Implementation of multi-rigid-body dynamics within a robotic grasping simulator

Abstract

Robotic simulation systems allow researchers, engineers, and students to test control algorithms in a safe environment, hut until recently these systems only simulated the dynamics of the mechanism itself and could not simulate (complex) contacts with other bodies in the environment However, if the robot's task involves grasping an object, accurate simulation of contact and friction forces is a necessity. Recently developed methods formulate the constrains as a linear complementarity problem, allowing a solution to he computed using proven algorithms, hut for anyone implementing such a system, several additional . considerations must he taken into account. In this paper we present the implementation of the dynamics module of our freely available grasping simulator and present an example grasping task.

Direct Trajectory Optimization of Rigid Body Dynamical Systems through Contact

“…We have also focused on purely inelastic collisions where the effective coefficient of restitution vanishes. The works in [1,11] have developed LCP based simulation tools for multi-body contact and elastic collisions, and we believe our methods should extend to these areas as well.…”

“…Perhaps as a result, there is an apparent lack of planning solutions for robotic manipulation which plan through contact -most planners plan up to a pre-grasp then activate a separate grasping controller. Indeed, the multi-contact dynamics engines used to simulate grasping [10,11] do not use hybrid models of the dynamics, because the permutations of different possible modes grows exponentially with the number of links and contact points, and because hybrid models can be plagued by infinitely-frequent collisions (e.g., when a bouncing Fig. 1 The bipedal FastRunner robot is designed to run at speeds of over 20 mph.…”

“…Instead, simulation tools make use of time-stepping solutions that solve contact constraints using numerical solutions to a linear complementarity problem (LCP) which can be solved with well known methods like Lemke's Algorithm [17]. Significant additional work has been done to extend the original LCP methods to guarantee solutions to multi-body contact [1,11].…”

A constraint‐stabilized time‐stepping approach for rigid multibody dynamics with joints, contact and friction

“…A variant of the scheme presented here is currently used for the dynamical simulation of dynamical robotic grasps [7,37]. This scheme needs no computational effort other than that for solving the basic LCP subproblem, though the free term of the LCP is modified compared with other time-stepping LCP approaches [8,9,49].…”

From robotic hands to human hands: a visualization and simulation engine for grasping research

“…In the following sections we provide a brief overview of the components and features of the system, as well as describe some of its applications. Further information regarding the system and its applications can be found in the following papers [12,14,15,16,17,23].…”