STOMP and MoveIt! - robot joint limits not respected

[Stefania Pellegrinelli]

Hi,
I'm using STOMP with industrial MoveIt! (https://github.com/ros-industrial/industrial_moveit). Sometimes, the generated trajectories do not respect the joint limits listed in the URDF file. I also added the joint limits to the "joint_limits.yaml" file without any success. I'm using the robot lbr iiwa 14 r820. 

Contents of "joint_limits.yaml":

joint_limits:
  joint_a1:
    min_position: -2.9668
    max_position: 2.9668
    has_velocity_limits: true
    max_velocity: 1.7 
    has_acceleration_limits: true
    max_acceleration: 5. 
  joint_a2:
    min_position: -2.9668
    max_position: 2.9668
    has_velocity_limits: true
    max_velocity: 1.7 
    has_acceleration_limits: true
    max_acceleration: 5. 
  joint_a3:
    min_position: -2.9668
    max_position: 2.9668
    has_velocity_limits: true
    max_velocity: 2.0 
    has_acceleration_limits: true
    max_acceleration: 5. 
  joint_a4:
    min_position: -2.0942
    max_position: 2.0942
    #min_position: -2.0000
    #max_position: 2.0000
    has_velocity_limits: true
    max_velocity: 1.6 
    has_acceleration_limits: true
    max_acceleration: 5. 
  joint_a5:
    min_position: -2.9668
    max_position: 2.9668
    has_velocity_limits: true
    max_velocity: 2.5 
    has_acceleration_limits: true
    max_acceleration: 5. 
  joint_a6:
    min_position: -2.0942
    max_position: 2.0942
    has_velocity_limits: true
    max_velocity: 2.6 
    has_acceleration_limits: true
    max_acceleration: 5. 
  joint_a7:
    min_position: -3.051
    max_position: 3.051
    has_velocity_limits: true   
    max_velocity: 2.6 
    has_acceleration_limits: true
    max_acceleration: 5. 

Do you have any ideas?
Thank you,
Stefania

[Jorge Nicho]

Hello Stefania,

The STOMP planner does not take the joint_limits.yaml into account but it can be configured to obey joint limits as defined in the URDF.  The configuration for STOMP is specified in a yaml file , can you provide your stomp_config.yaml file?  Thanks

[G.A. vd. Hoorn - 3ME]

On 7-9-2016 16:45, Jorge Nicho wrote:
> Hello Stefania,
> The STOMP planner does not take the joint_limits.yaml into account but it
> can be configured to obey joint limits as defined in the URDF. The
> configuration for STOMP is specified in a yaml

> <https://github.com/ros-industrial/industrial_moveit/blob/indigo-devel/stomp_test_kr210_moveit_config/config/stomp_config.yaml#L23>

> file , can you provide your stomp_config.yaml file? Thanks

Jorge,


is that something that you plan on changing/fixing?

I think it's reasonable for users of MoveIt to assume that planners will
use the parameters configured through the various files in a MoveIt
configuration package, so it would be nice if that would be possible for
STOMP as well.


Gijs

[Jorge Nicho]

Gijs,

 My understanding is that the joint_limits.yaml overwrites the URDF specified settings for each joint; if this is the case then STOMP (when properly configured) should obey such overwritten joint limits as it gets them from the moveit::core::RobotModel which is available within the planning pipeline.   At the moment, STOMP stores configurations for each planning and custom joint limits should be group specific as well.  This isn't a feature yet but I think it makes sense to add it.

[Stefania Pellegrinelli]

Hi Jorge,
thank you for the clarification in relation to the joint_limits.yaml. Attached the stomp_config.yaml file I'm using.

Stefania

[Jorge Nicho]

Stefania,

I just looked at it and it appears to be configured correctly How are you verifying that the joint limits aren't being obeyed?

[Stefania Pellegrinelli]

Given:

  moveit::planning_interface::MoveGroup group("manipulator");  
  moveit::planning_interface::MoveGroup::Plan plan;
  group.plan(plan);

I check for all point_id that:

  plan.trajectory_.joint_trajectory.points.at(point_id).positions.at(joint_id)

is within the joint limits of the joint corresponding to joint_id. The considered joint limits are those listed in the URDF file.

I noticed the problem for the first time trying to execute the generated trajectory on the real robot. Then, I started checking the joint values of the trajectories as here described.

Stefania

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[Jorge Nicho]

Stefania,

If I understand you correctly, the joint values in the planned trajectory are within the joint limits as defined in the urdf but not those that you define in joint_limits.yaml right?  My understanding was that the joint_limits file would override the limits in the URDF, this is steps that should take place regardless of which planner you use as far as I know, but it seems that that isn't happening.  Which joint limit is being exceeded, min max, speed or acceleration?

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[Stefania Pellegrinelli]

Jorge,

I have the same joint limits in the URDF and in the joint_limits.yaml. I'm exceeding the min-max (the joint position).

Thank you a lot for your support

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[G.A. vd. Hoorn - 3ME]

On 7-9-2016 17:57, Jorge Nicho wrote:
> Gijs,
> My understanding is that the joint_limits.yaml overwrites the URDF
> specified settings for each joint; if this is the case then STOMP (when
> properly configured) should obey such overwritten joint limits as it gets
> them from the moveit::core::RobotModel which is available within the
> planning pipeline. At the moment, STOMP stores configurations for each
> planning and custom joint limits should be group specific as well. This
> isn't a feature yet but I think it makes sense to add it.

I'm not sure I completely understand your before-last sentence, but if
the STOMP infrastructure uses the RobotModel, then I would assume that
the overrides from joint_limits.yaml should be taken into account. As
you say.

[Jorge Nicho]

Stefania,

The specs on the iiwa 14 r820 show different joint limits for joint 2 (A2 in the specs).  Could it be that the planner is obeying the URDF/joint_limits.yaml  limits but the values in those files differ from those on the real robot?  Thanks