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Problem with Approximatetime policy

asked 2016-09-21 11:44:15 -0600

b-sriram gravatar image

updated 2016-09-22 03:44:58 -0600

gvdhoorn gravatar image

Hi,

I'm having a little trouble figuring out how to use the Approximate time policy. I'm able to run the code provide as a tutorial here. ( http://wiki.ros.org/message_filters ) But when I use classes I'm getting a lot of error.

typedef sync_policies::ApproximateTime<sensor_msgs::NavSatFix, sensor_msgs::Imu, sensor_msgs::LaserScan> MySyncPolicy;

class myclass
{
public:            
myclass();   
ros::NodeHandle nh;
void callback(const sensor_msgs::NavSatFixConstPtr& , const sensor_msgs::ImuConstPtr& , const sensor_msgs::LaserScanConstPtr& );


private:
  message_filters::Subscriber<sensor_msgs::NavSatFix> *sub_fix;
  message_filters::Subscriber<sensor_msgs::Imu> *sub_imu;
  message_filters::Subscriber<sensor_msgs::LaserScan> *sub_laserscan;
  Synchronizer<MySyncPolicy> *sync;
};

myclass::myclass()
{

sub_fix = new message_filters::Subscriber<sensor_msgs::NavSatFix>(nh, "kitti_player/oxts/gps", 100);
sub_imu = new message_filters::Subscriber<sensor_msgs::Imu>(nh, "kitti_player/oxts/imu", 100);
sub_laserscan = new message_filters::Subscriber<sensor_msgs::LaserScan>(nh, "scan", 100);

   sync = new message_filters::sync::ApproximateTime<MySyncPolicy> (*sub_fix, *sub_imu, *sub_laserscan,1000);
   sync->registerCallback(boost::bind(&myclass::callback, _1, _2, _3));
}


void myclass::callback(const sensor_msgs::NavSatFixConstPtr& gps, const sensor_msgs::ImuConstPtr& imu, const sensor_msgs::LaserScanConstPtr& scan)
{
 std::cout<<" "<< gps->header.stamp <<"   " << scan->header.stamp << "\n" ;
}

Can someone please suggest a way to write this properly.

Thanks & Regards Sriram

PS:: some of the errors

/home/student/students/sriram/test_ws/src/test_sub/src/test_sub.cpp: In constructor ‘myclass::myclass()’:
/home/student/students/sriram/test_ws/src/test_sub/src/test_sub.cpp:47:15: error: expected type-specifier
    sync = new message_filters::sync::ApproximateTime<MySyncPolicy> (*sub_fix, *sub_imu, *sub_laserscan,1000);
               ^
/home/student/students/sriram/test_ws/src/test_sub/src/test_sub.cpp:47:15: error: expected ‘;’
In file included from /usr/include/boost/bind.hpp:22:0,
                 from /opt/ros/indigo/include/ros/publisher.h:35,
                 from /opt/ros/indigo/include/ros/node_handle.h:32,
                 from /opt/ros/indigo/include/ros/ros.h:45,
                 from /home/student/students/sriram/test_ws/src/test_sub/src/test_sub.cpp:1:
/usr/include/boost/bind/bind.hpp: In instantiation of ‘struct boost::_bi::result_traits<boost::_bi::unspecified, void (myclass::*)(const boost::shared_ptr<const sensor_msgs::NavSatFix_<std::allocator<void> > >&, const boost::shared_ptr<const sensor_msgs::Imu_<std::allocator<void> > >&, const boost::shared_ptr<const sensor_msgs::LaserScan_<std::allocator<void> > >&)>’:
/usr/include/boost/bind/bind_template.hpp:15:48:   required from ‘class boost::_bi::bind_t<boost::_bi::unspecified, void (myclass::*)(const boost::shared_ptr<const sensor_msgs::NavSatFix_<std::allocator<void> > >&, const boost::shared_ptr<const sensor_msgs::Imu_<std::allocator<void> > >&, const boost::shared_ptr<const sensor_msgs::LaserScan_<std::allocator<void> > >&), boost::_bi::list3<boost::arg<1>, boost::arg<2>, boost::arg<3> > >’
/home/student/students/sriram/test_ws/src/test_sub/src/test_sub.cpp:48:69:   required from here
/usr/include/boost/bind/bind.hpp:69:37: error: ‘void (myclass::*)(const boost::shared_ptr<const sensor_msgs::NavSatFix_<std::allocator<void> > >&, const boost::shared_ptr<const sensor_msgs::Imu_<std::allocator<void> > >&, const boost::shared_ptr<const sensor_msgs::LaserScan_<std::allocator<void> > >&)’ is not a class, struct, or union type
     typedef typename F::result_type type;
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answered 2016-09-21 21:22:53 -0600

kmhallen gravatar image

When passing a class to boost::bind, it needs an instance too. Try this.

sync->registerCallback(boost::bind(&myclass::callback, this, _1, _2, _3));
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Comments

hi, thanks. i tried what you suggested and it think the previous error is solved. Now I have a diiferent one.

In constructor ‘myclass::myclass()’:
sub.cpp:45:15:error: expected type-specifier sync = new message_filters::sync::ApproximateTime<MySyncPolicy> (*sub_fix, *sub_imu, *sub_laserscan, 1000);
b-sriram gravatar imageb-sriram ( 2016-09-22 03:39:17 -0600 )edit

I think my mistake is the way I'm using this line

sync = new message_filters::sync::ApproximateTime<MySyncPolicy> (*sub_fix, *sub_imu, *sub_laserscan,1000);

I used the example provided here link text and i works

b-sriram gravatar imageb-sriram ( 2016-09-22 04:09:17 -0600 )edit

And changing it to this made it work

 sync = new Synchronizer<MySyncPolicy> (MySyncPolicy(10), *sub_fix, *sub_imu, *sub_laserscan);
b-sriram gravatar imageb-sriram ( 2016-09-22 04:47:52 -0600 )edit

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Asked: 2016-09-21 11:44:15 -0600

Seen: 462 times

Last updated: Sep 22 '16