IK with Robotiq gripper 2f 85 attached on UR5e

[rrapi]

Hello everyone,

I am a master science student and for my thesis I am working on a UR5e robot with a Robotiq 2f 85 gripper directly attached. In this project I have to grasp some objects in different positions and orientations, so for this reason I am using MoveIt to get directly the Inverse Kinematics of a desired position and orientation depending on the object detected. But the problem is that MoveIt considers as the reference frame of the endeffector the original one that ends in tool0, but as I am working with the gripper, I need that the referenze frame of the ee has to be of the robotiq gripper, so tranlates of ~19 cm wrt z-azis of previous one. Without this setting the IK is always wrong as it changes completely the result. Unfortunately ur5e_moveit_config package of has no gripper in the configuration, i tried to make one by me but did not work.

Could you please help me to solve this problem? Thank you very much in advance!

Best regards, Franci

[welcome[bot]]

Thanks for reporting an issue. Because we're a volunteer community, providing a pull request with suggested changes is always welcomed.

[rhaschke]

Please follow the SRDF tutorial to define your planning group. The arm group needs to include the end-effector frame. If you don't succeed, explicitly state your problem. "It did not work" doesn't help to pinpoint your issue. In general, this question should be better asked at https://answers.ros.org. Please, post real issues and bug reports here.

[rrapi]

Hi @rhaschke! Thank you for your answer! I solved that issue modifying the ur_macro.xacro file.

But now I have another issue when using moveit to send the gripper in a desired Pose. The Pose is in front of the robot, so it would be easy to reach for him, but often he wants to reach this Poses doing some joint movements (for example going behind or rotate a lot of times) that makes him to collide with some object in the environment. I tried various planners as RRTConnect, PRM or TRRT but no one worked well and with no collisions.

Could you suggest me a solution please? Maybe another planner that works different and is fine in this case, some parameter changes or to set like some space movement allowances.

[rhaschke]

Probably the orientation of your target pose strongly differs from your ee pose, enforcing rather large joint motions to match them

[rrapi]

And which is the reason that this happened? And how I can solve/avoid this??

[rhaschke]

It is your job to specify the correct target orientation as well - not only target position.

[rrapi]

I understand...I am working on it for further target orientation improvements. I have another question, I tried to set the velocity of the robot while going to a desired pose (because I need a slower movement for opening a drawer for example) with moveit function set_max_velocity_scaling_factor(value) (with value=0.25 to set 1/4 of the maximum speed), but it doen't work, do you have any suggestions for that?