Traffic Components
This section
This section is still under development!
This is a section that describes in detail all components related to simulated traffic in the Environment
prefab.
Architecture#
The random traffic system consists of the following components:
-
It is a top level interface meant to be used on the Unity scene.
TrafficManager
runs all elements needed for a successful traffic simulation. This component manages allTrafficSimulators
so they don't work against each other. It gives you the possibility to configure theTrafficSimulators
.
-
TrafficSimulator
Technically it is not a component, it is crucial to understand what it is and what it does in order to correctly configure the
TrafficManager
.TrafficSimulator
managesNPCVehicles
spawning. There can be manyTrafficSimulators
on the scene. They are added and configured in theTrafficManager
component. EveryTrafficSimulator
manages some part of the traffic it is responsible for - meaning it has spawned theNPCVehicles
and set their configuration.RandomTrafficSimulator
- spawns and controlsNPCVehicles
driving randomlyRouteTrafficSimulator
- spawns and controlsNPCVehicles
driving on a defined route
TrafficSimulator inaccessibility
It is not possible to get direct access to the
TrafficSimulator
. It should be added and configured through theTrafficManager
component.
-
TrafficLane
,TrafficIntersection
andStopLine
These components represent traffic entities. They are used to control and manage the traffic with respect to traffic rules and current road situation.
-
The vehicle models (NPCs) spawned by one of the
TrafficSimulators
. They are spawned according to theTrafficSimulator
configuration and either drive around the map randomly (when spawned by aRandomTrafficSimulator
) or follow the predefined path (when spawned by aRouteTrafficSimulator
).NPCVehicles
are managed by one central knowledge base.
The process of spawning a NPCVehicle
and its later behavior control is presented on the following sequence diagram.
Sequence Diagram Composition
Please note that the diagram composition has been simplified to the level of GameObjects and chosen elements of the GameObjects for the purpose of improving readability.
Lanelet2#
Lanelet2 is a library created for handling a map focused on automated driving.
It also supports ROS and ROS2 natively.
In AWSIM Lanelet2 is used for reading and handling a map of all roads.
Specifically it does contain all TrafficLanes
and StopLines
.
You may also see us referring to the actual map data file (*.osm
) as a Lanelet2.
Lanelet2 official page
If you want to learn more we encourage to visit the official project page.
RandomTrafficSimulator#
Nomenclature
Please note that
are named RandomTrafficSimulator
.
Keep this in mind when reading the following page - so you don't get confused.
RandomTrafficSimulator
simulates traffic with respect to all traffic rules. The system allows for random selection of car models and the paths they follow. It also allows adding static vehicles in the simulation.
Link in the default Scene#
The RandomTrafficSimulator
consists of several GameObjects.
RandomTrafficSimulator
- this is an Object consisting of a Traffic Manager (script).
You can learn more about it here.TrafficIntersections
- this is a parent Object for allTrafficIntersections
.
You can learn more about it here.TrafficLanes
- this is a parent Object for allTrafficLanes
.
You can learn more about it here.StopLines
- this is a parent Object for allStopLines
.
You can learn more about it here.
Components#
RandomTrafficSimulator
only has one component: Traffic Manager (script) which is described below.
TrafficManager (script)#
Traffic Manager (script) is responsible for all of top level management of the NPCVehicles
.
It managed spawning of NPCVehicles
on TrafficLanes
.
TrafficManager
uses the concept of TrafficSimulators
.
One TrafficSimulator
is responsible for managing its set of NPCVehicles
.
Every TrafficSimulator
spawns its own NPCVehicles
independently.
The vehicles spawned by one TrafficSimulator
do respect its configuration.
TrafficSimulators
can be interpreted as NPCVehicle
spawners with different configurations each.
Many different TrafficSimulators
can be added to the TrafficManager
.
If a random mode is selected (RandomTrafficSimulator
) then NPCVehicles
will spawn in random places (from the selected list) and drive in random directions.
To be able to reproduce the behavior of the RandomTrafficSimulator
a Seed
can be specified - which is used for the pseudo-random numbers generation.
TrafficManager
script also configures all of the spawned NPCVehicles
, so that they all have common parameters
Acceleration
- the acceleration used by the vehicles at all times when accelerating.Deceleration
- the value of deceleration used in ordinary situations.Sudden Deceleration
- deceleration used when standardDeceleration
is not sufficient to avoid accident.Absolute Deceleration
- value of deceleration used when no other deceleration allows to avoid the accident.
