AMBF Trace Plugin

A plugin for the Asynchronous Multibody Framework (AMBF), see https://github.com/WPI-AIM/ambf The plugin allows static traces at init or body traces during runtime in the AMBF simulator environment

Developed by Henry Phalen

This was something I made as a convenience tool for my own work, but thought it might be useful to others, so I am putting it here. There are several features that still could be added (expressed in code TODOs), but it is functional and (I hope) useful as is.

Features:

1. Show static trace at simulator startup (example screenshot at startup)

2. Dynamically and togglably trace the position of a body. This example video shows toggling collection on and off and showing and hiding the trace

ambf_body_trace_example.mp4

Building

Find most updated instructions for building AMBF on that git repository (https://github.com/WPI-AIM/ambf)

This plugin can be built stand-alone or in a catkin workspace.

Stand-Alone build

git clone this repository <plugin_path> onto your machine

cd <plugin_path>
mkdir build && cd build
cmake .. -DBUILD_PLUGIN_WITH_ROS=False
make

Build within a catkin workspace (ROS1)

A simple package.xml has been included in this repository to enable catkin to find and build it <plugin_path> should be located within catkin_ws/src/

cd <catkin_ws>
catkin build ambf_trace_plugin

Using plugin

Starting plugin

Find most updated instructions for starting AMBF with plugins on that git repository (https://github.com/WPI-AIM/ambf)

You can test this plugin on the example by: <ambf_exe_dir> ---> e.g. ~/ambf/bin/lin-x86_64

Test body trace:

cd <ambf_exe_dir>
./ambf_simulator --plugins <plugin_path>/build/libambf_trace_plugin.so --name_body_to_trace Chassis

Test static trace:

cd <ambf_exe_dir>
./ambf_simulator --plugins <plugin_path>/build/libambf_trace_plugin.so --csv_filename_static_traces <plugin_path>/example_static_trace.csv

Input args

1. --name_body_to_trace arg : Name of body in ADF yaml which will have position traced. No body trace if blank (default)
2. --csv_filename_static_traces arg : Path to CSV file with 3d points for static trace. No static trace if blank (default)
3. --static_trace_rel_body_name arg : Name of body given in ADF yaml for static trace to be relative to. Relative to world origin if blank (default)

Keyboard commands

(KP means keypad)

1. [Ctrl + KP*] : start/stop tracing specified body
2. [Ctrl + KP-] : show/hide body traces
3. [Ctrl + KP0] : reload static trace from file

Starting from launch file

A launch.yaml file can by used to set many simulator parameters at once (world configs, input devices, multibody configs, etc.). You can also add plugins using the following, which would be placed in some <launch_file.yaml>

plugins: [
  {
    name: TRACE_PLUGIN,
    filename: libambf_trace_plugin.so,
    path: <plugin_path>/build/
  }
]

Then you can start the simulator using:

./ambf_simulator --launch_file <launch_file.yaml> [<-- plugin_args>]

NOTE if you built this plugin using catkin at location <catkin_ws>/src/ambf_trace_plugin, the path will be

path: ../../build/ambf_trace_plugin/

Features if built with ROS

For now, these features are included based on whether a compiler flag is set at build time. I think there is likely a cleaner way to do that, but unless/until things get long, this should not be an issue.

If built with ROS, the functionality to set the body trace to [show / hide] and [collect / don't collect] are accessible with ROS topics, in addition to the keyboard press

By default, these topics are at /ambf/trace_plugin/set_body_trace_collect and /ambf/trace_plugin/set_body_trace_visible respectively, and accept messages of type std_msgs::Bool

Features to add

Something I hope to get to someday (or you could do it too! :) )

1. Allow passing in a list of bodies, for multiple traces
2. Allow specification of color, line_width
3. Make option for default on/off
4. Allow for multiple static traces
5. Have show/hide functionality also apply to static trace, or make both toggleable separately
6. Allow for throttling of body trace (only happens every x frames)