urROSNode

Connection to simulated cobot or physical cobot from Universal Robots over ROS

Since R2024a

Description

The urROSNode object represents a connection from the ROS enabled host computer to MATLAB. The ROS master running inside the ROS enabled host computer is further connected to a simulated collaborative robot (cobot) from Universal Robots (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator) or to a physical cobot. To interact with the simulated cobot to read robot state data, send joint and cartesian control commands, and follow set of joint-space or task-space waypoints, use this object with the functions listed in Object Functions.

Creation

Syntax

ur = urROSNode

ur = urROSNode(hostname)

ur = urROSNode(hostname,port)

ur = urROSNode(URI)

ur = urROSNode(hostname,Name=Value)

Description

ur = urROSNode creates a connection, ur, and tries to connect to the ROS master at default URI: http://localhost:11311. The ROS master is further connected to a simulated cobot or physical cobot from Universal Robots.

However, before initiating the connection, the command checks for the value of the standard ROS environmental variable, ROS_MASTER_URI, which defines the ROS master. Therefore, you can use the syntax ur = urROSNode to create connection to simulated cobot in a different host computer if you have already specified a different address for the ROS master using that variable.

ur = urROSNode(hostname) creates a connection, ur, to the ROS master at the specified IP address or host name. This syntax assumes that the ROS master is running on the ROS default port number, 11311.

ur = urROSNode(hostname,port) creates a connection, ur, to the ROS master at the specified IP address or host name, and the specified port.

ur = urROSNode(URI)creates a connection, ur, to the ROS master at the specified URI (Uniform Resource Identifier).

ur = urROSNode(hostname,Name=Value) also specifies the IP address if the automatic detection fails (NodeHost), or sets the JointStateTopic, FollowJointTrajectoryAction, and RigidBodyTree properties using one or more optional name-value arguments.

Input Arguments

hostname — Host name or IP address

string scalar | character vector

Host name or IP address, specified as a string scalar or character vector.

port — Port number

numeric scalar

Port number used to connect to the ROS master, specified as a numeric scalar.

URI — URI for ROS master

string scalar | character vector

URI for ROS master, specified as a string scalar or character vector. Standard format for URIs is either http://ipaddress:port or http://hostname:port.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

NodeHost — Host name or IP address that is advertised

character vector

Host name or IP address that the node uses to advertise itself to the ROS network, specified as the pair consisting of NodeHost and a character vector. This argument is useful if the automatic detection of ROS master fails.

Example: ur = urROSNode('172.19.98.176',11311,NodeHost='172.20.224.1')

Example: ur = urROSNode('172.19.98.176',11311,NodeHost='comp-home')

Properties

JointStateTopic — Name of ROS topic to read robot state

/joint_states (default)

Name of the ROS topic to read robot state, specified as a string scalar or character vector.

Example: ur = urROSNode('172.19.98.176',11311,JointStateTopic='/joint_states')

Data Types: char | string

FollowJointTrajectoryAction — Name of the ROS action to move the robot

/arm_controller/follow_joint_trajectory (default)

Name of the ROS action to move the robot, specified as a string scalar or character vector.

Example: ur = urROSNode('http://172.19.98.176:11311',FollowJointTrajectoryAction='/arm_controller/follow_joint_trajectory')

Data Types: char | string

RigidBodyTree — Rigid body tree robot model

object

Rigid body tree robot model, specified as a rigidBodyTree object.

Example: ur = universalrobot('http://172.19.98.176:11311',RigidBodyTree=loadrobot('universalUR5e','DataFormat','row'))

NumberOfJoints — Number of joints in the robot

numeric

This property is read-only.

Number of joints in the robot, specified as a numeric scalar.

Data Types: double

EndEffectorName — End effector body name for frame transformation

character vector

This property is read-only.

End effector body name for frame transformation, specified as a character vector.

Data Types: char

Object Functions

getJointConfiguration	Get current joint configuration from the robot
getCartesianPose	Get current end-effector pose from the robot
getEndEffectorVelocity	Get current end-effector velocities from the robot
getJointVelocity	Get current joint velocities from the robot
getMotionStatus	Get current motion status of the robot
followTrajectory	Command robot to move along the desired joint space waypoints
followWaypoints	Command robot to move along the desired task space waypoints
sendCartesianPose	Command robot to move to desired Cartesian pose
sendCartesianPoseAndWait	Command robot to move to desired Cartesian pose and wait for the motion to complete
sendJointConfiguration	Command robot to move to desired joint configuration
sendJointConfigurationAndWait	Command robot to move to joint configuration and wait for the motion to complete
recordRobotState	Log the key robot state parameters during motion of robot
executePrimaryURScriptCommand	Execute primary URScript command to control cobot over ROS interface
executeSecondaryURScriptCommand	Execute secondary URScript command over ROS interface
handBackControl	Get the control back from the External Control program node in the UR program tree

Examples

Connect to a Cobot Using Auto-detection

Connect to the physical or simulated cobot (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator), in the same host computer.

ur = urROSNode;

Connect to the physical or simulated cobot (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator), in a different host computer. Specify the address of the ROS master by using the ROS_MASTER_URI environmental variable.

setenv('ROS_MASTER_URI',['http://192.168.58.128:11311']);
ur = urROSNode;

Connect to a Cobot by Specifying the IP Address

Connect to the physical or simulated cobot (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator), in the host computer identified by the IP address in the ROS network.

ur = urROSNode('172.19.98.176');

Connect to a Cobot by Specifying the IP Address and Port Number

Connect to the physical or simulated cobot (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator), in the host computer identified by the IP address in the ROS network and its port number.

ur = urROSNode('172.19.98.176',11312);

Connect to a Cobot by Specifying the URI

Connect to the physical or simulated cobot (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator), in the host computer identified by the URI in the ROS network.

ur = urROSNode('http://172.19.98.176:11311');

Connect to a Cobot by Specifying the Advertised Address and Other Optional Arguments

Connect to the physical or simulated cobot (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator), in the host computer by mentioning the advertised address (for example, 172.20.224.1) of the host computer in the ROS network.

ur = urROSNode('172.19.98.176',NodeHost='172.20.224.1');

Connect to a Cobot by Specifying the RBT Object

Connect to the physical or simulated cobot (either in the URSim offline simulator from Universal Robots or in the Gazebo simulator), in the host computer by mentioning the rigid body tree object.

ur = urROSNode('172.19.98.176',RigidBodyTree=ur5);

ur = 
  urROSNode with properties:

                  RigidBodyTree: [1×1 rigidBodyTree]
                JointStateTopic: '/joint_states'
    FollowJointTrajectoryAction: '/scaled_pos_joint_traj_controller/follow_joint_trajectory'
                 NumberOfJoints: 6
                EndEffectorName: 'tool0'

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

• The hostname and port input arguments are redundant in code generation. Therefore, you can either keep them as it is or add an empty char array (‘ ’) as an argument. For example, see the last command line shown below:

  ur5e = loadrobot('universalUR5','DataFormat','row');
  ur = urROSNode('','RigidBodyTree',ur5e);

• During code generation, there can be certain warnings that are expected, similar to the one displayed below. You can ignore them because they do not have any impact on the performance. Warning: The "JointNames" field of the "trajectory_msgs/JointTrajectory" message is a cell string which is not supported in code generation. Do not access the "JointNames" field in your MATLAB code.

Version History

Introduced in R2024a