本文介绍了一种软同步法，即算法同步法，如果要进行硬件同步，请参阅论文：VersaVIS—An Open Versatile Multi-Camera Visual-Inertial Sensor Suite(似乎有源码)。
message_filters有两种同步策略，一种是时间戳完全对齐的策略(ExactTime Policy)，另一种是时间戳相似的策略(ApproximateTime Policy)。
下面是C 如果要使用同步策略框架代码(根据自己的需要更改)，可以同步多个传感器数据。python代码，可以查阅ros官网。
：创建ros注意加包message_filters，类似于roscpp、sensor_msgs等
ExactTime Policy
message_filters :: sync_policies :: ExactTime战略要求新闻有完全相同的时间戳来匹配。 只有在所有具有相同确切时间戳的指定通道上收到消息时，才会调用回调。
#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(const ImageConstPtr& image, const 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);///同步接收数据 message_filters::Subscriber<CameraInfo> info_sub(nh, "camera_info", 1); typedef sync_policies::ExactTime<Image, CameraInfo> MySyncPolicy; // ExactTime takes a queue size as its constructor argument, hence MySyncPolicy(10) Synchronizer<MySyncPolcy> sync(MySyncPolicy(10), image_sub, info_sub);
sync.registerCallback(boost::bind(&callback, _1, _2));
ros::spin();
return 0;
}
ApproximateTime Policy
message_filters :: sync_policies :: ApproximateTime策略使用自适应算法来匹配基于其时间戳的消息。
#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(const ImageConstPtr& image1, const 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 constructor argument, hence MySyncPolicy(10)
Synchronizer<MySyncPolicy> sync(MySyncPolicy(10), image1_sub, image2_sub);
sync.registerCallback(boost::bind(&callback, _1, _2));
ros::spin();
return 0;
}
参考：
http://wiki.ros.org/message_filters https://www.cnblogs.com/qiuheng/p/9254557.html