tum_simulator on Indigo and Gazebo 7

These packages are used to simulate the flying robot Ardrone in ROS environment using gazebo simulator. Totally they are 4 packages. Their functions are descript as below:

cvg_sim_gazebo: contains object models, sensor models, quadrocopter models, flying environment information and individual launch files for each objects and pure environment without any other objects.
cvg_sim_gazebo_plugins: contains gazebo plugins for the quadrocopter model. quadrotor_simple_controller is used to control the robot motion and deliver navigation information, such as: /ardrone/navdata. Others are plugins for sensors in the quadrocopter, such as: IMU sensor, sonar sensor, GPS sensor.
message_to_tf: is a package used to create a ros node, which transfers the ros topic /ground_truth/state to a /tf topic.
cvg_sim_msgs: contains message forms for the simulator.

Some packages are based on the tu-darmstadt-ros-pkg by Stefan Kohlbrecher, TU Darmstadt.

This package depends on ardrone_autonomy package and gazebo7 so install these first.

How to install the simulator:

Install gazebo7 and ardrone_autonomy package

Create a workspace for the simulator

mkdir -p ~/ardrone_simulator/src
cd  ~/ardrone_simulator/src
catkin_init_workspace

Download package

git clone https://github.com/iolyp/ardrone_simulator_gazebo7

Build the simulator
```
cd ..
catkin_make
```
Source the environment
```
source devel/setup.bash
```

How to run a simulation:

Run a simulation by executing a launch file in cvg_sim_gazebo package:
```
roslaunch cvg_sim_gazebo ardrone_testworld.launch
```

How to run a simulation using ar_track_alvar tags:

Move the contents of ~/ardrone_simulator/src/cvg_sim_gazebo/meshes/ar_track_alvar_tags/ to ~/.gazebo/models
Run simulation
```
roslaunch cvg_sim_gazebo ar_tag.launch
```