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interact_with_knowrob_via_ros [2012/12/01 12:51] – created tenorthinteract_with_knowrob_via_ros [2014/06/05 11:38] (current) – external edit 127.0.0.1
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-====== Interact with KnowRob via ROS ====== +#REDIRECT doc:interact_with_knowrob_via_ros
- +
-The interactive Prolog shell that [[http://ros.org/wiki/rosprolog|rosprolog]] provides is good for exploring KnowRob, visualizing knowledge, developing new functions and debugging Prolog code. However, if you would like to use KnowRob in your robot's control program, you need a way to send queries from your program. This functionality is provided by the [[http://ros.org/wiki/json_prolog|json_prolog]] package. It provides a service that exposes a Prolog shell via ROS. +
- +
-You can run the //json_prolog// service using the following command. It has the same structure as rosprolog, taking a KnowRob package as final argument. +
-<code> +
-rosrun json_prolog json_prolog ias_semantic_map +
-</code> +
- +
-===== Client libraries ===== +
-The communication with the //json_prolog// service uses a [[http://json.org/|JSON-encoded]] format for representing the Prolog terms that form the query. While you can construct these terms manually and call the service directly, it is usally much easier to use one of the provided client libraries. There are libraries for Python, C++, Java and Lisp. Example clients are available in the //json_prolog/examples// folder; below is the code for sending KnowRob queries from Python via //json_prolog//. +
- +
-<code python> +
- +
-#!/usr/bin/env python +
- +
-import roslib; roslib.load_manifest('json_prolog') +
- +
-import rospy +
-import json_prolog +
- +
-if __name__ == '__main__': +
-    rospy.init_node('test_json_prolog') +
-    prolog = json_prolog.Prolog() +
-    query = prolog.query("member(A, [1, 2, 3, 4]), B = ['x', A]") +
-    for solution in query.solutions(): +
-        print 'Found solution. A = %s, B = %s' % (solution['A'], solution['B']) +
-    query.finish() +
- +
-</code> +
- +