Support dynamics integration inside Simulink

[gabrielenava]

In the devel branch, I've modified all the Simulink controllers to isolate all the input/outputs from/to the Gazebo simulator:

This new configuration will be one day exploited for allowing the user to choose between performing the simulation with Gazebo or instead interface the controller's I/O using a forward dynamics block that will integrate the dynamics inside Simulink without the need of Gazebo.

[gabrielenava]

@Giulero let's discuss about this task today afternoon. Is is fine for you?

[traversaro]

Related WB-Toolbox issue: robotology/wb-toolbox#164 .

[traversaro]

Ideally in the future it would be great to automatically generate a BlockFactory or FMI block for the "MOMENTUM BASE TORQUE CONTROL" model (see for example https://github.com/CATIA-Systems/FMIKit-Simulink), instead of just generating a complete executable of the complete simulation as we are doing now. Ideally, this would enable us for example to import the momentum based torque control in the walking controller, and just execute it with zero delay.

[traversaro]

cc @nunoguedelha

[gabrielenava]

For the moment, I will create a simple subsystem that:

• compute the forward dynamics for a floating base robot, assuming the joint torques are given by the controller;

• integrate the forward dynamics;

• can switch from one foot to two feet balancing, but only assuming contacts are rigid and ideal (no proper modeling of contacts like in Gazebo);

• only interface our over-used controller, i.e. the yoga controller.

The subsystem will be stored in the library folder, so that it can be used as example for other controllers. A copy of the subsystem will be integrated in the yoga controller.

TO BE VERIFIED: can we use Gazebo with no physics just as visualizer? Otherwise, no visualization will be present, but only plots of dynamics and kinematics quantities.

[gabrielenava]

This has been now done due to unexpected necessities. There is now a simulink-balancing-simulator in devel branch that implements forward dynamics integration in Simulink. It is a first version and some things can be improved, but it =can be used as baseline for developing more complex simulators in the future. Closing the issue.