In high dynamic applications, an understanding of both your position and motion in the world is necessary. But how do you design a GNSS receiver to be responsive to motion?
SPAN® technology from Hexagon | NovAtel® combines GNSS and Inertial Navigation Systems (INS) for a holistic understanding of your location and movement in the world. We demonstrated this combined GNSS+INS system in our 2019 wingsuit testing.
The GNSS+INS enclosure was strapped to our skydiving engineer to monitor his heading, velocity, and attitude.
During the wingsuit test, we strapped a PwrPak7D-E2 to our skydiving engineer Andrew Levson. As he jumped out of the plane at 10,000 feet, the small enclosure observed and tracked Andrew’s movements, including several aerial maneuvers.
The PwrPak7D-E2 enclosure includes an OEM7720 multi-frequency, dual antenna receiver tightly–coupled with an Inertial Measurement Unit (IMU) from Epson.
With a high data frequency rate, the enclosure quickly observes and collects satellite positioning and inertial movement data that can be used for post-processing.
Through the tight coupling of the GNSS receiver and IMU, the PwrPak7D-E2 delivered excellent performance in this highly dynamic testing environment.
Combining GNSS and INS Positioning
What makes GNSS and INS technologies so compatible?
GNSS receivers track your position through either pseudorange or carrier phase measurements and your line-of-sight to at least four satellites. These calculations determine where you were when your receiver could receive measurements from GNSS satellites. But, if your receiver is unable to see at least four satellites, your position can be inaccurate or undetermined.
Conversely, the INS uses gyroscopes within IMUs to calculate your direction, speed and attitude. Within a three-dimensional space, an INS reads your movement. However, without an external reference point, these readings do not provide an accurate position in the world.
GNSS and satellite calculations measure our absolute position, while INS readings understand our orientation in the world. Episode five of our on-demand webinar series on GNSS technologies goes into further detail about INS, as well as use-cases for these technologies.
For the PwrPak7D-E2, its GNSS+INS integration is tightly-coupled. This describes how the INS filter uses GNSS measurements. Through this tight-coupling, the GNSS+INS system can still provide an accurate solution even when the system does not have line-of-sight to four satellites, and the INS can use the satellite positioning to constrain potential inertial drift. This responsive solution provides continuous measurements of three-dimensional position, velocity and attitude in highly dynamic environments.
See Tightly-Coupled GNSS+INS in Action
When engineer and experienced wingsuit diver Andrew Levson jumped out of an airplane with the PwrPak7D-E2, he performed several aerial maneuvers to determine the tightly-coupled enclosure’s sensitivity to dynamic changes in motion.
As we described in this past blog post, the three aerial maneuvers included the S-Turn, the Dart and the Reverse Immelmann. As Andrew performed the maneuvers, the PwrPak7D-E2 captured precise movement, velocity and attitude data.
Our 360° video lets the viewer experience the same dynamic environment as our equipment. For the optimal experience, you can watch the video with a VR headset, or on a horizontal mobile device; you’ll be able to move the device around for a full 360° view of the skydive. If watching on desktop, use your mouse to change your view in any direction.
How SPAN Technology Performed in a Highly Dynamic Environment
The data our team collected was aggregated and analyzed in post-processing software. Our data presentation compares our expectations with the real data, and our conclusions for how GNSS+INS performs in highly dynamic environments.
Watch our full data presentation on this experiment to continue learning how GNSS+INS performs in dynamic environments