Simulation problems about navigation: amcl and use_sim_time
I'm using navigation stack on PX4 drones, after learning tutorials I managed to set up the stack on my real drone system, with Pixhawk controller, Hokuyo UTM-30LX and jetson TX1,and everything seems work well in RVIZ, rqt_gragh and rqt_tf_tree.
I think a successful simulation is necessary before a real flight, but I met some problems.
First, amcl continuously send warnings about: No laser scan received.... and move_base send warnings like: timed out waiting for transform from base_link to map become avaliable before running costmap... I think a real laser lidar is not needed in simulation, and the urg_node(hokuyo node) should not be started, and who should send /scan topic to amcl?
What's more, I want to know if amcl is necessary in navigation stack, I know that amcl helps localize the robot in the map, and it should send tf between /odm and /map,but in my real system gmapping did this work, so can I remove amcl in the system?
Second, I tried set parameter use_sim_time to true in launch file, and no warnings exist after that. However other nodes, for example uav_base_controller node just don't send moving commands to UAV and even simulation in gazebo stopped. What's the problem? Should use_sim_time set to true in simulation?