ScenarIO

In this getting started section we show how to use the Gazebo ScenarIO library to simulate a pendulum system. We will use the models of the ground plane and the pendulum stored in the repository gym_gz_models.

The final outcome of this section is shown in the following GIF:

Tip

We fully support Gz Fuel, a constantly enlarging database of SDF models. You can use get_model_file_from_fuel() to download any model of the database:

from scenario import gazebo as scenario_gazebo

model_name = "Electrical Box"

model_file = scenario_gazebo.get_model_file_from_fuel(
    uri=f"https://fuel.gazebosim.org/openrobotics/models/{model_name}")

Python

example.py

import time
import gym_gz_models
from scenario import gazebo as scenario_gazebo

# Create the simulator
gazebo = scenario_gazebo.GazeboSimulator(step_size=0.001,
                                         rtf=1.0,
                                         steps_per_run=1)

# Initialize the simulator
gazebo.initialize()

# Get the default world and insert the ground plane
world = gazebo.get_world()
world.insert_model(gym_gz_models.get_model_file("ground_plane"))

# Select the physics engine
world.set_physics_engine(scenario_gazebo.PhysicsEngine_dart)

# Open the GUI
gazebo.gui()
time.sleep(3)
gazebo.run(paused=True)

# Insert a pendulum
world.insert_model(gym_gz_models.get_model_file("pendulum"))
gazebo.run(paused=True)
time.sleep(3)

# Get the pendulum model
pendulum = world.get_model("pendulum")

# Reset the pole position
pendulum.get_joint("pivot").to_gazebo().reset_position(0.01)
gazebo.run(paused=True)
time.sleep(3)

# Simulate 30 seconds
for _ in range(int(30.0 / gazebo.step_size())):
    gazebo.run()

# Close the simulator
time.sleep(5)
gazebo.close()

C++

example.cppCMakeLists.txt

#include <scenario/gazebo/GazeboSimulator.h>
#include <scenario/gazebo/Joint.h>
#include <scenario/gazebo/Model.h>
#include <scenario/gazebo/World.h>

#include <chrono>
#include <string>
#include <thread>

int main(int argc, char* argv[])
{
    // Create the simulator
    auto gazebo = scenario::gazebo::GazeboSimulator(
        /*stepSize=*/0.001, /*rtf=*/1.0, /*stepsPerRun=*/1);

    // Initialize the simulator
    gazebo.initialize();

    // Get the default world
    auto world = gazebo.getWorld();

    // Insert the ground plane
    const std::string groundPlaneSDF = "ground_plane.sdf";
    world->insertModel(groundPlaneSDF);

    // Select the physics engine
    world->setPhysicsEngine(scenario::gazebo::PhysicsEngine::Dart);

    // Open the GUI
    gazebo.gui();
    std::this_thread::sleep_for(std::chrono::seconds(3));
    gazebo.run(/*paused=*/true);

    // Insert a pendulum
    const std::string pendulumURDF = "pendulum.urdf";
    world->insertModel(/*modelFile=*/pendulumURDF);
    gazebo.run(/*paused=*/true);

    // Get the pendulum
    auto pendulum = world->getModel(/*modelName=*/"pendulum");

    // Reset the pole position
    auto pivot = pendulum->getJoint("pivot");
    auto pivotGazebo = std::static_pointer_cast<scenario::gazebo::Joint>(pivot);
    pivotGazebo->resetPosition(0.001);

    // Simulate 30 seconds
    for (size_t i = 0; i < 30.0 / gazebo.stepSize(); ++i) {
        gazebo.run();
    }

    // Close the simulator
    std::this_thread::sleep_for(std::chrono::seconds(3));
    gazebo.close();

    return 0;
}

Note

The environment should be properly configured to find the plugins and the models. Use GZ_SIM_SYSTEM_PLUGIN_PATH for the plugins and GZ_SIM_RESOURCE_PATH for the models and meshes.