The Vehicle Layer Mask
and Ground Layer Mask
are used to make sure all vehicles can correctly interact with the ground to guarantee simulation accuracy.
Max Vehicle Count
specifies how many NPCVehicles
can be present on the scene at once.
When the number of NPCVehicles
on the scene is equal to this value the RandomTrafficSimulator
stops spawning new vehicles until some existing vehicles drive away and disappear.
The EgoVehicle
field provides the information about Ego vehicle used for correct behavior ofNPCVehicles
when interacting with Ego.
Show Gizmos
checkbox specifies whether the Gizmos visualization should be displayed when running the simulation.
Show Yielding Phase
checkbox specifies whether yielding phases should be displayed by Gizmos - in the form of spheres above vehicles, details in the Markings section.
Show Obstacle Checking
checkbox specifies whether obstacle checking should be displayed by Gizmos - in the form of boxes in front of vehicles
Show Spawn Points
checkbox specifies whether spawn points should be displayed by Gizmos - in the form of flat cuboids on roads.
Gizmos performance
Gizmos have a high computational load. Enabling them may cause the simulation to lag.
As mentioned earlier - TrafficManager
may contain multiple TrafficSimulators
.
The two available variants of TrafficSimulator
are described below
TrafficSimulators
should be interpreted as spawning configurations for some group of NPCVehicles
on the scene.
Random Traffic#
When using RandomTrafficSimulator
the NPCVehicle
prefabs (NPC Prefabs) can be chosen as well as Spawnable Lanes.
The later are the only TrafficLanes
on which the NPCVehicles
can spawn.
Upon spawning one of the Spawnabe Lanes is chosen and - given the vehicle limits are not reached - one random NPCVehicle from the Npc prefabs list is spawned on that lane.
After spawning, the NPCVehicle takes a random route until it drives out of the map - then it is destroyed.
The Maximum Spawns
field specifies how many Vehicles should be spawned before this TrafficSimulator
stops working.
Set to 0
to disable this restriction.
Route Traffic#
When using Route traffic Simulator
the NPCVehicle
prefabs (NPC Prefabs) as well as Route can be chosen.
The later is an ordered list of TrafficLanes
that all spawned vehicles will drive on.
Given the vehicle limit is not reached - the RouteTrafficSimulator
will spawn one of the Npc Prefabs chosen randomly on the first Route element (Element 0
).
After the first vehicle drives off the next one will spawn according to the configuration.
It is important for all Route elements to be connected and to be arranged in order of appearance on the map.
The NPCVehicle disappears after completing the Route.
The Maximum Spawns
field specifies how many Vehicles should be spawned before this TrafficSimulator
stops working.
Set to 0
to disable this restriction.
Parameter explanation#
Parameter | Description |
---|---|
General Settings | |
Seed | Seed value for random generator |
Ego Vehicle | Transform of ego vehicle |
Vehicle Layer Mask | LayerMask that masks only vehicle(NPC and ego) colliders |
Ground Layer Mask | LayerMask that masks only ground colliders of the map |
Culling Distance | Distance at which NPCs are culled relative to EgoVehicle |
Culling Hz | Culling operation cycle |
NPCVehicle Settings | |
Max Vehicle Count | Maximum number of NPC vehicles to be spawned in simulation |
NPC Prefabs | Prefabs representing controlled vehicles. They must have NPCVehicle component attached. |
Spawnable Lanes | TrafficLane components where NPC vehicles can be spawned during traffic simulation |
Vehicle Config | Parameters for NPC vehicle controlSudden Deceleration is a deceleration related to emergency braking |
Debug | |
Show Gizmos | Enable the checkbox to show editor gizmos that visualize behaviours of NPCs |
Traffic Light (script)#
Traffic Light (script) is a component added to every TrafficLight
on the scene.
It is responsible for configuring the TrafficLight
behavior - the bulbs and their colors.
The Renderer
filed points to the renderer that should be configured - in this case it is always a TrafficLight
renderer.
Bulbs Emission Config
is a list describing available colors for this Traffic Light.
Every element of this list configures the following
Bulb Color
- the name of the configured color that will be used to reference this colorColor
- the actual color with which a bulb should light upIntensity
- the intensity of the colorExposure Weight
- how bright should the color be when lighting up
The Bulb Material Config
is a list of available bulbs in a given Traffic Light.
Every element describes a different bulb.
