problem of determining the nodal velocities is formulated as a linear algebraic relationship for ease of analytical and numerical manipulation. Once each nodal velocity is known, a general description of the overall manipulator velocity is formed by determining the instantaneous screw axis for the output plane. An analytical method for characterizing this output velocity in terms of the instantaneous screw axis is presented.
Analysis of each of the four basic variable geometry truss modules (tetrahedron, octahedron, decahedron, and dodecahedron) is presented. Although ad hoc velocity analyses of many of these manipulators have been presented in the past, the technique presented in this paper is unified for any truss-type manipulator.
Steering Algorithms for an Actively Configurable Wheeled Vehicle
Authors: Waldron Kenneth J. 
Published: February 2021

Abstract
This article describes strategies and algorithms used to steer an unconventionally configured vehicle with twelve continuously controllable degrees of freedom. The WAAV vehicle is a laboratory scale prototype of a vehicle configuration first conceived and studied in simulation as a Mars roving vehicle. It’s configuration is quite different from an automotive vehicle and requires different approaches to directional control. The work described here is restricted to smooth, level terrain, but will be generalized for use on arbitrary, rough terrain.
Extension of Euler’s Principal Axes to Articulated Inertia
Authors: Lipkin Harvey 
Published: February 2021

Abstract
An effective inertia of a serially jointed chain of bodies, such as a robotic arm, is often referred to as the articulated or operational space inertia. Six principal axes and six principal values of inertia are proposed to decouple articulated inertia into geometric and constitutive properties respectively. In the case of a single rigid body, these concepts naturally coincide with familiar descriptions of inertia.
Trajectory Pattern Method Based Trajectory Synthesis and Inverse Dynamics Formulation for Minimal Vibrational Excitation for Flexible Structures
Authors: Tu Q. , Rastegar J. 
Published: February 2021

Abstract
A new approach to trajectory synthesis and formulation of the inverse dynamics model of flexible structures for point to point motions with minimal high frequency component of the actuating torques (forces) is presented. Trajectories are synthesized such that the flexible structure comes to rest undeformed at the completion of motion. The developed method is based on the Trajectory Pattern Method. In this approach, an appropriate trajectory pattern is selected and described in parametric form. The inverse dynamics model of the system is formulated in terms of the trajectory parameters. The trajectory patterns used are in terms of a number of basic sinusoidal time functions and their harmonics. The basic frequencies are selected such that the harmonics appearing in the actuating torques do not excite the natural modes of vibration of the system. For each motion, the trajectory parameters are determined for minimal amplitudes of the higher actuating torque harmonics, noting that from the vibration and control points of view, such trajectories are more desirable. The higher harmonics refers to the harmonics of the actuating torques with frequencies above the highest trajectory harmonic frequency. As an example, a flexible beam undergoing large displacements and rotations in a plane is considered. The effectiveness of the approach is illustrated by an example.
Active Control of Elastodynamic Vibrations of a Four-Bar Mechanism System With a Smart Coupler Link Using Optimal Multivariable Control: Experimental Implementation
Authors: Sannah Muhammad , Smaili Ahmad 
Published: February 2021

Abstract
This paper presents an experimental investigation on active control of the elastodynamic response of a four-bar (4R) mechanism system using “smart” materials featuring piezoelectric sensor/actuator (S/A) pairs and muitivariable optimal control. The experimental (4R) mechanism is made such that its coupler link is flexible, its follower link is slightly less flexible and its crank is relatively rigid. Two thin plate-type piezoceramic S/A pairs are bonded to the flanks of the coupler link at the high strain locations corresponding to the first and second vibration modes. Based on the optimal multivariable control theory, a controller which consists of a linear quadratic regulator (LQR) and a Luenberger observer as a state estimator is designed and implemented.
The results of the experimental investigation prove that in order to prevent high mode excitations, the controller design should be based on the modes representing vibrations of all components comprising the mechanism system rather than the modes corresponding to the link to which the S/A pairs are bonded. Response amplitude attenuation ratios up to 50 percent are achieved and high mode excitations are prevented.
Critical Speed Analysis of Multi-Cylider Engines As Spatial Elastic Linkage Systems
Authors: Kurnool Sirihari , Bagei Cemil 
Published: February 2021

