urdf in rviz is too deep

Hi, I setup my robot system and its working good. I am using hector mapping with urdf and a laserscanner and I am getting the following result:  I dont know why exactly the robot is kind of swimming in the world, here is my tf tree:  Another Question is now, how can I make the Robot move autonomously and how can I integrate a path planner? What is a common used module to make the robot move and avoid obstacles and crashes? thanks in advance, felix