View source for Dead Reckoning feature

=== <u>Introduction</u> ===
'''Dead Reckoning''' is a navigation technique used to estimate current position of vehicle   , direction of movement, based on its previous position and known speed.  It uses additional sensor data to correct the position received from GNSS receiver.<br>

Usage of Dead Reckoning is essential in scenarios where GNSS signal is weak or unavailable, such as underground parking lots, tunnels or dense forests.<br>

'''Note:''' Dead Reckoning is enabled for all FT platform devices with gyroscope. At the moment, it’s not possible to disable it.<br>

=== <u>Prerequisites</u> ===
Key points to understand before utilizing the Dead Reckoning functionality:
* Installation
* Configuration
* Alignment

'''<u>Installation</u>'''<br>

The device must be mounted firmly in the vehicle, with good visibility of the sky. Failure to ensure proper mounting will result in inability to calibrate the device or inaccurate position estimation. Following examples ensure that the GNSS antenna is facing towards the sky and there are no
physical obstacles, like metal plates,  wires, are blocking the GNSS signal.

Good '''mounting''' examples:<br>
<div style="display: flex; flex-direction: row;">
[[File:FTC927 under the front dashboard in the middle of the car.jpg|thumb|left|280px|Dashboard in the middle of the car mount]]
[[File:FTC927 beneath the speedometer panel.jpg|thumb|left|300px|Beneath the speedometer panel]]
[[File:FTC927 above the glove box.jpg|thumb|left|300px|Above glove box]]
</div>

Bad '''mounting'''  examples:<br>
<div style="display: flex; flex-direction: row;">
[[File:Dead Reckoning Unwanted movements will be detected by the IMU.png|thumb|left|280px|Unwanted movements will be detected by the IMU]]
[[File:Dead Reckoning Metal parts above the mount.png|thumb|left|300px|Metal parts above the mount]]
[[File:Dead Reckoning vibration could cause unwanted device movements.png|thumb|left|300px|Places, where vibration could cause unwanted device movements]]
</div>

'''<u>Configuration</u>'''<br>

[[File:Dead Recknonig TCT panel_2.png|right|500px]]

''The Dead Reckoning feature is configurable via the Dead Reckoning section in the GNSS settings group under System view in TCT.''

Parameter list can be found [[Template:FTX_System#Parameter_list|here]].

===== Dead Reckoning alignment status =====

The Dead Reckoning alignment status is a 1-byte AVL ID (1433) that indicates the current status of the Dead Reckoning alignment. The possible values are:<br>
* '''0''' - Unknown: Dead Reckoning status is unknown.
* '''1''' - Init: Dead Reckoning alignment is initializing.
* '''2''' - Coarse: Dead Reckoning is in alignment stage.
* '''3''' - Stable: Dead Reckoning alignment stage has been completed. Estimation stage is in progress.
* '''99''' - Standby: Dead Reckoning is in standby mode ('''NOTE''': this status is availabe with 3.7.X or newer firmware version)
<!--===== Turning alignment =====

The turning alignment is a 1-byte AVL ID ('''1434''') that indicates the current percentage of the turning alignment of the device.

===== Straight alignment =====

The straight alignment is a 1-byte AVL ID ('''1435''') that indicates the current percentage of the straight alignment of the device.
'''
===== Dead Reckoning realignment reason =====
The Dead Reckoning realignment reason is a 1-byte AVL ID ('''1473''') that indicates the reason for the Dead Reckoning realignment. The possible values are:
* '''-1''' or '''-2:''' GNSS cross check failed. The algorithm detected that the estimated position differs from the GNSS position vastly.
* '''-3''' or '''-4:''' Unexpected vibrations detected.
* '''-5:''' Unexpected rotation detected.
* '''-6:''' GNSS signal quality dropped before the alignment was completed.
* '''-7:''' Abnormal reversing action detected.-->