Abstract
A multi-cylinder engine is a cluster of slider-crank linkages. Presently used conventional pure torsional shaft models predict results far from the results predicted considering actual three-dimensional linkage and crankshaft geometries. Pure torsional model doesn’t sense the variation in frequency with the variation in engine geometry. It predicts one constant frequency value for each mode; it does not permit the use of flexible bearings. Article offers a finite element method for performing frequency and critical speed analysis of multi-cylinder engines considering three-dimensional geometries of the linkage loops, crankshaft, and the crankshaft throws, as a spatial elastic mechanism system. Any number of cylinders in any angular orientations with respect to each other may be considered. A three-dimensional flexural finite-line element with isoparametric joint freedom irregularity is developed and used to formulate the eigenvalue equations of motion for the system. Consistent mass matrix as well as lumped mass matrix methods can be used. The element can be restrained to perform coupled torsional and flexural or pure torsional frequency analysis of geared rotor model of engines and shafts on many rigid or flexible bearings. Geared connections can also be considered flexible. A generalized computer program is made available for industrial use. It determines frequencies, mode shapes and critical speed bands of an engine for complete crankshaft rotation for as many modes as desired. The frequency and critical speed analysis of a four-cylinder MGB automobile engine with in-plane crank throws, with and without bearing flexibilities, is performed and the results are compared with those obtained using the conventional pure torsional shaft model. Geared tandem ship drive system is studied to test the reliability of the developments.
Using Chaos to Obtain Global Solutions in Computational Kinematics
Authors: Jovanovic Vojin T. , Kazerounian Kazem 
Published: February 2021

Abstract
In this paper we examine the sensitive dependence on the initial conditions of the Newton-Raphson search technique. It is demonstrated that this sensitivity has a fractal nature which can be effectively utilized to find all solutions to a nonlinear equation. The developed technique uses an important feature of fractals to preserve shape of basins of attraction on infinitely small scales.
A New Circuit Rectification Method in Four-Bar Linkages
Authors: Bawab Sebastian , Li Haitao 
Published: February 2021

Abstract
A circuit defect exists in four-bar linkages when a linkage cannot pass through all the design positions without being disassembled and reassembled in a different configuration. This paper describes a new and efficient procedure to rectify circuit defects in four-bar linkages at the synthesis level prior to the analysis level. It is achieved by controlling the change of sign of one of the angles opposite to the shortest link. The procedure utilizes the algebraic method where special points are employed to eliminate the solutions with circuit defects as a function of the design positions. Complete rectification is accomplished at the mid-synthesis level by controlling the critical angles of the linkage that identify the existence of circuit defects. This accounts for the rectification of circuit defects at the synthesis stage.
Kinetostatic Analysis for the Ross Yoke-Drive Stirling Engine
Authors: Williams Robert L. 
Published: February 2021

Abstract
This paper presents a complete rigid body dynamics model for the Ross yoke-drive mechanism which is used to transfer power in some Stirling engines. The kinematics model is derived, followed by the kinetics model. Results are given for a representative mechanism. The shaking force and moment results are compared with those predicted by a simplified model previously used for balancing design; a significant difference is demonstrated. In the future, the model presented in this paper will be used to design more effective balancing.
Systematic Enumeration of 1:1 Constant-Velocity Shaft Couplings
Authors: Tsai Lung-Wen , Madhavan Bharath 
Published: February 2021

Abstract
A systematic methodology is employed for the enumeration of 1:-1 constant-velocity shaft couplings. As a result, four potential 1:-1 constant-velocity shaft couplings that are free from singular conditions are enumerated. A promising mechanism is selected for the dynamic analysis. The analysis shows that the mechanism does have the potential for use as a 1:-1 constant-velocity shaft coupling and as a gearless differential.
A New Approach for Curvatures of Conjugate Surfaces
Authors: Chen Ningxin 
Published: February 2021

