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Simulation is an important step of a robotics project. It helps saving time and resources during the project development phase reducing hardware requirements and field tests deployments. Through simulations it is possible to test algorithms in virtually any environment. As complex robots are usually manged by robotics frameworks, a framework-simulator integration is a powerful tool, which allows design and verification of algorithms implemented straight into frameworks. The Gazebo simulator is already integrated with the Robot Operating System (ROS) endorsing its importance to the robotics community. This paper introduces the integration between the Gazebo simulator and the Robot Construction Kit (Rock) framework to allow a real-time simulation. To export simulation resources, framework components are instantiated and synchronized inside a Gazebo system plugin. Each component is a C++ class implemented separately from others classes. Through this approach new components can be easily integrated to extend the simulation capabilities. An Autonomous Underwater Vehicle (AUV) simulation is presented as a use case of the integration. This use case comprises fluid statics and dynamics simulation, thruster models and an underwater environment visualization.

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Simulating sonar devices requires modeling complex underwater acoustics, simultaneously rendering time-efficient data. Existing methods focus on basic implementation of one sonar type, where most of sound properties are disregarded. In this context, this work presents a multi-device sonar simulator capable of processing an underwater scene by a hybrid pipeline on GPU: Rasterization computes the primary intersections, while only the reflective areas are ray-traced. Our proposed system launches few rays when compared to a full ray-tracing based method, achieving a significant performance gain without quality loss in the final rendering. Resulting reflections are then characterized as two sonar parameters: Echo intensity and pulse distance. Underwater acoustic features, such as speckle noise, transmission loss, reverberation and material properties of observable objects are also computed in the final generated acoustic image. Visual and numerical performance assessments demonstrated the effectiveness of the proposed simulator to render underwater scenes in comparison to real-world sonar devices.