Non-Jamming Conditions in Multi-Contact Constrained Rigid-Body Dynamics

Volume 6: 5th International Conference on Multibody Systems, Nonlinear Dynamics, and Control, Parts A, B, and C ◽

10.1115/detc2005-85651 ◽

2005 ◽

Cited By ~ 1

Author(s):

Tong Liu ◽

Michael Yu Wang

Keyword(s):

Rigid Body ◽

Rigid Body Dynamics ◽

Applied Force ◽

Necessary Condition ◽

Sufficient Condition ◽

Contact Points ◽

Multiple Contacts ◽

Unilateral Contacts ◽

Body Dynamics ◽

Free Body

In this paper, we study a rigid body system of one free body (e.g., workpiece) in contact with multiple fixed bodies (e.g., locators). The contacts are unilateral. The investigation is motivated for planning the task of insertion of a workpiece in a fixture. The key issue of the problem is to determine an applied force that can move the workpiece while maintaining all existing contacts with the locators. We first analyze the kinematics of the rigid body constrained by multiple unilateral contacts. The contact constraints are classified into two categories, the configuration constraints and kinematic constraints. We then find a sufficient condition for non-jamming among the multiple contacts in the constrained rigid-body dynamics. This condition is also a necessary condition when the number of contacts is no less than four. Moreover, a method to find the applied force on the workpiece that results in sliding on all contact points is presented, based on the sufficient condition for non-jamming. Numerical examples are presented and the results of the method are compared with the results of a quasistatic method.

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Slipping–rolling transitions of a body with two contact points

Nonlinear Dynamics ◽

10.1007/s11071-021-06538-5 ◽

2021 ◽

Author(s):

Mate Antali ◽

Gabor Stepan

Keyword(s):

Rigid Body ◽

Contact Point ◽

Static Friction ◽

Rigid Body Dynamics ◽

Contact Forces ◽

Friction Forces ◽

Contact Points ◽

Body Dynamics ◽

Coulomb Model ◽

Rigid Surfaces

AbstractIn this paper, the general kinematics and dynamics of a rigid body is analysed, which is in contact with two rigid surfaces in the presence of dry friction. Due to the rolling or slipping state at each contact point, four kinematic scenarios occur. In the two-point rolling case, the contact forces are undetermined; consequently, the condition of the static friction forces cannot be checked from the Coulomb model to decide whether two-point rolling is possible. However, this issue can be resolved within the scope of rigid body dynamics by analysing the nonsmooth vector field of the system at the possible transitions between slipping and rolling. Based on the concept of limit directions of codimension-2 discontinuities, a method is presented to determine the conditions when the two-point rolling is realizable without slipping.

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Context Dependent Contact Preserving Off-Line Model Simplification for Interactive Rigid Body Dynamics Simulations

Volume 2: 29th Computers and Information in Engineering Conference, Parts A and B ◽

10.1115/detc2009-87119 ◽

2009 ◽

Author(s):

Atul D. Thakur ◽

Satyandra K. Gupta

Keyword(s):

Rigid Body ◽

Collision Detection ◽

A Priori ◽

Rigid Body Dynamics ◽

Model Simplification ◽

Detection Algorithms ◽

Contact Points ◽

Body Dynamics ◽

Speed Up ◽

Dynamics Simulations

Rigid body dynamics simulations require use of accurate computation of contacts among bodies. Often collision detection algorithms are used for determining the contact between moving bodies. Many mechanical parts have a large number of features and hence collision detection with the detailed part models often slows down the rigid body dynamics simulations. Model simplification techniques developed for efficient graphical rendering may change the part geometry in such a manner that the contact points between parts may change as a result of the simplification. Hence, such simplifications may alter the resulting simulated behavior. In many simulation scenarios, all the parts participating in the simulation are known in advance. In such cases, the simulation context (i.e., a priori knowledge of parts) can be exploited to simplify the part geometries such that the contact points among parts do not change. For example, parts with significant concavities may have regions on their boundaries that will be inaccessible to other parts in the simulation and hence contact points cannot lie on such inaccessible regions. Removing such regions from the parts can simplify the model and hence speed up the simulation for interactive applications.

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