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1) When I run the launch file I cant see the wheels of the robots in gazebo. but If I changed the wheels to type fixed I can see the wheels.

@rukn's answer is good.

• Give your wheel realistic approximate inertial values. See: https://en.wikipedia.org/wiki/List_of_moments_of_inertia
• Start gazebo in paused mode, then advance the simulation in single time steps. This will help you figure out what is causing the model to fly apart.

2) Also, what is the tag property to convert from <static> false </static> (this one in SDF) from SDF to xacro ?

Sorry, I don't understand what you are asking here. Please rephrase your question.

3) Moreover, if the size of the box mobile robot is 0.3 0.3 0.2 are the links (left and right wheels) and joint's position, visual and geometry I created for this size are acceptable ?

It depends on what you're trying to simulate and what you are using the simulation for. You want your simulation to match either a real robot or a planned robot as closely as possible.

• If your focus is physical interactions, then it's important to get the collision elements right (link masses, inertial matrices, etc...).
• Whereas if your focus is image processing/object recognition, then you can "fake" the physics - really since it's faking the fake physics - but you'll need to have really good visual elements (colors, textures, meshes, etc...).

4) If I want to control this robot using keyboard, what should I do to make this robot publish and subscribe topics to connect it with ROS ?

You can:

• Use Differential Drive or Skid Steering Drive Gazebo Plugins
• Write your own Gazebo Plugin. See the Velodyne Control plugin tutorial.
• Use ros_control.

1) When I run the launch file I cant see the wheels of the robots in gazebo. but If I changed the wheels to type fixed I can see the wheels.

@rukn's answer answer is good.

• Give your wheel realistic approximate inertial values. See: https://en.wikipedia.org/wiki/List_of_moments_of_inertia
• Start gazebo in paused mode, then advance the simulation in single time steps. This will help you figure out what is causing the model to fly apart.

2) Also, what is the tag property to convert from <static> false </static> (this one in SDF) from SDF to xacro ?

Sorry, I don't understand what you are asking here. Please rephrase your question.

3) Moreover, if the size of the box mobile robot is 0.3 0.3 0.2 are the links (left and right wheels) and joint's position, visual and geometry I created for this size are acceptable ?

It depends on what you're trying to simulate and what you are using the simulation for. You want your simulation to match either a real robot or a planned robot as closely as possible.

• If your focus is physical interactions, then it's important to get the collision elements right (link masses, inertial matrices, etc...).
• Whereas if your focus is image processing/object recognition, then you can "fake" the physics - really since it's faking the fake physics - but you'll need to have really good visual elements (colors, textures, meshes, etc...).

4) If I want to control this robot using keyboard, what should I do to make this robot publish and subscribe topics to connect it with ROS ?

You can:

• Use Differential Drive or Skid Steering Drive Gazebo Plugins
• Write your own Gazebo Plugin. See the Velodyne Control plugin tutorial.
• Use ros_control.

1) When I run the launch file I cant see the wheels of the robots in gazebo. but If I changed the wheels to type fixed I can see the wheels.

@rukn's answer is good.

• Give your wheel realistic approximate inertial values. See: https://en.wikipedia.org/wiki/List_of_moments_of_inertia
• Start gazebo in paused mode, then advance the simulation in single time steps. This will help you figure out what is causing the model to fly apart.

2) Also, what is the tag property to convert from <static> false </static> (this one in SDF) from SDF to xacro ?

Sorry, I don't understand what you are asking here. Please rephrase your question.

3) Moreover, if the size of the box mobile robot is 0.3 0.3 0.2 are the links (left and right wheels) and joint's position, visual and geometry I created for this size are acceptable ?

It depends on what you're trying to simulate and what you are using the simulation for. You want your simulation to match either a real robot or a planned robot as closely as possible.

• If your focus is physical interactions, then it's important to get the collision elements right (link masses, inertial matrices, etc...).
• Whereas if your focus is image processing/object recognition, then you can "fake" the physics - really since it's you're faking the fake physics - but you'll need to have really good visual elements (colors, textures, meshes, etc...).

4) If I want to control this robot using keyboard, what should I do to make this robot publish and subscribe topics to connect it with ROS ?

You can:

• Use Differential Drive or Skid Steering Drive Gazebo Plugins
• Write your own Gazebo Plugin. See the Velodyne Control plugin tutorial.
• Use ros_control.