The client libraries provide some tools to facilitate the development of a CRTK compatible client over ROS, i.e. create a "proxy" class to communicate with an existing CRTK compatible ROS device. We currently support two client libraries, one for Python and one for Matlab.
The main class in the client library is crtk.utils. It can be used
to quickly populate an existing class by adding CRTK like
methods. These methods will handle the following for you:
- Declare all required ROS publishers and wrap publisher calls in methods to send data to the device
- Declare all required ROS subscribers and provide callbacks to receive the data from the device
- Convert ROS messages to more convenient data types. The Python client use numpy arrays for joint values and PyKDL types for cartesian data. The Matlab client uses vectors and matrices.
- Some events to manage asynchronous communication between the device
and the "proxy" class (e.g. end of
movecommand, change of state...)
The class crtk.utils is designed to add CRTK features "a la
carte", i.e. it doesn't assume that all CRTK features are
available. This allows to:
- Match only the features that are available on the CRTK devices one wants to use (server side)
- Reduce the number of features to those strictly needed for the application (client side). Reducing the number of ROS topics used helps in terms of performance.
In version 1.2, crtk also includes a ROS Abstraction Layer. The
ral goal is to hide which version of ROS is used so the end-user
script can run with either ROS 1 or ROS 2. The ral doesn't cover
all the ROS features (either in Python or Matlab) so not all scripts
can be totally portable.
Note
As of December 2023, the Python client libraries have been used extensively and are well tested. The Matlab version is not as mature. More specifically the RAL implementation is buggy on ROS 2 and missing in the ROS 1 implementation.