The use of simulators in robotics research is widespread, underpinning the majority of recent advances in the field. There are now more options available to researchers than ever before, however navigating through the plethora of choices in search of the right simulator is often non-trivial. Depending on the field of research and the scenario to be simulated there will often be a range of suitable physics simulators from which it is difficult to ascertain the most relevant one. We have compiled a broad review of physics simulators for use within the major fields of robotics research. More specifically, we navigate through key sub-domains and discuss the features, benefits, applications and use-cases of the different simulators categorised by the respective research communities. Our review provides an extensive index of the leading physics simulators applicable to robotics researchers and aims to assist them in choosing the best simulator for their use case.

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A Review of Physics Simulators for Robotic Applications

In this paper, we propose a mapping approach that constructs a globally deformable virtual occupancy grid map (VOG-map) based on local submaps. Such a representation allows pose graph SLAM systems to correct globally accumulated drift via loop closures while maintaining free space information for the purpose of path planning. We demonstrate use of such a representation for implementing an underwater SLAM system in which the robot actively plans paths to generate accurate 3D scene reconstructions. We evaluate performance on simulated as well as real-world experiments. Our work furthers capabilities of mobile robots actively mapping and exploring unstructured, three dimensional environments.

Virtual Occupancy Grid Map for Submap-based Pose Graph SLAM and Planning in 3D Environments

AUV position tracking and trajectory control based on fast-deployed deep reinforcement learning method

Simulation plays an important role in the development, testing and evaluation of new robotic applications, reducing implementation time, cost and risk. For much of the robotics community, the open-source Gazebo robot simulator has emerged as the de facto standard environment for prototyping and testing robotic systems. While Gazebo offers strong support for terrestrial, aerial and space robotics applications, less support is available for marine applications involving vehicles at and below the water surface. To address this deficiency, we present the Virtual RobotX (VRX) simulation, a general purpose open-source development and testing tool, based on Gazebo, capable of approximating the behavior of unmanned surface vessels operating in complex ocean environments. We highlight the application of these capabilities using the VRX challenge reference implementation, a new simulation-based robot competition designed to complement the physical Maritime RobotX Challenge.

Toward Maritime Robotic Simulation in Gazebo

As technology advances, the places we have been able to explore have drastically increased. However, the advancements in the underwater realm have staggered behind both the exploration of surface and air domains. This is due in part to the challenges that arise when placing a robot in water. One current shift has seen the use of a swarm of robots that are cheaper and are of a lower quality, that work together to accomplish a common goal, as opposed to using a single expensive robot. Swarm robotics benefits from being more tolerant of catastrophic failure and can cover large areas in smaller time frames. However, unlike other advancements in technology, underwater swarm robotics have struggled to compete with its counterparts on the surface and in the air. This is mainly due to the problems with communication underwater, the hazardous environment, the cost and difficulties with construction of underwater robots. This article conducts a literature review into the current state of underwater swarm robotics; it covers the design of the underwater robots, the methods used by the individual robot to perceive their environment, how they can localize to said environment, the methods of communication available underwater, centralized and decentralized control, the basis of swarm algorithms, the behaviors that are exhibited when a swarm works collectively and how swarms have been applied underwater.

Current Algorithms, Communication Methods and Designs for Underwater Swarm Robotics: A Review

This paper describes the Unmanned Underwater Vehicle (UUV) Simulator, an extension of the open-source robotics simulator Gazebo to underwater scenarios, that can simulate multiple underwater robots and intervention tasks using robotic manipulators. This is achieved mainly through a set of newly implemented plugins that model underwater hydrostatic and hydrodynamic effects, thrusters, sensors, and external disturbances. In contrast to existing solutions, it reuses and extends a general-purpose robotics simulation platform to underwater environments.

UUV Simulator: A Gazebo-based package for underwater intervention and multi-robot simulation

Tasks with underwater vehicles present several challenges that include complex and hazardous environments, and unmodeled and/or unknown uncertainties. The setup of positioning controllers is therefore a difficult and laborious task and very often leads to suboptimal performance results on the field. This paper shows a framework for methodical evaluation and setup of dynamic positioning controllers for underwater vehicles with simulation-based optimization method using performance metrics. The proposed method can be configured to be mission specific and delivers a controller configuration that also allows a fair numerical comparison between control algorithms on similar scenarios.

Framework for Fair Comparisons of Underwater Vehicle Controllers - Showcasing the Robustness Properties of a Model-free Sliding Mode Controller Tuned with a Random-forest-based Bayesian Optimization Approach

This paper explores the versatility of performance metrics in setting up, evaluating and comparing dynamic positioning controllers. Given the nature of subsea mission with highly nonlinear vehicle models and unmodeled disturbances, performance-based evaluations can improve the understanding of the system behavior in different scenarios and allow better decisions regarding mission strategies before testing the real system. This analysis, however, can only be extensively done with the use of simulations, using the same strategy used for the improvement of safety and performance conditions in other research areas, such as flight control.

Use of simulation-based performance metrics on the evaluation of dynamic positioning controllers

At construction sites and off-road scenarios people are often in danger, because drivers of heavy machinery have to focus on their tasks and might recognize dangerous situations too late. They, therefore, heavily rely on driver assistance systems. For people detection in such environments not all inference results (true positives, false positives or false negatives) are equally relevant. In this paper we propose a novel metric for people detection, providing an increased emphasis on human hazard prevention. Most works blindly allocate efforts for improving detection performance using situation-agnostic metrics like mean average precision or F1-score. The objective of this work is to determine solid pragmatic variables that directly relate to a person's safety and judiciously combine them, coming up with a safety-aware metric for people detection. To set up a system focusing on safety and reliability, the results of a neural network have to be subsequently verified. We therefore propose a new detection plausibility check based on an extension of the stixel algorithm and a multi-object tracker. Our results are evaluated on a new self-recorded off-road dataset for people detection and compared with standard evaluation metrics. Furthermore, results obtained from training are compared against the proposed plausibility algorithm.

Luiz Ricardo Douat

Papers

UUV Simulator: A Gazebo-based package for underwater intervention and multi-robot simulation

Framework for Fair Comparisons of Underwater Vehicle Controllers - Showcasing the Robustness Properties of a Model-free Sliding Mode Controller Tuned with a Random-forest-based Bayesian Optimization Approach

Use of simulation-based performance metrics on the evaluation of dynamic positioning controllers

Safety-Aware Metric for People Detection