WEBVTT

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To solve the forward kinematics problem.

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We had to employ the transformation matrices and we have seen how useful and powerful they are in the

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hands of our robotic software developer to solve complex mathematical problems in an easy and intuitive

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way.

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Not only are transformation matrices useful to solve the kinematics problem, but they are practically

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useful everywhere in robotics.

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Everything can be represented and schematized with a reference frame and can be defined with a transformation

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matrix.

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The importance of this tool in Ros2 and in robotics world is clear, which is why there is already a

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library available in Ros2 that allows to manipulate and combine reference frames through transformation

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matrices.

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This library is called TF2.

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In any robotics application, you will always find yourself dealing with this library.

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In fact, even unconsciously, we have already used this package during this course when defining the

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Urdf model with the links and the joints of our manipulator robot.

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The robot model can be seen as a tree composed of different reference frame connected to each other,

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whose transformation matrices between the various reference frame of the robot are automatically calculated

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based on the urdf model of the robot.

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In fact, in the urdf model of the robot, each link we defined corresponds to the definition of a new

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reference frame, and each joint corresponds to the definition of the rotation and translation of a

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certain link with the respect to the previous one.

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Therefore, it practically corresponds to the definition of the transformation matrix between two consecutive

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links connected to each other.

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This translation from the RDF model of the robot where all the links and therefore the reference frame

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and all the joints and therefore the transformation matrices are defined is the task of the robot estate

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publisher node.

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It reads The RDF model of the robot interprets it and publishes the links and the transformation within

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a topic called TF.

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Subsequently, Aav's.

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Subscribe to this same topic in order to display in its graphical interface the reference frames that

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make up the robot in the correct position with their correct translation and relative orientation.