Driving Towards Autonomy
The idea of autonomous vehicles sharing the road is slowly becoming a reality due to advances in positioning and sensor integration. High precision Global Navigation Satellite System (GNSS) technology provides the accuracy, availability and reliability that a vehicle requires to be self-driving.
A fully autonomous vehicle needs an accurate localization solution paired with the confidence that the localization solution is correct. Our GNSS technology is capable of providing decimeter-level accuracy to ensure a vehicle stays in its lane or a safe distance from other vehicles.
Our technology solutions for autonomous vehicles include GNSS receivers that use multiple frequencies and multiple GNSS constellations, Synchronous Position Attitude and Navigation (SPAN) technology, GPS Anti-Jam technology and interference mitigation, and correction services to provide the positioning and sensor integration that autonomous vehicles need.
Components like radar, LiDAR and cameras are used to provide the distance to objects that surround the vehicle. If the exact location of the surrounding objects is known, this technology can provide the absolute vehicle location with assistance from a high amount of map data. When integrated with complimentary technology such as: ultrasonic, inertial motion, digital maps, radar/LiDAR and cameras, GNSS acts as the sixth sense to deliver the positioning performance required by autonomous vehicles.
Many technologies onboard vehicles provide local or relative localization. GNSS provides an absolute localization solution, and with the following technologies can achieve the accuracy and availability requirements of a full autonomous driving solution.
SPAN® GNSS+INS Navigation
With the growing developments in automotive technology, the need for accurate, reliable and robust ground reference has emerged. Global Navigation Satellite Systems (GNSS) + Inertial Navigation Systems (INS) are an essential component of achieving high accuracy ground truth, mobile mapping and real-time precise positioning for autonomy. NovAtel delivers SPAN® GNSS+INS technology in easy-to-integrate packages designed to determine truth trajectories and benchmark your autonomous solution.
Why use SPAN?
High Rate Data:
Users have access to high-rate, smooth solutions, essential for high-speed freeway/highway driving.
Accuracy and Flexibility:
When combined with Real-Time Kinematic (RTK) corrections and post-processing, SPAN offers the best possible solution even through tunnels and ultra-challenging urban canyon situations. Flexibility of the system allows for the addition of a wheel sensor and other external inputs to further refine your solution.
Internal logging and multiple communication interfaces allow for customized utilization and flexibility when integrating into test vehicles.
The Interference Toolkit (ITK) provides the functionality to monitor, quantify and remove those unintentional interference sources that impact receiver performance. ITK has built-in features to pre-survey demonstration sites, scan for possible interference sources within the vehicle and remove interference.
ITK includes two main components:
1. Spectrum analysis output:
Plot signal levels on the vertical axis over a range of frequencies on the horizontal axis. The spectral analysis tools show how much signal power is being sensed across the different GNSS frequency bands. When an interference signal is present it can be visualized in the spectral analysis plot.
2. Advanced signal processing and digital filtering:
Mitigate and remove interference with built-in software, applied signal processing and digital filters. These processing techniques suppress interference, allowing the GNSS signals to track and the receiver to continue to operate normally.
Why use ITK for Ground Truth?
- To pre-survey demonstration areas to identify and remove possible sources of interference
- To identify interference sources within the vehicle
- To remove interference with built-in filters
Waypoint Software provides an ideal solution for applications that require accurate post-mission position, velocity or attitude. Post-processing with Waypoint maximizes the accuracy of the ground truth trajectory by processing forward and reverse in time, backsmoothing and combining the results. It provides the ability to assess the solution reliability and accuracy with extensive quality analysis and plotting tools.
Why use Waypoint for Ground Truth?
- It maximizes accuracy of GNSS+INS test trajectories
- It provides the ability to offset and transform between reference datums
- Export profiles are customizable to meet varying needs
- Real-time and post-processed quality can be compared
- It is easy to export to Google Earth for test review
GNSS signals, without corrections, provide positioning accuracy of five to ten meters (16-32 feet). Corrections can be generated by a number of sources or methods, and system developers must choose the corrections method that best meets the demands of their application.
Corrections work in combinations with multi-frequency measurements from the GNSS to provide sub-decimeter to centimeter-level accuracy – depending on the correction source.
Precision Time Protocol (PTP)
Precise time is critical for autonomous driving applications. With the PTP functionality provided on OEM7 receivers from Hexagon | NovAtel, you can achieve timing synchronisation for system networks, enabling a trusted timing source for all devices on your platform. Up to 20 devices can be synchronised using a local Ethernet network to <5 ns accuracy, eliminating the need for many hardwired connections. Learn more about how PTP works here.
In order to receive the best possible accuracy, it is recommended that two or three frequencies broadcasted by each GNSS constellation (GPS, GLONASS, BeiDou and Galileo) be used.
- Using multi-frequency receivers mitigates errors caused by variable signal delays caused by atmospheric conditions
- L1/L2 frequency combination is most common; L5 is used for modernized GPS, BeiDou and Galileo
- The more constellations used, the higher the likelihood of observing satellites; particularly important in urban or obstructed environments
- GNSS receivers and antennas capable of receiving multiple frequencies and constellations must be utilized
PPP (Precise Point Positioning)
PPP uses globally available corrections using a world-wide network of reference receivers. Corrections are transmitted to the vehicle via satellite or by cellular. NovAtel utilizes TerraStar corrections to deliver a sub-decimeter solution. For more information visit the Positioning Services tab.
RTK (Real-Time Kinematic)
RTK sends data from reference receivers in the vicinity of the vehicle. Location can be covered by one or more RTK networks, available free of charge or for a subscription fee.