Linear Velocity Plugin Tutorial #2911

Pk-Sic · 2025-05-18T19:13:45Z

Summary

This folder contains a simple example on how to create a plugin which set a linear velocity on a link entity.

In the example, the world contains a ground plane and a box that is freely moving. Through the custom plugin, a linear velocity vector will be applied to the box to make it move along a linear path.

The code presented is commented to provide a clear overview of what each part aims to achieve.

This folder contains a simple example on how to create a plugin which set a linear velocity on a link entity. The CMakeLists.txt file is set for the gz-sim8. Signed-off-by: Pasquale Siciliano <[email protected]>

arjo129

We already have an example System. Of course, its always nice to have a bit more docs and I can see the code has been thoroughly commented. I wonder if we can point users here from the tutorials. Also can you change your PR title to something more descriptive.

I want to check if an LLM was used for this. (If it was that's OK we just need to know which LLM).

examples/plugin/velocity_plugin/CMakeLists.txt

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

examples/plugin/velocity_plugin/PluginLinearVelocity.hh

examples/plugin/velocity_plugin/velocity_world_plugin.sdf

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

Pk-Sic · 2025-05-20T10:55:07Z

Of course, It would be great to create a section where a lot of little tutorials are loaded. I will review your comments for the code and I will implement them.
Thank you.

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

ahcorde · 2025-05-20T20:02:22Z

examples/plugin/velocity_plugin/PluginLinearVelocity.hh

+    // On the other hand the Configure callback is called only once.
+
+    public: void Configure(const Entity &_entity,
+                         const std::shared_ptr<const sdf::Element> &_sdf,


include <memory>

examples/plugin/velocity_plugin/PluginLinearVelocity.hh

examples/plugin/velocity_plugin/README.md

examples/plugin/velocity_plugin/velocity_world_plugin.sdf

Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Comments accepted Signed-off-by: Pasquale Siciliano <[email protected]>

Identation added. Signed-off-by: Pasquale Siciliano <[email protected]>

namespace changed Signed-off-by: Pasquale Siciliano <[email protected]>

- License Header added - Namespace correction - minor correction performed Signed-off-by: Pasquale Siciliano <[email protected]>

New space added at the end of the file. Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic

Comments reviewed and applied.

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

ahcorde · 2025-05-23T11:37:08Z

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

+    // Look for link entity using "LinkByName" into "model" defined above 
+
+    this->linkEntity = model.LinkByName(_ecm, linkName);


Suggested change

// Look for link entity using "LinkByName" into "model" defined above

this->linkEntity = model.LinkByName(_ecm, linkName);

// Look for link entity using "LinkByName" into "model" defined above

this->linkEntity = model.LinkByName(_ecm, linkName);

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

ahcorde · 2025-05-23T11:38:31Z

examples/plugin/velocity_plugin/PluginLinearVelocity.hh

+using namespace gz;
+using namespace sim;
+using namespace systems;


remove this and use the right namespace where required

examples/plugin/velocity_plugin/README.md

ahcorde · 2025-05-23T11:39:38Z

examples/plugin/velocity_plugin/velocity_world_plugin.sdf

@@ -0,0 +1,76 @@
+<?xml version="1.0" ?>


can you use 2 spaces instead of 4 ?

still pending

done. Now it should be ok.

Let me know if the modification was applied.

ok Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Reviewed Signed-off-by: Pasquale Siciliano <[email protected]>

reviewed. Signed-off-by: Pasquale Siciliano <[email protected]>

Reviewed. Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic

Code updated

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

ahcorde · 2025-05-26T12:22:41Z

examples/plugin/velocity_plugin/velocity_world_plugin.sdf

@@ -0,0 +1,76 @@
+<?xml version="1.0" ?>


still pending

License Header + <memory> included Signed-off-by: Pasquale Siciliano <[email protected]>

Signed-off-by: Pasquale Siciliano <[email protected]>

2 spaces format. Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic

Header changed and minor corrections applied.

