Minimal example: asynchronous mode#

It is time to run your first example!

Goals

Test the installation of the DQ Robotics library.
Get familiar with the class DQ_VrepInterface().
Know the method get_object_pose().
Understand the asynchronous mode (default mode).

Open the DQ_Robotics_lab.ttt scene (see One scene to rule them all). Suppose we want to get the position of object Frame_x via code. If you check the scene, you’ll notice that is located in the position [-1,0,0]. Therefore, we expect as result the pure quaternion -i.

For this example, we are going to use the asynchronous mode. This is the default operation mode of CoppeliaSim. This mode means that the simulation on CoppeliaSim will advance without taking into account the progress of your script. Alternatively, CoppeliaSim supports the synchronous mode. (see Minimal example: synchronous mode).

To get the pose (position and orientation) of an object we need to use the method get_object_pose() of the class DQ_VrepInterface().

Roughly speaking, in the default mode (asynchronous mode), you need to do the following steps:

Instantiate an object of the DQ_VrepInterface() class.
Establish the connection to an specific IP and port. If you are running both the script and the simulation in the same computer, the default IP is 127.0.0.1 and the default port is 19997.
Start the simulation.
Do whatever you want to do. For instance, get the object pose.
Stop the simulation.
Disconnect.

Templates:#

The following templates are minimal scripts with the DQ_VrepInterface() class and contain good practices for Matlab, Python, and C++. Those are based on hundreds of feedbacks provided by the Maintainers of the DQ Robotics.

The templates show how to establish communication with a CoppeliaSim scene in asynchronous mode (default mode) using the default port. It’s assumed that both the script and the scene are running in the same computer (default IP).

Matlab

template.m

clear all;
close all;
clc;


include_namespace_dq;
vi = DQ_VrepInterface();

try
    vi.connect('127.0.0.1', 19997);
    vi.start_simulation();
    pause(0.1);
    %-----------Your code here-------------------

    %----------------------------------------------
    vi.stop_simulation();
    vi.disconnect();
catch ME
    vi.stop_simulation();
    vi.disconnect();
    rethrow(ME)
end

Python

template.py

#!/bin/python3
from dqrobotics.interfaces.vrep import DQ_VrepInterface
import time

vi = DQ_VrepInterface()


def main() -> None:
    vi = DQ_VrepInterface()
    try:
        if not vi.connect("127.0.0.1", 19997, 100, 10):
            raise RuntimeError("Unable to connect to CoppeliaSim.")

        vi.start_simulation()
        time.sleep(0.1)
        # --------------Your code here----------------------------

        # ---------------------------------------------------------

    except (Exception, KeyboardInterrupt) as e:
        print(e)
        pass

    finally:
        vi.stop_simulation()
        vi.disconnect()


if __name__ == "__main__":
    main()

C++

template.cpp

#include <iostream>
#include <dqrobotics/interfaces/vrep/DQ_VrepInterface.h>
#include <thread>

int main()
{
    auto vi = DQ_VrepInterface();
    try {
        if (!vi.connect("127.0.0.1", 19997,100,10))
            throw std::runtime_error("Unable to connect to CoppeliaSim.");
        vi.start_simulation();
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        //-----------------Your code here--------------------------

        //---------------------------------------------------------
        vi.stop_simulation();
        vi.disconnect();
    } catch (std::exception& e) {
        std::cout<<e.what()<<std::endl;
        vi.stop_simulation();
        vi.disconnect();
    }
    return 0;
}

CMake

Example#

Matlab

communication_test.m

clear all;
close all;
clc;


include_namespace_dq;
vi = DQ_VrepInterface();

try
    vi.connect('127.0.0.1', 19997);
    vi.start_simulation();
    pause(0.1);
    x = vi.get_object_pose('/Frame_x');
    disp('Position: ')
    translation(x)
    disp('The test was succesful!')
    vi.stop_simulation();
    vi.disconnect();
catch ME
    vi.stop_simulation();
    vi.disconnect();
    rethrow(ME)
end

Python

communication_test.py

#!/bin/python3
from dqrobotics.interfaces.vrep import DQ_VrepInterface
import time




def main() -> None:
    vi = DQ_VrepInterface()
    try:
        if not vi.connect("127.0.0.1", 19997, 100, 10):
            raise RuntimeError("Unable to connect to CoppeliaSim.")

        vi.start_simulation()
        time.sleep(0.1)
        x = vi.get_object_pose("/Frame_x")
        print("Position: ", x.translation())
        print("The test was successful!")

    except (Exception, KeyboardInterrupt) as e:
        print(e)
        pass

    finally:
        vi.stop_simulation()
        vi.disconnect()


if __name__ == "__main__":
    main()

C++

communication_test.cpp

#include <iostream>
#include <dqrobotics/interfaces/vrep/DQ_VrepInterface.h>
#include <thread>

int main()
{
    auto vi = DQ_VrepInterface();
    try {
        if (!vi.connect("127.0.0.1", 19997,100,10))
            throw std::runtime_error("Unable to connect to CoppeliaSim.");
        vi.start_simulation();
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
        DQ x = vi.get_object_pose("/Frame_x");
        std::cout<<"Position: "<<x.translation()<<std::endl;
        std::cout<<"the test was successful!"<<std::endl;
        vi.stop_simulation();
        vi.disconnect();

    } catch (std::exception& e) {
        std::cout<<e.what()<<std::endl;
        vi.stop_simulation();
        vi.disconnect();
    }
    return 0;
}

You will have the following output:

Position: - 1i

The test was successful!