Context Gamma Planner (Experimental)

Warning

Context Gamma Planner is currently experimental. The interface and behavior may change without notice. For production use, we recommend using a mature, existing planner.

Overview

In the current scenario simulator, NPCs cannot proactively avoid dynamic objects around them. For example, a pedestrian NPC cannot continue moving by avoiding a vehicle even if it detects one ahead. Context Gamma Planner integrates the ORCA (Optimal Reciprocal Collision Avoidance) algorithm into NPC locomotion logic to enable dynamic obstacle avoidance.

How to Run the Sample

The sample scenario parked_at_crosswalk covers a pedestrian crossing a crosswalk. It lets you quickly compare the behavior of the conventional planner with that of Context Gamma.

ros2 launch cpp_mock_scenarios mock_test.launch.py \
    scenario:=parked_at_crosswalk \
    launch_rviz:=true timeout:=120.0

How to Customize a Scenario

To enable the Context Gamma Planner in a C++ scenario, simply pass traffic_simulator::PedestrianBehavior::contextGamma() as the 4th argument to the NPC creation function api_.spawn(). Support for OpenSCENARIO scenarios is described below.

Example from the parked_at_crosswalk scenario:

api_.spawn(
  "bob_gamma",
  traffic_simulator::helper::constructCanonicalizedLaneletPose(34378, 0.0, 0.0),
  getPedestrianParameters(),
  traffic_simulator::PedestrianBehavior::contextGamma()
);

There may be cases where you don’t want a specific NPC to be affected by “consideration” (reciprocal avoidance). In that case, add __CONTEXT_GAMMA_IGNORE__ to the NPC’s name.

Example from the parked_at_crosswalk scenario:

api_.spawn(
  "__CONTEXT_GAMMA_IGNORE__bob_normal",
  traffic_simulator::helper::constructCanonicalizedLaneletPose(34378, 0.0, 0.0),
  getPedestrianParameters()
);

Using Context Gamma Planner with OpenSCENARIO

When authoring an OpenSCENARIO scenario, assign the context_gamma_planner/PedestrianPlugin controller to the pedestrian entity so it uses the Context Gamma Planner:

      - name: npc
        Pedestrian:
          name: ''
          mass: 60
          model: ""
          pedestrianCategory: pedestrian
          BoundingBox:
            Center: { x: 0, y: 0, z: 1 }
            Dimensions: { width: 0.8, length: 0.8, height: 2 }
          Properties:
            Property: []
        ObjectController:
          Controller:
            name: 'context_gamma_planner/PedestrianPlugin'
            Properties:
              Property: []

Known Limitations

• Currently supports pedestrians only.