Swift Navigation Test Track Data

April 2017

Introduction

This document is intended as a guide to the data that was generated and recorded by Swift Navigation during the Self Racing Cars autonomous vehicle event that took place at Thunderhill Raceway in Willows, California on April 1, 2017. In the open spirit of the event, Swift has recorded and posted its data publicly.

Equipment Setup

Swift Navigation installed and configured a differential GPS base station powered by a Piksi Multi™ RTK GPS receiver in the center of the west track at Thunderhill Raceway. A GNSS corrections service was used to determine the location of the differential station. Correction data from this base station was communicated to the test vehicle over 915 MHz radio link.

Surveyed Latitude

Surveyed Longitude

Surveyed Altitude (ellipsoidal)

39.5371254637

-122.337089374

95.076

Table 1 - Base Station Location

Note: the absolute position reported by an RTK system is limited in accuracy (but not precision) by the determined location of the base station.

The test vehicle utilized 3 Piksi Multi RTK GPS receivers receiving correction data from the base station described above, a corrections service, and the P336 CORS station respectively. Redundant communication efforts (radio and cellular) were utilized to avoid any uncertainty in cellular coverage at the raceway. Redundant sources of correction data (local base station, CORS, corrections service) were utilized to avoid any uncertainty in correction data availability.

Additionally, the test vehicle was equipped with a Novatel FlexPak 6 and IMU-IGM-S1 to serve as a source of ground truth for performance evaluations. During laps, the FlexPak 6 produced RTK position solutions in real-time, using correction data from the P336 CORS station - but not using the IMU. Additionally, the raw GNSS observables and IMU data were captured, and later used to produce a high-accuracy reference trajectory as ground truth in post processing.

All receivers on the test vehicle were connected to the same GNSS antenna. The Piksi Multi receivers were running v1.0.0-branch-100, a pre-release build of the Piksi Multi 1.1 firmware which is scheduled to be released in May 2017.


GNSS Receiver

Corrections Source

Novatel FlexPak 6 with IMU-IGM-S1

Continuously Operating Reference Station

Piksi Multi 1

Corrections Service

Piksi Multi 2

Local Piksi Multi Base Station

Piksi Multi 3

Continuously Operating Reference Station

Table 2 - GNSS Receivers and Corrections Sources

The diagram below sketches the setup on the race day.  Please contact Swift Navigation for any detailed questions about implementation.


Test Methodology

Multiple sessions were run over the course of the event. With this report, we present a subset of the data that includes an inside line, outside line, and centerline of the racetrack. The presented position tracks are intended to show the precision achievable from real time kinematic positioning techniques. Note that these positioning tracks are derived from GPS measurements only; there is no inertial sensing or dead reckoning included in the solution.

Figure 1 - Inside Line (green) and Outside Line (Blue)

Performance Analysis

Using the raw data gathered from the Novatel FlexPak receiver and IMU, a reference trajectory was calculated with Novatel Waypoint. P336 was used as the reference station and the inertial data was tightly coupled in the solution. This reference trajectory was then used to calculate the horizontal error for each receiver. The results are presented in the tables and graphs on the following pages.

Centerline

GNSS Receiver

50%

68%

95%

99%

Std. Dev.

Novatel FlexPak 6

0.017

0.021

0.038

0.064

0.012

Piksi Multi 1

0.019

0.022

0.031

0.037

0.007

Piksi Multi 2

0.027

0.031

0.042

0.049

0.009

Piksi Multi 3

0.037

0.041

0.051

0.059

0.009


Inside Track

GNSS Receiver

50%

68%

95%

99%

Std. Dev.

Novatel FlexPak 6

0.013

0.017

0.026

0.031

0.007

Piksi Multi 1

0.023

0.027

0.037

0.047

0.008

Piksi Multi 2

0.018

0.022

0.032

0.041

0.008

Piksi Multi 3

0.026

0.031

0.041

0.050

0.008


Outside Track

GNSS Receiver

50%

68%

95%

99%

Std. Dev.

