edrumwri / wedge-juggler Goto Github PK

This directory should be installed under the Gazebo models directory (typically
$HOME/.gazebo/models). 

Build the controller for the juggler using CMake.

Then start juggling with:

  $ gazebo ../juggler.world

from your directory used for building the plugin.

--------------------------------------------------

Searching for parameters:

For new physics engines- or getting existing physics working with
the wedge juggler- it may take a parameter search to find reasonable
parameters.

Replace the text "libjuggler.so" with "libjuggler-search.so" and run the
juggler as usual- except now you will tell Gazebo to use the alternative
physics engine. For example:

  $ gazebo -e dart ../juggler.world 

will use the DART physics engine and attempt to find good parameter settings
for the juggler. The method used is grid search, and the search will likely take
several hours. Before running the grid search you will need to set
two environment variables:

  $ export GZ_BRUTE_PARAM_FILE=params
  $ export GZ_BRUTE_OUTPUT_FILE=output

The first line will tell the search the ranges and steps for the parameter
search. The second line indicates where the evaluation results should go.
The grid search will terminate Gazebo when complete. Assuming that
your file is named 'output', you will likely want to sort it to find
parameters that yield juggling, like so:

  $ sort -g -k6 -k5 < output

The tail of this output should look something like this:

bounce:0.10000000000000001:ball-geom mu:0:ball-geom limit:-0.27488999999999997 period:12 20000 1.71585

This means that the parameters bounce=0.1, mu=0.0, limit=-0.275, and 
period=12.0 yielded a juggle for 20000 iterations (the maximum used in the
search) with a mean ball height of 1.71585. If the juggle does not last 20000 
iterations, the ball was ejected from the juggler some time before. If the
mean height for the juggle is lower- say 1.2- then the ball became trapped
at the bottom of the wedge (there was no or little ballistic flight phase
after some time).