Introduction

This page deals with tracking parameters.

Contents

Overview

Every radar sensor is linked directly to its own Track Engine, whose job it is to process raw radar data into valid trackable targets. Every tracker contains two channels in order to efficiently monitor vehicles travelling in either direction along the carriageways. The output of each tracker channel is interpreted by Tracking Parameters that are customised to suit each carriageway direction. The tracking parameters are common modules that can be applied to tracker channels emanating from multiple radar sensors.

Tracking Parameters determine how the radar data that has been interpreted by the tracker is used to produce valid information about targets. Think of tracking parameters as a set of filters that determine how objects seen within that area are converted into valid targets to which logical rules can be applied. 

Type of Parameter

• Debris Detection

• Partial

• High Sensitivity 

• Medium Sensitivity 

• Low Sensitivity 

Open

Improving Tracking Performance

In order to determine and follow tracks, the system attempts to predict where each track will next be positioned based on the speed, direction and acceleration. The tracking parameters can be tuned to improve this process. In addition the parameters include settings that can alter size and amplitude thresholds to help filter out unwanted targets and hold onto important targets.

Tracking Parameter Configuration 

Open

Name: The name for this set of tracking parameters. 

User ID: A unique numeric identification that can be used for external control, associated with whomever uses or created the tracking parameter.

Min Coast Age (hits) / Max. Coast Age (hits): Defines the number of times the radar has to have seen the target before the coast value is applied. If min./max. are the same value, the coast will apply at this value. If they are different values, the coast amount will be set linearly as the target goes from minimum to maximum (and beyond). The concept is essentially that the older a track (the more sightings a track has had), the more it is trusted to a be an actual track, and more coast sightings can be applied before the track is deleted. In the example below, the first carriageway demonstrates the ability of a track value to change between seen and coasting if the minimum coast age is reached. In the second and third carriageways, a lost track with many previous sightings is awarded more coast track sightings before being discarded, and vice versa. 

Coasts (hits): Defines the number of times the radar will predict the position of a track that it can no longer see. If this is set to 2, then the tracker will maintain a track for 2 radar sensor rotations after losing it. This is to account for instances such as a vehicle being obscured by a gantry, and then emerging within a couple of radar rotations. The result is that the operator will not know that the track was temporarily obscured. 

Plot Amplitude ATI (pwr): Defines the threshold level required of a plot to be promoted to a track. This value will be set per tracking parameter, and can therefore be used to apply a different threshold per detection zone. This parameter is only activated if the Threshold Output parameter is set to Input Level within the tracker settings. 

Plot Amplitude Tracks (pwr): Determines the minimum power amplitude of the plot before it is considered for tracking. 

Min Plot Range Size (m): Determines the minimum size of the plot (in range metres) before it is considered for tracking. This process of rejection is similar to plot extraction in theTracker Settings (Radar Settings). However, this gives the opportunity to allow a plot through the plot extraction process, but discard it prior to use for tracking. 

Min Plot Azimuth Size (°): Determines the minimum size of the plot (in azimuth) before it is considered for tracking. This process of rejection is similar to plot extraction in the advanced tracker settings. However, this gives the opportunity to allow a plot through the plot extraction process but discard it prior to use for tracking.

Min Plot Weight ATI (cells): Determines the minimum number of cells (where a cell is a single power reading in either range or azimuth) before it is considered for Automatic Track Initiation (ATI).

Min Plot Weight Track (cells): Determines the minimum number of cells (where a cell is a single power reading in either range or azimuth) before it is considered for tracking.

Turn Rate (°): Determines the maximum expected turn rate of any target, in degrees, between sightings. 

Turn Acceleration (m/s²): Determines the maximum expected rate of change of speed during changes of direction.

Max Acceleration (m/s²):  Determines the maximum expected acceleration of any target at any point. Anything outside this parameter will not be tracked.

Min Tracking Speed (mph) / Max. Tracking Speed (mph): Determines the minimum and maximum expected speeds of targets during tracking. Anything outside these parameters will not be tracked. 

