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instantaneous center rotation

Ameet Aiyangar, Liying Zheng, William Anderst, Xudong Zhang
The study aimed to map instantaneous centers of rotation (ICRs) of lumbar motion segments during a functional lifting task and examine differences across segments and variations caused by magnitude of weight lifted. Eleven healthy participants lifted loads of three different magnitudes (4.5, 9, and 13.5kg) from a trunk-flexed (~75°) to an upright position, while being imaged by a dynamic stereo X-ray (DSX) system. Tracked lumbar vertebral (L2-S1) motion data were processed into highly accurate 6DOF intervertebral (L2L3, L3L4, L4L5, L5S1) kinematics...
December 29, 2016: Journal of Biomechanics
Claire Bruna-Rosso, Pierre-Jean Arnoux, Rohan-Jean Bianco, Yves Godio-Raboutet, Léo Fradet, Carl-Éric Aubin
BACKGROUND: Sacroiliac joint (SIJ) is a known chronic pain-generator. The last resort of treatment is the arthrodesis. Different implants allow fixation of the joint, but to date there is no tool to analyze their influence on the SIJ biomechanics under physiological loads. The objective was to develop a computational model to biomechanically analyze different parameters of the stable SIJ fixation instrumentation. METHODS: A comprehensive finite element model (FEM) of the pelvis was built with detailed SIJ representation...
2016: International Journal of Spine Surgery
X Ding, M Bues
PURPOSE: To present an analytical formula for deriving mechanical isocenter (MIC) of a rotational gantry treatment unit. The input data to the formula is obtained by a custom-made device. The formula has been implemented and used in an operational proton therapy facility since 2005. METHODS: The custom made device consisted of 3 mutually perpendicular dial indicators and 5 clinometers, to obtain displacement data and gantry angle data simultaneously. During measurement, a steel sphere was affixed to the patient couch, and the device was attached to the snout rotating with the gantry...
June 2015: Medical Physics
Tianmiao Wang, Yao Wu, Jianhong Liang, Chenhao Han, Jiao Chen, Qiteng Zhao
Skid-steering mobile robots are widely used because of their simple mechanism and robustness. However, due to the complex wheel-ground interactions and the kinematic constraints, it is a challenge to understand the kinematics and dynamics of such a robotic platform. In this paper, we develop an analysis and experimental kinematic scheme for a skid-steering wheeled vehicle based-on a laser scanner sensor. The kinematics model is established based on the boundedness of the instantaneous centers of rotation (ICR) of treads on the 2D motion plane...
2015: Sensors
Baoge Liu, Zheng Zeng, Tom Van Hoof, Jean Pierre Kalala, Zhenyu Liu, Bingxuan Wu
BACKGROUND: Multi-level cervical degeneration of the spine is a common clinical pathology that is often repaired by anterior cervical discectomy and fusion (ACDF). The aim of this study was to investigate the kinematics of the cervical spine after hybrid surgery compared with 2-level ACDF. MATERIAL AND METHODS: Five freshly frozen, unembalmed whole human cadavers were used including 3 males and 2 females with a mean age of 51 ± 8 years. After evaluating the intact spine for range of motion (ROM), sagittal alignment and instantaneous center of rotation (ICR), each cadaver underwent 4 consecutive surgeries: 2-level artificial disc replacement (ADR) from C4 to C6 (ADR surgery); 2-level ACDF from C4 to C6 (ACDF surgery); hybrid C4-5 ACDF and C5-6 ADR (ACDF+ADR surgery); and hybrid C4-5 ADR and C5-6 ACDF (ADR+ACDF surgery)...
April 8, 2015: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
Yuanxi Sun, Wenjie Ge, Jia Zheng, Dianbiao Dong
This paper presents the mechanical design, dynamics analysis and ankle trajectory analysis of a prosthetic knee joint using the geared five-bar mechanism. Compared with traditional four-bar or six-bar mechanisms, the geared five-bar mechanism is better at performing diverse movements and is easy to control. This prosthetic knee joint with the geared five-bar mechanism is capable of fine-tuning its relative instantaneous center of rotation and ankle trajectory. The centrode of this prosthetic knee joint, which is mechanically optimized according to the centrode of human knee joint, is better in the bionic performance than that of a prosthetic knee joint using the four-bar mechanism...
