[Rock-dev] New JointState / Joints representation type

[Sylvain Joyeux]

On 06/06/2013 01:51 PM, Janosch Machowinski wrote:
> Hi,
> sorry for the late response.
> I am missing the possibility to represent
> joints with multiple positions. (E.g. Asguard / Spaceclimber joint)
You create two joints. I can't speak for SpaceClimber, but that is 
definitely what Asguard is: two separate joints with the same axis.

> Also I wonder why everything is a float, I thought we
> agreed on using double...
Yes, and we started reconsidering that choice. Since that reduces the 
size of the structure significantly, and since the precision is really 
not needed there, we settled for float.

> I would also like to add some sort of JointDescription, that
> offers information about the working space, max speed
> or other information about the joint.
This is kinematic information. It is going into the URDF description 
file, and possibly into other libraries that manage kinematic 
information (e.g. KDL)

> For the Position field, I would more like the suggestion from
> Matthias, to use base::Angles in combination with a turn
> counter.
I really dislike this idea as it makes the interpretation for 
ever-revolving joints (e.g. wheels) really a lot harder and has only 
minimal benefit for other types of joints. Moreover, it forces the 
placement of zero positions. I for instance currently have an arm where 
the "natural" zero position is actually the lower bound of the joint 
(i.e. the arm moves in [0, 2pi]).
---
Sylvain Joyeux (Dr.Ing.)
Space & Security Robotics

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