NiryoTopic

Pyniryo2 is based on the python library roslibpy to collect information from the robot. This information is sent by ROS via topics. This class is an overlay of the API roslibpy Topic. It allows you to subscribe to a topic to collect the information from the topic as soon as it is published, or ask for only one value. Please refer to the Niryo robot ROS doc to see the compatible topics.

NiryoTopic - Usage

Here is a simple example of using the class without conversion:

>> robot = NiryoRobot(<robot_ip_address>)
>> client = robot.client
>> joint_states_topic = NiryoTopic(client, '/joint_states', 'sensor_msgs/JointState')
>> joint_states_topic()
{u'header': {u'stamp': {u'secs': 1626092430, u'nsecs': 945618510}, u'frame_id': u'', u'seq': 13699},
u'position': [0.0, 0.6, -1.3, 0.0, 0.0, 0.0], u'effort': [0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
u'name': [u'joint_1', u'joint_2', u'joint_3', u'joint_4', u'joint_5', u'joint_6'],
u'velocity': [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}

Here is a simple example of using the class with conversion:

>> def joint_states_topic_conversion(msg):
        return msg["position"]

>> robot = NiryoRobot(<robot_ip_address>)
>> client = robot.client
>> joint_states_topic = NiryoTopic(client, '/joint_states', 'sensor_msgs/JointState', joint_states_topic_conversion)
>> joint_states_topic()
[0.0, 0.6, -1.3, 0.0, 0.0, 0.0]
>> joint_states_topic.value
[0.0, 0.6, -1.3, 0.0, 0.0, 0.0]

Here is a simple example of using the class with a callback:

def joint_states_topic_conversion(msg):
    return msg["position"]

def joint_states_callback(msg):
    print(msg) # print the list of joints position

robot = NiryoRobot("127.0.0.1")
client = robot.client
joint_states_topic = NiryoTopic(client, '/joint_states', 'sensor_msgs/JointState', joint_states_topic_conversion)
joint_states_topic.subscribe(joint_states_callback)

...

joint_states_topic.unsubscribe()

NiryoTopic - Class

• NiryoTopic

class pyniryo2.niryo_topic.NiryoTopic(client, topic_name, topic_type, conversion_function=None, timeout=3)

Parameters:

• client (roslibpy.Ros) – Instance of the ROS connection.

• topic_name (str) – Topic name.

• topic_type (str) – Topic type.

• conversion_function (function) – convert the response of the topic in a specific type.

• timeout (float) – Timeout while waiting a message.

property is_subscribed

Return the topic connection status.

Returns:

True if already subscribed, False otherwise.

Return type:

Bool

property value

Return the last value of the topic.

Returns:

The last value of the topic. The value depends on the conversion function of the topic. By default, it will be a dict.

Return type:

subscribe(callback)

Subscribe a callback to the topic. A TopicException will be thrown if the topic is already subscribed.

Parameters:

callback (function(dict, )) – The callback function which is called at each incoming topic message.

Returns:

None

Return type:

None

unsubscribe()

Unsubscribe to the topic.

Return type:

None

publish(msg)

Publish a message on the topic

Parameters:

msg (dict of roslibpy.Message) – jsonified topic message content

Return type:

None