ROS_Bridge

Introduction

ROS_Bridge is the Modelica package complement of the ROS package modelica_bridge.

The purpose of ROS_Bridge and modelica_bridge is to provide an interface between Modelica tools and ROS. This interface, or bridge, is accomplished by running tcp/ip sockets in ROS, and in an external C-function from Modelica.

Usage Summary

The ROS_Bridge package consists of the external function ROS_Socket_Call, through which the interface to ROS is run, and the block model wrapping the function, ROS_Sampler.

ROS_Sampler is extended from the DiscreteMIMO block interface, and uses a sampler call to run the function call every sample period. It has the four parameters of the DiscreteMIMO interface - samplePeriod, startTime, nin, and nout; it has two additional parameters, portNumber and hostName. portNumber is the port on which the server socket is listening (where the ROS node is listening). hostName is the name of the machine ROS is running on (i.e. 192.168.0.1, etc.)

• Note that the portNumber parameter must match the port_num_ parameter in modelica_bridge.
• Regardless of the number of control values coming from ROS, ROS_Socket_Call only reads nout many, so overflow will not happen.
  • It does not provide zero-padding for insufficient control inputs; instead, it leaves the associated control value unaltered. If control values were never provided for that input, it will be assumed zero.

The package can take up to 256 inputs from the ROS controllers, and can send a maximum of 1024 characters over a character buffer to Modelica. It has two parameters: port_num and update_rate. Ensure that the port_num matches the value of the Modelica model's port number parameter.

Tutorials

For tutorials, see the modelica_bridge tutorials.