Help needed with TF issues .

asked 2018-02-27 22:33:46 -0600

updated 2018-02-28 01:37:24 -0600

jayess gravatar image

Hey , i am working on a 4 wheel drive differential robot , I am using Rosserial to talk to the arduino (cmd_vel) and arduino publishes back (tf , in which the odom is there).

Timed out waiting for transform from base_link to map to become available before running costmap, tf error: Could not find a connection between 'map' and 'base_link' because they are not part of the same tree.Tf has two or more unconnected trees.. canTransform returned after 0.101146 timeout was 0.1.

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As you can see from the image , the error is No transform from camera to odom . I have done all simulations and it works properly ,but when i am using the Real robot , this error pops up .

What could be the error , the possibilities that i could think of are the below

  1. The frames not being synced , will i have to subscribe to a /clock topic on the arduino to synchronize the /tf topic .
  2. /odom as a dedicated topic doesnt exist .

Also can someone explain me the differences between

  1. /odometry/filtered image description
  2. /velocity_controller/odom image description
  3. /tf topic image description

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Additional information , the Arduino code which communicates to kangaroo x2.

enter code here

#include <ros.h>
#include <std_msgs/Empty.h>
#include <ros/time.h>
#include <tf/tf.h>
#include <tf/transform_broadcaster.h>
#include <nav_msgs/Odometry.h>
#include <geometry_msgs/Twist.h>
#include <std_msgs/String.h>
#include <std_msgs/Empty.h>
#include <std_msgs/Bool.h>

#include <SoftwareSerial.h>
#include <Kangaroo.h>
#define TX_PIN 13 //s1
#define RX_PIN 12 //s2
// Arduino TX (pin 2) goes to Kangaroo S1
// Arduino RX (pin 3) goes to Kangaroo S2

// Independent mode channels on Kangaroo are, by default, '1' and '2'.
SoftwareSerial  SerialPort(RX_PIN, TX_PIN);

KangarooSerial  K(SerialPort);

#define Mixed_mode true
 bool position_control =  true;
 #ifdef Mixed_mode
   KangarooChannel Drive(K, 'D');
   KangarooChannel Turn(K, 'T');

#ifndef Mixed_mode
  KangarooChannel KL(K, '1');
  KangarooChannel KR(K, '2');

ros::NodeHandle  nh;
long WHEEL_DIST = 2 ;

std_msgs::Bool position_control_msg;
std_msgs::Bool mixed_mode_msg;


double x = 1.0;
double y = 0.0;
double theta = 1.57;

void cmd_velCallback( const geometry_msgs::Twist& CVel){
  //geometry_msgs::Twist twist = twist_msg;

   long vel_x = CVel.linear.x*200;

   long vel_th = -CVel.angular.z*200;

   x += cos(theta)*CVel.linear.x*0.1;
   y += sin(theta)*CVel.linear.x*0.1;
   theta += CVel.angular.z*0.1;

   long  speed_right = (vel_th*WHEEL_DIST)/2 + vel_x;
   long  speed_left = (vel_x*2) - speed_right;
   long right_vel = 0.0;
   long left_vel = 0.0;
   //right_vel = vel_th * WheelSeparation / 2.0;
   //left_vel = (-1) * right_vel;
   //left_vel = vel_x - vel_th * WheelSeparation / 2.0;
   //right_vel = vel_x + vel_th * WheelSeparation / 2.0;
    // turning

    #ifdef Mixed_mode
    if(int(vel_x) == 0 && int(vel_th)==0){  
      if (position_control){

   // forward / backward
   else if(abs(vel_x) > abs(vel_th)  ){ 
      if (position_control){
   // moving doing arcs
      if (position_control){


    #ifndef Mixed_mode
       KR.pi ...
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As you can see on your tf tree map and odom are linked together but not with the other tf which is the issue. Do you launch joint_state_publisher and robot_state_publisher ?

Delb gravatar image Delb  ( 2018-02-28 02:29:32 -0600 )edit

Thanks , just checked , i had missed to include joint_state_publisher .

Now the tf issues between base_link and odom is solved .

But when i am launching the freenect node for using the kinect , its still saying

"No transform from [camera_depth_frame] to [odom]"

chrissunny94 gravatar image chrissunny94  ( 2018-02-28 02:55:48 -0600 )edit

First, is your camera_depth_frame in your tf tree ? Also check in rviz on the display pannel -> Grid -> Reference Frame, is it <fixed frame=""> or have you redefined it (which you should do) ?

Delb gravatar image Delb  ( 2018-02-28 03:56:38 -0600 )edit

Yes camera_depth_frame is there in the tf tree. On Rviz i have tried setting the reference frame as /odom , /base_link , /camera_link .

Still doesnt work .

Infact the Tf tree changes when i launch the freenect node/

chrissunny94 gravatar image chrissunny94  ( 2018-02-28 04:36:23 -0600 )edit

This might be due to the topics you're publishing/subscribing in your code that are not the same as the freenect's ones, have you checked that ? That could be solved with some remapping.

Delb gravatar image Delb  ( 2018-02-28 05:01:51 -0600 )edit