ROS Subscriber

Block Category: Extensions > ROS

Outputs: Determined by the ROS Message Type parameter.

•      A: Alpha values of pixels; double

•      angular[x,y,z]: Angular acceleration in x y and z direction; 3x1 matrix double

•      B: Blue color intensity; double

•      Byte[data]: Array of data matrix

•      char data: Character data

•      com[x,y,z]: Center of mass; 3x1 matrix double

•      covariance[36]: Row-major representation of the 6x6 covariance matrix;  36x1 matrix double

•      Empty data: Empty data

•      floatx [data]: Multidimensional array

•      force[x,y,z]: Force in x, y, and z direction; 3x1 matrix double

•      frame_id: Frame associated with the data; string

•      G: Green color pixel value; double

•      intx [data]: Multidimensional array; matrix double

•      ixx: The moment of inertia of a body along the horizontal axis passing throgh the centroid of the body; double

•      iyx: The moment of inertia of a body along the vertical axis passing through the centroid of the body; double

•      izz: The moment of inertia of a body along the axis perpendicular to both the horizontal and vertical axes through the centroid of the body; double

•      [label]: Label of given dimension; string

•      linear[x,y,z]: Linear acceleration in x, y, and z direction; 3x1 matrix double

•      M: Mass in kilograms; double

•      offset: Padding values preceding data; unsigned integer

•      position[x,y,z]: Position in free space in x, y, and z coordinates; 3x1 matrix double

•      quaternion[x,y,z,w]: Orientation in free space in quaternion form; 4x1 matrix double

•      R: Red color pixel value; double

•      Rotation[x,y,z,w]: Orientation in free space in quaternion form; 4x1 matrix double

•      seq: Consecutively increasing ID; integer

•      [size]: Size of given dimension; unsigned integer

•      [stride]: Stride of given dimension; unsigned integer

•      string data: String data

•      theta: Rotation angle in radiance; double

•      time: Current ROS server time; double

•      timestamp: Time at which the data is received; double

•      torque[x,y,z]: 3x1 matrix double

•      translation[x,y,z]: Vector in free space in x y and z direction; 3x1 matrix double

•      UIntx [data]: Multidimensional array

•      [x]: Position of array in x direction that can support up to 32 inputs of data; matrix

•      X: Position in X direction; double

•      [y]: Position of array in y direction that can support up to 32 inputs of data; matrix

•      Y: Position in Y direction; double

•      [z]: Position of array in z direction that can support up to 32 inputs of data; matrix

•      Z: Position in Z direction; double

 

Description: The ROS Subscriber block allows communication with ROS-enabled robots. ROS Subscriber receives ROS messages of a specific type from the specified ROS topic. The message is updated, if necessary, at each time step. Messages are exchanged between ROS Publisher and ROS Subscriber blocks until the simulation terminates.

A screenshot of a computer Description automatically generated

Communication protocol: Indicates UDP or Websocket communication protocol. UDP is faster, but works only with ROS 1.

Port: Indicates a dedicated port number set by the ROS bridge server.

ROS Message Type: Defines the type of message and the data format. The ROS Message Type determines the outputs on the ROS Subscriber block. For example, geometry_msgs/Pose is a representation of pose in free space, composed of position and quaternion (orientation), which are the outputs to the block.

ROS Subscriber recognizes two types of messages: geometry and standard. Message types are described at https://index.ros.org/p/geometry_msgs/ and https://index.ros.org/p/std_msgs/.

ROS Server IP: Indicates the ROS bridge server name or IP address. If you do not have a ROS bridge server, you can install one on Windows Subsystem for Linux (WSL) on Windows 10+. If you do, to access the IP address, open a Linux shell by entering WSL in the Search box in the lower left corner of your screen and enter ifconfig | grep -o 'inet [0-9.]\+' Use the first inet address from the displayed list.

ROS Topic: Lists the available ROS topics. Click Refresh Topics to refresh the list.

Status: Displays the connectivity to the ROS server. Click Check Status to see the current connectivity.

Subscriber Client ID: Indicates the ID required to differentiate between different instances of the subscriber.

Examples

See Examples > Blocks > Extensions > ROS.