Abstract
A new and general approach for curvatures of conjugate surfaces is provided in this paper. The main characteristic of the approach is that relative curvatures and geodesic torsions of the conjugate surfaces are directly calculated in terms of the normal curvatures and geodesic torsions of the generating surface on two non-orthogonal tangents of surface curvilinears in global surface system. In comparison with the current approaches that use two orthogonal tangents or the principal directions in local system at each calculating point, the approach developed in this paper has a simple calculating process and a simple computer program. Based on the curvature equations, sliding velocities and sliding ratios of the conjugate surfaces are studied. The approach is illustrated by a numerical example of a plane enveloping globoidal wormgear drive.
Synthesis of Non-Uniform Stroke Piston Engines
Authors: Chew M. , Good T. A. 
Published: February 2021

Abstract
Piston engines have generally been designed with strokes that are uniform throughout the engine cycle. Variable-stroke engines have been designed with the capability to change the stroke lengths from cycle to cycle depending on load requirement. This article examines the synthesis of piston engines that are designed to have different stroke lengths and different relative stroke timing over an engine cycle. Such piston trajectories have been found to exhibit very high thermal efficiencies without resorting to high compression ratios. An investigation into different mechanisms and approaches toward the synthesis of such engine mechanisms is presented.
Workspace of a Gimbal With Joint Limits
Authors: Yeh Har-Jou , Abdel-Malek Karim A. 
Published: February 2021

Abstract
An analytical formulation for determining the workspace of a point on a body suspended in a Gimbal mechanism is presented. Although the gimbal mechanism comprises three degrees of freedom, the resulting workspace is a region on a spherical surface. The constraint function of the underlying mechanism is studied for singularities using a row-rank deficiency condition of its constraint Jacobian. Singular curves on the resultant spherical surface are determined by a similar analytical criterion imposed on the system’s subjacobian, to compute a set of two joint singularities. These singular curves define regions on the spherical surface that may or may not be accessible. A perturbation technique is then used to identify singular curve segments that are boundary to the workspace region. The methodology is illustrated through a numerical example.
A New Method for Displacement Analysis of Multi-Loop Spatial Linkages Based on Ordered Simple-Opened-Chains
Authors: Kong Xian-Wen , Yang Ting-Li 
Published: February 2021

Abstract
This paper presents systematically a new method for the displacement analysis (DA) of multi-loop spatial linkages (MLSLs) based on ordered simple-opened-chains (SOCs). In performing DA, a MLSL is converted into not a set of base points, a set of isolated links or a tree with/without isolated links in common use, but a weakly coupled MLSL in this paper. The characteristics of the proposed method are: (a) The number of unknowns in the set of equations for displacement analysis (EDA) of a MLSL is reduced to the minimum; (b) All the possible configurations corresponding to a given set of inputs of a weakly coupled MLSL or a strongly coupled MLSL with the coupled degree k = 1 can be obtained quickly. As compared with the other two methods available to find all the solutions to the DA in the case of MLSL with k = 1, the proposed method is superior to the resultant method in that it is applicable to more complex MLSLs and superior to the continuation method in that it takes much less CPU time to find all the solutions; (c) The set of EDA can be formulated and solved automatically; and (d) The new approach makes it possible to perform the kinematic and kineto-static analyses in a unified and simplified way.
Adhesive Performance of Quadruped Walking Vehicle With Pantograph Legs
Authors: Xu Peijun , Song Shin-Min 
Published: February 2021

Abstract
In this paper, the adhesive performance (walking without foot slippage) of quadruped walking vehicles with pantograph legs while walking on level ground was studied. The ground reactional forces acting on the feet at various body positions were computed using a compliant vehicle model. The effects of leg dimensions, leg mounting arrangements and gait parameters on the adhesive performance were then analyzed and methods to improve the adhesive performance were proposed.
Active Balancing of Joint Forces in High-Speed Linkages by Redundant Drives and Learning Control
Authors: Thuemmel Thomas , Brandl Marc 
Published: February 2021

