scholarly journals Simulation of the Lumbar Spine as a Multi-Module Paralel Manipulator

2011 ◽  
Vol 8 (3-4) ◽  
pp. 399-410 ◽  
Author(s):  
M. Ceccarelli ◽  
R. C. Saltarelo ◽  
G. Carbone ◽  
J. C. M. Carvalho
Keyword(s):  
Lumbar Spine ◽  
Mechanical Model ◽  
Parallel Manipulators ◽  
Intervertebral Discs ◽  
Spring Stiffness ◽  
Human Spine ◽  
Lumbar Segment ◽  
Reaction Forces ◽  
Simulation Results ◽  
Spine Structure

In this paper a simulation of movements of lumbar spine is proposed by using a model with serially connected parallel manipulators. An analysis has been computed for the human spine structure and its movements, in order to simulate the motions and forces that actuate a spine specifically in the lumbar segment. A mechanical model has been designed with available identified parameters of human spine, by using characteristics of parallel manipulators and spring stiffness. This model is suitable to properly simulate the trunk behavior at macroscopic level but also the smooth behavior of intervertebral discs and actuating motions of muscles and tendons. Simulation results for spring actions and joints reaction forces can give an evaluation of the forces that intervertebral discs supports during motions of a real spine.

Percutaneous Discectomy: An Anatomical Study

Neurosurgery ◽  
1985 ◽  
Vol 16 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Steven L. Kanter ◽  
William A. Friedman
Keyword(s):  
Computed Tomography ◽  
Lumbar Spine ◽  
Vascular Injury ◽  
Anatomical Study ◽  
Intervertebral Discs ◽  
Viable Alternative ◽  
Percutaneous Discectomy ◽  
Computed Tomographic ◽  
Anatomical Analysis ◽  
Computed Tomographic Scan

Abstract Percutaneous discectomy is a viable alternative in the treatment of herniated intervertebral discs of the lumbar spine. Anatomical analysis of the retroperitoneal surgical path utilizing computed tomography suggests that the risk of vascular injury is negligible at the L-4, L-5 level, but substantial at the L-5, S-1 level. In addition, one-third of patients otherwise suitable for percutaneous discectomy have segments of bowel obstructing the surgical path. Obtaining an abdominal computed tomographic scan with the patient in the surgical position seems to be a valuable screening technique in the evaluation of candidates for this procedure.

Computed Tomographic Discography in the Evaluation of Extreme Lateral Disc Herniation

Neurosurgery ◽  
1984 ◽  
Vol 14 (3) ◽  
pp. 350-352 ◽  
Author(s):  
J. C. Angtuaco Edgardo ◽  
C. Holder John ◽  
C. Boop Warren ◽  
F. Binet Eugene
Keyword(s):  
Lumbar Spine ◽  
High Resolution ◽  
Contrast Enhancement ◽  
Thin Section ◽  
Preoperative Evaluation ◽  
Intervertebral Discs ◽  
Ct Scans ◽  
Computed Tomographic ◽  
Disc Herniations ◽  
Lateral Disc Herniation

Abstract Thin section, high resolution computed tomographic (CT) scans of the lumbar spine produce images that can show herniated intervertebral discs without intravenous or intrathecal contrast enhancement. With this technique, the diagnosis of posterolateral and midline herniation has been greatly facilitated. This communication reports the use of CT discography in the preoperative evaluation of two patients who were shown at discography and proven at operation to have extreme lateral disc herniations.

Biomechanical in Vitro and Finite Element Study On Different Sagittal Alignment Postures of the Lumbar Spine During Multiaxial Daily Motion

2021 ◽  
Author(s):  
Nadja Wilmanns ◽  
Agnes Beckmann ◽  
Luis Fernando Nicolini ◽  
Christian Herren ◽  
Rolf Sobottke ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Planning Process ◽  
Axial Rotation ◽  
Intervertebral Discs ◽  
Fe Model ◽  
Bending Moments ◽  
Sagittal Spinal Alignment ◽  
Biomechanical Response

Abstract Lumbar Lordotic correction (LLC), the gold standard treatment for Sagittal Spinal malalignment (SMA), and its effect on sagittal balance have been critically discussed in recent studies. This paper assesses the biomechanical response of the spinal components to LLC as an additional factor for the evaluation of LLC. Human lumbar spines (L2L5) were loaded with combined bending moments in Flexion (Flex)/Extension (Ex) or Lateral Bending (LatBend) and Axial Rotation (AxRot) in a physiological environment. We examined the dependency of AxRot range of motion (RoM) on the applied bending moment. The results were used to validate a Finite Element (FE) model of the lumbar spine. With this model, the biomechanical response of the intervertebral discs (IVD) and facet joints under daily motion was studied for different sagittal spinal alignment (SA) postures, simulated by a motion in Flex/Ex direction. Applied bending moments decreased AxRot RoM significantly (all P<0.001). A stronger decline of AxRot RoM for Ex than for Flex direction was observed (all P<0.0001). Our simulated results largely agreed with the experimental data (all R2>0.79). During daily motion, the IVD was loaded higher with increasing lumbar lordosis (LL) for all evaluated values at L2L3 and L3L4 and posterior Annulus Stress (AS) at L4L5 (all P<0.0476). The results of this study indicate that LLC with large extensions of LL may not always be advantageous regarding the biomechanical loading of the IVD. This finding may be used to improve the planning process of LLC treatments.

