Check out the ROS 2 Documentation, roslaunch/XML/remap explanation and examples. As a quick summary of ROS command line capabilities: For name remapping, use either --remap from:=to or -r from:=to. Know your namespaces (global, relative, ). To show you how to remap a ROS topic, Ill use this simple publisher node. The replacement side of a rule must have a FQN which will become the new default namespace. Here the syntax is the same, and additionally it can be prefixed with a nodes current name. The various ROS libraries provide client support for easily stripping remapping arguments out of your own argument parsing. Make sure both topics (if youre remapping on an existing topic with already existing subscribers) have the same data type. A user may want to change a name used in one node without affecting the rest. To avoid confusion they are required to be separated from tokens, substitutions, and each other by a /. First, we record data from our initial node which is publishing on topic1. Yes, why should we even think about that? This means it should be possible to make a rule that replaces all uses of this token. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. And to do that, you'll use the ros2 launch command line tool. Give us more details about what you want to learn! Use the tag to remap a topic. Then the name is expanded to a FQN. The remapping on topic1 wont work. The first case requires a wildcard to match the rest of a namespace. Command line static remapping (ROS1 compatible syntax + nodename prefix) add support for command line arguments to rmw_init, it would need to: take argc and argv and have a way to indicate which indices in argv were "consumed" by the middleware and should/could be remove for the user Special Rule for Changing the Default Namespace, Supporting: Exact Relative Name Replacement, Supporting: Remap Topic and Service Names Separately, A user wants the node to subscribe to the same data after some processing, A company sells a generic mobile robot base with a ROS 2 driver. Names are conceptually divided into two pieces: namespace and basename. This is to avoid a mismatch between the scheme type of the match side and of the replacement side. The URL schemes rosservice:// and rostopic:// may only be given to topic or service name rules. In ROS 1 remapping works by passing in arguments to each node. Its possible a user may want to change multiple instances of a basename to another token. Nodes are said to be in a namespace or have a default namespace. Specifying a URL scheme on the match side of the rule makes it exclusive to one type of name. This is the ability to replace a name by exactly matching it. Finally the name is replaced with the replacement. and [] dont appear to enable more uses cases above. The name is remapped to the right side only if it exactly matches the left side of a rule. Use of this keyword is generally not encouraged as it is provided for special cases where environment variables cannot be set. Remapping rules are applied in the following order: Within each category, the rules are applied in the order in which the user gave them. This is also part of ROS 1 remapping. The replacement side must have a single token. There are two cases: changing part of a namespace, and changing the entire namespace. Is there a way to remap a parameter by command line using the $ ros2 launch command? To solve this problem, you can remap /my_images to /abc_images with the ROS remap functionality (and of course, be sure that if you remap a topic on another topic, both topics have the same data type!). The driver uses lots of names with the companys name in it: Another company incorporates the base into their product, and their customers want a ROS 2 interface, The second company doesnt want their interface to contain, Both sides of the remap rule are expanded to, First rule remaps token used in namespace, Second rule remaps token used as basename. Before a name is remapped it is also expanded to FQN. I'd like to use something like we do in ROS1: If you start this launch file youll still see topic1, and topic2 wont be here. The strings __name or __node can be given on the match part of a rule to signal a change of the nodes name. Topics, parameters, and services are identified by Names. This repository contains the source code for ROS 2 command line interface tools included with a standard install of any ROS 2 distro. I guess I can use Python arguments, but I do not know if there is a better way. Remapping rules have two parts. Use of this keyword is generally not encouraged as it is provided for special cases where environment variables cannot be set. Remapping rules are the instructions describing how a node should change the names it uses. In this tutorial Ill show you how to remap a ROS topic. Remapping names allows reusing the same node executable in different parts of the system. The argument __node:= has the same effect. This feature of ROS allows you to defer complex name assignments to the actual runtime loading of the system. On the match side it may be used by itself or with a nodename: prefix. You can also ask the node to remap a name to another name (this also applies to parameters and services, not only topics). The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. As you could see during this tutorial, its really easy to remap a topic. If the node name is not prefixed, the rule will be applied to all nodes in the process. The effect of this is that you are remapping a full name, whereas before the remappings only applied to a specific string. In ROS 1 the argument __ns:= could change the default namespace. This is because searchParam itself works on unresolved names. You can also provide assignment for private node parameters. Supporting this use case with a single rule is not a priority. Example of partial namespace replacement: Changing a basename requires a wildcard which matches the entire namespace. