[Research] Systems in drake

[Agustin Alba Chicar]

Research on how is the life-cycle of a System. One option is the LeafSystem.

Try to get a simple example of a moving box or something similar.

[Agustin Alba Chicar]

The Simulator, Context and System class interaction is described here --> http://drake.mit.edu/doxygen_cxx/classdrake_1_1systems_1_1_simulator.html#details

[Agustin Alba Chicar]

The main classes are related as follows (down --> top):

1. The RigidBody class is the representation of a rigid body element.
2. The DrakeJoint class joins two rigid bodies and describes how they are related.
3. The Element class of a RigidBody is used for the collisions of the bodies.
4. The System class is a base interface for generic systems. A LeafSystem class is a derived class of a system that provides some useful utilities to the System class.
5. The RigidBodyTree is a derived class of a LeafSystem and keeps multiple RigidBodies interactions (with their joints).

They System behaviour is based in the following:

1. Given a Context you give to a System which is the initial state.
2. A System has a collection of input and output ports. On each time iteration the System must calc the output ports values and publish them. This is how the system evolves in time.

[Agustin Alba Chicar]

Created the system_sample branch with an example to simulate a 1DOF particle for better understanding of the complete interaction.

[Agustin Alba Chicar]

The sample has been updated with a moving particle with a constant accelaration.

[Agustin Alba Chicar]

This issue is closed as we are currently finishing this work on issue #106