Mechanism Analysis Using Implicit Constraints

2008 ◽  
Author(s):  
George H. Sutherland
Keyword(s):  
Equations Of Motion ◽  
Reaction Force ◽  
Mechanism Analysis ◽  
Kinematic Parameters ◽  
Joint Reaction Force ◽  
Dynamic Mechanisms ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Mechanism Kinematic ◽  
Joint Reaction

This paper introduces an approach to kinematic and dynamic mechanisms analysis where one or more joints are modeled using joint component relative displacements that approximate real joint behavior. This approach allows for the simultaneous nonrecursive solution for both mechanism kinematic parameters and selected dynamic joint reaction forces. Also, for closed loop mechanisms, the approach eliminates the need for forming explicit loop closure constraint equations, so that the dynamic equations of motion, derived using either the Newtonian or Lagrangian method, have a simplified unconstrained form. The key element underlying the approach is the formation of axioms for the standard mechanism joint types that describe the form of the joint reaction force and/or moment in terms of a virtual (or real) displacement between the joint components.

Are sound dogs mechanically symmetric at trot?

2008 ◽  
Vol 21 (03) ◽  
pp. 294-301 ◽  
Author(s):  
G. R. Colborne
Keyword(s):  
Hind Limb ◽  
Reaction Force ◽  
Joint Mechanics ◽  
Joint Reaction Force ◽  
Stifle Joint ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
The Right ◽  
Vertical Joint ◽  
Joint Reaction

SummaryA two-year-old, sound Labrador Retriever was determined to be ’right hind limb dominant’ by comparison of total hind limb moments of support using inverse dynamics. Net joint moments at the hip, tarsal and metatarsophalangeal joints were larger on the right side. Vertical joint reaction forces at the stifle were larger on the right, and horizontal stifle joint reaction forces were smaller on the right. The crus segment was more cranially inclined on the right side through most of stance, but the angle of the resultant stifle joint reaction force vector against the long axis of the crus segment was identical between the right and left sides. The cranially inclined crus segment orientation on one side, coupled with the larger vertical joint reaction force, may result in an internal asymmetry in stifle joint mechanics, although the effects of this on cruciate ligament stresses remain to be determined.

Recovery of Joint Reaction Force for Real-Time Recursive Multibody Dynamics

1997 ◽  
Author(s):  
Fuh-Feng Tsai ◽  
Masoud Mirtaheri
Keyword(s):  
Parallel Algorithm ◽  
Multibody Dynamics ◽  
Lagrange Multipliers ◽  
Reaction Force ◽  
Joint Reaction Force ◽  
Component Design ◽  
Vehicle Component ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Reaction

Abstract This paper proposes a formulation and parallel algorithm for the computation of all joint reaction forces in the recursive multibody dynamics. First, the Lagrange Multipliers associated with cut joints in each decoupled loop of a mechanical system are recovered. Then the joint reaction forces for the cut joints are computed directly using the obtained Lagrange Multipliers. After that, joint reaction forces associated with uncut joints are computed in backward computational paths, using synchronization in all junction nodes. A parallel algorithm for recovering reaction forces and torques for all cut joints and uncut joints is proposed. For validation, a space slider 3-D model is illustrated to compare the simulation results with those obtained from a commercial code DADS. Finally, A passenger car 14-body model is generated and simulated to obtain the joint reaction forces for the purpose of vehicle component design purpose.

Computational Analysis of Multibody Dynamic Systems Using Nonlinear Recursive Formulation

2009 ◽  
Vol 419-420 ◽  
pp. 289-292
Author(s):  
Yunn Lin Hwang ◽  
Shen Jenn Hwang ◽  
Zi Gui Huang ◽  
Ming Tzong Lin ◽  
Yen Chien Mao ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Recursive Formulation ◽  
Loosely Coupled ◽  
Multibody Dynamic ◽  
Joint Coordinates ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Strong Dynamic ◽  
Joint Reaction

