Kinematic Analysis (kinematic + analysis)

Distribution by Scientific Domains

Selected Abstracts

Kinematic Analysis of Leaf Growth in Grasses: A Comment on Spatial and Temporal Quantitative Analysis of Cell Division and Elongation Rate in Growing Wheat Leaves under Saline Conditions

Hans Schnyder

A new family of hybrid 4-DOF parallel mechanisms with two platforms and its application to a footpad device

Jungwon Yoon
This paper proposes a new family of 4-degrees-of-freedom (DOF) parallel mechanisms with two platforms and its application to a footpad device that can simulate the spatial motions of the human foot. The new mechanism consists of front and rear platforms, and three limbs. Two limbs with 6-DOF serial joints (P -S-P-P) are attached to each platform and are perpendicular to the base plate, while the middle limb is attached to the revolute joint that connects the front and rear platforms. The middle limb is driven by the 2-DOF driving mechanism that is equivalent to active serial prismatic and revolute joints (Pe - Re), or prismatic and prismatic joints (Pe - Pe) with two base-fixed prismatic actuators. Since the middle limb perpendicular to the base plate has 3-DOF serial joints (Pe - Re -R or Pe - Pe -R), two new 4-DOF parallel mechanisms with two platforms can generate pitch motion of each platform, and roll and heave motions (1T-3R) or pitch motion of each platform and two translational motions (2T-2R) at both platforms, according to the type of the 2-DOF driving mechanism. Kinematic analyses of the 1T-3R mechanism were performed, including inverse and forward kinematics and velocity analysis. Based on the 1T-3R mechanism, a footpad device was designed to generate foot trajectories for natural walking. © 2005 Wiley Periodicals, Inc. [source]

Geared robot manipulators with a jointed unit: Kinematic analysis and its application

Dar-Zen Chen
An efficient and systematic methodology for the kinematic analysis of geared robot manipulators (GRMs) with a jointed unit is presented. It is shown that, by decomposing mechanical transmission lines of a GRM into serially connected jointed and disjointed units, kinematic relation between local inputs and local outputs of admissible jointed units can be systematically formulated. Accordingly, angular displacements of input links with respect to their associated primary links can be symbolically expressed in terms of joint angles by a unit-by-unit evaluation procedure. This unit-by-unit evaluation procedure provides better kinematic insights into how input torques are transmitted to various joints. It is also shown that an actuator in a GRM with a jointed unit can drive nonconsecutive joints by proper design of its gear train. A 3 degrees of freedom GRM with a jointed unit is used as an illustrative example. © 2001 John Wiley & Sons, Inc. [source]

Kinematic analysis of kneeling in cruciate-retaining and posterior-stabilized total knee arthroplasties

Satoshi Hamai
Abstract Kneeling is an important function of the knee for many activities of daily living. In this study, we evaluated the in vivo kinematics of kneeling after total knee arthroplasty (TKA) using radiographic based image-matching techniques. Kneeling from 90 to 120° of knee flexion produced a posterior femoral rollback after both cruciate-retaining and posterior-stabilized TKA. It could be assumed that the posterior cruciate ligament and the post-cam mechanism were functioning. The posterior-stabilized TKA design had contact regions located far posterior on the tibial insert in comparison to the cruciate-retaining TKA. Specifically, the lateral femoral condyle in posterior-stabilized TKA translated to the posterior edge of the tibial surface, although there was no finding of subluxation. After posterior-stabilized TKA, the contact position of the post-cam translated to the posterior medial corner of the post with external rotation of the femoral component. Because edge loading can induce accelerated polyethylene wear, the configuration of the post-cam mechanism should be designed to provide a larger contact area when the femoral component rotates. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:435,442, 2008 [source]

Kinematic analysis of the pelvic limbs of healthy dogs during stair and decline slope walking

