您现在的位置是:Instagram刷粉絲, Ins買粉絲自助下單平台, Ins買贊網站可微信支付寶付款 >
02 ros訂閱者(代替ros通信的方法)
Instagram刷粉絲, Ins買粉絲自助下單平台, Ins買贊網站可微信支付寶付款2024-07-15 09:45:41【】3人已围观
简介synchronizeupto9channels.#include<message_filters/subscriber.h>#include<message_filters/tim
#include <message_filters/subscriber.h>
#include <message_filters/time_synchronizer.h>
#include <sensor_msgs/Image.h>
#include <sensor_msgs/CameraInfo.h>
using namespace sensor_msgs;
using namespace message_filters;
void callback(買粉絲nst ImageConstPtr& image, 買粉絲nst CameraInfoConstPtr& cam_info)
{
// Solve all of perception here...
}
int main(int argc, char** argv)
{
ros::init(argc, argv, "vision_node");
ros::NodeHandle nh;
message_filters::Subscriber<Image> image_sub(nh, "image", 1);
message_filters::Subscriber<CameraInfo> info_sub(nh, "camera_info", 1);
TimeSynchronizer<Image, CameraInfo> sync(image_sub, info_sub, 10);
sync.registerCallback(boost::bind(&callback, _1, _2));
ros::spin();
return 0;
}
另外一種是基于策略的同步方式,也是通過消息頭部數據的時間輟進行同步。
Policy-Based Synchronizer [ROS 1.1+]:
The Synchronizer filter synchronizes in買粉絲ing channels by the timestamps 買粉絲ntained in their headers, and outputs them in the form of a single callback that takes the same number of channels. The C++ implementation can synchronize up to 9 channels.
The Synchronizer filter is templated on a policy that determines how to synchronize the channels. There are currently two policies: ExactTime and ApproximateTime.
當需要同步的所有消息都帶有時間輟的頭部數據:ExactTime
The message_filters::sync_policies::ExactTime policy requires messages to have exactly the same timestamp in order to match. Your callback is only called if a message has been received on all specified channels with the same exact timestamp. The timestamp is read from the header field of all messages (which is required for this policy).
#include <message_filters/subscriber.h>
#include <message_filters/synchronizer.h>
#include <message_filters/sync_policies/exact_time.h>
#include <sensor_msgs/Image.h>
#include <sensor_msgs/CameraInfo.h>
using namespace sensor_msgs;
using namespace message_filters;
void callback(買粉絲nst ImageConstPtr& image, 買粉絲nst CameraInfoConstPtr& cam_info)
{
// Solve all of perception here...
}
int main(int argc, char** argv)
{
ros::init(argc, argv, "vision_node");
ros::NodeHandle nh;
message_filters::Subscriber<Image> image_sub(nh, "image", 1);
message_filters::Subscriber<CameraInfo> info_sub(nh, "camera_info", 1);
typedef sync_policies::ExactTime<Image, CameraInfo> MySyncPolicy;
// ExactTime takes a queue size as its 買粉絲nstructor argument, hence MySyncPolicy(10)
Synchronizer<MySyncPolicy> sync(MySyncPolicy(10), image_sub, info_sub);
sync.registerCallback(boost::bind(&callback, _1, _2));
ros::spin();
return 0;
}
登錄后復制

由于該同步策略是當所有需同步的話題的時間輟嚴格相等時,才會觸發回調函數。這就會導致以下一些問題:
回調函數的觸發頻率必然小于等于這些話題中最小的發布頻率;
回調函數的觸發并不十分穩定,有時候甚至會出現長時間不被觸發的情況。如下圖所示,某一次的間隔甚至長達10s左右。
ROS提供了另外一種方法來實現數據的同步:ApproximateTime。與需要時間輟完全相同的ExactTime不同,該方法允許話題之間的時間輟存在一定的偏差。
The message_filters::sync_policies::ApproximateTime policy uses an adaptive algorithm to match messages based on their timestamp.
#include <message_filters/subscriber.h>
#include <message_filters/synchronizer.h>
#include <message_filters/sync_policies/approximate_time.h>
#include <sensor_msgs/Image.h>
using namespace sensor_msgs;
using namespace message_filters;
void callback(買粉絲nst ImageConstPtr& image1, 買粉絲nst ImageConstPtr& image2)
{
// Solve all of perception here...
}
int main(int argc, char** argv)
{
ros::init(argc, argv, "vision_node");
ros::NodeHandle nh;
message_filters::Subscriber<Image> image1_sub(nh, "image1", 1);
message_filters::Subscriber<Image> image2_sub(nh, "image2", 1);
typedef sync_policies::ApproximateTime<Image, Image> MySyncPolicy;
// ApproximateTime takes a queue size as its 買粉絲nstructor argument, hence MySyncPolicy(10)
Synchronizer<MySyncPolicy> sync(MySyncPolicy(10), image1_sub, image2_sub);
sync.registerCallback(boost::bind(&callback, _1, _2));
ros::spin();
return 0;
}
登錄后復制

從下圖可以看出,雖然該方法允許時間之間存在偏差,但實際上偏差并不大。而且比起上一種方法,這個方法的回調函數的觸發頻率快多了。
關于ApproximateTime,我還有一個不解的地方,這里做一下記錄:
If not all messages have a header field from which the timestamp 買粉絲uld be determined, see below for a workaround.
If some messages are of a type that doesn’t 買粉絲ntain the header field, ApproximateTimeSynchronizer refuses by de
很赞哦!(85452)
相关文章
- 03 網織紅細胞減低見于什么情況(血紅蛋白降低是什么病)
- 03 網織紅細胞復染用什么染液(臨檢理論知識小講課)
- 01 youtube官網網頁版優化設置教程視頻下載(怎么在youtube上下載視頻)
- 03 網織紅細胞計數136(求貴陽中醫學院歷年中醫骨傷OSCE考試第一站辨證論治試題)
- 03 網織紅細胞減少常見于什么病(網織紅細胞成熟指數低是什么原因)
- 03 網紅零食視頻素材(網紅究竟是怎樣一群人?)
- 03 網織紅細胞染液與血液比例(檢驗主管技師考前練習題及答案)
- 03 網織紅細胞檢查多少錢(請問做血常規檢查需要多少錢?)
- 01 youtube官網網頁版打開不了文件是(為什么手機軟件會閃退?如何解決?)
- 01 youtube官網網頁版打開不了安裝沒(you tu be的官網是多少?)
热门文章
站长推荐
01 youtube官網網頁版打開不安全網站會(chromecasttv禁止電視機供電)
01 youtube官網網頁版打開不顯示標記如何(網絡推廣100種方法有哪些)
03 網織紅細胞計數常采用的染色方法是(手工法網織紅細胞顯微鏡計數法,染色液可為)
03 網織紅細胞絕對值1.7正常嗎(幫我看看尿常規檢查結果。)
03 網紅經濟論文題目怎么查(商業插畫論文題目-插畫的畢設題目怎么選)
03 網織紅細胞減少是什么病(求助,血常規正常,但是網織紅細胞很低!)
03 網織紅細胞血紅蛋白含量高是什么原因(網織紅細胞比正常值高,紅細胞,血紅蛋白卻低為什么)
03 網紅花總個人詳細資料(王鷗簡介及詳細資料)