Dead Reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and then incorporating estimations of speed, heading direction, and course over elapsed time. Knowledge about the vehicle's kinematic constraints (i.e. wheels on the ground) is applied to reduce drift and improve position estimation.

Inertial Sense has added dead reckoning capability to uINS to estimate position for extended periods of time during GNSS outages. In this report RTK-GNSS is used.

The following are examples dead reckoning of a car test vehicle. No wheel sensors were used in these examples. The dead reckoning position is shown in the yellow "INS" line and GNSS position in the red "GNSS" line.

## Parking Lot Simulated GNSS Outage¶

In this example GNSS outage was simulated by disabling GNSS fusion into the INS Kalman filter (EKF). This was done by setting the Disable Fusion - GPS1 option found in the General settings of the EvalTool app. By disabling GPS fusion and keeping fix, we can use the GNSS position as truth and compare it to the dead reckoning solution.

Max position error: 2.5 meters

In the drive the car starts and ends the drive at the bottom right corner of the image. The numbered path segments show the order of travel. GPS fusion was disabled in the middle of path segment 5.

When GNSS fusion is re-enabled, error in the INS solution is removed and the INS position estimate jumps back onto the GNSS position. There is 2.5m of error between the dead reckoning position and the GNSS position.

## Multi-Level Parking Garage¶

In this example our test vehicle drove in and out of a parking garage. The drive consisted of starting outside with GNSS fix, entering the garage (losing GNSS fix), driving up one level, parking, and then following the path back down and out of the garage where GNSS fix was regained.