. In this paper the computer implementation of the nonlinear recursive formulation in multibody dynamics systems is described. The organization of the computer algorithm which is used to automatically construct and numerically solve the system of loosely coupled dynamic equations expressed in terms of the absolute and joint coordinates is discussed. The inertia projection schemes used in most existing recursive formulations for the dynamic analysis of deformable mechanisms lead to dense coefficient matrices in the equations of motion. Consequently, there are strong dynamic couplings between the joint and elastic coordinates. By using the inertia matrix structure of deformable mechanical systems and the fact that the joint reaction forces associated with the elastic coordinates do represent independent variables, a reduced system of equations whose dimension is dependent of the number of elastic degrees of freedom is obtained. This system can be solved for the joint accelerations as well as the joint reaction forces. The multibody flexible four-bar system is used as an example to demonstrate the use of the procedure discussed in this paper.

scholarly journals THREE-DIMENSIONAL MULTI-SEGMENTED SPINE JOINT REACTION FORCES DURING COMMON WORKPLACE PHYSICAL DEMANDS/ACTIVITIES OF DAILY LIVING

2017 ◽  
Vol 29 (04) ◽  
pp. 1750025
Author(s):  
Scott P. Breloff ◽  
Li-Shan Chou
Keyword(s):  
Activities Of Daily Living ◽  
Daily Living ◽  
Reaction Force ◽  
Three Dimensional ◽  
Physical Demands ◽  
Stair Descent ◽  
Joint Reaction Forces ◽  
Spine Model ◽  
Reaction Forces ◽  
Joint Reaction

Objective: The quantification of inter-segmental spine joint reaction forces during common workplace physical demands. Background: Many spine reaction force models have focused on the L5/S1 or L4/L5 joints to quantify the vertebral joint reaction forces. However, the L5/S1 or L4/L5 approach neglects most of the intervertebral joints. Methods: The current study presents a clinically applicable and noninvasive model which calculates the spinal joint reaction forces at six different regions of the spine. Subjects completed four ambulatory activities of daily living: level walking, obstacle crossing, stair ascent, and stair descent. Results: Peak joint spinal reaction forces were compared between tasks and spine regions. Differences existed in the bodyweight normalized vertical joint reaction forces where the walking (8.05[Formula: see text][Formula: see text][Formula: see text]3.19[Formula: see text]N/kg) task had significantly smaller peak reaction forces than the stair descent (12.12[Formula: see text][Formula: see text][Formula: see text]1.32[Formula: see text]N/kg) agreeing with lower extremity data comparing walking and stair descent tasks. Conclusion: This method appears to be effective in estimating the joint reaction forces using a segmental spine model. The results suggesting the main effect of peak reactions forces in the segmental spine can be influenced by task.

scholarly journals A Forefoot Strike Requires the Highest Forces Applied to the Foot Among Foot Strike Patterns

2017 ◽  
Vol 01 (02) ◽  
pp. E37-E42 ◽  
Author(s):  
Satoru Hashizume ◽  
Toshio Yanagiya
Keyword(s):  
Achilles Tendon ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Moment Arm ◽  
Moment Arms ◽  
Joint Reaction Forces ◽  
Force Moment ◽  
Foot Strike ◽  
Reaction Forces ◽  
Joint Reaction

AbstractGround reaction force is often used to predict the potential risk of injuries but may not coincide with the forces applied to commonly injured regions of the foot. This study examined the forces applied to the foot, and the associated moment arms made by three foot strike patterns. 10 male runners ran barefoot along a runway at 3.3 m/s using forefoot, midfoot, and rearfoot strikes. The Achilles tendon and ground reaction force moment arms represented the shortest distance between the ankle joint axis and the line of action of each force. The Achilles tendon and joint reaction forces were calculated by solving equations of foot motion. The Achilles tendon and joint reaction forces were greatest for the forefoot strike (2 194 and 3 137 N), followed by the midfoot strike (1 929 and 2 853 N), and the rearfoot strike (1 526 and 2 394 N). The ground reaction force moment arm was greater for the forefoot strike than for the other foot strikes, and was greater for the midfoot strike than for the rearfoot strike. Meanwhile, there were no differences in the Achilles tendon moment arm among all foot strikes. These differences were attributed mainly to differences in the ground reaction force moment arm among the three foot strike patterns.

scholarly journals Minimization of dynamic joint reaction forces of the 2-DOF serial manipulators based on interpolating polynomials and counterweights

