# Robot rotates around a point instead of navigating to Goal Position when working with amcl

Hello,

I have a custom robot with 2 wheels, a camera, and a laser rangefinder. I am trying to localize the robot using amcl.

I had everything set up. When rviz was launched I would define the initial 2D pose estimate and the used to define the 2d Nav Goal in RViz as well.

However, I implemented a basic node to publish to the topic so that I could have the robot move to the goal directly. When I run that node, RViz displays the correct path to the goal. But the robot starts moving forward and after a while (usually around the same spot) it starts to rotate around a single point for some reason.

I am not sure why that's the case. It works fine when I try to run it via RViz but not via the node. The code I am working with for the node -

    #include <ros/ros.h>
#include <move_base_msgs/MoveBaseAction.h>
#include <actionlib/client/simple_action_client.h>
#include <tf/transform_datatypes.h>

typedef actionlib::SimpleActionClient<move_base_msgs::MoveBaseAction> MoveBaseClient;

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

// create the action client
// true causes the client to spin its own thread
MoveBaseClient ac("move_base", true);

// Wait 60 seconds for the action server to become available
ROS_INFO("Waiting for the move_base action server");
ac.waitForServer(ros::Duration(5));

ROS_INFO("Connected to move base server");

// Send a goal to move_base
move_base_msgs::MoveBaseGoal goal;

goal.target_pose.pose.position.x = 0.995;
goal.target_pose.pose.position.y = -2.996;
goal.target_pose.pose.orientation.w = 1;

ac.sendGoal(goal);

// Wait for the action to return
ac.waitForResult();

if (ac.getState() == actionlib::SimpleClientGoalState::SUCCEEDED)
ROS_INFO("You have reached the goal!");
else
ROS_INFO("The base failed for some reason");

return 0;
}


I run the above using rosrun package_name node_name

This is what it looks like right now. The robot started to rotate instead of following the green path.

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This is not related to amcl, which provides localization. I guess this has something to do with how you setup move_base and the respective planners. I don't see anything wrong in particular with you code, so IMO this should work. You could check the return value of waitForServer to see if ...

( 2017-11-23 01:09:57 -0500 )edit

... you are actually connected, but if the Robot starts to drive, all should be fine.

Maybe Elaborate on the Problem, does the localization get lost (i.e. real/simulated Position vs. Position in rviz), what is your move_base configuration...

( 2017-11-23 01:11:07 -0500 )edit

@mig Thanks for the reply. As of now, it was because of either an additional planner or a planner parameter added by mistake that was causing this. It's been working since I removed that. I will go through some tests to confirm and then add an answer.

( 2017-11-30 00:22:57 -0500 )edit

@nemesis Sir Kindly help me, i'm also facing the same problem since a month.Kindly provide me the solution. it would be a great help. Thanks

( 2018-12-08 06:40:14 -0500 )edit