November 2015: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Sug-Joon Ahn, Ling Tsou, C Antonio Sánchez, Sidney Fels, Ho-Beom Kwon
The traditional hinge axis theory for guiding clinical procedures in dentistry and dental articulators has been challenged by the concept of an instantaneous center of rotation (ICR), which is becoming more prevalent in modern explanations of mandibular movement. The purpose of this study was to analyze traditional hinge axis theory using three-dimensional computer simulations and to compare it with ICR. Three-dimensional computational models that reproduced the traditional pantograph tracing method were created to simulate the opening and closing movements of the jaw...
February 26, 2015: Journal of Biomechanics
Andreas M Mueller, Claudio Rosso, Vahid Entezari, Brett McKenzie, Andrew Hasebroock, Andrea Cereatti, Ugo Della Croce, Ara Nazarian, Arun J Ramappa, Joseph P DeAngelis
BACKGROUND: Supraspinatus tears are common in pitchers. However, the effect of these tears on glenohumeral (GH) mechanics is incompletely understood. PURPOSE/HYPOTHESIS: To describe the effect of supraspinatus tears and repairs on GH kinematics during an abbreviated throwing motion using the intact shoulder girdle. The hypothesis was that supraspinatus tears would lead to an increase of GH translation in the coronal plane and supraspinatus repairs would restore GH kinematics...
October 2014: American Journal of Sports Medicine
Zhen-Yu Liu, Bao-Ge Liu, Xin Lin
OBJECTIVE: To clarify the effectiveness of Chinese herbal fomentation in treating chronic neck pain by means of changes in cervical kinematics. METHODS: Seventy-six patients with chronic neck pain were included in the study and were randomized into two groups based on the random number generator of the SPSS software: fomentation combined with Chinese herbal (Group 1) and fomentation without any medicine (Group 2). In both groups, the fomentation lasted for 60 min and heated to 35 °C, once a day for 28 consecutive days...
December 2014: Chinese Journal of Integrative Medicine
Raymond C Z Cohen, Paul W Cleary, Simon M Harrison, Bruce R Mason, David L Pease
The purpose of this study was to determine the pitching effects of buoyancy during all competitive swimming strokes--freestyle, backstroke, butterfly, and breaststroke. Laser body scans of national-level athletes and synchronized multiangle swimming footage were used in a novel markerless motion capture process to produce three-dimensional biomechanical models of the swimming athletes. The deforming surface meshes were then used to calculate swimmer center-of-mass (CoM) positions, center-of-buoyancy (CoB) positions, pitch buoyancy torques, and sagittal plane moments of inertia (MoI) throughout each stroke cycle...
October 2014: Journal of Applied Biomechanics
Baoge Liu, Zhenyu Liu, Tom VanHoof, JeanPierre Kalala, Zheng Zeng, Xin Lin
PURPOSE: We located the instantaneous center of rotation (ICR) for the cervical spine at various ages and investigated age-related changes. We evaluated the impact of cervical disc degeneration on the ICR using a scoring system based on plain radiographs. METHODS: Flexion, extension, and neutral lateral radiographs were obtained from 680 asymptomatic subjects (363 men, 317 women; ages 20-79 years) divided into six 10-year-age groups. The ICRs from C3/C4 to C6/C7 were determined from the radiographs using MIMICS software...
November 2014: European Spine Journal
Yafei Lu, Yuan Zhou, Mo Hei, Dapeng Fan
A dual-wedge scanner has potential applications in laser imaging radar. To realize fast scanning imaging without a blind region, the rotation rates of the wedges have to be controlled to perform beam scanning along appropriate track paths. The first-order paraxial approximation method is employed to investigate the 2D scan patterns and path density for different angular frequency ratios of the wedges rotating steadily in the same and opposite directions. The frame rate of no-blind-region scanning imaging is estimated in terms of the imaging coverage requirement...
June 1, 2014: Applied Optics
Todd C Pataky, Mark A Robinson, Jos Vanrenterghem, Russell Savage, Karl T Bates, Robin H Crompton
Center of pressure (COP) trajectories summarize the complex mechanical interaction between the foot and a contacted surface. Each trajectory itself is also complex, comprising hundreds of instantaneous vectors over the duration of stance phase. To simplify statistical analysis often a small number of scalars are extracted from each COP trajectory. The purpose of this paper was to demonstrate how a more objective approach to COP analysis can avoid particular sensitivities of scalar extraction analysis. A previously published dataset describing the effects of walking speed on plantar pressure (PP) distributions was re-analyzed...
