SeanCurtis-TRI
commented
6 years ago Further description
This happens because the lcm contacta results associates quantities with (body name1, body name 2) pairs. For bodies with multiple collision geometries, each geometry will still be registered with the same body-name-pair. The python script that handles the visualization performs aggregation -- so all contact forces associated with the same name pair are put into a single body-body-named object.
Proposal
In drake_visualizer, instead of having (body1, body2) display with all contact forces, we'll break them down per collision geometry pair. We'll do that by changing the names to (body1 - geometry name, body2 - geometry name).
Implementation
- :heavy_check_mark: Geometry names: I have a PR in flight that will introduce geometry names - for both collision and visual geometries. This will provide the fodder for distinguishing contacts. (Resolved in #9147)
- Getting the name to the LCM message: The
ContactResultsdata structure will be extended to provide collision object names. The MBP will populate this additional data. - Including the name:
ContactResultsToLcmSystemwill use the collision object name in theContactResultsdata and encode it into the contact name.
rcory
DamrongGuoy
jwnimmer-tri
Description
We have an MBP with multiple bodies. One body has multiple collision geometries associated with it. For instance, say we have a body named "my_body" with two associated collision geometries named "my_body_collision_1" and "my_body_collision_2" and a second body named "other_body" with a single collision geometry named "other_body_collision". Now assume that both "my_body_collision_1" and "my_body_collision_2" are in contact with "other_body_collision". When visualizing contact results in
drake_visualizerthese contacts are reported using body names and not geometry names, i.e., for our example above, we would see a single contact result reported as(my_body(1),other_body(1)). It is useful to have lcm contact results be reported on a per-collision-geometry level such that collision geometry names are included in the contact results. For the example above, we would see two contact result reported as(my_body(1)_my_body_collision_1, other_body(1)_other_body_collision)and(my_body(1)_my_body_collision_2, other_body(1)_other_body_collision).