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. The syntax cant change all uses of a token with one rule. Are you sure you want to create this branch? A syntax like fnmatch is being considered. Precisely what the title says. (TODO verify name remappings being evaluated at places equivalently to roscpp) This use case is the ability to change the namespace of multiple names with one rule. Client libraries also have APIs in code to pass remapping rules when the node is initialized. Usage Run ros2 --help to see all available commands. ROS 1 remapping works on Fully Qualified Names (FQN). This article describes the requirements, rationale, and mechanisms for remapping names in ROS 2. Exact FQN replacement requires no wildcards. If the match part of a rule does not begin with /, *, or ** it is prefixed with /namespace/ to make it a FQN. If no URL scheme is given then the rule applies to both topics and services. First things first, lets understand why. The extra wildcards ? These references are required to be separated from tokens by a /. This way the new rule matches against the name the user sees with introspection tools rather than the original name used in code. This command will take 2 arguments: name of the package + name of the launch file. This repository contains the source code for ROS 2 command line interface tools included with a standard install of any ROS 2 distro. Matching works on FQN only. For multiple parameter assignments, use --params-file path/to/file.yaml and a parameters YAML file. These cookies will be stored in your browser only with your consent. The cookies is used to store the user consent for the cookies in the category "Necessary". This website uses cookies to improve your experience while you navigate through the website. Fnmatch syntax may or may not match text with slashes depending on the option FNM_PATHNAME. Run ros2 --help for more information on individual command usage. All resource names can be remapped. Instead, were seeing a new topic, named topic2. A new rcl_arguments_get_param_overrides() API is introduced to retrieve those parameters after command line arguments parsing. ROS For Beginners - A Step By Step Course. The match part of a rule uses these operators: The operators * and ** are similar to the globbing behavior in bash. Lets say you have 5 publishers from 5 sensors (in different namespaces) and you want the data to go on only one topic. Lets see how to do that. Use of this keyword is generally not encouraged -- it is mainly provided for use by ROS tools like roslaunch. There is no workaround. *, and ** match whole tokens only. >> ROS For Beginners - A Step By Step Course <<. The replacement side must have a FQN with no special operators. Then: This also isnt a true remapping rule, but the syntax is similar. This could be useful when two different names expand to the same FQN. Of course you can also remap topics from/to different namespaces. Lets replay it on topic2 instead. Because a process can contain multiple nodes, there must be a way to uniquely identify a node in a process. If you pay attention to the following points you should be fine: Do you want to learn how to program with ROS? By clicking Accept All, you consent to the use of ALL the cookies. Here the syntax is the same, and additionally it can be prefixed with a nodes name. A robot that has multiple sensors of the same type could launch multiple instances of the same node with outputs remapped to different topics. Wiki: Remapping Arguments (last edited 2020-10-08 20:33:16 by Gabriel Staples), Except where otherwise noted, the ROS wiki is licensed under the. The second requires a wildcard to match the basename at the end. This allows a user to remap a relative name to another name. This is the ability to change a token in multiple names regardless of where it appears. You can use Python entry points to create new commands and verbs for the CLI. Without remapping every instance of a node would require changes in code. These cookies ensure basic functionalities and security features of the website, anonymously. The basename is the last token in a name. These special operators are unique to the replacement part of a rule: The syntax for \1 through \9 was taken from backreferences in POSIX BRE. You also have the option to opt-out of these cookies. This can be very handy if you have several pieces of hardware (multiple robots, cameras, sensors, ) in different namespaces, and want to aggregate some data. What you could do is create an intermediate node which listens to all 5 topics, and when receiving some data, publish it on the global topic. If both a node name prefix and URL scheme are given, the node name prefix must come first. The substitution operators (~ and {}) are replaced first. [ROS2] CLI Parameter remapping for launch file, Creative Commons Attribution Share Alike 3.0. Remappings either must come from the command line, or they must be given as if they were command line arguments to the argv argument of rospy.init_node. When this creates a name with // one slash is automatically deleted. Its also possible to remap a topic played by a ROS bag. rosbag command-line tool: The rosbag command-line tool provides functionality for ROS bags. