Robot not following path in Nav. Stack

Question

Hi community. I'm setting up the navigation stack in my own robot. As I see in a REP, the tf tree is the next:

map -> odom -> chassis_footprint -> chassis -> others (wheels, lasers, ...)

Well, the robot it's represented correctly in rViz (for this, first I launch the robot in gazebo, next I launch the nav. stack and finally I launch the rViz) and furthermore if I set a 2D Goal the robot make a correct path, although the robot doesn't follow it.

In addition, if I change the fixed frame - target frame in the rViz to anything that isn't the chassis (like /odom, /map, /chassis_footprint) the robot is saw like this:

I think that there be a problem in the tf, but rViz not give any error, although I must say that some frames "jumps" in a rare way.

My tf's are the next:

In tf_broadcaster:

broadcaster.sendTransform(tf::StampedTransform(tf::Transform(tf::Quaternion(0, 0, 0, 1), tf::Vector3(0.0,0.0,0.0)),ros::Time::now(), "map", "odom"));
broadcaster.sendTransform(tf::StampedTransform(tf::Transform(tf::Quaternion(0, 0, 0, 1), tf::Vector3(0.0,0.0,0.0)),ros::Time::now(),"chassis_footprint", "chassis"));
broadcaster.sendTransform(tf::StampedTransform(tf::Transform(tf::Quaternion(0, 0, 0, 1), tf::Vector3(0.12,0.0,0.285)),ros::Time::now(),"chassis", "hokuyo_laser_link"));

In the odometry node:

//since all odometry is 6DOF we'll need a quaternion created from yaw
geometry_msgs::Quaternion odom_quat = tf::createQuaternionMsgFromYaw(robot_pose_pa_);

//first, we'll publish the transform over tf
geometry_msgs::TransformStamped odom_trans;
odom_trans.header.stamp = current_time;
odom_trans.header.frame_id = "odom";
odom_trans.child_frame_id = "chassis_footprint";

odom_trans.transform.translation.x = robot_pose_px_;
odom_trans.transform.translation.y = robot_pose_py_;
odom_trans.transform.translation.z = 0.0;
odom_trans.transform.rotation = odom_quat;

//send the transform over /tf
odom_broadcaster.sendTransform(odom_trans);

What is happening and what I'm doing incorrectly? I am very new in the tf's and any idea is appreciated. Thanks!

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Originally posted by mbj on ROS Answers with karma: 197 on 2011-05-16

Post score: 0

Answer 1

Hello,

To me, your problem comes either from wrong parameters for the base controller, and/or a wrong odometry. Could you post your config files for navigation? Check also the twist part of the odometry message, it must be expressed in the local frame of the robot.

Another problem could be that move_base does not output the velocity command on the right topic.

It could also be that your base driver is not working. Did you try controlling your roboy with a joystick or pr2_teleop pr2_teleop_keyboard? That way you could make sure that your base driver is correct and accepts velocity commands.

You should also have a look at this post, which contains a detailed guide to navigation issues.

I hope this helps

Raph

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Originally posted by raphael favier with karma: 1382 on 2011-05-19

This answer was ACCEPTED on the original site

Post score: 1

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Original comments

Comment by raphael favier on 2011-05-30:
Hey, glad to see you solved your pbl. Thx for the feedback.

Comment by mbj on 2011-05-30:
Hello Raphael. Effectively, the navigation stack expected to receive the speeds on "cmd_vel" topic and I was sending it to another topic. I solved this remapping the correct topics in the move_base.launch. Now, everything is solved, even the tf issue! Thanks.