RobotHand.world File Reference

Detailed Description

[Introduction] [Geometry] [Process] [Statistics] [Results]

Introduction

This is an instance of a 4 fingered robot hand with a particular geometry that corresponds to the MA-I developed at IOC.

Please, see our IJRR-11 for more information on the use of CuikSuite in the context of grasping.

Geometry

The geometry for this hand is given by the following anchor points of the fingers on the hand ( $\mathbf{q}_{i,1}$)

Finger ( $j$)
Anchor
Point 		1 2 3 4
$\mathbf{q}_{j,1}^x$ 9.5 9.5 9.5 40.1650
$\mathbf{q}_{j,1}^y$ -67 0 67 30.012
$\mathbf{q}_{j,1}^z$ 197.55 197.55 197.55 66.8142

and by the length of the phalanges ( $p_{j,i}$)

$p_{j,i}$ Finger ( $j$)
Phalanx ( $i$) 1 2 3 4
2 76.66 76.66 76.66 76.66
3 56 56 56 66
4 33.805151243 33.805151243 33.805151243 39.862238567

The ranges for the universal joint attaching finger $i$ to the hand palm are given by the minimum and maximum values for $\phi_{i,1}$ and $\phi_{i,2}$ and the limits for the two revolute joints in-between the phalanx $j$ and $j+1$ are given by the minimum and maximum values for $r_{i,j}$.

The grasp is defined given the contact points and normals on the fingertips

Finger ( $j$)
Contact
Point 		1 2 3 4
$\bf{x}_{j}^x$ 131 133.900801528 133.900801528 175
$\bf{x}_{j}^y$ -49 0 67 34
$\bf{x}_{j}^z$ 149 244.859338136 245 131.653563187
$\hat{\bf{n}}_{j}^x$ -0.925508818115500 -0.381407578434000 -0.381407578434000 -0.924406976992878
$\hat{\bf{n}}_{j}^y$ 0.144595776785000 0 0 0
$\hat{\bf{n}}_{j}^z$ -0.405390387471765 -0.924406976992878 -0.924406976992878 0.381407578434000

and on the object

Finger ( $j$)
Contact
Point 		1 2 3 4
$\bf{q}_{j,4}^x$ 27.856821097374684 27.856821097374684 27.856821097374684 34.762406989603285
$\bf{q}_{j,4}^y$ 0 0 0 0
$\bf{q}_{j,4}^z$ 19.151400000000000 19.151651859208762 19.151651859208762 19.508283467663215
$\hat{\bf{m}}_{j}^x$ 0 0 0 0
$\hat{\bf{m}}_{j}^y$ 0 0 0 0
$\hat{\bf{m}}_{j}^z$ 1 1 1 1

Process

This example is treated following this steps (from the main CuikSuite folder):

  • Generate the equations:
  • Solve the positional analysis problem: Use the parallel version of cuik since this is a large problem with 190 variables and more than 150 equations. Observe that the process stops as soon as the first solution is found
    • scripts/rmpicuik examples/RobotHand/RobotHand
  • Visualize the obtained configuration:

Statistics

Characteristics of the problem:

Nr. of indep. loops 3
Nr. of links 14
Nr. of joints 16
Nr. of equations (in the simplified system) 136
Nr. of variables (in the simplified system) 134

Here you have the statistics about the execution (on a grid with 160 processors). The process stops as soon as one solution is found.

Nr. of Empty boxes 201
Nr. of Solution boxes 1
Execution time (s) 80

References

This is a screenshot of the configuration we obtained:

Definition in file RobotHand.world.