R. P. Millard
Objectives: To evaluate range of motion (ROM) of the pelvic limb in healthy dogs descending stairs compared with decline slope walking. Methods: Reflective spheres were placed on the skin over the joints of the right pelvic limb of seven adult, hound-type dogs with no clinical signs of orthopaedic or neurologic disease. Five trials of stair and ramp descent of each dog were recorded using four 60 Hz digital infrared cameras. Two-dimensional kinematic data were collected as dogs walked down stairs and on a continuous decline of equivalent slope. Maximum and minimum joint angles and ROM were calculated for the coxofemoral, femorotibial and tibiotarsal joints. Results: Stair descent resulted in significantly greater femorotibial flexion and tibiotarsal flexion and extension compared with continuous slope descent. Significantly greater ROM was achieved in the coxofemoral, femorotibial and tibiotarsal joints during stair descent. Clinical Significance: Compared with a continuous slope, stair descent achieves greater ROM in the pelvic limbs of dogs. Stair descent may be a useful therapeutic exercise to improve ROM in dogs with musculoskeletal disease of the pelvic limb, and ramp descent may be easier for dogs with limited motion of pelvic limb joints. [source]

The intertarsal joint of the ostrich (Struthio camelus): Anatomical examination and function of passive structures in locomotion

Nina U. Schaller
Abstract The ostrich (Struthio camelus) is the largest extant biped. Being flightless, it exhibits advanced cursorial abilities primarily evident in its characteristic speed and endurance. In addition to the active musculoskeletal complex, its powerful pelvic limbs incorporate passive structures wherein ligaments interact with joint surfaces, cartilage and other connective tissue in their course of motion. This arrangement may enable energy conservation by providing joint stabilisation, optimised limb segment orientation and automated positioning of ground contact elements independently of direct muscle control. The intertarsal joint is of particular interest considering its position near the mid-point of the extended limb and its exposure to high load during stance with significant inertial forces during swing phase. Functional-anatomical analysis of the dissected isolated joint describes the interaction of ligaments with intertarsal joint contours through the full motion cycle. Manual manipulation identified a passive engage-disengage mechanism (EDM) that establishes joint extension, provides bi-directional resistance prior to a transition point located at 115° and contributes to rapid intertarsal flexion at toe off and full extension prior to touch down. This effect was subsequently quantified by measurement of intertarsal joint moments in prepared anatomical specimens in a neutral horizontal position and axially-loaded vertical position. Correlation with kinematic analyses of walking and running ostriches confirms the contribution of the EDM in vivo. We hypothesise that the passive EDM operates in tandem with a stringently coupled multi-jointed muscle-tendon system to conserve the metabolic cost of locomotion in the ostrich, suggesting that a complete understanding of terrestrial locomotion across extinct and extant taxa must include functional consideration of the ligamentous system. [source]

Supraspinal input is dispensable to generate glycine-mediated locomotive behaviors in the zebrafish embryo

Gerald B. Downes
Abstract The anatomy of the developing zebrafish spinal cord is relatively simple but, despite this simplicity, it generates a sequence of three patterns of locomotive behaviors. The first behavior exhibited is spontaneous movement, then touch-evoked coiling, and finally swimming. Previous studies in zebrafish have suggested that spontaneous movements occur independent of supraspinal input and do not require chemical neurotransmission, while touch-evoked coiling and swimming depend on glycinergic neurotransmission as well as supraspinal input. In contrast, studies in other vertebrate preparations have shown that spontaneous movement requires glycine and other neurotransmitters and that later behaviors do not require supraspinal input. Here, we use lesion analysis combined with high-speed kinematic analysis to re-examine the role of glycine and supraspinal input in each of the three behaviors. We find that, similar to other vertebrate preparations, supraspinal input is not essential for spontaneous movement, touch-evoked coiling, or swimming behavior. Moreover, we find that blockade of glycinergic neurotransmission decreases the rate of spontaneous movement and impairs touch-evoked coiling and swimming, suggesting that glycinergic neurotransmission plays critical yet distinct roles for individual patterns of locomotive behaviors. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source]

Spontaneous facial motility in infancy: A 3D kinematic analysis

Jordan R. Green
Abstract Early spontaneous orofacial movements have rarely been studied experimentally, though the motor experiences gained from these behaviors may influence the development of motor skills emerging for speech. This investigation quantitatively describes developmental changes in silent, spontaneous lip and jaw movements from 1 to 12 months of age using optically based 3D motion capture technology. Twenty-nine typically developing infants at five ages (1, 5, 7, 9, and 12 months) were studied cross-sectionally. Infants exhibited spontaneous facial movements at all ages studied. Several age-related changes were detected in lip and jaw kinematics: the occurrence of spontaneous movements increased, movement speed increased, the duration of movement epochs decreased and movement coupling among different facial regions increased. Additionally, evidence for stereotypic movements was not strong. The present findings suggest that, during the first year of life, early spontaneous facial movements undergo significant developmental change in the direction of skill development for speech. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 48: 16,28, 2006. [source]