Every bulb has the following aspects configured
Bulb Type
- the name that will be usd to reference the configured bulbMaterial Index
- The index of a material of the configured bulb. This is an index of a sub-mesh of the configured bulb in the Traffic Light mesh. The material indices are described in detail here and here.
TrafficIntersections#
TrafficIntersection
is a representation of a road intersection.
It consists of several components.
TrafficIntersection
is used in the Scene
for managing TrafficLights
.
All Traffic Lights present on one Traffic Intersection
must be synchronized - this is why the logic of TrafficLight
operation is included in the TrafficIntersection
.
Link in the default Scene#
Every TrafficIntersection
has its own GameObject and is added as a child of the aggregate TrafficIntersections
Object.
TrafficIntersections
are elements of an Environment
, so they should be placed as children of an appropriate Environment
Object.
Components#
TrafficIntersection
has the following components:
- Box Collider - marks the area of the Traffic Intersection, it should cover the whole intersection area
- Traffic Intersection (script) - controls all Traffic Lights on the given intersection according to the configuration
Collider#
Every TrafficIntersection
contains a Box Collider element.
It needs to accurately cover the whole area of the TrafficIntersection
.
Box Collider - together with the Traffic Intersection (script) - is used for detecting vehicles entering the TrafficIntersection
.
Traffic Intersection (script)#
Traffic Intersection (script) is used for controlling all TrafficLights
on a given intersection.
The Collider Mask
field is a mask on which all Vehicle Colliders are present.
It - together with Box Collider - is used for keeping track of how many Vehicles are currently present on the Traffic Intersection.
The Traffic Light Groups
and Lighting Sequences
are described below.
Traffic Light Groups#
Traffic Light Group
is a collection of all Traffic Lights
that are in the same state at all times.
This includes all redundant Traffic Lights
shining in one direction as well as the ones in the opposite direction.
In other words - as long as two Traffic Lights
indicate exactly the same thing they should be added to the same Traffic Light Group
.
This grouping simplifies the creation of Lighting Sequences
.
Lighting Sequences#
Lighting Sequences
is the field in which the whole intersection Traffic Lights
logic is defined.
It consists of many different Elements.
Each Element is a collection of Orders that should take an effect for the period of time specified in the Interval Sec
field.
Lighting Sequences
Elements are executed sequentially, in order of definition and looped - after the last element sequence goes back to the first element.
The Group Lighting Orders
field defines which Traffic Light Groups
should change their state and how.
For every Group Lighting Orders
Element the Traffic Lights Group
is specified with the exact description of the goal state for all Traffic Lights in that group - which bulb should light up and with what color.
One Lighting Sequences
Element has many Group Lighting Orders
, which means that for one period of time many different orders can be given.
E.g. when Traffic Lights
in one direction change color to green - Traffic Lights
in the parallel direction change color to red.
Traffic Light state persistance
If in the given Lighting Sequences
Element no order is given to some Traffic Light Group - this Group will keep its current state.
When the next Lighting Sequences
Element activates - the given Traffic Light Group
will remain in an unchanged state.
Lighting Sequence Sample - details
Description | Editor |
Traffic Lights in Pedestrian Group 1 change color to flashing green. Other Groups keep their current state. This state lasts for 5 seconds. |
|
Traffic Lights in Pedestrian Group 1 change color to solid red. Other Groups keep their current state. This state lasts for 1 second. |
|
Traffic Lights in Vehicle Group 1 change color to solid yellow. Other Groups keep their current state. This state lasts for 5 seconds. |
|
Traffic Lights in Vehicle Group 1 change color to solid red. Other Groups keep their current state. This state lasts for 3 seconds. |
|
Traffic Lights in Vehicle Group 2 change color to solid green. Traffic Lights in Pedestrian Group 2 change color to solid green. Other Groups keep their current state. This state lasts for 15 seconds. |
|
Traffic Lights in Pedestrian Group 2 change color to flashing green. Other Groups keep their current state. This state lasts for 5 seconds. |
|
Traffic Lights in Pedestrian Group 2 change color to solid red. Other Groups keep their current state. This state lasts for 1 second. |
|
Traffic Lights in Vehicle Group 2 change color to solid yellow. Other Groups keep their current state. This state lasts for 5 seconds. |
|
Traffic Lights in Vehicle Group 2 change color to solid red. Other Groups keep their current state. This state lasts for 3 second. Sequence loops back to the first element of the list. |
TrafficLanes#
TrafficLane
is a representation of a short road segment.
It consists of several waypoints that are connected by straight lines.
