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Hi everyone, i want to make 3d map using hokuyo UTM-30 LX.

asked 2016-02-01 15:15:55 -0500

ARCHANA gravatar image

updated 2016-03-10 09:19:34 -0500

I downloded loam_continuous package. Firstly i run the launch file provided in this package. And When i play the bagfiles provided then i am able to see pointcloud in rviz but when i connect my laser with laptop and spins it then nothing comes up in rviz. Can somebody tell me step by step what changes i have to make in that? Regards.

#include <ros ros.h=""> #include <tf transform_broadcaster.h=""> #include <dynamixel_msgs jointstate.h=""> #include "sensor_msgs/PointCloud2.h" #include <sensor_msgs jointstate.h="">

#include "laser_assembler/AssembleScans.h"

void transform_Callback(const dynamixel_msgs::JointState& msg) { ROS_INFO("broadcasting transform"); }

int main(int argc, char** argv){ ros::init(argc, argv, "tf_broadcaster");

ros::NodeHandle node; ros::Rate rate(30.0); static tf::TransformBroadcaster br; tf::Transform transform; while(ros::ok()) {

transform.setOrigin( tf::Vector3(0.0, 0.0, 0.0) ); tf::Quaternion q; q.setRPY(0, 0, 0); transform.setRotation(q); br.sendTransform(tf::StampedTransform(transform, ros::Time::now(), "/tilt_laser", "/laser")); ros::Subscriber sub = node.subscribe("/tilt_controller/command", 1000, transform_Callback);

rate.sleep(); ros::spinOnce(); }

return 0; };

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hi did you complete your project. I am doing the same, i want to create 3D model using hokuyo lidar for that using loam_continuous package. I have sample data with me but it is in sensor_msg/LaserScan form so i have to convert it into Sensor_msg/PointCloude form how do i do it? Thank you

Nikka gravatar imageNikka ( 2017-07-08 09:13:57 -0500 )edit

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answered 2016-02-01 15:45:13 -0500

You cannot just plug your LIDAR into your laptop and use it, as you need to mount it on a motorized slipring that spins it continuously and provides the associated joint angles. You might want to look at some basic tutorials such as Setting up your robot using tf to get a basic idea of how that works.

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Can you please suggest me which motor i have to use for creating 3d map using loam package? May be a silly question, can 9 DOF razor imu solve the need of motor? Thanks.

ARCHANA gravatar imageARCHANA ( 2016-02-02 04:33:33 -0500 )edit

No, a IMU can be used to measure inertial parameters (and angles can be estimated from them), but it cannot actuate things. You could in theory manually rotate the LIDAR and measure angles using the IMU but it is highly unlikely that this would work sufficiently well for LOAM.

Stefan Kohlbrecher gravatar imageStefan Kohlbrecher ( 2016-02-02 08:00:23 -0500 )edit

Thanks alot for clearing my doubt. Now will you please tell me which motor should I purchase that supports ROS JADE version?

ARCHANA gravatar imageARCHANA ( 2016-02-02 09:15:09 -0500 )edit

There are infinite possibilities, but one that is pretty straightforward is using a Dynamixel servo (driver here: http://wiki.ros.org/dynamixel_motor )

Here's an example packge for using it with a spinning LIDAR: https://github.com/tu-darmstadt-ros-p...

Stefan Kohlbrecher gravatar imageStefan Kohlbrecher ( 2016-02-02 11:45:04 -0500 )edit

Thanks for guiding me. I will work on that as you mentioned.

ARCHANA gravatar imageARCHANA ( 2016-02-02 12:26:39 -0500 )edit

Hi Stefan, can you please tell me in detail what should be the tf tree for providing transform between dynamixel and laser?

ARCHANA gravatar imageARCHANA ( 2016-02-21 03:52:54 -0500 )edit

See the launch files referenced here: https://github.com/tu-darmstadt-ros-p... . This setup is also using Dynamixel servos, so it should be more or less directly applicable.

Stefan Kohlbrecher gravatar imageStefan Kohlbrecher ( 2016-02-22 15:17:13 -0500 )edit

Hi Stefan, i provide a tf_broadcaster between laser and dynamixel motor following this tutorial but was not able to get 3d pointcloud. My tf_broadcaster is provided above. Can you please tell me where i am wrong?

ARCHANA gravatar imageARCHANA ( 2016-03-10 09:16:22 -0500 )edit

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Asked: 2016-02-01 15:15:55 -0500

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Last updated: Mar 10 '16