Clutter Hold Multiplier:

M (hits) and N (hits): these two values define the number of times a target must be seen within a given number of sensor rotations before it is considered to be a track.

a. M represents the number of times an object is seen. N represents the number of scans (sensor rotations).

b. The default values of M=3 and N=4 mean that an object must have been seen at least 3 times in 5 scans. If so, then the tracker creates it as a proper target track and shows it within the user interface.

c. If not, then the object remains provisional and is not sent to the user interface.

d. The lower this ratio, the more false alarms will be caused. Thus, a ratio of 2/5 will create more false alarms than say 4/5.

e. The maximum values for each are 30, however, the larger the numbers, the longer it will take for new targets to appear. 

Advanced Settings

Clutter Control: 

Clutter control is a process that will dynamically adjust the M & N ATI parameters that control how quickly we acquire a track. It uses the quantity of very short-lived tracks in each 10m2 area to decide if there are two many detections from clutter or noise. As the the number of detections increase this process will increase the M & N to make it harder to acquire tracks. This will reduce the number of false alarms. A good example of there this is process can be used is over water. The water state can change depending on environment and weather conditions and this process can dynamically adjust the ATI parameters to ensure we maintain a sensible false alarm rate in poor conditions.

Disabled - No clutter control is enabled.

Low - Clutter control is the least aggressive. The M & N parameters will be dynamically increased based on the level of clutter.

Medium - Clutter control is more aggressive. M & N parameters will be dynamically increased until it reaches the highest level of clutter where the ATI will be disabled.

High - This is even more aggressive. At both medium and highest level of clutter this mode will disable ATI.

ATI Off - In this mode any level of clutter will cause the ATI to be disabled.

Report As Lost: When this option is selected, any track which is deleted or dropped in a detection area will be reported as lost. Tracks that are deleted because they reach the edge of a detection area will not. You can search for tracks which have been lost to identify areas where tracking performance needs to be improved or to highlight line of sight problems.

Directional Mode: Determines whether tracks should be detected travelling both ways along a monitored area, such as a road. Generally, this is set to Unidirectional (with separate tracking parameters for the opposite sides of the road) as it helps to increase the efficiency of detection.

None - Do not use directional mode ATI. Normal ATI parameters will apply.

Unidirectional - This favours performing ATI in the specified direction. The direction is specified in degrees using Direction. ATI will be performed in the opposite direction but only for slow moving targets. The speed threshold is set using Max Tracking Speed Reverse (mph). Using Direction Error you can set a +/- value to allow a margin of error in the direction checking.

Bidirectional - This will favour ATI in the specified direction and the opposite direction. The direction is specified in degrees using Direction. This will work for targets of any speed in both directions. Using Direction Error you can set a +/- value to allow a margin of error in the direction checking.

Direction (°): Determines the overall angle of the monitored road, measured clockwise relative to North. (Displayed only when Directional Mode setting is Unidirectional or Bidirectional). 

Direction Error (°): This value establishes the tolerance of deviation from the stated angle of the monitored road within the Direction field. This tolerance is applied + and - to the direction value. (Displayed only when Directional Mode setting is Unidirectional or Bidirectional).

Max. Tracking Speed Reverse (mph): Defines the maximum expected speed that a target is expected to travel in the opposite direction from the norm. (Displayed only when Directional Mode setting is Unidirectional). 

Coast Mature Extension (s): This option will extend the amount of time a track will coast but only if the tracker considers the track to be genuine. This extension will only be activated after 20 scans and if the track is going slower than 10m/s or the track is moving faster but with a stable course. This setting configures the amount of time, in seconds, that the track will coast once these conditions are met.

Proximity Suppression: Please view .

Where Used

Name: Name of the entity that uses the tracking parameter.

ID: The Id of the entity that uses the tracking parameter. 

Type: The type of the entity that uses the tracking parameter.

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