'''<u>Alignment</u>'''<br>
Once device mounting adheres to the guidelines, alignment can be performed. The device '''must finish''' a specific alignment process to '''determine''' its mounting orientation. During this process, there are specific conditions that must be met:
# The device must be '''stationary''' for at least 3 minutes.
# A great number of '''left and right''' turns must be performed.
# The speed of the vehicle '''ideally''' must not be bellow 10 km/h or exceed 50 km/h.
# Avoid driving in underground tunnels or areas with poor GNSS signal.
[[File:Dead Reckoning TCT Swift .png|right|400px]]

In order to speed up alignment at the cost of some accuracy, use '''Swift''' alignment.

<!--=== <u>How It Works</u> ===
//Dead Reckoning functionality consists of two stages:<br> 
//* '''Alignment stage''' - The algorithm tries to find the mounting orientation of the device.
* '''Estimation stage''' - The algorithm estimates the current position of the device based on IMU and ('''if available''') GNSS data.

'''<u>Alignment stage</u>'''
Before the algorithm can start estimating the position, it needs to calculate the mounting orientation of the device - this is called the '''alignment''' of IMU and vehicle frames. The result of the alignment is a set of angles that represent the orientation of the device in space, which is used to transform the IMU data into the vehicle frame during Estimation stage.<br>

Alignment is started automatically and constantly observes following parameters: <br>

* '''GNSS signal quality''' - The algorithm needs to have a good GNSS fix to calculate the mounting orientation. If during the alignment the signal quality drops below a certain threshold, the algorithm will trigger a realignment.
* '''IMU data''' - The algorithm constantly observes the received IMU data. If it detects that the device movement/rotation exceeded a certain threshold, it will trigger a realignment.<br>

'''Note:''' The Dead Reckoning alignment status AVL ID ('''1433''') will change from '''2''' (Coarse) to '''3''' (Stable). Positional data in records will contain Dead Reckoning data.

'''<u>Estimation stage</u>'''
Once the alignment stage is completed, the algorithm enters the estimation stage. The algorithm uses the IMU data to estimate the current position of the device, and if GNSS data is available, it uses it to correct the estimated position. The Dead Reckoning algorithm itself is based on the application of an extended Kalman filter (EKF), which operates in two main states:<br>

# '''Predict''' - The algorithm predicts the current position of the device using IMU sensor readings and the previously estimated position.
# '''Update''' - The predicted position is corrected using the calculated GNSS position from GNSS receiver.-->


=== <u>Limitations</u> ===
There are some important things to keep in mind when using the Dead Reckoning functionality. The algorithm tries to correct for these issues, but sometimes they can still affect how well Dead Reckoning works.

* '''Position accuracy may decrease''' - If the device cannot receive a GNSS signal for a long time, the estimated position may become less accurate. This is because the sensors inside the device can only estimate the position for a limited time without help from GNSS.
For example: If a courier spends up to 30 minutes unloading in the underground car park, DR will remain accurate. Otherwise, positioning information will become less accurate.
* '''Temperature effects''' - The accuracy of the position can change if the temperature is very different from when the device was last calibrated. .
* '''Alignment reset''' - If the device loses power or goes into sleep mode, it will need to be calibrated again.

'''Tip:''' If alignment auto-save is enabled, realignment will be faster.

* '''Position jumps after GNSS outages''' - After the device has been in an area with no GNSS signal for a while (such as near tall buildings or obstacles), you might notice sudden jumps in the position when the signal returns. This happens because the device uses the GNSS signal to correct its estimated position, and the type of GNSS signal used is more sensitive to interference from nearby objects.
* '''Stand by mode''' - This feature allows calibration data to be stored for unlimited time, meaning that Dead Reckoning will work accurately even if a week has passed while vehicle was left in underground parking. Functionality will be present in 3.7.X firmware version, so current solution is  limited and tracker will lose Dead Reckoning alignment after an hour has passed since ignition OFF event. If vehicle was parked for less than 1 hour, track might be slightly tilted, but if parking lasts more than an hour - GNSS fix needs to be re-acquired. This applies for above and underground parking.

