An Iterative Approach to Multibody Simulation Dynamics Suitable for Parallel Implementation

1993 ◽  
Vol 115 (4) ◽  
pp. 730-735 ◽  
Author(s):  
I. Sharf ◽  
G. M. T. D’Eleuterio
Keyword(s):  
Multibody Systems ◽  
Parallel Implementation ◽  
Solution Procedure ◽  
Parallel Structure ◽  
Iterative Approach ◽  
Multibody Simulation ◽  
Constraint Forces ◽  
Overhead Cost ◽  
Dynamics Of Multibody Systems ◽  
Jacobi Iteration

This paper presents a new solution procedure for simulation dynamics of multibody systems. The method is applicable to open chains with general interbody constraints. It is based on obtaining an explicit solution for the joint constraint forces by means of iterative techniques. We show that the algorithm possesses a parallel structure which matches the topology of the system. Numerical results for an anthropomorphic manipulator indicate that the conjugate-gradient Jacobi iteration is computationally most efficient. An estimate for the parallel efficiency of this scheme is obtained by combining the theoretical bound for parallel complexity with an approximate overhead cost associated with parallel implementation.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2005 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

On MBS Constraints and Projections

2021 ◽  
Author(s):  
Friedrich Pfeiffer
Keyword(s):  
Quadratic Form ◽  
Differential Equations ◽  
Multibody Systems ◽  
Equations Of Motion ◽  
Machine Process ◽  
Constraint Forces ◽  
Process Dynamics ◽  
Robot Tracking ◽  
Minimal Coordinates ◽  
Linear Differential

Abstract Constraints in multibody systems are usually treated by a Lagrange I - method resulting in equations of motion together with the constraint forces. Going from non-minimal coordinates to minimal ones opens the possibility to project the original equations directly to the minimal ones, thus eliminating the constraint forces. The necessary procedure is described, a general example of combined machine-process dynamics discussed and a specific example given. For a n-link robot tracking a path the equations of motion are projected onto this path resulting in quadratic form linear differential equations. They define the space of allowed motion, which is generated by a polygon-system.

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