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 | 1 | initial version |
The "ball" (official terminology: interactive marker) is essentially a virtual 6dof input device. So it has position and orientation.
By dragging the marker, you are changing all of those at the same time. A < 6dof serial chain will not be able to follow the marker around for all combinations of positions and orientations, as it solution space is a subset of the 6dof set for the marker. That is the reason the marker becomes 'detached' (it's really the robot that stops following the marker, not the other way around).
The 'jumping' you describe could be due to MoveIt asking the kinematics solver for alternative solutions in an attempt to resolve this (which it can't, because the 6dof pose will remain unreachable by the arm).
Your problems with moveit_joy could basically be the same problem: moveit_joy essentially allows you to 'drag' the interactive marker but then using a joystick.
| | 2 | No.2 Revision |
The "ball" (official terminology: interactive marker) is essentially a virtual 6dof input device. So it has position and orientation.
By dragging the marker, you are changing all of those at the same time. A < 6dof serial chain will not be able to follow the marker around for all combinations of positions and orientations, as it solution space is a subset of the 6dof set for the marker. That The MoveIt RViz plugin allows you to ask the IK solver to ignore the orientation if necessary (the "approximate IK solutions" you mention), but that only works-around the problem. This is the reason the marker becomes 'detached' (it's really the robot that stops following the marker, not the other way around).
The 'jumping' you describe could be due to MoveIt asking the kinematics solver for alternative solutions in an attempt to resolve this (which it can't, because the 6dof pose will remain unreachable by the arm).
Your problems with moveit_joy could basically be the same problem: moveit_joy essentially allows you to 'drag' the interactive marker but then using a joystick.
| | 3 | No.3 Revision |
The "ball" (official terminology: interactive marker) is essentially a virtual 6dof input device. So it has position and orientation.
By dragging the marker, you are changing all of those at the same time. A < 6dof serial chain will not be able to follow the marker around for all combinations of positions and orientations, as it solution space is a subset of the 6dof set for the marker. The MoveIt RViz plugin allows you to ask the IK solver to ignore the orientation if necessary (the "approximate IK solutions" you mention), but that only works-around the problem. This is the reason the marker becomes 'detached' (it's really the robot that stops following the marker, not the other way around).
The 'jumping' you describe could be due to MoveIt asking the kinematics solver for alternative solutions in an attempt to resolve this (which it can't, because the 6dof pose will remain unreachable by the arm).arm). Another possible cause could be that (MoveIt 'thinks') your links are in collision and tries to find a solution that makes them not collide.
Your problems with moveit_joy could basically be the same problem: moveit_joy essentially allows you to 'drag' the interactive marker but then using a joystick.
| | 4 | No.4 Revision |
The "ball" (official terminology: interactive marker) is essentially a virtual 6dof input device. So it has position and orientation.
By dragging the marker, you are changing all of those at the same time. A < 6dof serial chain will not be able to follow the marker around for all combinations of positions and orientations, as it solution space is a subset of the 6dof set for the marker. The MoveIt RViz plugin allows you to ask the IK solver to ignore the orientation if necessary (the "approximate IK solutions" you mention), but that only works-around the problem. This is the reason the marker becomes 'detached' (it's really the robot that stops following the marker, not the other way around).
The 'jumping' you describe could be due to MoveIt asking the kinematics solver for alternative solutions in an attempt to resolve this (which it can't, because the 6dof pose will remain unreachable by the arm). Another possible cause could be that (MoveIt 'thinks') your links are in collision and tries to find a solution that makes them not collide.
Your problems with moveit_joy could basically be the same problem: moveit_joy essentially allows you to 'drag' the interactive marker but then by using a joystick.
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