# Simple URDF vehicle model

Hi,

I have been using Gazebo for a few days and I need to simulate a wheeled vehicle, guided via keyboard, housing a GPS and an IMU. In order to do that, I found and followed this tutorial, explaining how to create and simulate an URDF model of a robot:

https://www.generationrobots.com/blog...

However I have noticed the following problems:

1) the graphic simulation is not consistent with the keyboard input commands: a "real time response" occurs only after many minutes from the simulation start.

2) I added a GPS to the "mybot.gazebo" file, using the following code:

 <gazebo>
<plugin name="name_gps" filename="libhector_gazebo_ros_gps.so">
<alwayson>1</alwayson>
<updaterate>10.0</updaterate>
<bodyname>chassis</bodyname>
<topicname>mybot/gps_fix</topicname>
<velocitytopicname>mybot/gps_fixvelocity</velocitytopicname>
<drift>5.0 5.0 5.0</drift>
<gaussiannoise>0.1 0.1 0.1</gaussiannoise>
<velocitydrift>0 0 0</velocitydrift>
<velocitygaussiannoise>0.1 0.1 0.1</velocitygaussiannoise>
</plugin>
</gazebo>


However, despite not having encountered any error/warning from the GPS plugin, the /mybot/gps_fix and /mybot/gps_fixvelocity do not appear on the rostopic list.

Does anyone know how to fix these problems?