Revision as of 05:56, 15 April 2017

References

• ROS tf
• Coordinate Frames
• Tutorials
• TF Setup
• Transform Map to Odom
• Transform Odom to Base
• See lesson 5

Base_link to Laser

 cat tf_laser.launch

 <launch>
   <node pkg="tf" type="static_transform_publisher" name="base_to_laser" 
         args="0.202 0 0.111 0 0 0 1 base_link neato_laser 100" />
 </launch>

See floor_hugger.urdf URDF Representation of Floor Hugger

 base_link => extended_base => Laser_layer => laser_sensor
 x = 0.004 + 0.000 + 0.192 + 0.006 = 0.202
 z = 0.021 + 0.018 + 0.011 + 0.061 = 0.111

Odom to Base_link

TBD: Where is this specified? In Odometry?

Map to Odom

 cat tf_map.launch

 <launch>
   <node pkg="tf" type="static_transform_publisher" name="odom_to_map" 
         args="0 0 0.045 0 0 0 1.0 map odom 100" />
 </launch>

Wheel radius is 45 mm. Calibrate_Phidgets_Odometry#From_Specs

Navigation Stack Test

Setup

Terminal 1

 roscore

Terminal 2

 roslaunch floor_hugger nav.launch

Display Tree

Terminal 3

 rosrun tf view_frames

 evince frames.pdf

Exploration Tools

monitor

Monitor the transforms between frames. See complete tree below.

 rosrun tf tf_monitor
     All Broadcasters:
     Node: unknown_publisher 96.979 Hz, Average Delay: -0.260119 Max Delay: 0.102549
 
     RESULTS: for all Frames
 
     Frames:
     Frame: base published by unknown_publisher Average Delay: -0.474372 Max Delay: 0
     Frame: base_link published by unknown_publisher Average Delay: 0.000405951 Max Delay: 0.00156847
     Frame: battery_layer published by unknown_publisher Average Delay: -0.474377 Max Delay: 0
     Frame: camera_layer published by unknown_publisher Average Delay: -0.474374 Max Delay: 0
     Frame: compute_layer published by unknown_publisher Average Delay: -0.474374 Max Delay: 0
     Frame: computer published by unknown_publisher Average Delay: -0.474373 Max Delay: 0
     Frame: control_layer published by unknown_publisher Average Delay: -0.474377 Max Delay: 0
     Frame: extended_base published by unknown_publisher Average Delay: -0.474378 Max Delay: 0
     Frame: laser_layer published by unknown_publisher Average Delay: -0.474373 Max Delay: 0
     Frame: laser_sensor published by unknown_publisher Average Delay: -0.474372 Max Delay: 0
     Frame: left_wheel published by unknown_publisher Average Delay: -0.474379 Max Delay: 0
     Frame: neato_laser published by unknown_publisher Average Delay: -0.0996256 Max Delay: 0
     Frame: odom published by unknown_publisher Average Delay: -0.0327469 Max Delay: 0.104149
     Frame: right_wheel published by unknown_publisher Average Delay: -0.474377 Max Delay: 0
     Frame: usb_hub published by unknown_publisher Average Delay: -0.474375 Max Delay: 0
     Frame: webcam_sensor published by unknown_publisher Average Delay: -0.474375 Max Delay: 0

map to odom transform

See tf_map.launch script above to confirm the z value below

 rosrun tf tf_echo map odom
     At time 1492259778.541
     - Translation: [0.000, 0.000, 0.045]
     - Rotation: in Quaternion [0.000, 0.000, 0.000, 1.000]
                 in RPY (radian) [0.000, -0.000, 0.000]
                 in RPY (degree) [0.000, -0.000, 0.000]

odom to base_link

The odom to base_link transform in all zeros at startup.

 rosrun tf tf_echo odom base_link
     At time 1492260129.428
     - Translation: [0.000, 0.000, 0.000]
     - Rotation: in Quaternion [0.000, 0.000, 0.000, 1.000]
                 in RPY (radian) [0.000, -0.000, 0.000]
                 in RPY (degree) [0.000, -0.000, 0.000]

base_link to neato_laser

See tf_laser.launch for how these were derived.

 rosrun tf tf_echo base_link neato_laser
     At time 1492260448.546
     - Translation: [0.202, 0.000, 0.111]
     - Rotation: in Quaternion [0.000, 0.000, 0.000, 1.000]
                 in RPY (radian) [0.000, -0.000, 0.000]
                 in RPY (degree) [0.000, -0.000, 0.000]

=== base_link to laser_sensor

This is derived from the URDF and is the same as the base_link to the neato_laser. So I wonder whether the tf_laser.launch script is redundant. They fortunately give the same results.

 rosrun tf tf_echo base_link laser_sensor
     At time 1492260747.860
     - Translation: [0.202, 0.000, 0.111]
     - Rotation: in Quaternion [0.000, 0.000, 0.000, 1.000]
                 in RPY (radian) [0.000, -0.000, 0.000]
                 in RPY (degree) [0.000, -0.000, 0.000]

Display Complete Tree

Initial Test

Terminal 1

 roscore

Terminal 2

Set sim time to false in case it was set to true during gmapping.

 rosparam set use_sim_time false
 roslaunch floor_hugger odometry.launch

Terminal 3

 rosrun xv_11_laser_driver neato_laser_publisher _port:=/dev/ttyUSB0 _firmware_version:=2

Terminal 4

 roslaunch floor_hugger tf_laser.launch

Terminal 5

 roslaunch floor_hugger tf_map.launch

Terminal 6

 rosrun tf view_frames
 
 evince frames.pdf

Result is a file named frames.pdf.