2014: Gait & Posture
Helios De Rosario, Alvaro Page, Vicente Mata
This paper proposes a variation of the instantaneous helical pivot technique for locating centers of rotation. The point of optimal kinematic error (POKE), which minimizes the velocity at the center of rotation, may be obtained by just adding a weighting factor equal to the square of angular velocity in Woltring׳s equation of the pivot of instantaneous helical axes (PIHA). Calculations are simplified with respect to the original method, since it is not necessary to make explicit calculations of the helical axis, and the effect of accidental errors is reduced...
May 7, 2014: Journal of Biomechanics
Dilip K Sengupta, Haibo Fan
STUDY DESIGN: A biomechanical study in cadaveric lumbar spine. OBJECTIVE: To establish the basis of mechanical stability in degenerative disc disease from the relationship between range of motion (ROM), neutral zone motion (NZ), intradiscal pressure profile, and instantaneous axis or rotation (IAR) in advancing grades of disc degeneration. SUMMARY OF BACKGROUND DATA: The basis of mechanical instability in lumbar disc degeneration remains poorly understood...
June 1, 2014: Spine
Michael R Tucker, Adrian Moser, Olivier Lambercy, James Sulzer, Roger Gassert
Mechanical impedance modulation is the key to natural, stable and efficient human locomotion. An improved understanding of this mechanism is necessary for the development of the next generation of intelligent prosthetic and orthotic devices. This paper documents the design methodologies that were employed to realize a knee perturbator that can experimentally estimate human knee impedance during gait through the application of angular velocity perturbations. The proposed experiment requires a light, transparent, wearable, and remotely actuated device that closely follows the movement of the biological joint...
June 2013: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
Helios De Rosario, Álvaro Page, Antonio Besa, Ángel Valera
This paper presents a mathematical model for the propagation of errors in body segment kinematics to the location of the center of rotation. Three functional calibration techniques, usually employed for the gleno-humeral joint, are studied: the methods based on the pivot of the instantaneous helical axis (PIHA) or the finite helical axis (PFHA), and the "symmetrical center of rotation estimation" (SCoRE). A procedure for correcting the effect of soft tissue artifacts is also proposed, based on the equations of those techniques and a model of the artifact, like the one that can be obtained by double calibration...
October 18, 2013: Journal of Biomechanics
Ya Yang, Hulin Zhang, Jun Chen, Qingshen Jing, Yu Sheng Zhou, Xiaonan Wen, Zhong Lin Wang
We report a single-electrode-based sliding-mode triboelectric nanogenerator (TENG) that not only can harvest mechanical energy but also is a self-powered displacement vector sensor system for touching pad technology. By utilizing the relative sliding between an electrodeless polytetrafluoroethylene (PTFE) patch with surface-etched nanoparticles and an Al electrode that is grounded, the fabricated TENG can produce an open-circuit voltage up to 1100 V, a short-circuit current density of 6 mA/m(2), and a maximum power density of 350 mW/m(2) on a load of 100 MΩ, which can be used to instantaneously drive 100 green-light-emitting diodes (LEDs)...
August 27, 2013: ACS Nano
Christopher David Blair, Jessica Goold, Kyle Killebrew, Gideon Paul Caplovitz
As an object rotates, each location on the object moves with an instantaneous linear velocity, dependent upon its distance from the center of rotation, whereas the object as a whole rotates with a fixed angular velocity. Does the perceived rotational speed of an object correspond to its angular velocity, linear velocities, or some combination of the two? We had observers perform relative speed judgments of different-sized objects, as changing the size of an object changes the linear velocity of each location on the object's surface, while maintaining the object's angular velocity...
February 2014: Journal of Experimental Psychology. Human Perception and Performance
Yunus Alapan, Cihan Demir, Tuncay Kaner, Rahmi Guclu, Serkan Inceoğlu
OBJECT: The goal of this study was to investigate the effect of ligament failure on the instantaneous center of rotation (ICR) in the lower lumbar spine. METHODS: A 3D finite element model of the L4-5 segment was obtained and validated. Ligament failure was simulated by reducing ligaments in a stepwise manner from posterior to anterior. A pure bending moment of 7.5 Nm was applied to the model in 3 anatomical planes for the purpose of validation, and a 6-Nm moment was applied to analyze the effect of ligament failure...
June 2013: Journal of Neurosurgery. Spine
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