Implementation:CARLA simulator Carla RssSensor

Knowledge Sources	CARLA
Domains	Safety, Sensors, RSS
Last Updated	2026-02-15 05:00 GMT

Overview

RssSensor is a client-side sensor implementation that manages the lifecycle of RSS (Responsibility-Sensitive Safety) checks within the CARLA simulation, integrating map initialization, tick-based processing, and callback management.

Description

The RssSensor class extends carla::client::Sensor and orchestrates the RSS safety checking pipeline. Key responsibilities include:

• Map initialization -- On Listen(), the sensor retrieves the OpenDRIVE map content and initializes the AD Map Access library with intersection and traffic light type configurations. A global atomic counter (_global_map_initialization_counter_) tracks how many sensors have initialized the map to ensure proper cleanup.
• Vehicle parameter extraction -- Automatically extracts the maximum steering angle from the parent vehicle's physics control (wheel parameters) for RSS computations.
• Actor constellation callback registration -- Supports registering a custom ActorConstellationCallbackFunctionType before listening begins via RegisterActorConstellationCallback. If no callback is registered, a default RssCheck instance is created.
• Tick-based processing -- Subscribes to the episode's tick event and calls TickRssSensor each frame with the current timestamp and user callback, protected by a _processing_lock mutex.
• Lifecycle management -- Stop() unsubscribes from tick events, resets the RssCheck instance under a scoped lock, and decrements the global map counter (cleaning up the map when the last sensor stops).
• Log level control -- SetLogLevel and SetMapLogLevel delegate to the underlying RssCheck instance.

Usage

Attach an RssSensor to a vehicle actor, optionally register a custom actor constellation callback, then call Listen() with a response callback. The sensor will automatically perform RSS checks each tick and invoke the callback with RSS response data.

Code Reference

Source Location

• Repository: CARLA
• File: LibCarla/source/carla/rss/RssSensor.cpp (378 lines)

Signature

namespace carla {
namespace client {

class RssSensor : public Sensor {
public:
  using ActorConstellationCallbackFunctionType =
      rss::RssCheck::ActorConstellationCallbackFunctionType;

  RssSensor(ActorInitializer init);
  ~RssSensor();

  void RegisterActorConstellationCallback(ActorConstellationCallbackFunctionType callback);
  void Listen(CallbackFunctionType callback);
  void Stop();

  void SetLogLevel(const uint8_t &log_level);
  void SetMapLogLevel(const uint8_t &map_log_level);

private:
  static std::atomic_uint _global_map_initialization_counter_;
  std::shared_ptr<carla::rss::RssCheck> _rss_check;
  ActorConstellationCallbackFunctionType _rss_actor_constellation_callback;
  size_t _on_tick_register_id;
  bool _drop_route;
  std::mutex _processing_lock;
};

} // namespace client
} // namespace carla

Import

#include "carla/rss/RssSensor.h"

I/O Contract

Inputs

Name	Type	Required	Description
init	ActorInitializer	Yes	Actor initialization data from the simulator
callback	CallbackFunctionType	Yes	Callback invoked with RSS response data each tick
log_level	uint8_t	No	spdlog log level for RSS check output
map_log_level	uint8_t	No	spdlog log level for map-related output

Outputs

Name	Type	Description
RSS response callback	CallbackFunctionType invocation	Delivers RSS response data per tick via user callback

Usage Examples

// Attach RSS sensor to a vehicle and start listening
auto rss_sensor = world.SpawnActor(rss_blueprint, transform, vehicle);
auto rss = std::static_pointer_cast<carla::client::RssSensor>(rss_sensor);

// Optionally register custom constellation callback
rss->RegisterActorConstellationCallback(my_callback);

// Start listening for RSS responses
rss->Listen([](auto data) {
  auto rss_response = std::static_pointer_cast<carla::sensor::data::RssResponse>(data);
  // Process RSS response
});

// Stop when done
rss->Stop();

Related Pages

• Environment:CARLA_simulator_Carla_Simulation_Runtime
• CARLA_simulator_Carla_RssCheck - Core RSS check implementation used by this sensor
• CARLA_simulator_Carla_RssCheck_Interface - RssCheck interface definition
• CARLA_simulator_Carla_ServerSideSensor - Base server-side sensor pattern