CoppeliaSim ROS Interface

1. Overview

Here we offer ROS-CoppeliaSim interface modules for the manipulators, the grippers, the vision sensors, etc. Whole packages are based on B0-based remote API and run with synchronous mode.

2. Requirements

1. Download CoppeliaSim on here. You must download 4.2.0 version for Ubuntu 18.04

   • Add the following line to the end of the usrset.txt file.

     allowOldEduRelease = 7775
     

2. Install MessagePack for Python2.

   pip2 install msgpack

3. Activate B0 Remote API Server

3.1 Load

Drag and drop B0 Remote API Server.ttm on the scene. The module can be found on [Model browser]-[tools]. If B0 Remote API Server.ttm is successfuly loaded, b0RemoteApiServer object will show on the Secene hierarachy.

3.2 Channel name

Channel name should be set as b0RemoteApi.

4. CoppeliaSim master

Only coppeliasim master node may send a SynchronousTrigger signal and base modules must not send the trigger signal by themselves. You must have a coppeliasim master node running in order for base modules to run other modules synchronously.

4.1 Usage

The coppeliasim master can be launched using the roslaunch.

roslaunch coppeliasim_master coppeliasim_master.launch

Note: coppeliasim master must be launched only once.

4.2 Asynchronous operation

Clients do not need to signal anything to master node. Master node should still be run to trigger coppelia simulatior.

4.3 Synchronous operation

For a client to run in synchronous mode it most subscribe to rostopic: "/coppeliasim_synchronous". On that topic, triggers from master node will be posted. When the client node finishes its calculations for one step, it has to signal that to [coppeliasim master] over "/coppeliasim_synchronous" topic. \

Below is an example class code of a client running in synchronous mode.

import rospy

from coppeliasim_remote_api.bluezero import b0RemoteApi
from coppeliasim_master.msg import CoppeliaSimSynchronous

class SynchronousClient(object):
    def __init__(self, client, client_ID):
        """
        This is a coppeliasim client running in synchronous mode.
        Client_ID must not be equal to "coppeliasim_master"
        """
        self.client = client
        self.client_ID = client_ID

        self.do_next_step=False
        self.client.runInSynchronousMode=True


        # set ros publishers
        self.coppeliasim_synchronous_trigger_pub = rospy.Publisher(
            "/coppeliasim_synchronous", CoppeliaSimSynchronous, queue_size=100)

        # set ros subscribers
        self.coppeliasim_synchronous_trigger_sub = rospy.Subscriber(
            "/coppeliasim_synchronous", CoppeliaSimSynchronous, callback = self.coppeliasim_synchronous_cb)

        rospy.sleep(0.2)
        rospy.loginfo("Robotiq Synchronous Client ROS interface turned on!")

    def coppeliasim_synchronous_cb(self, msg):
        """
        Callback for synchronous operation. If message is received from "coppeliasim_master",
        "self.do_next_step" is set to True
        and "self.sequence_number" is updated.
        --------------
        msg : CoppeliaSimSynchronous
            ros message containing a time stamp,  sequence_number and client_ID

        Returns
        --------------
        Bool : True/False
            True if message from "coppeliasim_master"
        """
        if msg.client_ID == "coppeliasim_master":
            self.sequence_number = msg.sequence_number
            self.do_next_step = True
            return True
        else:
            return False


    def coppeliasim_synchronous_done(self):
        """
        Call this function when the client has finished doing all the calculations.
        To call this the object must have the attributes:
            - self.sequence_number
            - self.client_ID
        --------------
        Returns
        --------------
        None : None
        """

        if not hasattr(self, "sequence_number"):
            return
        # Publish the trigger to all other synchronous clients
        trigger_msg = CoppeliaSimSynchronous()
        trigger_msg.stamp = rospy.Time.now()
        trigger_msg.sequence_number = self.sequence_number
        trigger_msg.client_ID = self.client_ID
        self.coppeliasim_synchronous_trigger_pub.publish(trigger_msg)
        return

    def sim_step_done_cb(self):
        # -------------------------------------------------------------------------------------
        # ---------------- PUT HERE CODE TO RUN EACH SIM STEP ---------------------------------
        pass
        # -------------------------------------------------------------------------------------


    def step_simulation(self):
        """
        Perform one step of the simulation.
        --------------
        Returns
        --------------
        None : None
        """
        while not self.do_next_step:
            self.client.simxSpinOnce()
            # Check if simulation on. Makes for a clean exit
            if hasattr(self, "sequence_number"):
                if self.sequence_number == -1:
                    rospy.signal_shutdown("Synchronous client STOP: Master signaled shutdown")
                    return
            rospy.sleep(0.002)

        # -------------------------------------------------------------------------------------
        # ---- Function that gets called each simulation step ---------------------------------
        self.sim_step_done_cb()
        # -------------------------------------------------------------------------------------

        self.do_next_step = False
        self.coppeliasim_synchronous_done()

if __name__ == '__main__':
    # init ros
    rospy.init_node('synchronous_coppeliasim_client')

    # init sim
    client_ID = 'b0RemoteApi_epick_gripper_client_{}'.format(id_generator())
    client = b0RemoteApi.RemoteApiClient(client_ID, 'b0RemoteApi')

    client.do_next_step=False
    client.runInSynchronousMode=True

    sim = synchronousClient(client, client_ID)

    print("synchronousClient Start")

    while not rospy.is_shutdown():
        sim.step_simulation()

Contributors

• Sungwon Seo
• Jure Hudoklin
• Hong-ryul Jung