Follow following steps to run training for Felzenszwalb detector-
Make sure you have right directory structure read in training_data node(described here)
Add a training file to ImageSets with name category_train.txt (e.g., toy_Stegosaurus_train.txt)
Add list of xml files(without extension) as positive examples.
Add list of jpg images(without extension) for negative examples.
pyUtil package has a node list_files to make above two steps easier(type $rosrun pyUtils list_files.py --help )
Modify(or create a new)launch file dpm_train.launch to enter category you'd like to train for.(make sure you have a corresponding train file available, see second step)