Novatel FlexPak 6

0.015

0.018

0.026

0.031

0.007

Piksi Multi 1

0.018

0.022

0.031

0.035

0.008

Piksi Multi 2

0.015

0.018

0.026

0.030

0.007

Piksi Multi 3

0.021

0.025

0.034

0.037

0.008


Reference Data

On the following pages, data for each receiver is presented in the Swift Binary Protocol expanded to a JSON representation, a Google Earth KML, and a CSV of position information. The Google Earth KML was produced with the altitude clamped to the ground and is intended to be opened with the google earth desktop software. The root of the data directory is available here that includes this report and all files: https://drive.google.com/open?id=0B5X2nBadaPD1RUhsUzlJYW1PT2M


Piksi Multi 1

Inside Track - PM1

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-122215-inner-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1Nk5Mcm9LMnpNcGM

KML position track

swift-gnss-20170401-122215-inner-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1Sm90RWZUTlhGeFE

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-122215-inner-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1ZkwxUmpjTkZIWUk

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Outside Track - PM1

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-122215-outer-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1Tk1jc096QjVZalU

KML position track

swift-gnss-20170401-122215-outer-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1MTF0U1pPSjVZcms

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-122215-outer-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1djlQazEwdS1sLTg

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Centerline - PM1

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-141738-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1My1CSDE5Wk1mTFE

KML position track

swift-gnss-20170401-141738-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1MThrTEJMXzFfczg

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-141738-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1M2F1RFVDNDdIV00

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Piksi Multi 2

Inside Track - PM2

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-122223-inner-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1alJZd3lxdDJuczg

KML position track

swift-gnss-20170401-122223-inner-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1b0I2NzNjQ1BXY1U

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-122223-inner-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1eFBEWWI0ZGJ0MUE

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Outside Track - PM2

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-122223-outer-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1ZFg5LU1RSHZHVkU

KML position track

swift-gnss-20170401-122223-outer-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1N1EzMW0yQlpmUHM

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-122223-outer-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1VHgtb00ybWhMc2s

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Centerline - PM2

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-141743-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1LXRtQWFMREQwVjA

KML position track

swift-gnss-20170401-141743-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1TFlodnVJdGxqYXc

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-141743-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1cGM0Mkc0c2tJdlk

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Piksi Multi 3

Inside Track - PM3

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-122226-inner-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1aW11OUw0VHczMlk

KML position track

swift-gnss-20170401-122226-inner-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1QlZPNk1WTXJjTEE

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-122226-inner-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1cmZRdWpMOVQ4SW8

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Outside Track - PM3

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-122226-outer-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1VWV5ZnpYZjhuMWc

KML position track

swift-gnss-20170401-122226-outer-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1ak1jcmJ4WW91bWs

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-122226-outer-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1YkowMHlwZ0FIcVE

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Centerline - PM3

Data Type

Name

Link

Notes

JSON encapsulated SBP

swift-gnss-20170401-141748-trimmed.sbp.json

https://drive.google.com/open?id=0B5X2nBadaPD1SFhFN3l5MEVYT1k

KML position track

swift-gnss-20170401-141748-trimmed.kml

https://drive.google.com/open?id=0B5X2nBadaPD1dzNjTmtFQTJmeTg

KML file should be opened in Google Earth.

CSV position

swift-gnss-20170401-141748-trimmed.csv

https://drive.google.com/open?id=0B5X2nBadaPD1bTZGMWI5dEJSS1E

Flags field indicates fix type:
0 - Single Point

1 - RTK Float

2 - RTK Fixed

Reference Trajectory

Inside Track

Data Type

Name

Link

Notes

Novatel Waypoint Text File

2017-04-01-drive3-mapping-pp.txt

https://drive.google.com/open?id=0B5X2nBadaPD1WFVVMENCUFVhMXM

Start TOW: 589523

End TOW: 589797

Outside Track

Data Type

Name

Link

Notes

Novatel Waypoint Text File

2017-04-01-drive3-mapping-pp.txt

https://drive.google.com/open?id=0B5X2nBadaPD1WFVVMENCUFVhMXM

Start TOW: 588569

End TOW: 588907

Centerline

Data Type

Name

Link

Notes

Novatel Waypoint Text File

2017-04-01-drive4-pp.txt

https://drive.google.com/open?id=0B5X2nBadaPD1bWh5bDdtSHRIaW8

Start TOW: 595821

End TOW: 595623

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