373. Crash checker

The crash_checker uses the upon_w watcher operator to trigger a crash interval when a collision event is detected between two physical objects in the simulation.

373.0.1 Start condition

The crash_checker monitors all physical objects in the simulation and raises issues when collisions occur between them.

373.0.2 End condition

The crash_checker creates a zero-time interval for every detected collision. This interval starts and ends in the same simulation step, meaning it ends instantly at the moment of collision without requiring a separate end condition.

373.1 Attributes

The following attributes define the behavior and characteristics of the evaluator.

Checker attribute	Description
Parent object	`physical_object.global_checkers`
Issue category	`sut` or `other`
Issue kind	`collision_in_hybrid_control`, `collision_in_sut_control`, `collision_in_manual_control`
Default severity	error
Trigger condition	Based on `upon_w` watcher

373.2 Configuration parameters

No configuration parameters found.

373.3 Metrics

The following metrics are recorded and tracked by the evaluator.

Metric item	Unit / Type	Description
`side`	enum (`front`, `front_left`, `left`, `back_left`, `back`, `back_right`, `right`, `front_right`, `other`)	Side of object on which the collision happened
`other_side`	enum (`front`, `front_left`, `left`, `back_left`, `back`, `back_right`, `right`, `front_right`, `other`)	Side of other object on which the collision happened
`velocity`	kph	Longitudinal velocity at collision, in local coordinate system
`other_velocity`	kph	Longitudinal velocity at collision of the other object, in local coordinate system
`acceleration`	mpsps	Longitudinal acceleration at collision, in local coordinate system
`other_acceleration`	mpsps	Longitudinal acceleration of the other object at collision, in local coordinate system
`delta_v`	kph	Delta-V between this object and the other object it collided with (kph). Relevant only for a collision between two vehicles. In case one of the objects is not a vehicle, the recorded value is -1kph.
`pdof`	degree	PDOF between this object and the other object it collided with. Relevant only for a collision between two vehicles. If one of the objects is not a vehicle, the recorded value is -999degree.
`pdof_side`	enum (`front`, `rear`, `left`, `right`, `not_applicable`)	PDOF side for this object
`crash_severity`	enum (`S0`, `S1`, `S2`, `S3`, `not_applicable`)	Individual crash severity for this object involved in the collision. Relevant only for a collision between two vehicles. If one of the objects is not a vehicle, the recorded value is not_applicable.
`other_crash_severity`	enum (`S0`, `S1`, `S2`, `S3`, `not_applicable`)	Individual crash severity for other object involved in the collision. Relevant only for a collision between two vehicles. If one of the objects is not a vehicle, the recorded value is not_applicable.
`overall_crash_severity`	enum (`S0`, `S1`, `S2`, `S3`, `not_applicable`)	Overall crash severity computed between this_object and other_object. Relevant only for a collision between two vehicles. In case one of the objects is not a vehicle, the recorded value is not_applicable.
`other_category`	enum (`car`, `bus`, `truck`, `trailer`, `bicycle`, `motorcycle`, `person`, `animal`, `other`)	Category of the other object

373.4 Log and Error Messages

No error messages found.

373.5 Additional information

Collision targeting

For compound objects (e.g., truck, trailer), the this_object field identifies the specific part impacted.

Delta-V metrics
- Vehicles: Contains the calculated Delta-V value.
- Non-vehicles: Set to -1kph.
Disabling options
- Global: Disable for all objects
OSC2 code: disable crash globally
```
extend physical_object.global_checkers:
on @start:
    override(crash, run_mode: freeze)
```
- Selective: Disable by object subtypes, for example NPCs
OSC2 code: disable crash for subtype npc vehicles
```
extend npc_vehicle.global_checkers:
on @start:
    override(crash, run_mode: freeze)
```
See Metrics examples for the full examples.

Severity control

Use set_issue() to:

Downgrade all crash issues

OSC2 code: downgrade all crash issues

extend physical_object.global_checkers:
set_issue(target_checker: crash, severity: warning)

See Metrics examples for the full examples.

Conditionally modify severity levels

OSC2 code: conditionally downgrade collision issues

extend physical_object.global_checkers:
set_issue(target_checker: crash, severity: warning,
    # In the context of set_issue(), 'it' refers to the 'data' object of the checker
    condition: it.this_object.is(sut_vehicle) and it.other_object.is(npc_vehicle))

See Metrics examples for the full examples.

Issue classification

Issues are tagged by the controller at impact:
- collision_in_hybrid_control
- collision_in_sut_control
- collision_in_manual_control