controller_spawner node missing
I want to simulate many uavs in gazebo, when I launched 20uavs in gazebo, I found 17th-20th uav can't be controlled. I checked the rqt_graph and found that the node /gazebo had subscribed all uavs' topic (/pose_action) but the last four. So I want to know is there any limitation on topics a node can subscribe?
update1: I found 17th-20th uavs didn't have the topic "cmd_vel". On the other hand, I checked the rqt_graph and found that the node /gazebo had subscribed all uavs' topic (/command/pose) but the last four. I checked the log and found that the four uavs' log had the following warning:
Controller Spawner couldn't find the expected controller_manager ROS interface.
But other uavs all correctly load controller_manager and upload the controller. I had tried many times and sometimes there were 5 wrong and sometimes 3 and etc. Why some of them can't?
update2: I also found the four uavs' node (controller_spawner) were not created.