ROS2 std_msgs/Header header
时间: 2024-05-24 07:12:45 浏览: 17
The std_msgs/Header is a message type in ROS2 that contains a header field of type std_msgs/Header. The header field contains the following information:
- sequence number (uint32) - a unique ID for each message sent
- timestamp (time) - the time when the message was sent
- frame_id (string) - the coordinate frame in which the data is defined
The header field is used to provide context to the message data and to ensure that messages are processed in the correct order.
相关问题
Traceback (most recent call last): File "/home/ros/catkin_ctr/src/jiangluo/scripts/eight_zi.py", line 47, in <module> local_pos_pub3.publish(poscom_twist) File "/opt/ros/noetic/lib/python3/dist-packages/rospy/topics.py", line 879, in publish data = args_kwds_to_message(self.data_class, args, kwds) File "/opt/ros/noetic/lib/python3/dist-packages/rospy/msg.py", line 121, in args_kwds_to_message raise TypeError("expected [%s] but got [%s]"%(data_class._slot_types[0], arg._type)) TypeError: expected [std_msgs/Header] but got [geometry_msgs/TwistStamped]
这个错误提示意味着在 `local_pos_pub3.publish(poscom_twist)` 这一行代码中,你正在尝试将一个 `geometry_msgs/TwistStamped` 对象发布到了 `poscom` 这个话题上,但是这两者的消息类型并不匹配。
根据错误提示,`poscom` 这个话题所期望的消息类型是 `std_msgs/Header`,而不是 `geometry_msgs/TwistStamped`。因此,你需要将 `poscom` 话题和 `poscom_twist` 话题分别发布。
修改后的代码应该类似于以下代码:
```
while not rospy.is_shutdown():
poscom.header.stamp = rospy.Time.now()
poscom.header.frame_id = "world"
poscom.pose.position.x = 2.5 * math.sin(math.pi * i / 400)
poscom.pose.position.y = 5 * math.sin(math.pi * i / 800)
poscom.pose.position.z = 2
poscom_twist = TwistStamped()
poscom_twist.header.stamp = rospy.Time.now()
poscom_twist.header.frame_id = "base_link"
poscom_twist.twist.linear.x = 0
poscom_twist.twist.linear.y = 0
poscom_twist.twist.linear.z = 0
poscom_twist.twist.angular.x = 0
poscom_twist.twist.angular.y = 0
poscom_twist.twist.angular.z = 0
local_pos_pub3.publish(poscom)
local_pos_pub4.publish(poscom_twist) # 将 poscom_twist 发布到另一个话题上
```
你需要在你的代码中找到 `local_pos_pub3` 这个发布者,并对其进行修改,使其发布到正确的话题上(也就是 `poscom_twist`)。记得要在你的代码中添加一个新的发布者 `local_pos_pub4`,并将其发布到 `poscom_twist` 这个话题上。
希望这可以帮助你解决问题。
ROSpython如何得出一个类里两个sensor_msgs/Image话题的频率差
在ROS中,可以通过使用rospy模块来获取两个sensor_msgs/Image话题的频率差。下面是一个示例代码:
```python
import rospy
from sensor_msgs.msg import Image
from std_msgs.msg import Header
class ImageFrequencyDifference:
def __init__(self):
self.image1_timestamp = None
self.image2_timestamp = None
self.image1_sub = rospy.Subscriber("/image1_topic", Image, self.image1_callback)
self.image2_sub = rospy.Subscriber("/image2_topic", Image, self.image2_callback)
def image1_callback(self, msg):
self.image1_timestamp = msg.header.stamp
def image2_callback(self, msg):
self.image2_timestamp = msg.header.stamp
if self.image1_timestamp is not None:
frequency_difference = self.image2_timestamp - self.image1_timestamp
rospy.loginfo("Frequency difference: %s", frequency_difference)
if __name__ == '__main__':
rospy.init_node("image_frequency_difference_node")
image_frequency_difference = ImageFrequencyDifference()
rospy.spin()
```
在上面的代码中,我们创建了一个名为ImageFrequencyDifference的类,其中初始化函数中订阅了两个sensor_msgs/Image话题的消息。当接收到image1_topic和image2_topic的消息时,分别将它们的时间戳保存下来。然后在image2_callback函数中,如果image1_timestamp不为空,则计算出两个时间戳的差值,并打印出来。
请注意,上述代码中的/image1_topic和/image2_topic是示例话题名称,你需要将其替换为你实际使用的话题名称。
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