ROS 订阅者回调丢失消息

Question

总结：我有一个节点以 ~300hz 的频率发布消息，但订阅另一个节点中的主题的回调仅在 ~25hz 时被调用。订阅者节点中的 spinOnce 在 ~700hz 被调用，所以我不知道为什么它丢失消息。

发布者节点：

#include <ros/ros.h>
#include <ros/console.h>
#include <nav_msgs/Odometry.h>

...

int main(int argc, char** argv)
{
    ros::init(argc, argv, "sim_node");
    ros::NodeHandle nh;

    ...

    // Publishers
    tf::TransformBroadcaster tfbr;
    ros::Publisher odomPub = nh.advertise<nav_msgs::Odometry>("pose",10);

   ...

    ros::Rate r(300); // loop rate
    while(ros::ok())
    {
        ...

        // Publish pose and velocity
            ...
        odomPub.publish(msg);

        ros::spinOnce();
        r.sleep();
    }
    
    ros::waitForShutdown();
    return 0;
}

订阅者节点：

#include <ros/ros.h>
#include <ros/console.h>
#include <nav_msgs/Odometry.h>

...

std::mutex mtx1, mtx2;

class DataHandler
{
private:
    ros::NodeHandle nh;
    ros::Publisher odomPub;
    double lastTime;
    int lastSeq;
    
public:
    Eigen::Vector3d x, xDot, w;
    Eigen::Vector3d xDes, xDesDot, xDesDotDot, b1Des, b1DesDot;
    Eigen::Matrix3d R;
    
    DataHandler()
    {
        // Initialize data
        xDes = Eigen::Vector3d(1,0,1);
        xDesDot = Eigen::Vector3d::Zero();
        xDesDotDot = Eigen::Vector3d::Zero();
        b1Des = Eigen::Vector3d(1,0,0);
        b1DesDot = Eigen::Vector3d::Zero();
        x = Eigen::Vector3d::Zero();
        xDot = Eigen::Vector3d::Zero();
        R = Eigen::Matrix3d::Identity();

        odomPub = nh.advertise<nav_msgs::Odometry>("controller_pose",10);
        trajPub = nh.advertise<asap_control::DesiredTrajectory>("controller_desTraj",10);
        lastTime = ros::Time::now().toSec();
        lastSeq = 0;
    }
    
    // Get current pose and velocity
    void odomCB(const nav_msgs::OdometryConstPtr& odomMsg)
    {

        mtx1.lock();
        // Get data
        double time1 = ros::Time::now().toSec();
        x << odomMsg->pose.pose.position.x, odomMsg->pose.pose.position.y, ...;
        xDot << odomMsg->twist.twist.linear.x, odomMsg->twist.twist.linear.y, ...;
        R = Eigen::Quaterniond(odomMsg->pose.pose.orientation.w, odomMsg->pose.pose.orientation.x,...;
        w << odomMsg->twist.twist.angular.x, odomMsg->twist.twist.angular.y, ...;
        double time2 = ros::Time::now().toSec();
            
        // Time to extract data, < 1ms
        double delTproc = time2 - time1;
        std::cout << "\n\n";
        std::cout << "proc elapsed time: " << delTproc << "\n";
        std::cout << "proc frequency: " << 1.0/delTproc << "\n";

        odomPub.publish(odomMsg); // rostopic hz says this is publishing at ~25Hz
           
        // Time between callback calls, ~25Hz
        double timeNow = ros::Time::now().toSec();
        double delT = timeNow - lastTime;
        lastTime = timeNow;
        std::cout << "elapsed time: " << delT << "\n";
        std::cout << "frequency: " << 1.0/delT << "\n";
            
        // Message sequence IDs, shows 12 msgs skipped every call
        int seqNow = odomMsg->header.seq;
        int delSeq = seqNow - lastSeq;
        lastSeq = seqNow;
        std::cout << "delta seq: " << delSeq << "\n";
        mtx1.unlock();
    }
    
};

...

int main(int argc, char** argv)
{
    ros::init(argc, argv, "asap_control");
    ros::NodeHandle nh;

    ...

    // Publishers
    ros::Publisher outputPub = nh.advertise<geometry_msgs::WrenchStamped>("wrench_command",10);
    ros::Publisher debugPub = nh.advertise<control::ControllerSignals>("controller_debug",10);
    tf::TransformBroadcaster tfbr;

    // Subscribers
    DataHandler callbacks;
    ros::Subscriber poseSub = nh.subscribe("pose",10,&DataHandler::odomCB,&callbacks);

    // Asynchronous threads for callback handling
    //ros::AsyncSpinner spinner(2);
    //spinner.start();

    double lastTime = ros::Time::now().toSec();

    
    // Main loop
    ros::Rate r(700); // loop rate
    while(ros::ok())
    {
        // Data (extracted for cleanliness further down, and thread safety)
        mtx1.lock();
        Eigen::Vector3d x = callbacks.x;
        Eigen::Vector3d xDot = callbacks.xDot;
        Eigen::Matrix3d R = callbacks.R;
        Eigen::Vector3d w = callbacks.w;
        mtx1.unlock();
        
            ...
        
        // Publish
            ...
        outputPub.publish(msg);
            
        // Publish debug signals
        control::ControllerSignals debugMsg;
        debugMsg.x[0] = x(0);
        ...
        debugPub.publish(debugMsg);
            
        //double timeNow = ros::Time::now().toSec();
        //double delT = timeNow - lastTime;
        //lastTime = timeNow;
        //std::cout << "\n\n";
        //std::cout << "elapsed time: " << delT << "\n";
        //std::cout << "frequency: " << 1.0/delT << "\n";
        
        ros::spinOnce();
        r.sleep();
    }
    
    ros::waitForShutdown();
    return 0;
}

附加信息：

发布者以 ~300Hz 的频率发布（由“姿势”主题的 rostopic hz 确认）
订阅者节点中的主循环是运行 ~700Hz（由循环中发布到“wrench_command”主题的 rostopic hz 确认，以及循环通过 ros::Time::now() 计时），因此，spinOnce 以相同的速率被调用。
姿势主题的回调以约 25 Hz 的频率调用（已在回调中发布到“controller_pose”主题的 rostopic hz 确认，以及通过 ros::Time::now())
即使我使用 AsyncSpinner 而不是 spinOnce，我也会得到相同的行为，尽管只能使用 rostopic hz 确认。正如预期的那样，时序产生不稳定的输出
将订阅者 queue_length 增加到例如 10 会将回调率增加到 ~250Hz，但是，我想保持 queue_length 为 1 以仅获取最新数据。
Ubuntu 中的系统监视器显示利用率不到 50% cpu，因此我认为这不是 cpu 瓶颈问题。

Answer 1

我前段时间解决了传输里程计数据的类似问题，其中里程计数据以 100Hz 的频率传输，但仅以 25Hz 的频率接收。事实证明，底层 TCP 套接字正在缓冲数据，将 4 条消息集中到一个 TCP 数据包中以节省传输成本。我相信您需要在 TransportHints():

中将 tcpNoDelay 设置为 true

node.subscribe(...,ros::TransportHints().tcpNoDelay(true));

请注意，这发生在订阅端。

http://wiki.ros.org/roscpp/Overview/Publishers%20and%20Subscribers#Transport_Hints

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