No transform from baselink to world
I am trying to use tum_simulator to map an environment following the example of hector_slam. I added the sensors which are included in hector_slam. And I added the mapping and visualization nodes from hector_slam to tum_simulator launch files. But in rviz, I get the following errors,
Global Status: Fixed Frame [world] does not exist
Robot Model: No transform from [ardrone_base_bottomcam], [ardrone_base_frontcam], [base_link], [bottom_link], [front_link], [sonar_link] to [world]
Map: No transform from [map] to [world]
Camera: No Image received
tf: No transform from [ardrone_base_bottomcam], [ardrone_base_frontcam], [base_footprint], [base_stabilized], [base_link], [bottom_link], [front_link], [nav], [sonar_link] to [world]
How do I solve this problem?
How do I add the missing transform?