ROS node for NMMI device.

This repository contains the building blocks for ROS related applications based on NMMI devices. It is composed by all the device-independent structures to interface our devices with the ROS ecosystem, therefore is barely usable as is.

Table of Contents

1. Installation
   1. Requirements
   2. Sources
   3. Device Setup
2. Usage
   1. Communication Handler

Installation

Requirements

If you have never set it up, you probably need to add your linux user to the dialout group to grant right access to the serial port resources. To do so, just open a terminal and execute the following command:

sudo gpasswd -a <user_name> dialout

where you need to replace the <user_name> with your current linux username.

Note: don't forget to logout or reboot.

Sources

Since you are interested in the ROS interfaces for our devices, it is assumed that you are familiar at least with the very basics of the ROS environment. If not, it might be useful to spend some of your time with ROS and catkin tutorials. After that, don't forget to come back here and start having fun with our Nodes.

Install the NMMI device packages for a ROS user is straightforward. Nonetheless the following are the detailed steps which should be easy to understand even for ROS beginners:

1. Clone both the ROS-NMMI and ROS-base packages to your Catkin Workspace, e.g. ~/catkin_ws:

2. Compile the packages using catkin:

   cd `~/catkin_ws`
   catkin_make
   

   Note: depending on your ROS installation, you may need some extra packages to properly compile the code. Please, be sure that you have already installed at least ros-kinetic-ros-controllers, ros-kinetic-transmission-interface, ros-kinetic-joint-limits-interface, and their dependencies (e.g. use sudo apt install <ros-pkg>).

Device Setup

Connect a NMMI device to your system is basically a matter of plugging in a USB cable. Nonetheless, read carefully the manual to understand all the requirements and advices about either single-device or chained configurations.

Usage

Even if these ROS packages can be installed properly as a standalone application, they are barely usable alone. In addition to this package, please install also ROS-base package.

Communication Handler

The Communication Handler Node has no parameters to be set, therefore it is always launched like this:

roslaunch nmmi_driver communication_handler.launch

On start, it scans the serial communication resources connected to your system and shows a list of the devices it has found. By default, it never scans again for new devices, apart from asking it explicitly during the initialization of a control Node.

This is a simple example when starting the Communication Handler with two NMMI devices connected on two distinct USB ports:

[ INFO] [1524044523.511369300]: [CommunicationHandler] handles [/dev/ttyUSB1].
[ INFO] [1524044524.426984697]: [CommunicationHandler] handles [/dev/ttyUSB0].
[ INFO] [1524044525.218613760]: [CommunicationHandler] has found [2] devices connected:
[ INFO] [1524044525.218696997]:                        - device [1] connected through [/dev/ttyUSB0]
[ INFO] [1524044525.218736612]:                        - device [2] connected through [/dev/ttyUSB1]

When the Communication Handler is on, it provides all the Services required to interact with the connected devices: e.g. get info or measurements, activate or deactivate motors, set commands, and even more...