GNSS

Introduction

This is a port of the Apollo GNSS driver to pure ROS. We removed dependencies on the protocol buffer messaging infrastructure used by Apollo.

This driver has been tested to work with a Novatel ProPak 6 on the University of Nevada, Reno's MKZ platform from AutonomouStuff.

This work was supported by the Nevada Governor's Office of Economic Development and the State of Nevada's Knowledge Fund.

Purpose

Integrate Apollo's framework into the ROS framework through remove of protocol buffer dependencies for messages and instead use the ROS message framework to publish and subscribe to sensor topics.
Publish, subscribe, and log gnss data including gps, imu, ins, and wheel encoder.
Stream RTK correction to the GPS receiver if available.

Design

This GNSS driver has two nodelets: a data stream nodelet and a parser nodelet. The stream nodelet communicates between the host PC and the device and grabs the RTK data from a NTRIP caster. The parser nodelet subscribes the raw data from the stream nodelet, parses the data, and publishes ROS messages.

Input

GPS data, e.g. velocity latency, position and velocity and their standard deviations
INS data, e.g. position, linear and angular velocity and covariance
IMU pose data, e.g. orientation, velocity, & acceleration

Output

data stream status
gnss status
ins status
imu data
localization data

Configuration

We use protocol buffers to store the driver configuration. The configuration file is stored in path share/gnss_driver/conf/ which is quoted by gnss_driver.launch. File gnss_driver.launch is stored in path share/gnss_driver/launch/. When using the gnss_driver, the following should be checked before deployment:

To use the location with UTM projection, check the zone id configuration in gnss_driver.launch.
Check the the lever arm distance.
Confirm the imu install method, as this affects the vehicle's frame and orientation compute.