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

Pk-Sic · 2025-05-28T20:14:28Z

examples/plugin/velocity_plugin/PluginLinearVelocity.hh

@@ -0,0 +1,54 @@
+#ifndef SYSTEM_PLUGIN_HELLOWORLD_HH_


There is the 2025 license header. Is this wrong? I used the http://www.apache.org/licenses/LICENSE-2.0

Pk-Sic · 2025-05-28T20:48:52Z

examples/plugin/velocity_plugin/velocity_world_plugin.sdf

@@ -0,0 +1,76 @@
+<?xml version="1.0" ?>


done. Now it should be ok.

Pk-Sic · 2025-05-28T20:49:36Z

examples/plugin/velocity_plugin/velocity_world_plugin.sdf

@@ -0,0 +1,76 @@
+<?xml version="1.0" ?>


Let me know if the modification was applied.

ahcorde

@iche033 do you mind to take a look ?

iche033

Thanks for adding the linear vel plugin example and tutorial. The example works for me. I left comments mostly related to coding style to that they are consistent with the rest of this library.

I noticed that the gz deps listed in CMakeLists is for Harmonic / gz-sim8. Since this is targeted at gz-sim9, I made suggestions to update those dependency versions.

examples/plugin/velocity_plugin/CMakeLists.txt

iche033 · 2025-05-30T17:47:18Z

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

+
+    this -> lName = linkName; // Do not forget to declare the lName variable in the plugin's header file (see line 61 in the PluginLinearVelocity.hh file))
+
+    // Store the _identity value using the "this ->".


nit:

Suggested change

// Store the _identity value using the "this ->".

// Store the _identity value in "this->entity" member variable

iche033 · 2025-05-30T17:48:25Z

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

+    // Create the model object to access all the function using as attibute the "entity" variable.
+    // The function "Model()" enables to get some important details 


I think we can simplify this to:

Suggested change

// Create the model object to access all the function using as attibute the "entity" variable.

// The function "Model()" enables to get some important details

// Create a Model object from the "entity" to access all model-related functions

iche033 · 2025-05-30T17:54:09Z

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

+#include <gz/sim/Util.hh>
+
+// This header is required to register plugins.
+// The good practice suggests to recall it in the ".cc" file


Is this comment referring to the <gz/plugin/Register.hh> header?

iche033 · 2025-05-30T17:54:19Z

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

+#include <gz/sim/components/Pose.hh>
+#include <gz/math/Vector3.hh>
+
+// The next row recalls the plugin's header.


Suggested change

// The next row recalls the plugin's header.

// The next row includes the plugin's header.

iche033 · 2025-05-30T17:54:34Z

examples/plugin/velocity_plugin/PluginLinearVelocity.cc

+
+using namespace plugin_velocity;
+
+// In the next section, all the functions that we need are recalled.


Suggested change

// In the next section, all the functions that we need are recalled.

// In the next section, all the functions that we need are defined.

Co-authored-by: Ian Chen <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic

CMakelists file adapted to gz-sim9.

Add files via upload

5723fa5

This folder contains a simple example on how to create a plugin which set a linear velocity on a link entity. The CMakeLists.txt file is set for the gz-sim8. Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic requested a review from mjcarroll as a code owner May 18, 2025 19:13

github-actions bot added the 🏛️ ionic Gazebo Ionic label May 18, 2025

azeey added this to Core development May 18, 2025

github-project-automation bot moved this to Inbox in Core development May 18, 2025

arjo129 reviewed May 19, 2025

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Pk-Sic changed the title ~~Add files via upload~~ Linear Velocity Plguin Tutorial May 20, 2025

Pk-Sic changed the title ~~Linear Velocity Plguin Tutorial~~ Linear Velocity Plugin Tutorial May 20, 2025

Merge branch 'gz-sim9' into gz-sim9

44ca1bb

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Pk-Sic and others added 4 commits May 21, 2025 18:49

Update examples/plugin/velocity_plugin/PluginLinearVelocity.cc

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Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/PluginLinearVelocity.cc

