unizar-pound-ros-pkg

The Pound ROS node enables topic prioritization and supports multiple ROS cores in addition to the options of compression and configurations. It is mainly designed to improve communication performance (in terms of delay and jitter) in wireless multi-hop networks.

Usage: rosrun ros_pound ros-pound --node-id 0 --num-of-nodes 3

Parameter node-id specifies the identifier of the local node, parameter num-of-nodes specifies the total number of nodos in the robotic network

By default, ros-pound uses UDP/IP communication. The network must have an address of the type 192.168.XX.YY. XX is the network identificator while YY is related with the node-id parameter. Suppose the network is 192.168.1.YY:

• Node with --node-id 0 must have IP 192.168.1.1
• Node with --node-id 1 must have IP 192.168.1.2

etc.

The base IP is by default 192.168.1.1; this can be changed in the YAML configuration file specifying the parameter:

base_ip = 192.168.2.1

for example.

The topics to be transported must be specified in the config/config.h file with the format:

TOPIC(type, topic_name, source, dest, priority, period, time_to_live)

where

• type specifies the data type for example std_msgs::Float64
• topic_name specifies the name of the topic, for example "float_number"
• source is the source node of the topic, for example 0
• dest specifies the destination node(s) as text for example "0,1,2" however for the moment Pound only support unicast (only one node should be specified)
• priority specifies the priority associated to the topic for example 56. Must be between 0 and 127
• period the expected period of the topic in ms, for example 100
• time_to_live period during the which the message is considered valid in ms, for example 500

The data type used must be specified in the config/data_types.h file. For example:

#include <std_msgs/Float64.h>

The complete list of options for the YAML file is:

use_ip: true
device: wlan0
base_ip: 192.168.1.1
nodes:
 - id: 3
   mac: 22:44:55:FF:00:01
 - id: 2
   mac: 18:19:20:21:22:23
routes:
 - dest: 3
   next: 5
 - dest: 4
   next: 5
feedback: false
auto_tuning: false
port: 32000
queue: 50
delay: 2500
rate_mbps: 6.0
use_discard: false
quiet: false

The Pound node is similar to RT-WMP package available at http://wiki.ros.org/ros-rt-wmp. While the RT-WMP assigns global priorities, the Pound assigns local (node or machine level) priorities. For more information, please contact dantard@unizar.es