2015 ◽  
Vol 42 (4) ◽  
pp. 249-260 ◽  
Author(s):  
Slavisa Salinic ◽  
Marina Boskovic ◽  
Radovan Bulatovic
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Lagrange Equations ◽  
Symbolic Form ◽  
Serial Manipulators ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Inertia Forces ◽  
Joint Reaction ◽  
Selection Of

This paper presents two ways for the minimization of joint reaction forces due to inertia forces (dynamic joint reaction forces) in a two degrees of freedom (2-DOF) planar serial manipulator. The first way is based on the optimal selection of the angular rotations laws of the manipulator links and the second one is by attaching counterweights to the manipulator links. The influence of the payload carrying by the manipulator on the dynamic joint reaction forces is also considered. The expressions for the joint reaction forces are obtained in a symbolic form by means of the Lagrange equations of motion. The inertial properties of the manipulator links are represented by dynamical equivalent systems of two point masses. The weighted sum of the root mean squares of the magnitudes of the dynamic joint reactions is used as an objective function. The effectiveness of the two ways mentioned is discussed.

scholarly journals Dynamic Simulation of a Hydraulic Excavator to Determine the Joint Reaction Forces of Boom, Stick, Bucket, and Driving Forces of Hydraulic Cylinders

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Tan Nguyen Dang
Keyword(s):  
Driving Forces ◽  
Reaction Force ◽  
Computer Software ◽  
Hydraulic Excavator ◽  
Working Cycle ◽  
Maximum Reaction ◽  
Joint Reaction Forces ◽  
Hydraulic Cylinders ◽  
Reaction Forces ◽  
Joint Reaction

To optimize the dimensions of the boom, stick of the hydraulic excavator and select the suitable hydraulic bucket, stick, and boom cylinders, the designer must determine the joint reaction forces and driving forces. These forces always alter in an excavator's working cycle. They are conventionally calculated by mathematical method. This conventional method is complicated and challenging to determine the maximum reaction forces, which can break the stick and boom. This article builds a 3D model and simulates a working cycle of the hydraulic excavator to find the reaction force diagrams of boom and stick as well as driving forces of hydraulic cylinders by using computer software PTC Creo Parametric. Based on these results, the designer easily calculates the maximum tensions of the dimensions of boom and stick in a working cycle to optimize their dimensions as well as selects suitable hydraulic cylinders.

scholarly journals The role of the contralateral limb in below-knee amputee gait

1990 ◽  
Vol 14 (1) ◽  
pp. 33-42 ◽  
Author(s):  
G. R. B. Hurley ◽  
R. McKenney ◽  
M. Robinson ◽  
M. Zadravec ◽  
M. R. Pierrynowski
Keyword(s):  
Lower Limb ◽  
Reaction Force ◽  
Force Plate ◽  
Lower Limbs ◽  
Contralateral Limb ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Reaction ◽  
Amputee Gait

Very little quantitative biomechanical research has been carried out evaluating issues relevant to prosthetic management. The literature available suggests that amputees may demonstrate an asymmetrical gait pattern. Furthermore, studies suggest that the forces occurring during amputee gait may be unequally distributed between the contralateral and prosthetic lower limbs/This study investigates the role of the contralateral limb in amputee gait by determining lower limb joint reaction forces and symmetry of motion in an amputee and non-amputee population. Seven adult below-knee amputees and four non-amputees participated in the study. Testing involved collection of kinematic coordinate data employing a WATSMART video system and ground reaction force data using a Kistler force plate. The degree of lower limb symmetry was determined using bilateral angle-angle diagrams and a chain encoding technique. Ankle, knee and hip joint reaction forces were estimated in order to evaluate the forces acting across the joints of the amputee's contralateral limb. The amputees demonstrated a lesser degree of lower limb symmetry than the non-amputees. This asymmetrical movement was attributed to the inherent variability of the actions of the prosthetic lower limb. The forces acting across the joints of the contralateral limb were not significantly higher than that of the non-amputee. This suggests that, providing the adult amputee has a good prosthetic fit, there will not be increased forces across the joints of the contralateral limb and consequently no predisposition for the long-term wearer to develop premature degenerative arthritis.

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