ros2param

Create object to access parameters from ROS 2 nodes

Since R2022b

Description

Create a ros2param object and use its object functions to interact with the parameters associated with any node on the ROS 2 network. You can get, set, list and search for parameters of the specified ROS 2 node.

Creation

Syntax

paramObj = ros2param(nodeName)

paramObj = ros2param(nodeName,DomainID=ID)

Description

example

paramObj = ros2param(nodeName) returns a ros2param object paramObj which you can use to interact with the parameters associated with the specified ROS 2 node, nodeName.

paramObj = ros2param(nodeName,DomainID=ID) specifies a Domain identification of the ROS 2 network to connect to using name-value argument DomainID.

Input Arguments

expand all

`nodeName` — Name of the node
string | char array

The name of the node on the ROS 2 network.

Note

In ROS 1, node names are unique and this is being enforced by shutting down existing nodes when a new node with the same name is started. In ROS 2, the uniqueness of node names is not enforced. When creating a new node, use ros2 function to list existing nodes.

Object Functions

`get`	Get value of parameter in associated ROS 2 node
`set`	Set value of parameter in associated ROS 2 node
`list`	List all parameters in associated ROS 2 node
`has`	Check if parameter exists in ROS 2 node
`search`	Search for parameter names in ROS 2 node

Examples

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Interact with Parameters of ROS 2 Node

Open Live Script

Create a ROS 2 node with parameters.

nodeParams.my_double = 2.0;
nodeParams.my_namespace.my_int = int64(1);
nodeParams.my_double_array = [1.1 2.2 3.3];
nodeParams.my_string = "Keyparams";
node1 = ros2node("/node1",Parameters=nodeParams);

Create a ros2param object to interact with the parameters of the ROS 2 node, /node1.

paramObj = ros2param("/node1");

Warning: The specified node "/node1" cannot be found in domain 0 or external parameter sharing has been disabled in the specified node. Make sure the node is running and parameter sharing is enabled.

Use the set function to change the value of the parameter my_string.

set(paramObj,"my_string","Newparams");

Use the get function to obtain the new value of my_string.

stringVal = get(paramObj,"my_string")

stringVal = 
'Newparams'

Use the has function to check if the parameter my_char exists in the ROS 2 node, /node1.

flag = has(paramObj,"my_char")

flag = logical
   0

Use the search function to search for names of all the parameters that contain the string "my_d". Obtain the values of the matching parameters.

[pNames,pVals] = search(paramObj,"my_d")

pNames = 2x1 cell
    {'my_double'      }
    {'my_double_array'}

pVals=2×1 cell array
    {[                   2]}
    {[1.1000 2.2000 3.3000]}

Use the list function to list the names of all parameters in the ROS 2 node.

pList = list(paramObj)

pList = 9x1 cell
    {'my_double'                                            }
    {'my_double_array'                                      }
    {'my_namespace.my_int'                                  }
    {'my_string'                                            }
    {'qos_overrides./parameter_events.publisher.depth'      }
    {'qos_overrides./parameter_events.publisher.durability' }
    {'qos_overrides./parameter_events.publisher.history'    }
    {'qos_overrides./parameter_events.publisher.reliability'}
    {'use_sim_time'                                         }