Verification of skin-based markers for 3-dimensional kinematic analysis of the equine tarsal joint

Summary Reasons for performing study: Kinematic studies are usually based on tracking markers attached to the skin. However, complex joints, such as the tarsal joint, function in 3-dimensions (3D), and have therefore necessitated application of the invasive bone pin technique, limiting kinematic studies to the research laboratory. This study investigates the feasibility of using skin-based markers for 3D analysis of tarsal joint motion. Hypothesis: Three-dimensional motions of the tarsal joint can be measured with an acceptable degree of accuracy using skin markers. Methods: Retroreflective markers were attached over the tibial and metatarsal segments. Markers were tracked automatically at trot. Three-dimensional skin correction algorithms were used for correction of skin displacement, and 3D motions derived from the corrected (CSD) and uncorrected (USD) skin displacement were compared with data from a previous study in which those motions were described using bone-fixed markers (BFM) by correlation, root mean square errors (RMS) and shape agreement (SA) of the curves. Results: The RMS of BFM and CSD were smaller than those of BFM and USD for all motions. The correlation coefficients of BFM and CSD were higher than those of BFM and USD. SA was good or fair for all motions except internal/external rotation and medial/lateral translation. Conclusions and potential relevance: With appropriate correction for skin movement relative to skeletal landmarks, skin markers can identify tarsal 3D motions for flexion/extension, abduction/adduction, cranial/caudal translation, and proximal/distal translation, allowing analysis and comparison of information between horses during swing and stance phases. [source]

Electromyographic and kinematic indicators of fatigue in horses: a pilot study

Summary Muscle fatigue can be quantified using Fourier analysis of the recorded EMG signal. Median frequency is the frequency at which the Fourier profile is bisected, and this measure typically shifts to smaller values during fatigue. This technique was combined with kinematic analysis to describe the time course of fatigue in horses galloping on an inclined treadmill. It was hypothesised that EMG median frequency would decrease in tandem with changes in kinematic variables through the exercise test. Three fit Thoroughbred horses had retroreflective markers placed on their hooves and withers. Surface electrodes were attached to the skin over the forelimb deltoid muscle. After warm-up at walk and trot, each horse galloped at 110% VO2max on a treadmill inclined to 7.5% until fatigue onset. Kinematic data were recorded at 200 Hz for 5 s at 30s intervals, and raw EMG data were recorded at 1024 Hz for 3 s at 15 s intervals. Fatigue onset was the point in time when the horse could not keep up with the treadmill speed with minimal encouragement. One horse performed the entire exercise test on the same lead, while the other 2 horses changed leads periodically, interrupting the changes in both the EMG and kinematic measurements. Overall, through the course of the trials, mean stride length increased by 0.34 m and stride duration increased by 0.03 s. Vertical excursion of the trunk marker increased by 0.03 m. For the horse that did not change lead, median frequency of the EMG signal decreased by 36%. In the other 2 horses, lead changes were interspersed between smaller decreases in median frequency, whereupon median frequency recovered to starting levels immediately following a lead change. The median frequency decreased by 12-20% between lead changes. Kinematic changes are more global indictors of fatigue, while the EMG indicators are dependent upon lead changes. [source]

Insights into biaxial extensional tectonics: an examplefrom the Sand,kl, Graben, West Anatolia, Turkey

Mustafa Cihan
Abstract West Anatolia, together with the Aegean Sea and the easternmost part of Europe, is one of the best examples of continental extensional tectonics. It is a complex area bounded by the Aegean,Cyprus Arc to the south and the North Anatolian Fault Zone (NAFZ) to the north. Within this complex and enigmatic framework, the Sand,kl, Graben (10,km wide, 30,km long) has formed at the eastern continuation of the Western Anatolian extensional province at the north-northwestward edge of the Isparta Angle. Recent studies have suggested that the horst,graben structures in West Anatolia formed in two distinct extensional phases. According to this model the first phase of extension commenced in the Early,Middle Miocene and the last, which is accepted as the onset of neotectonic regime, in Early Pliocene. However, it is controversial whether two-phase extension was separated by a short period of erosion or compression during Late Miocene,Early Pliocene. Both field observations and kinematic analysis imply that the Sand,kl, Graben has existed since the Late Pliocene, with biaxial extension on its margins which does not necessarily indicate rotation of regional stress distribution in time. Although the graben formed later in the neotectonic period, the commencement of extension in the area could be Early Pliocene (c. 5,Ma) following a severe but short time of erosion at the end of Late Miocene. The onset of the extensional regime might be due to the initiation of westward motion of Anatolian Platelet along the NAFZ that could be triggered by the higher rate of subduction at the east Aegean,Cyprus Arc in the south of the Aegean Sea. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Numerical direct kinematic analysis of fully parallel linearly actuated platform type manipulators

