ROS如何使用从一个回调函数到另一个回调函数的值

Question

抱歉，英语不是我的母语。希望你能正确理解我的问题。

我正在使用带有 ROS Melodic 的 Ubuntu 18.04。我正在尝试从 mapCallback 和 odometryCallback 函数中获取数据，并在 SampleTree 函数中使用这些值。当我运行下面的代码时，我想返回 frontCones 数组，但我的输出是空数组。如何使SampleTree 函数获取在mapCallback 和odometryCallback 函数中发布的值，并在循环中使用这些数据返回frontCones 数组？

这是我的代码：

# !/usr/bin/python

import rospy

from nav_msgs.msg import Odometry
from egn_messages.msg import Map
from tf.transformations import euler_from_quaternion

odometry = Odometry()
map = Map()


class Test:
    def __init__(self):
        rospy.init_node('test_node')

        rospy.Subscriber('/map1', Map, self.mapCallback)
        rospy.Subscriber('/odometry', Odometry, self.odometryCallback)
        self.map = []

        self.carPosX = 0.0
        self.carPosY = 0.0
        self.carPosYaw = 0.0

    def odometryCallback(self, odometry):
        orientation_q = odometry.pose.pose.orientation
        orientation_list = [orientation_q.x, orientation_q.y,
                            orientation_q.z, orientation_q.w]
        (roll, pitch, yaw) = euler_from_quaternion(orientation_list)
        self.carPosX = odometry.pose.pose.position.x
        self.carPosY = odometry.pose.pose.position.y
        self.carPosYaw = yaw

    def mapCallback(self, map):
        self.map = map

    def SampleTree(self):
        if not self.map:
            print
            'map is empty, return'
            return

        frontConesDist = 12
        frontCones = self.getFrontConeObstacles(frontConesDist)
        print(frontCones)

    def getFrontConeObstacles(self, frontDist):
        if not map:
            return []

        headingVector = [1.0, 0]

        behindDist = 0.5
        carPosBehindPoint = [self.carPosX - behindDist * headingVector[0], self.carPosY - behindDist * headingVector[1]]

        frontDistSq = frontDist ** 2

        frontConeList = []
        for cone in map.cones:
            if (headingVectorOrt[0] * (cone.y - carPosBehindPoint[1]) - headingVectorOrt[1] * (
                    cone.x - carPosBehindPoint[0])) < 0:
                if ((cone.x - self.carPosX) ** 2 + (cone.y - self.carPosY) ** 2) < frontDistSq:
                    frontConeList.append(cone)
        return frontConeList


if __name__ == "__main__":
    inst = Test()
    inst.SampleTree()
    try:
        rospy.spin()
    except KeyboardInterrupt:
        print("Shutting down")

Answer 1

通过在回调函数中打印新的地图信息来确保 self.map 中的值实际上正在更新。

同时添加：

if __name__ == "__main__"():
    inst = Test()
    inst.SampleTree()
    try:
        rospy.spin()
    except KeyboardInterrupt:
        print("Shutting down")

rospy.spin() 将无限循环执行代码，除非被中断。

建议：

你可以给函数命名

def getFrontConeObstacles(self, frontDist):

而不是

def getFrontConeObstacles(self, map, frontDist):

因为您可以在课堂上轻松访问 self.map。