Gnss

Gnss Sensor

GNSS sensor script simulates measurements from Global Navigation Satellite System. This sensor gives measurements for longitude, latitude, and altitude/elevation.

Multiple parameters can be set to configure GNSS measurements. If you set this IMU object as the child of an object with a Vehicle tag, the name of that object will be automatically inserted as namespace to Frame Id parameter. This parameter can have custom naming. GNSS measurements will be arriving with frequency set in Sample Frequency parameter. Using Measurement Noise you can choose between few reconfigured noises and set noise parameters. In the image NoiseType is set to Gaussian with bias of 0.1 and standard deviation of 0.01. In Precision field you can set Is RTK parameter, this parameter will be included in message but it will not change the measurements, accuracy of the measurement is set with the noise parameters. Using Maximum Operating Depth, it is possible to set depth after which the GNSS will no longer provide data.

Gnss ROS

Gnss ROS script publishes GNSS measurements to the ROS topic.

This script should be added to a game object which has Gnss Sensor script attached to it. If Gnss Sensor script does not exist in the object it will be automatically added together with Gnss ROS script. Tf streamer script will also be included automatically, even though it is not required for Gnss ROS script to work.

GNSs ROS script has only two parameters that need to be set. Address parameter in the name of the ROS topic and Update Frequency is the frequency at which it will be published.

To get topic back to ROS make sure ROS server is launched. This is included in grpc_ros_adapter (link) package and can be called from terminal with roslaunch grpc_ros_adapter launch_server.launch.

Server should be live when simulation is started. At this point you should be able to see your topic being published in ROS.