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.