[Robotics] Force/torque/collision sensor

[Anna Chiara Bellini]

Hello Gilberto,

I'll try to explain it better... I need to detect forces for two reasons:

1 - our robot is an UAV, and as it flies, it will get in touch with objects
and environment. On the robot I need to have a few force/torque sensors,
that will tell me the force/torque applied in that spot, and then we combine
the different values to get a resulting force that will get back to the user
using a force-feedback device.

2 - the robot features a grasp/manipulate tool, and I need to read the force
applied on it.

Now, my first idea is this: if I model the sensor as a small pivoting
damper, then I could read the position and pose of the damper to calculate
force and torque... but this is just a very basic idea, I don't know if it's
correct or if there are better ways. (Ideally, this should end up being a
MORSE sensor, but that would be a second step, hence why I posted the
question here instead on the morse mailing list)

I have also found this on the Bullet forum:
http://www.bulletphysics.org/Bullet/phpBB3/viewtopic.php?p=&f=9&t=3637, but
I'm not understanding it completely, for instance I do not know what a
"proxy" object is and how to set it up.

Hope this is clear enough :-)

You are saying that the Bullet engine is not extremely precise... can you
tell me what are the limitations, or point me to a place where I can get
more information?

Thank you again

Anna Chiara Bellini


On 6 June 2011 18:09, Gilberto Echeverria <gilberto.echeverria at laas.fr>wrote:

>  Hello Anna Chiara,
>
> For the moment, MORSE does not include this sort of force sensors in
> joints. So far, the main developers of MORSE have not approached this sort
> of simulation, so it remains an open area for development. However, maybe
> other people in the Blender community may have worked on similar problems.
>
> It should be possible to measure forces in Blender, but the physics engine
> used by default (Bullet) is not extremely precise. It will depend on what
> exactly you want to model.
> If you can provide more details, we can give you a better insight on how to
> deal with this kind of sensors.
>
> Best regards,
> Gilberto Echeverria
>
>
> On 06/06/2011 04:16 PM, Anna Chiara Bellini wrote:
>
> Dear all,
>
> I am working on a robot simulation project ( http://www.airobots.eu/ )
> with Blender and I am trying to do something which I'm sure someone else has
> already done, so I'm asking for directions: I need to model passive
> compliant joints and detect the forces acting on them. I guess that the way
> is through Blender's rigid body joint constraint , possibly the
> 6DofSpringConstraint, but I'm not really sure about it and I really don't
> know which would be the best solution.
>
> In our project, we are using MORSE for sensors/actuators/middleware, so if
> anyone had a MORSE-specific solution or suggestion, that would be great.
>
> Any ideas?
>
> Thank you in advance
>
> Anna Chiara Bellini
>
>
> _______________________________________________
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>
>
>
> --
> Gilberto Echeverria
> Research Engineer
> Robotics and Interactions Group (RIS)
> LAAS/CNRS, Toulouse
> +33 (0)5 61 33 78 95
>
>
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