=== <u>Parameter list</u> ===
<table class="nd-othertables_2" style="width:100%; border-collapse: collapse;">
<tr>
<th style="width:8%; vertical-align: middle; text-align: left;">Property ID in AVL packet</th>
<th style="width:15%; vertical-align: middle; text-align: center;">Property Name</th>
<th style="width:5%; vertical-align: middle; text-align: center;">Bytes</th>
<th style="width:10%; vertical-align: middle; text-align: center;">Min Value</th>
<th style="width:10%; vertical-align: middle; text-align: center;">Max Value</th>
<th style="width:5%; vertical-align: middle; text-align: center;">Multiplier</th>
<th style="width:5%; vertical-align: middle; text-align: center;">Units</th>
<th style="width:32%; vertical-align: middle; text-align: left;">Description</th>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1433</td>
<td style="vertical-align: middle; text-align: center;">Dead Reckoning alignment status</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">99</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">[[Dead_Reckoning_feature#Dead_Reckoning_alignment_status|Dead Reckoning alignment status]]</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1434</td>
<td style="vertical-align: middle; text-align: center;">Turning alignment</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">100</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">%</td>
<td style="vertical-align: middle; text-align: center;">[[Dead_Reckoning_feature#Turning_alignment|Turning alignment]]</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1435</td>
<td style="vertical-align: middle; text-align: center;">Straight alignment</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">100</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">%</td>
<td style="vertical-align: middle; text-align: center;">[[Dead_Reckoning_feature#Straight alignment|Straight alignment]]</td>
</tr>
<!--<tr>
<td style="vertical-align: middle; text-align: center;">1454</td>
<td style="vertical-align: middle; text-align: center;">Mounting angle - Z</td>
<td style="vertical-align: middle; text-align: center;">2</td>
<td style="vertical-align: middle; text-align: center;">-3600</td>
<td style="vertical-align: middle; text-align: center;">3600</td>
<td style="vertical-align: middle; text-align: center;">0.1</td>
<td style="vertical-align: middle; text-align: center;">°</td>
<td style="vertical-align: middle; text-align: center;">Device orientation in Z axis (yaw).</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1455</td>
<td style="vertical-align: middle; text-align: center;">Mounting angle - Y</td>
<td style="vertical-align: middle; text-align: center;">2</td>
<td style="vertical-align: middle; text-align: center;">-3600</td>
<td style="vertical-align: middle; text-align: center;">3600</td>
<td style="vertical-align: middle; text-align: center;">0.1</td>
<td style="vertical-align: middle; text-align: center;">°</td>
<td style="vertical-align: middle; text-align: center;">Device orientation in Y axis (pitch).</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1456</td>
<td style="vertical-align: middle; text-align: center;">Mounting angle - X</td>
<td style="vertical-align: middle; text-align: center;">2</td>
<td style="vertical-align: middle; text-align: center;">-3600</td>
<td style="vertical-align: middle; text-align: center;">3600</td>
<td style="vertical-align: middle; text-align: center;">0.1</td>
<td style="vertical-align: middle; text-align: center;">°</td>
<td style="vertical-align: middle; text-align: center;">Device orientation in X axis (roll).</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1457</td>
<td style="vertical-align: middle; text-align: center;">Device position - X</td>
<td style="vertical-align: middle; text-align: center;">2</td>
<td style="vertical-align: middle; text-align: center;">-32768</td>
<td style="vertical-align: middle; text-align: center;">32767</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">m</td>
<td style="vertical-align: middle; text-align: center;">Linear displacement in X axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1458</td>
<td style="vertical-align: middle; text-align: center;">Device position - Y</td>
<td style="vertical-align: middle; text-align: center;">2</td>
<td style="vertical-align: middle; text-align: center;">-32768</td>
<td style="vertical-align: middle; text-align: center;">32767</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">m</td>
<td style="vertical-align: middle; text-align: center;">Linear displacement in Y axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1459</td>
<td style="vertical-align: middle; text-align: center;">Device position - Z</td>
<td style="vertical-align: middle; text-align: center;">2</td>
<td style="vertical-align: middle; text-align: center;">-32768</td>
<td style="vertical-align: middle; text-align: center;">32767</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">m</td>