Kinematic-, Static- and Workspace Analysis of a 6-P-U-S Parallel Manipulator

2010 ◽  
Author(s):  
Madusudanan Sathia Narayanan ◽  
Sourish Chakravarty ◽  
Hrishi Shah ◽  
Venkat N. Krovi
Keyword(s):  
Structural Design ◽  
Parallel Manipulators ◽  
Type I ◽  
Kinematic Modeling ◽  
Workspace Analysis ◽  
Reaction Forces ◽  
Specific Configuration ◽  
Parallel Kinematic ◽  
Stewart Gough Platform

This paper examines the symbolic kinematic modeling of a general 6-P-U-S (prismatic-universal-spherical) parallel kinematic manipulator (PKM). The base location of actuators has been previously shown to lead to: (i) reduction of the (motor) weight carried by the legs; (ii) elimination of the actuation transmission requirement (through intermediary joints as in the case of the Stewart-Gough platform); and (iii) most-importantly absorption of reaction-forces by the ground. We focus on using the symbolic equations to derive the conditions for type I and II singularities of this class of parallel manipulators. Based on these conditions, this system of equations is specialized to a specific configuration of the platform that has superior structural design and comparatively minimal singularities within its workspace. A series of studies were conducted to investigate the quality of workspace as well as estimate the actuation requirements for a unit payload carried over their workspace using the symbolic Jacobian model for this specialized configuration.

scholarly journals Macro- and microelement content of intervertebral discs in hernias of the lumbar spine

2020 ◽  
Vol 0 (3) ◽  
pp. 29-35
Author(s):  
Sanjar Kochkartaev ◽  
Shahaidar Shatursunov ◽  
Elena Danilova ◽  
Natalija Osinskaya
Keyword(s):  
Lumbar Spine ◽  
Intervertebral Discs ◽  
Microelement Content

Tip-Over Stability Analysis for a Wheeled Mobile Manipulator

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Shuai Guo ◽  
Tao Song ◽  
Fengfeng (Jeff) Xi ◽  
Richard Phillip Mohamed
Keyword(s):  
Stability Analysis ◽  
Path Planning ◽  
Static Load ◽  
System Stability ◽  
Mobile Manipulator ◽  
Inertial Forces ◽  
Horizontal Position ◽  
Reaction Forces ◽  
Simulation Results

A method is presented for tip-over stability analysis of a wheeled mobile manipulator. A wheeled mobile manipulator may tip over resulting from its operation. In this study, first a Newton–Euler formulation is applied to formulate the manipulator’s reaction forces and moments exerted onto the mobile platform. Tip-over criterion is derived to judge the system stability. Three load and motion analyses are carried on. The first static load deals with links and payload to show the effect of the horizontal position of the system’s center of gravity (CG). The second and third are the inertial forces resulting from joint speeds and accelerations, respectively. Case study is path planning with tip-over criterion result which can make the system stable along the path. The simulation results demonstrate the effectiveness of the proposed method.

scholarly journals Incidental extraspinal findings in the lumbar spine during magnetic resonance imaging of intervertebral discs

Heliyon ◽  
2018 ◽  
Vol 4 (9) ◽  
pp. e00803 ◽  
Author(s):  
Mogahid M.A. Zidan ◽  
Ikhlas A. Hassan ◽  
Abdelrahaman M. Elnour ◽  
Wadah M. Ali ◽  
Mustafa Z. Mahmoud ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Lumbar Spine ◽  
Magnetic Resonance ◽  
Intervertebral Discs ◽  
Resonance Imaging

Path Tracking of Parallel Manipulators in the Presence of Force Singularity

2005 ◽  
Vol 127 (4) ◽  
pp. 550-563 ◽  
Author(s):  
C. K. Kevin Jui ◽  
Qiao Sun
Keyword(s):  
Motion Planning ◽  
Parallel Manipulator ◽  
Inverse Dynamics ◽  
Parallel Manipulators ◽  
Path Tracking ◽  
Singularity Avoidance ◽  
Design Complexity ◽  
Actuation Redundancy ◽  
Planar Parallel Manipulator ◽  
Simulation Results

Parallel manipulators are uncontrollable at force singularities due to the infeasibly high actuator forces required. Existing remedies include the application of actuation redundancy and motion planning for singularity avoidance. While actuation redundancy increases cost and design complexity, singularity avoidance reduces the effective workspace of a parallel manipulator. This article presents a path tracking type of approach to operate parallel manipulators when passing through force singularities. We study motion feasibility in the neighborhood of singularity and conclude that a parallel manipulator may track a path through singular poses if its velocity and acceleration are properly constrained. Techniques for path verification and tracking are presented, and an inverse dynamics algorithm that takes actuator bounds into account is examined. Simulation results for a planar parallel manipulator are given to demonstrate the details of this approach.

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