### How can my controller receive the position of another object recognised by the Vicon system?
In the ``calculateControlOutput`` function of your ``CustomControllerService.cpp`` file is called everytime that the Vicon system provides new data, where this data is provided to ``calculateControlOutput`` function in the ``request`` variable and the calculated control output to apply is returned in the ``response``. In this way the ``calculateControlOutput`` function is performing in ROS what is referred to as a service. This service is advertised in the ``main()`` function of your ``CustomControllerService.cpp`` file by the line of code:
The ``calculateControlOutput`` function of your ``CustomControllerService.cpp`` file is called everytime that the Vicon system provides new data, where this data is provided to the ``calculateControlOutput`` function in the ``request`` variable and the calculated control output to apply is returned in the ``response`` variable. In this way the ``calculateControlOutput`` function is performing in ROS what is referred to as a service. This service is advertised in the ``main()`` function of your ``CustomControllerService.cpp`` file by the line of code:
```
ros::ServiceServer service = nodeHandle.advertiseService("CustomController", calculateControlOutput);
```
and this service is called on from the ``PPSClient.cpp`` file, and expected to adhere to the data structures described in ``/srv/Controller.srv``:
This service is called on from the ``PPSClient.cpp`` file, and it is expected to adhere to the data structures described in ``/srv/Controller.srv``:
```
CrazyflieData ownCrazyflie
CrazyflieData[] otherCrazyflies
...
...
@@ -192,7 +192,7 @@ By default the property ``otherCrazyflies`` is left empty when the service reque
```
void viconCallback(const ViconData& viconData)
```
where ``viconData``is an structure define in ``ViconData.msg``:
where the argument ``viconData``has the structure defined in ``ViconData.msg``:
```
CrazyflieData[] crazyflies
UnlabeledMarker[] markers
...
...
@@ -220,13 +220,13 @@ where the plan is to fill in this variable with the data about the object of int
```
for(std::vector<CrazyflieData>::const_iterator it = viconData.crazyflies.begin(); it != viconData.crazyflies.end(); ++it)
{
CrazyflieData thisObject = *it;
CrazyflieData thisObject = *it;
if ( thisObject.crazyflieName == "name_of_object_I_am_searching_for" )
{
otherObject = thisCrazyflie;
break;
}
if ( thisObject.crazyflieName == "name_of_object_I_am_searching_for" )