Abstract
Critical loading and vibrations in high-speed linkages result from external forces at the output link and especially from varying inertia forces of irregular link motion. This paper deals with the active dynamic balancing of joint forces — Joint Force Control. Three possible balancing criterions indicated by joint forces are described: joint-stress, clearance-impact-noise and friction.
Active balancing requires additional drives. The two theoretical cases of arranging actuators are compared: redundantly and with an additional degree of freedom. Using the preferred redundant drives the internal forces in the joints may be varied according to special aims while the normal drive of the given mechanism maintains the motion.
An experimental setup consisting of a crank-and-rocker mechanism is used to study the control aim of a zero joint force at the crankshaft. The speed control of the original servo motor M1 is combined with the closed loop force control of the two redundant servo motors M2 and M3. Assuming a steady-state operation mode the learning control concept is applied successfully and compared with a digital PID force control. By learning control the time delay problem is solved. Furthermore the balancing of only one engine order is presented.
Comparison of Three Algorithms Using Thigh-Worn Accelerometers for Classifying Sitting, Standing, and Stepping in Free-Living Office Workers
Authors: Clark Bronwyn , Winker Elisabeth , Ahmadi Matthew , Trost Stewart 
Published: February 2021

Accurate measurement of time spent sitting, standing, and stepping is important in studies seeking to evaluate interventions to reduce sedentary behavior. In this study, the authors evaluated the agreement in classification of these activities from three algorithms applied to thigh-worn ActiGraph accelerometers using predictions from the widely used activPAL device as a criterion. Participants (n = 29, 72% female, age 23–68 years) wore the activPAL3™ micro (processed by PAL software, version 7.2.32) and the ActiGraph™ GT9X accelerometer on the right front thigh concurrently for working hours on one full workday (7.2 ± 1.2 hr). ActiGraph output was classified via the three test algorithms: ActiGraph’s ActiLife software (inclinometer); an open source method; and, a machine-learning algorithm reported in the literature (Acti4). Performance at an instance level was evaluated by computing classification accuracy (F scores) for 15-s windows. The F scores showed high accuracy relative to the criterion for identifying sitting (96.7–97.1) and were 84.7–85.1 for identifying standing and 78.1–80.6 for identifying stepping. The four methods agreed strongly in total time spent sitting, standing, and stepping, with intraclass correlation coefficients of .96 (95% confidence interval [.92, .96]), .92 (95% confidence interval [.81, .96]), and .87 (95% confidence interval [.53, .95]) but sometimes overestimated sitting time and underestimated standing time relative to activPAL. These algorithms for identifying sitting, standing, and stepping from thigh-worn accelerometers provide estimates that are very similar to those obtained using the activPAL.
Examining the Contribution of Dog Walking to Total Daily Physical Activity Among Dogs and Their Owners
Authors: Potter Katie , Marcotte Robert T. , Petrucci Greg J. , Rajala Caitlin , Linder Deborah E. , Balzer Laura B. 
Published: February 2021

Given high rates of obesity and chronic disease in both people and dogs, it is important to understand how dogs and dog owners influence each other’s health, including physical activity (PA) levels. Research suggests that dog owners who walk their dogs are more likely to meet PA guidelines than those who do not, but few studies have investigated dog walking intensity or its contribution to dog owners’ total moderate-to-vigorous PA using accelerometry. Furthermore, no studies have examined the contribution of dog walking to dogs’ total PA or the relationship between dog and dog owner PA using accelerometers on dogs. The authors used accelerometers on 33 dog owner–dog pairs to investigate (a) the intensity of dog walking behavior, (b) the contribution of dog walking to dog owners’ overall moderate-to-vigorous PA and dogs’ overall PA, and (c) the correlation between dog and dog owner PA. Dog owners wore an ActiGraph accelerometer and logged all dog walking for 7 days; dogs wore a Fitbark activity monitor. On average, 64.1% (95% confidence interval [55.2, 73.1]) of daily dog walking was moderate to vigorous intensity, and dog walking accounted for 51.2% (95% confidence interval [44.1, 58.3]) of dog owners’ daily moderate-to-vigorous PA. Dog walking accounted for 41.2% (95% confidence interval [36.0, 46.4]) of dogs’ daily PA. Dog owners’ daily steps were moderately correlated (r = .54) with dogs’ daily activity points. These findings demonstrate the interdependence of dog and dog owner PA and can inform interventions that leverage the dog–owner bond to promote PA and health in both species.