Li-Chun T. Wang
This article presents a new numerical approach for solving the direct kinematics problem of fully parallel, linearly actuated platform manipulators. The solution procedure consists of two stages. The first stage transforms the direct kinematics problem into an equivalent nonlinear programming program, and a robust search algorithm is developed to bring the moving platform from arbitrary initial approximation to a feasible configuration that is near to the true solution. The second stage uses the Newton-Raphson iterative method to converge the solution to the desired accuracy. This approach is numerically stable and computationally efficient. In addition, by randomly perturbing the initial approximations, it can be implemented successively to find multiple solutions to the direct kinematics problem. Two numerical examples are presented to demonstrate the stability and efficiency of this approach. © 2002 Wiley Periodicals, Inc. [source]

Geared robot manipulators with a jointed unit: Kinematic analysis and its application

Dar-Zen Chen
An efficient and systematic methodology for the kinematic analysis of geared robot manipulators (GRMs) with a jointed unit is presented. It is shown that, by decomposing mechanical transmission lines of a GRM into serially connected jointed and disjointed units, kinematic relation between local inputs and local outputs of admissible jointed units can be systematically formulated. Accordingly, angular displacements of input links with respect to their associated primary links can be symbolically expressed in terms of joint angles by a unit-by-unit evaluation procedure. This unit-by-unit evaluation procedure provides better kinematic insights into how input torques are transmitted to various joints. It is also shown that an actuator in a GRM with a jointed unit can drive nonconsecutive joints by proper design of its gear train. A 3 degrees of freedom GRM with a jointed unit is used as an illustrative example. © 2001 John Wiley & Sons, Inc. [source]

Tyrphostin-A47 inhibitable tyrosine phosphorylation of flagellar proteins is associated with distinct alteration of motility pattern in hamster spermatozoa

Daniel Mariappa
Abstract To acquire fertilizing potential, mammalian spermatozoa must undergo capacitation and acrosome reaction. Our earlier work showed that pentoxifylline (0.45 mM), a sperm motility stimulant, induced an early onset of hamster sperm capacitation associated with tyrosine phosphorylation of 45,80 kDa proteins, localized to the mid-piece of the sperm tail. To assess the role of protein tyrosine phosphorylation in sperm capacitation, we used tyrphostin-A47 (TP-47), a specific protein tyrosine kinase inhibitor. The dose-dependent (0.1,0.5 mM) inhibition of tyrosine phosphorylation by TP-47 was associated with inhibition of hyperactivated motility and 0.5 mM TP-47-treated spermatozoa exhibited a distinct circular motility pattern. This was accompanied by hypo-tyrosine phosphorylation of 45,60 kDa proteins, localized to the principal piece of the intact-sperm and the outer dense fiber-like structures in detergent treated-sperm. Sperm kinematic analysis (by CASA) of spermatozoa, exhibiting circular motility (at 1st hr), showed lower values of straight line velocity, curvilinear velocity and average path velocity, compared to untreated controls. Other TP-47 analogues, tyrphostin-AG1478 and -AG1296, had no effect either on kinematic parameters or sperm protein tyrosine phosphorylation. These studies indicate that TP-47-induced circular motility of spermatozoa is compound-specific and that the tyrosine phosphorylation status of 45,60 kDa flagellum-localized proteins could be key regulators of sperm flagellar bending pattern, associated with the hyperactivation of hamster spermatozoa. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source]

Kinematic structure in the Galactic halo at the North Galactic Pole: RR Lyrae and blue horizontal branch stars show different kinematics

