ROS错误。 “错误处理请求：信号只在主线程中起作用”

Question

我正在使用机器人操作系统（ROS），并且正在尝试制作服务器/客户机，其中服务器将启动由客户机指定的ROS节点。要执行“启动”我使用roslaunch基于这里找到的建议：http://wiki.ros.org/roslaunch/API%20Usage

我可以在窗口中运行roscore，然后我可以运行服务器启动罚款。然而，当我尝试发送我想通过客户端启动的节点名称，我得到以下错误：

“错误处理请求：信号只能在主线程”

它然后指向我还没有追踪的各个领域的一堆文件。

我试过对每个启动文件使用一个简单的roslaunch调用，我分别为我想要启动的节点（在本例中为turtlesim_node和turtle_teleop_key）启动，它们启动正常，只需运行roslaunch [package] turtlesim_launch.launch等

下面是我的服务器代码：

#!/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() 

这里是我的客户代码：

#!/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) 

这是我的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 

最后，这里是我已经发动龟模拟器两个发射文件：

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> 

我已经做了一些谷歌搜索，发现没有类似的问题fo ROS（虽然Django等存在一些类似的错误，但它们没有关联）。

我很感激帮助！

P.S.值得注意的是，当错误发生时（流程= launch.launch（node）），我将它设置为第34行。

Answer 1

实际上是文档

中提及你不是要求从Python主线程init_node（）。 Python只允许从主线程注册信号。

看这里rospyOverviewInitialization and Shutdown