Skip to content

Wiki

Gezebo simulation platform

About 10 min read

1.Brief description

Gazebo is currently mainly divided into two versions,

One is the old Gazebo Classic, and the other is the new Ignition Gazebo (Gazebo Fortress).

In this article, references to Gazebo all refer to Gazebo Classic, while Ignition Gazebo will be distinguished separately.

So now ROS2 Humble ships with Ignition Gazebo (Gazebo Fortress), but ROS2 Jazzy ships with Gazebo Harmonic; it is recommended to learn Gazebo Harmonic!

Scene

In ROS robot development, although physical robots have the advantages of directness and realism, they also have some shortcomings, such as:

  1. High costs: Developing an autonomous mobile robot requires purchasing expensive hardware components, such as sensors, motors, controllers, etc., and these hardware components may need to be frequently replaced or upgraded in the early stages of development, causing costs to rise sharply.

  2. Resource constraints: Due to limited funding and resources, it may not be possible to have multiple physical robots for testing at the same time. This can prolong the testing cycle and hinder R&D progress.

  3. Environmental uncertainty and complexity: When testing robots in real environments, various unpredictable situations may be encountered, such as changes in lighting, uneven ground, electromagnetic interference, etc., and these factors may all affect the robot's performance.

  4. Safety risks: During testing, if the robot's control algorithm or hardware fails, the robot may go out of control and cause harm to people or the environment.

In the field of ROS robot development, simulation technology is widely used to make up for the shortcomings in physical robot testing.

Concept

Robot simulation is a process that uses computer models and simulation technology to simulate the behavior and performance of robots in a virtual environment. By creating virtual robot and environment models, it simulates the robot's perception, control, and motion capabilities, as well as its interactions with the environment and other objects.

Function

Through simulation testing, robot R&D costs and risks can be reduced, the performance and reliability of the robot system can be improved, and references and guidance can be provided for actual robot deployment.

Simulation advantages:

Simulation plays a pivotal role in the development of robotic systems. Compared with implementation on physical robots during development and testing, simulation offers the following significant advantages:

  1. Low cost: Current robot costs remain high, often reaching hundreds of thousands, and simulation can greatly reduce costs and lower risks.

  2. High efficiency: The constructed environments are more diverse and flexible, which can improve testing efficiency and test coverage.

  3. High safety: In a simulation environment, there is no need to consider wear and tear issues.

Simulation technology provides developers with a comprehensive testing and verification platform that is efficient, safe, and low-cost.

Simulation defect:

Robots exhibit significant differences in performance between simulation environments and real environments; in other words, simulation cannot fully replicate the real physical world, and there are some "distortions." Reasons:

  1. The physics engine used by the simulator is currently unable to fully and accurately simulate real-world physical conditions.

  2. The simulator constructs an absolutely ideal scenario for joint actuators (motors and gearboxes), sensors, and signal communication. It currently does not support simulating actual hardware defects or certain critical states.

In summary, although simulation technology is important, it cannot completely replace physical testing. Physical testing can verify the accuracy of simulation results and uncover issues that may have been overlooked in simulations.

2.Chapter Summary

This chapter mainly introduces the application of the 2D simulation tool stage_ros2 and the 3D simulation tool ignition gazebo in ROS2.

The relevant knowledge points are as follows:

  • Theoretical knowledge of simulation;

  • Use in stage_ros2 of ROS2;

  • Use of Ignition Gazebo in ROS2.

Through the above content, we introduced the application scenarios and concepts of simulation in ROS2, as well as the advantages and disadvantages of simulation compared with physical robots. We also learned how to build simulation environments and simulate robots based on stage_ros2 and Ignition Gazebo respectively, laying the foundation for subsequent learning.

In addition, besides stage_ros2 and Ignition Gazebo, there are other software options available for ROS2 simulation. The following are some common choices:

  • Webots: Webots is a powerful open-source multi-robot simulation software platform that supports simulation of various robot hardware and sensors, and can be integrated with ROS 2.

  • Gazebo Classic: Gazebo Classic is a commonly used simulator in ROS 1, and can also be connected to and used through ROS 2.

  • MORSE: MORSE is an open-source simulator based on Python, which can be used for ROS 2 simulation and robot development, and supports multiple sensor and behavior models.

  • V-REP: V-REP is a powerful multi-robot simulation platform that supports ROS 2 communicating with it, enabling simulation of various robot models and scenarios.

These are some common ROS 2 simulation software options; you can choose the appropriate software for simulation and development based on your specific needs. Note that some simulators may require adaptation and configuration to be compatible with ROS 2.