ROS錯誤。 「錯誤處理請求：信號只在主線程中起作用」

Question

我正在使用機器人操作系統（ROS），並且正在嘗試製作服務器/客戶機，其中服務器將啓動由客戶機指定的ROS節點。要執行「啓動」我使用roslaunch基於這裏找到的建議：http://wiki.ros.org/roslaunch/API%20Usage

我可以在窗口中運行roscore，然後我可以運行服務器啓動罰款。然而，當我嘗試發送我想通過客戶端啓動的節點名稱，我得到以下錯誤：

「錯誤處理請求：信號只能在主線程」

它然後指向我還沒有追蹤的各個領域的一堆文件。

我試過對每個啓動文件使用一個簡單的roslaunch調用，我分別爲我想要啓動的節點（在本例中爲turtlesim_node和turtle_teleop_key）啓動，它們啓動正常，只需運行roslaunch [package] turtlesim_launch.launch等

下面是我的服務器代碼：

#!/usr/bin/env python 
#Filename: primary_server.py 

import rospy 
import roslaunch 
from robot_man.srv import * 

class StartUpServer(object): 
    def __init__(self): 
     self._nodes = [] 


    def handle_startup(self, names): 
     self._temp = names.nodes.split(",") #This reades in the 
     # information from the srv file sent by the client and 
     # separates each node/package pair 

     #This loop separates the input from pairs of 2 corresponding 
     # to the package and node names the user inputs 
     for i in range(len(self._temp)): 
      self._nodes.append(self._temp[i].split()) 

     #This loop will launch each node that the user has specified 
     for package, executable in self._nodes: 
      print('package is: {0}, executable is: {1}'.format(package, executable)) 
      node = roslaunch.core.Node(package, executable) 
      launch = roslaunch.scriptapi.ROSLaunch() 
      launch.start() 

      process = launch.launch(node) 
      print('running node: %s'%executable) 
     return StartUpResponse(self._nodes) #I will change this later 


if __name__ == '__main__': 
    rospy.init_node('startup_node') 
    server = StartUpServer() 
    rospy.Service('startup', StartUp, server.handle_startup) 
    print('The servers are up and running') 
    rospy.spin() 

這裏是我的客戶代碼：

#!/usr/bin/env python 
#Filename: primary_client_startup.py 

import rospy 
from robot_man.srv import * 

def main(nodes): 
    rospy.wait_for_service('startup') 
    proxy = rospy.ServiceProxy('startup', StartUp) 
    response = proxy(nodes) 
    return response 

if __name__ == '__main__': 
    nodes = input('Please enter the node packages followed by \ 
    node names separated by spaces. \n To activate multiple nodes \ 
    separate entries with a comma > ') 
    main(nodes) 

這是我的SRV文件：

#This should be a string of space/comma separated values 
string nodes 
--- 
#This should return "success" if node/s start up successfully, else "fail" 
string status 

最後，這裏是我已經發動龜模擬器兩個發射文件：

turtlesim_launch.launch

<launch> 
    <node name="turtlesim_node" pkg="turtlesim" type="turtlesim_node" /> 
</launch> 

turtle_teleop_launch.launch

<launch> 
    <node name="turtle_teleop_key" pkg="turtlesim" type="turtle_teleop_key" /> 
</launch> 

我已經做了一些谷歌搜索，發現沒有類似的問題fo ROS（雖然Django等存在一些類似的錯誤，但它們沒有關聯）。

我很感激幫助！

P.S.值得注意的是，當錯誤發生時（流程= launch.launch（node）），我將它設置爲第34行。

Answer 1

實際上是文檔

中提及你不是要求從Python主線程init_node（）。 Python只允許從主線程註冊信號。

看這裏rospyOverviewInitialization and Shutdown