Is it possible to get the end-effector to the desired position without knowing the orientation for the end-effector for a 4 DOF robot arm?

asked 2019-10-08 00:31:38 -0500

Mano gravatar image

updated 2019-10-08 00:38:23 -0500

I have a 4 DOF robot arm model and using lma kinematics solver. If I know the valid position(x,y,z) in space but don't know the orientation for the the end-effector, Is it possible to get the end-effector to the desired position ? (I'm sorry if the question is stupid)

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Hello, it's not stupid, it has been asked many time

Is it what you are looking for ? : https://answers.ros.org/question/2549...

lmathieu gravatar imagelmathieu ( 2019-10-08 06:09:29 -0500 )edit

Thank you, but I'm confused with the syntax, I have tried move_group.set_position_target(x,y,z, end_effector) or move_group.set_position_target([x,y,z]), both didn't work, former error says atmost 3 arguments (5 given) and the latter error says no motion plan found (given valid position). Or is it a kinematics solver problem?

Mano gravatar imageMano ( 2019-10-08 09:39:09 -0500 )edit

Probably a Kinematics solver problem but I can't say it for sure. The correct way in python is the second version :

def moveit_commander.move_group.MoveGroupCommander.set_position_target  (       self,
            xyz,
            end_effector_link = "" 
    )       

Specify a target position for the end-effector. Any orientation of the end-effector is acceptable.

You can try to get the current position and add a +0.01m to any direction to see if moveit can plan it for you (or get a random pose and try to plan a random trajectory)

Also, You can get the doc here : http://docs.ros.org/kinetic/api/movei...

lmathieu gravatar imagelmathieu ( 2019-10-08 11:07:09 -0500 )edit