<td style="vertical-align: middle; text-align: center;">Linear displacement in Z axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1460</td>
<td style="vertical-align: middle; text-align: center;">Fusion timestamp</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Fusion timestamp.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1461</td>
<td style="vertical-align: middle; text-align: center;">Fusion status</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">255</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Fusion status.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1462</td>
<td style="vertical-align: middle; text-align: center;">Sum of accelerometer axes std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Sum of accelerometer axes standard deviation.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1463</td>
<td style="vertical-align: middle; text-align: center;">Sum of gyroscope axes std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Sum of gyroscope axes standard deviation.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1464</td>
<td style="vertical-align: middle; text-align: center;">Accelerometer X axis std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Standard deviation of accelerometer readings along x axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1465</td>
<td style="vertical-align: middle; text-align: center;">Accelerometer Y axis std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Standard deviation of accelerometer readings along y axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1466</td>
<td style="vertical-align: middle; text-align: center;">Accelerometer Z axis std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Standard deviation of accelerometer readings along z axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1467</td>
<td style="vertical-align: middle; text-align: center;">Gyroscope X axis std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Standard deviation of gyroscope readings along x axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1468</td>
<td style="vertical-align: middle; text-align: center;">Gyroscope Y axis std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Standard deviation of gyroscope readings along y axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1469</td>
<td style="vertical-align: middle; text-align: center;">Gyroscope Z axis std</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">0</td>
<td style="vertical-align: middle; text-align: center;">4294967295</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">Standard deviation of gyroscope readings along z axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1470</td>
<td style="vertical-align: middle; text-align: center;">Acceleration X axis</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">-2147483648</td>
<td style="vertical-align: middle; text-align: center;">2147483647</td>
<td style="vertical-align: middle; text-align: center;">0.000001</td>
<td style="vertical-align: middle; text-align: center;">m/s^2</td>
<td style="vertical-align: middle; text-align: center;">Acceleration in x axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1471</td>
<td style="vertical-align: middle; text-align: center;">Acceleration Y axis</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">-2147483648</td>
<td style="vertical-align: middle; text-align: center;">2147483647</td>
<td style="vertical-align: middle; text-align: center;">0.000001</td>
<td style="vertical-align: middle; text-align: center;">m/s^2</td>
<td style="vertical-align: middle; text-align: center;">Acceleration in y axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1472</td>
<td style="vertical-align: middle; text-align: center;">Acceleration Z axis</td>
<td style="vertical-align: middle; text-align: center;">4</td>
<td style="vertical-align: middle; text-align: center;">-2147483648</td>
<td style="vertical-align: middle; text-align: center;">2147483647</td>
<td style="vertical-align: middle; text-align: center;">0.000001</td>
<td style="vertical-align: middle; text-align: center;">m/s^2</td>
<td style="vertical-align: middle; text-align: center;">Acceleration in z axis.</td>
</tr>
<tr>
<td style="vertical-align: middle; text-align: center;">1473</td>
<td style="vertical-align: middle; text-align: center;">Dead Reckoning realignment reason</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;">-128</td>
<td style="vertical-align: middle; text-align: center;">127</td>
<td style="vertical-align: middle; text-align: center;">1</td>
<td style="vertical-align: middle; text-align: center;"> </td>
<td style="vertical-align: middle; text-align: center;">[[Dead_Reckoning_feature#Dead_Reckoning_realignment_reason|Dead Reckoning realignment reason]]</td>
</tr>-->
</table>

[[Category:Frequently Asked Questions - FAQ]]