Overview of RoadRunner Scenario and CARLA Cosimulation

Cosimulation enables multiple simulation tools, such as RoadRunner Scenario, CARLA, and Automated Driving Toolbox™, to coordinate so that each tool either managing specific aspects of the simulation or grouping objects within the simulation to produce a complete simulation of a driving scenario. RoadRunner Scenario and CARLA can cosimulate a large number of actors within a simulation. Cosimulation enables RoadRunner Scenario to control target vehicles in a scene, with easy state and behavior control, while the CARLA software engine or Automated Driving Toolbox manages the ego vehicles in the scene without obfuscating the ego vehicle simulation. Cosimulation combines the ease of development and design provided by RoadRunner Scenario with the scalability provided by CARLA.

Scenario Simulation Engine (SSE)

The scenario simulation engine is a background server that coordinates simulations between multiple clients. These clients can include:

• RoadRunner Scenario

• CARLA

• MATLAB^® and Simulink^® with Automated Driving Toolbox

Each of these simulation tools manage their own respective physics and environment simulation and a specified group of actors. The SSE coordinates information and synchronizes the physics, environments, and actors between each of the simulation clients, enabling all of the simulations to synchronize states and simulation times. This diagram illustrates the organization of the clients and the SSE server.

CARLA and Cosimulation Bridge

CARLA, by default, executes as a standalone simulation and simulation server. To cosimulate with RoadRunner Scenario, CARLA requires a cosimulation bridge. The cosimulation bridge acts as an intermediary and connects CARLA to the SSE as a client. The CARLA cosimulation bridge uses the open-source remote procedure call (RPC) library gRPC^® as its communication bridge. For more information on gRPC, see https://grpc.io/. For instructions on how to set up the cosimulation bridge between RoadRunner Scenario and CARLA, see Set Up CARLA for Cosimulation.