drivers: add support for linear (or: non-revolute) axes

[gavanderhoorn]

Some industrial work cells include additional axes configured as rails or other types of linear actuation. URDF and MoveIt support these setups, but most (if not all) current driver implementations implicitly assume only rotational joints are used.

Either drivers should be extended to support non-revolute axes, or their current support should be validated.

Affected packages:

• ABB (ros-industrial/abb#135)
• Fanuc (see driver: add support for linear axes fanuc#106) (see: fanuc_driver_exp)
• Motoman

[gavanderhoorn]

As @JeremyZoss suggested (via email): we might need to think about how (and where) to configure this. Some controllers have this information accessible to user programs, others may not.

In all cases, the URDF should have this information: do we need any additional infrastructure to consistently support non-revolute axes (industrial_robot_client or simple_message nodes?).

[gavanderhoorn]

Status Fanuc: gavanderhoorn/fanuc_driver_exp has native support for linear axes (uses configuration data present on the controller to determine conversion factors).

Not ticking the checkmark as fanuc_driver_exp is not officially supported yet.

[gavanderhoorn]

Support added in ros-industrial/motoman#85.

[gavanderhoorn]

UR controllers don't (natively) support external axes, so I'm not sure whether 'add linear axes support' makes sense for those controllers.

[gavanderhoorn]

ABB got partial support (only for integrated axes) in ros-industrial/abb#150.

[gavanderhoorn]

URs don't integrate external axes as other robots do, so there will most likely always be a need for some custom code. Taking UR off the list because of that.

[gavanderhoorn]

Closing this in the end, as it's being tracked by issues in the individual repositories and with the small nr of drivers that we're still supporting not a general issue of policy I believe.