1bac297

Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/PluginLinearVelocity.cc

a02af81

Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/PluginLinearVelocity.hh

ccd5634

Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic requested a review from ahcorde May 21, 2025 16:51

Pk-Sic and others added 8 commits May 21, 2025 18:52

Update examples/plugin/velocity_plugin/PluginLinearVelocity.cc

395d65c

Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/PluginLinearVelocity.cc

c288f97

Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/PluginLinearVelocity.cc

6843a9f

Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update PluginLinearVelocity.cc

2c633d4

Comments accepted Signed-off-by: Pasquale Siciliano <[email protected]>

Update velocity_world_plugin.sdf

e9922e5

Identation added. Signed-off-by: Pasquale Siciliano <[email protected]>

Update PluginLinearVelocity.hh

ffb4098

namespace changed Signed-off-by: Pasquale Siciliano <[email protected]>

Update PluginLinearVelocity.cc

56590f6

- License Header added - Namespace correction - minor correction performed Signed-off-by: Pasquale Siciliano <[email protected]>

Update CMakeLists.txt

36af72c

New space added at the end of the file. Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic commented May 22, 2025

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Pk-Sic and others added 3 commits May 25, 2025 20:34

Update examples/plugin/velocity_plugin/README.md

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ok Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/README.md

f5cf4ff

ok Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/README.md

cce296c

ok Co-authored-by: Alejandro Hernández Cordero <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic added 3 commits May 25, 2025 21:06

Update PluginLinearVelocity.cc

e7d5ccf

Reviewed Signed-off-by: Pasquale Siciliano <[email protected]>

Update PluginLinearVelocity.hh

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reviewed. Signed-off-by: Pasquale Siciliano <[email protected]>

Update velocity_world_plugin.sdf

a0495d4

Reviewed. Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic commented May 25, 2025

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Pk-Sic added 3 commits May 28, 2025 22:14

Update PluginLinearVelocity.cc

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License Header + <memory> included Signed-off-by: Pasquale Siciliano <[email protected]>

Update PluginLinearVelocity.cc

8fc0a83

Signed-off-by: Pasquale Siciliano <[email protected]>

Update velocity_world_plugin.sdf

ae46bf2

2 spaces format. Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic commented May 28, 2025

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ahcorde approved these changes May 29, 2025

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Pk-Sic and others added 6 commits May 31, 2025 10:10

Update examples/plugin/velocity_plugin/CMakeLists.txt

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Co-authored-by: Ian Chen <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/CMakeLists.txt

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Co-authored-by: Ian Chen <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/CMakeLists.txt

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Co-authored-by: Ian Chen <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/CMakeLists.txt

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Co-authored-by: Ian Chen <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/CMakeLists.txt

1a692ef

Co-authored-by: Ian Chen <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Update examples/plugin/velocity_plugin/CMakeLists.txt

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Co-authored-by: Ian Chen <[email protected]> Signed-off-by: Pasquale Siciliano <[email protected]>

Pk-Sic commented May 31, 2025

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		// Look for link entity using "LinkByName" into "model" defined above

		this->linkEntity = model.LinkByName(_ecm, linkName);


		this -> lName = linkName; // Do not forget to declare the lName variable in the plugin's header file (see line 61 in the PluginLinearVelocity.hh file))

		// Store the _identity value using the "this ->".

	// Store the _identity value using the "this ->".
	// Store the _identity value in "this->entity" member variable

		// Create the model object to access all the function using as attibute the "entity" variable.
		// The function "Model()" enables to get some important details

	// Create the model object to access all the function using as attibute the "entity" variable.
	// The function "Model()" enables to get some important details
	// Create a Model object from the "entity" to access all model-related functions

	// The next row recalls the plugin's header.
	// The next row includes the plugin's header.


		using namespace plugin_velocity;

		// In the next section, all the functions that we need are recalled.

Linear Velocity Plugin Tutorial #2911

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Linear Velocity Plugin Tutorial #2911

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Pk-Sic commented May 18, 2025

Summary

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