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. On the match side __ns must be used by itself or with a nodename: prefix. I'm using ROS2 Eloquent. It is possible a token is used throughout an interface, but is undesirable to the end user. See this thread with working example for the detail. The one exception to this is when using searchParam, which keeps the old behavior. But this is quite an overkill. It works by first expanding the relative name and then doing FQN replacement. If a node publishes on topic1, then you can make it publish on topic2 instead, without having to change the code of the node. Remapping arguments can be passed to any node and use the syntax name:=new_name. Then if the replacment name does not begin with / it is automatically prefixed with the nodes default namespace to make it a FQN. Necessary cookies are absolutely essential for the website to function properly. The first part is used to determine if the rule applies to a name. It should be read before reading this article. The act of replacing one name with another is remapping. Then, if we replay the bag with rosbag play data.bag, it will send messages to topic1 again. In ROS 1 the argument __name:= could change the nodes name. This character may still be difficult on other shells, like zsh. The node name is used in log messages and to create private names. The replacement part of a rule may not have a URL scheme. For example, you could remap /robot1/camera2/my_images and /robot4/camera3/my_images to /face_recognition/my_images. This is a proposal for the ROS 2 remapping rule syntax. It does not store any personal data. Are you using ROS 2 (Dashing/Foxy/Rolling)? For single parameter assignment, use either --param name:=value or -p name:=value where value is in YAML format. replacement says what the new name will be. It allows for performing all kind of actions; from retrieving information about the codebase and/or the runtime system, to executing code and of course helping debugging in general. Then you can see the data published on topic1. For example. Now you can listen to topic2 and get the data. Run ros2 --help to see all available commands. The complete definition of a name is here. This namespace gets prepended to all relative names used by the node. One of the central pieces of the ROS ecosystem is its Command Line Interface (CLI). Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. I'd like to use something like we do in ROS1: $ ros2 launch param_name:=overloaded_value. Use of this keyword is generally not encouraged as it is provided for special cases where environment variables cannot be set. Assuming the nodes name is unique in a process, a rule can be prefixed with the name of the target node and a :. Changing the namespace of a node is an easy mechanism for integrating code, as all names within the node -- node name, topics, services, and parameters -- will be rescoped. The namespace is everything prior to the basename. Please start posting anonymously - your entry will be published after you log in or create a new account. I explain it better: my launch file loads the parameters for my node from some YAML files, but sometimes I want to test other parameters without modifying the YAML file using some kind of CLI overload. A remap rule consists of two names: one that should be replaced with another. For example, to configure the talker node to publish to /wg/chatter instead of chatter: We resolve the arguments before doing the match. First, go into another terminal and source your ROS2 workspace. Because processes in ROS 2 can contain multiple nodes, it is possible multiple nodes in a process may use the same name for different purposes. Then on another terminal, check that you see topic2 instead of topic1 with rostopic list. When you use the tag, it will remap any topic after the tag. The node will publish a message on the topic topic1 at 2 Hz. Remapping a node in a process requires a way to uniquely identify a node. NOTE: in order for this feature to work properly, it's important that your program avoids using global names and instead uses relative and private names. A popular ROS 1 package actionlib creates 5 topics with the same namespace. This syntax is identical to ROS 1. The character for the wild card * was chosen to match fnmatch. It can record a bag, republish the messages from one or more bags, summarize the contents of a bag, check a bag's message definitions, filter a bag's messages based on a Python expression, compress and decompress a bag and rebuild a bag's index. Lets see this with an example. ROS 1 has this feature using the argument __name. This is also a good place to set your topic redirection rules. The "from" key needs to be prefixed with ~. Exact relative replacement also requires no wildcards. For example */bar **/* ~/* are allowed, but *bar *** ~* are invalid. As all nodes launch in the global namespace, this in effect "pushes it down" into a child namespace. Everything before this tag wont be taken into account. The ROS_NAMESPACE environment variable lets you change the namespace of a node that is being launched, which effectively remaps all of the names in that node. Of course, starting each node from the terminal is not scalable. *bar looks like it would match foobar, but that would mean matching a partial token. Theres no reason to do any remapping. If we check the topic list on another terminal: topic1 has disappeared! The second part is the replacement for a matched name. Do you want to become better at programming robots, with Arduino, Raspberry Pi, or ROS2? You can also aggregate data from various nodes into a common topic. Hi all, ** behaves similar to its use in bash>=4.0 with the globstar option set. Instead, you can use ROS remap. For example **/bar:=/bar/\1 matches the name /foo/bar with ** capturing /foo, but the new name is /bar/foo. The structure of a remapping rule is match:=replacement. __log is a reserved keyword that designates the location that the node's log file should be written. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. They may not be prefixed to a node name or namespace replacement rule (__name, __node, or __ns). Because the user will see the name after it has been remapped by static rules, dynamic rules should be applied after static ones. You can also ask the node to remap a name to another name (this also applies to parameters and services, not only topics). Any ROS name within a node can be remapped when it is launched at the command-line. Remapping is a feature that also exists in ROS 1. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. It may be useful for a developer who has started a node and wants to connect it to a different source. This cookie is set by GDPR Cookie Consent plugin. sets ~param to 1.0. However, you may visit "Cookie Settings" to provide a controlled consent. It can only be used if the program that is being launched contains one node. In ROS 1 remapping an actionlib client or server means creating 5 remapping rules. It does not have an equivalent to NodeHandle. Example of topic/service remapping order: Example of node/namespace remapping order: Example of a default and node specific namespace remap: The following sections explain how the syntax enables the use cases above. This cookie is set by GDPR Cookie Consent plugin. Finally the name is compared against the match part of the rule. Remapping a ROS topic can be very handy when you dont have full control over which node is publishing on what, and which node is subscribing from what. I explain it better: my launch file loads the parameters for my node from some YAML files, but sometimes I want to test other parameters without modifying the YAML file using some kind of CLI overload. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. Run ros2 <command> --help for more information on individual command usage. terminal outputs appear after KeyboardInterrupt, Affix a joint when in contact with floor (humanoid feet in ROS2), ros2 transient_local durability (late joiners policy) does not work when using ros2 topic echo, can't launch Xtion Prolive with openni2.launch. In ROS 2 just one rule could remap them all. This cookie is set by GDPR Cookie Consent plugin. ROS 1 has this feature using either the environment variable ROS_NAMESPACE or the argument __ns. If you run rosrun my_robot_tutorials publisher.py topic1:=/ns1/another_namespace/topic2, or use in your launch file, then topic1 will be remapped to /ns1/another_namespace/topic2. The node you run receives images over the /abc_images topic. Problem: in your application, with another package, images are published on the /my_images topic! Just what we asked for. The syntax has been chosen to not conflict with special shell characters in bash. Run the ROS2 launch file Now that you have written and installed your launch file, it's now ready to be launched! You can find a historical discussion on this subject on Discourse. If yes, subscribe to receive exclusive content and special offers! The replacement must be a single token which will become the nodes new name. The cookie is used to store the user consent for the cookies in the category "Performance". This syntax is identical to ROS 1. The wildcard ** is useful because it matches every possible namespace when combined with a slash. All remappings in rospy are global. How can I set the footprint of my robot in nav2? __master is a substitute for ROS_MASTER_URI. Log messages use the new name immediately. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Afterwards the reference operators are replaced with the matched content. All private names are expanded to the new name before any remapping rules are applied to them. := behaves the same as it does in ROS 1. Both sides of a rule are expanded to FQN. ROS 2 Remapping Use cases These use cases are being considered for remapping in ROS 2: Remap One Node in a Process Change a Namespace Change a Basename Change a Token Pre-FQN Remapping Exact FQN Replacement Exact Relative Name Replacement Remap via Command Line Change the Default Namespace Change the Node Name If a name begins with / it is called a Fully Qualified Name (FQN) otherwise it is called a relative name. These cookies track visitors across websites and collect information to provide customized ads. Remapping a topic means that youll change the topic name at run-time. This cookie is set by GDPR Cookie Consent plugin. Dynamic remapping is the ability to remap a name while a node is running. Important note: the line order in launch files for remapping is very important. This is a feature of ROS 1 remapping. This should be changeable without affecting FQN. __ns is a substitute for ROS_NAMESPACE. We also use third-party cookies that help us analyze and understand how you use this website. A certain publisher publishes on topicA, and subscribers then subscribe to this topicA. The strings between slashes are called