T. D. Kinman
ABSTRACT Radial velocities and proper motions (derived from the GSC-II data base) are given for 38 RR Lyrae (RRL) stars and 79 blue horizontal branch (BHB) stars in a ,200 deg2 area around the North Galactic Pole (NGP). Both heliocentric (UVW) and galactocentric (VR, V,, Vz) space motions are derived for these stars using a homogeneous distance scale consistent with (m,M)0= 18.52 for the Large Magellanic Cloud (LMC). An analysis of the 26 RRL and 52 BHB stars whose height (Z) above the plane is less than 8 kpc shows that this halo sample is not homogeneous. Our BHB sample (like that of Sirko et al.) has a zero galactic rotation (V,) and roughly isotropic velocity dispersions. The RRL sample shows a definite retrograde rotation (V,=,95 ± 29 km s,1) and non-isotropic velocity dispersions. The combined BHB and RRL sample has a retrograde galactic rotation (V) that is similar to that found by Majewski for his sample of subdwarfs in Selected Area (SA) 57. The velocity dispersion of the RRL stars that have a positive W motion is significantly smaller than the dispersion of those ,streaming down' with a negative W. Also, the ratio of RRL to BHB stars is smaller for the sample that has positive W. Our halo sample occupies 10.4 kpc3 at a mean height of 5 kpc above the Galactic plane. In this volume, one component (rich in RRL stars) shows retrograde rotation and the streaming motion that we associate with the accretion process. The other component (traced by the BHB stars) shows essentially no rotation and less evidence of streaming. These two components have horizontal branch (HB) morphologies that suggest that they may be the field star equivalents of the young and old halo globular clusters, respectively. Clearly, it is quite desirable to use more than one tracer in any kinematic analysis of the halo. [source]

Nitrogen deficiency inhibits leaf blade growth in Lolium perenne by increasing cell cycle duration and decreasing mitotic and post-mitotic growth rates

ABSTRACT Nitrogen deficiency severely inhibits leaf growth. This response was analysed at the cellular level by growing Lolium perenne L. under 7.5 mm (high) or 1 mm (low) nitrate supply, and performing a kinematic analysis to assess the effect of nitrogen status on cell proliferation and cell growth in the leaf blade epidermis. Low nitrogen supply reduced leaf elongation rate (LER) by 43% through a similar decrease in the cell production rate and final cell length. The former was entirely because of a decreased average cell division rate (0.023 versus 0.032 h,1) and thus longer cell cycle duration (30 versus 22 h). Nitrogen status did not affect the number of division cycles of the initial cell's progeny (5.7), and accordingly the meristematic cell number (53). Meristematic cell length was unaffected by nitrogen deficiency, implying that the division and mitotic growth rates were equally impaired. The shorter mature cell length arose from a considerably reduced post-mitotic growth rate (0.033 versus 0.049 h,1). But, nitrogen stress did not affect the position where elongation stopped, and increased cell elongation duration. In conclusion, nitrogen deficiency limited leaf growth by increasing the cell cycle duration and decreasing mitotic and post-mitotic elongation rates, delaying cell maturation. [source]

Practitioner Review: Approaches to assessment and treatment of children with DCD: an evaluative review

Peter H. Wilson
Background:, Movement clumsiness (or Developmental Coordination Disorder , DCD) has gained increasing recognition as a significant condition of childhood. However, some uncertainty still exists about diagnosis. Accordingly, approaches to assessment and treatment are varied, each drawing on distinct theoretical assumptions about the aetiology of the condition and its developmental course. Method:, This review evaluates the current status of different approaches to motor assessment and treatment for children with DCD. These approaches are divided according to their broad conceptual origin (or explanatory framework): Normative Functional Skill Approach, General Abilities Approach, Neurodevelopmental Theory, Dynamical Systems Theory, and the Cognitive Neuroscientific Approach. Conclusions:, Each conceptual framework is shown to support assessment and treatment methods with varying degrees of conceptual and psychometric integrity. The normative functional skill approach supports the major screening devices for DCD and cognitive (or top-down) approaches to intervention. The general abilities approach and traditional neurodevelopmental theory are not well supported by recent research. The dynamical systems approach supports promising trends in biomechanical or kinematic analysis of movement, ecological task analysis, and task-specific intervention. Finally, and more recently, the cognitive neuroscientific approach has generated some examples of process-oriented assessment and treatment based on validated (brain,behaviour) models of motor control and learning. A multi-level approach to movement assessment and treatment is recommended for DCD, providing a more complete representation of motor development at different levels of function , behavioural, neurocognitive, and emotional. [source]