在 ROS 中使用来自多个主题的数据 - Python

Question

我能够显示来自两个主题的数据，但我无法在 ROS 中实时使用和计算来自这两个主题的数据（用 Python 代码编写）。

你有没有想过储存这些数据并实时计算？

谢谢 ;)

#!/usr/bin/env python

import rospy
import string
from std_msgs.msg import String 
from std_msgs.msg import Float64MultiArray
from std_msgs.msg import Float64
import numpy as np


class ListenerVilma:

    def __init__(self):
        self.orientation = rospy.Subscriber('/orientation', Float64MultiArray , self.orientation_callback)
        self.velocidade = rospy.Subscriber('/velocidade', Float64MultiArray, self.velocidade_callback)

    def orientation_callback(self, orientation):
        print orientation

    def velocidade_callback(self, velocidade):
        print velocidade


if __name__ == '__main__':
   rospy.init_node('listener', anonymous=True)
   myVilma = ListenerVilma()
   rospy.spin()

Answer 1

可能的解决方案：

#!/usr/bin/env python

import rospy
from std_msgs.msg import Float64MultiArray


class Server:
    def __init__(self):
        self.orientation = None
        self.velocity = None

    def orientation_callback(self, msg):
        # "Store" message received.
        self.orientation = msg

    def velocity_callback(self, msg):
        # "Store" the message received.
        self.velocity = msg


if __name__ == '__main__':
    rospy.init_node('listener')

    server = Server()

    rospy.Subscriber('/orientation', Float64MultiArray , server.orientation_callback)
    rospy.Subscriber('/velocity', Float64MultiArray, server.velocity_callback)

    rospy.spin()

现在您有一个 "stock of data"，形式为 self.orientation 和 self.velocity，您可以将其用于 "compute in real time"。

例如：

#!/usr/bin/env python

import rospy
from std_msgs.msg import Float64MultiArray


class Server:
    def __init__(self):
        self.orientation = None
        self.velocity = None

    def orientation_callback(self, msg):
        # "Store" message received.
        self.orientation = msg

        # Compute stuff.
        self.compute_stuff()

    def velocity_callback(self, msg):
        # "Store" the message received.
        self.velocity = msg

        # Compute stuff.
        self.compute_stuff()

    def compute_stuff(self):
        if self.orientation is not None and self.velocity is not None:
            pass  # Compute something.


if __name__ == '__main__':
    rospy.init_node('listener')

    server = Server()

    rospy.Subscriber('/orientation', Float64MultiArray , server.orientation_callback)
    rospy.Subscriber('/velocity', Float64MultiArray, server.velocity_callback)

    rospy.spin()

Answer 2

您需要message_filter来同步多条消息。阅读此 http://wiki.ros.org/message_filters#Example_.28Python.29-1

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