tokens. This is the ability to match a name by how it is used in code. And here's an example for how to add a command. These use cases are being considered for remapping in ROS 2: This is the ability to apply remap rules to one node in a process without affecting the other nodes. $ rosrun my_robot_tutorials publisher.py topic1:=topic2 And we didnt change anything in the code. This isnt really a remapping rule, but the syntax is similar. For example, /bar/*:=\1/bar matches the name /bar/foo use by a node with default namespace /ns with * capturing foo and replacement name /ns/foo/bar. Because remapping needs to capture text to use during replacement, the C function fnmatch() cannot be used as the implementation. For example, where foo:=bar previously only matched the exact string foo, it will also match //foo. The syntax doesnt have a way to specify that a rule should be applied Prior to FQN expansion. Remap the ROS topic With command line When you start a node on the terminal with rosrun , you can pass some arguments to it. A tag already exists with the provided branch name. It's a very valuable set of tools that ROS developers use on a daily basis. The topic1 wont be here anymore, instead youll get the messages from topic2. When you start a node on the terminal with rosrun, you can pass some arguments to it. The ROS Wiki is for ROS 1. This is a powerful feature of ROS that lets you launch the same node under multiple configurations from the command-line. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". If you run the launch file roslaunch my_robot_tutorials remap_test.launch youll have the same result as with the rosrun argument. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. It means relative names are first expanded to FQN, and then processed as during exact FQN replacement. __ip and __hostname are substitutes for ROS_IP and ROS_HOSTNAME. You signed in with another tab or window. The syntax here can be passed to a node via the command line. foo:=bar will match foo or //foo, but will not match foo/baz. This is part of the behavior of ROS 1 remapping, so it has proven useful and including it will ease the transition to ROS 2. Run ros2 --help for even more usage information on a specific command's verbs. If the name matches it is remapped. This is the ability to change the basename of multiple names with one rule. It lets you remap the node name without having to know its actual name. The default namespace is the one in which relative names get expanded to. This cheat sheet provides examples for commands and their verbs (some of which rely on the ROS 2 demos package). Remapping arguments can be passed to any node and use the syntax name:=new_name. It attempts to be the same as ROS 1 syntax when possible. For example in bash, the character * only has special behavior if it is surrounded by whitespace, but remap rules dont contain whitespace. You can assign private parameters for a node directly from the command-line using a single underscore _ as a prefix. Run roscore and then start the node with rosrun my_robot_tutorials publisher.py (replace package and executable names with what you have created). Also, remapping topics could be a great way to aggregate several sources (topics) into one. All relative names are expanded to the new namespace before any remapping rules are applied to them. A user can supply node specific remapping arguments via the command line. This feature of ROS allows you to defer complex name assignments to the actual runtime loading of the system. All resource names can be remapped. Static remapping is giving a node remapping rules at the time it is launched. The cookie is used to store the user consent for the cookies in the category "Analytics". match tests if a name should be remapped. Read Introspection with command line tools on ROS Index for more information and an example. Analytical cookies are used to understand how visitors interact with the website. Doing so requires matching prior to FQN expansion. The string __ns can be given on the match part of a rule to signal a change of the default namespace. Names are hard coded in ROS nodes, but they can be changed at runtime through remapping. Except where otherwise noted, these design documents are licensed under Creative Commons Attribution 3.0. __name is a special reserved keyword for "the name of the node." But, imagine youre working with an image processing package you installed with apt or apt-get. But opting out of some of these cookies may affect your browsing experience. As your application grows, youll use launch files to start all nodes and parameters in your application. Now we want to remap the topic1 to topic2. However, parenthesis are not used; the wild cards always capture. This is the ability to create a rule that will remap only topics or only services. After resolution, a direct string match is used, so you cannot use it to remap parts of Names, i.e. Is there a way to remap a parameter by command line using the $ ros2 launch command? When a name is to be tested the substitution operators (~ and {}) in the name and in the rule are replaced with the content they stand for. ROS uses YAML syntax to determine the parameter typing. Check out ROS For Beginners and learn ROS step by step. This is a powerful feature of ROS that lets you launch the same node under multiple configurations from the command-line. The cookie is used to store the user consent for the cookies in the category "Other. 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