mc_rtde

Interface between Universal robots and mc_rtc. Provides connectivity with UR5e | UR7e and UR10 robots.

1. Required dependencies

• mc_rtc
• ur10
  • robot_module : https://github.com/isri-aist/mc_ur10
  • description : https://github.com/isri-aist/mc_ur10_description
• ur5e | ur7e
  • robot_module : https://github.com/isri-aist/mc_ur5e
  • description : https://github.com/isri-aist/mc_ur5e_description
• ur_rtde library
• ur_modern_driver

2. Install dependencies

ur_rtde library

• From PPA :

sudo add-apt-repository ppa:sdurobotics/ur-rtde
sudo apt-get update
sudo apt install librtde librtde-dev

• From Source :

$ git clone https://gitlab.com/sdurobotics/ur_rtde.git
$ cd ur_rtde
$ mkdir build
$ cd build
$ cmake -DPYTHON_BINDINGS:BOOL=OFF ..
$ make
$ sudo make install

ur_modern_driver library

$ git clone https://github.com/jrl-umi3218/ur_modern_driver
$ cd ur_modern_driver
$ mkdir build
$ cd build
$ cmake ..
$ make
$ sudo make install

3. Install this project

Build instructions

$ git clone https://github.com/isri-aist/mc_rtde
$ cd mc_rtde
$ mkdir build
$ cd build
$ cmake ..
$ make
$ sudo make install

Set memory limits

Make sure user account has sufficient memory limits.

Edit /etc/security/limits.conf by adding the following line :

USERNAME - memlock 1000000000

Then log-out and log-in or reboot, to confirm the new limit :

ulimit -l

The path set to the ROS library

MCControlRtde will not pick up ROS libraries. If you're using mc_rtc's ROS plugin, create this file /etc/ld.so.conf.d/ros.conf with the following content:

/opt/ros/${ROS_DISTRO}/lib

Run the following command after this change:

$ sudo ldconfig

4. Usage

To use the interface and connect to a real robot run

$ MCControlRtde --help
MCControlRTDE options:
  --help                Display help message
  -f [ --conf ] arg     Configuration file

see etc/mc_rtc_ur.yaml for mc_rtde configuration example

$ MCControlRtde -f <mc_rtc_configuration_file.conf>

Where <mc_rtc_configuration_file.yaml> is based on (e.g).

<INSTALL_PREFIX>/etc/mc_rtde/<robot>.yaml --> /usr/local/etc/mc_rtde/mc_rtc_ur.yaml

Your mc_rtc configuration file (~/.config/mc_rtc/mc_rtc.yaml) should contain the following lines:

MainRobot: UR5e # or UR10 / UR7e
Enabled: YourController
Timestep: 0.001

# Set a LogPolicy suitable for real-time
LogPolicy : threaded

# Interface specific parameters (mc_rtde)
RTDE:
  ControlMode: Position # Can be: Position/Velocity/Torque

  ur5e: # Name of the robot in the controller
    ip: "localhost"
    driver: "ur_rtde" # Can be: "ur_rtde" (>=CB3) or "ur_modern_driver" (<=CB2). Default: ur_rtde
    gripper:
      name: "<gripper_name>" # Name of the gripper attached to the robot
      type: robotiq # Only robotiq is supported now
      ip: "localhost" # [Optional] Robot's ip is used by default
      port: 63352 # [Optional]

  ur7e: # Name of the robot in the controller
    ip: "localhost"

  ur10: # Name of the robot in the controller
    ip: "localhost"

Run the program:

$ MCControlRtde

You can also provide an additional configuration file (to swap between different network configurations easily for example):

$ MCControlRtde -f conf.yaml

Gripper Integration

The gripper is loaded as an independent robot in the mc_rtc controller and controlled via a posture task. It can be attached to the main robots by addContact.

robots().robot("<gripper>").posW(robots().robot("<main_robot").surfacePose("<mounting_surface>"));
addContact({"<main_robot>", "<gripper>", "<mounting_surface>", "<gripper_base>"});

Limitation

The tested Robotiq gripper does not support real-time control. To avoid flooding the gripper, the interface only sends a new command when the mc_rtc commanded position has reached steady state. As a result:

• The real gripper will lag behind the simulated gripper
• Posture task gains do not have the same effect as on other robots — the gripper moves at its own pace once a command is sent

5. Toubleshooting

Known issue

It may happen that some libraries are not found due to the high priviligies given for real-time scheduling. To overcome it, please consider running the following commands :

echo "$HOME/workspace/src/catkin_data_ws/install/lib" | sudo tee -a /etc/ld.so.conf.d/mc_rtc_ros.conf
echo "$HOME/workspace/install/lib" | sudo tee -a /etc/ld.so.conf.d/mc_rtc.conf
echo "/opt/ros/humble/lib" | sudo tee -a /etc/ld.so.conf.d/ros2.conf

Then run the following command :

sudo ldconfig

Segfault

We noticed that a segfault happens when using rmw_cyclonedds_cpp as RMW.

Please consider using the following one :

export RMW_IMPLEMENTATION=rmw_fastrtps_cpp

PolyScope 5

This is tested with PolyScope 5.25, but 5.23 and 5.24 versions of the software may run into the same issue.

Some of the services used to connection might be disable by default. Consider following these steps on the teach pendant to enable them.

1. Make sure you are in Local Control mode.
2. Go to Hamburger menu > Settings > Security > Services and enable these services:
   • Dashboard Server
   • Primary Client Interface
   • Secondary Client Interface
   • Real-Time Client Interfcae
   • Real-Time Data Exchange (RTDE)