TrafficLanes
are used as a base for a RandomTrafficSimulator.
They allow NPCVehicles
to drive on the specific lanes on the road and perform different maneuvers with respect to the traffic rules.
TrafficLanes create a network of drivable roads when connected.
Link in the default Scene#
Every TrafficLane
has its own GameObject and is added as a child of the aggregate TrafficLanes
Object.
TrafficLanes
are an element of an Environment
, so they should be placed as children of an appropriate Environment
Object.
TrafficLanes
can be imported from the lanelet2 *.osm
file.
Components#
TrafficLane
consists of an Object containing Traffic Lane (script).
TrafficLane
has a transformation property - as every Object in Unity - however it is not used in any way.
All details are configured in the Traffic Lane (script), the information in Object transformation is ignored.
Traffic Lane (script)#
Traffic Lane (script) defines the TrafficLane
structure.
The Waypoints
field is an ordered list of points that - when connected with straight lines - create a TrafficLane
.
Traffic Lane (script) coordinate system
Waypoints
are defined in the Environment
coordinate system, the transformation of GameObject is ignored.
Turn Direction
field contains information on what is the direction of this TrafficLane
- whether it is a right or left turn or straight road.
Traffic lanes are connected using Next Lanes
and Prev Lanes
fields.
This way individual TrafficLanes
can create a connected road network.
One Traffic Lane can have many Next Lanes
and Prev Lanes
.
This represents the situation of multiple lanes connecting to one or one lane splitting into many - e.g. the possibility to turn and to drive straight.
Right Of Way Lanes are described below.
Every TrafficLane
has to have a Stop Line
field configured when the Stop Line is present on the end of the TrafficLane
.
Additionally the Speed Limit
field contains the highest allowed speed on given TrafficLane
.
Right Of Way Lanes#
Right Of Way Lanes
is a collection of TrafficLanes
.
Vehicle moving on the given TrafficLane
has to give way to all vehicles moving on every Right Of Way Lane
.
It is determined based on basic traffic rules.
Setting Right Of Way Lanes
allows RandomTrafficSimulator
to manage all NPCVehicles
so they follow traffic rules and drive safely.
In the Unity editor - when a TrafficLane
is selected - aside from the selected TrafficLane
highlighted in blue, all Right Of Way Lanes
are highlighted in yellow.
Right Of Way Lanes Sample - details
The selected TrafficLane
(blue) is a right turn on an intersection.
This means, that before turning right the vehicle must give way to all vehicles driving from ahead - the ones driving straight as well as the ones turning left.
This can be observed as TrafficLanes
highlighted in yellow.
StopLines#
StopLine
is a representation of a place on the road where vehicles giving way to other vehicles should stop and wait.
They allow RandomTrafficSimulator
to manage NPCVehicles
in safe and correct way - according to the traffic rules.
All possible locations where a vehicle can stop in order to give way to other vehicles - that are enforced by an infrastructure, this does not include regular lane changing - need to be marked with StopLines
.
Link in the default Scene#
Every StopLine
has its own GameObject and is added as a child of the aggregate StopLines
Object.
Stop Lines are an element of an Environment
, so they should be placed as children of an appropriate Environment
Object.
StopLines
can be imported from the lanelet2 *.osm
file.
Components#
StopLine
consists of an Object containing Stop Line (script).
Stop Line has a transformation property - as every Object in Unity - however it is not used in any way. All details are configured in the Traffic Lane (script), the information in Object transformation is ignored.
Stop Line (script)#
Stop Line (script) defines StopLine
configuration.
The Points
field is an ordered list of points that - when connected - create a StopLine
.
The list of points should always have two elements that create a straight StopLine
.
Stop Line (script) coordinate system
Points
are defined in the Environment coordinate system, the transformation of GameObject is ignored.
The Has Stop Sign
field contains information whether the configured StopLine
has a corresponding StopSign
on the scene.
Every Stop Line needs to have a Traffic Light
field configured with the corresponding Traffic Light
.
This information allows the RandomTrafficSimulator
to manage the NPCVehicles
in such a way that they respect the Traffic Lights and behave on the Traffic Intersections
correctly.
Gizmos#
Gizmos are a in-simulation visualization showing current and future moves of the NPCVehicles
.
They are useful for checking current behavior of NPCs and its causes.
On the Scene they are visible as cuboid contours indicating which TrafficLanes will be taken by each vehicle in the near future.
Gizmos computing
Gizmos have a high computational load. Please disable them if the simulation is laggy.