Problem
The link 1 body is modelled as a constant cylinder mesh with the maximum diameter from its base. This simple shape had been chosen to simplify the mesh. However the actual link body reduces in diameter towards the top. The simple mesh does not take this into account.
While this approach is generally acceptable for collision checking and performant it has a problem:
After the robot has been homed, the gripper can be rotated in a way that it appears collides with the collision body (1), while the hardware is clear of the body (2). The robot is hence in a collision state and any motion planning fails since the start state is invalid.
Fig. 1: Collision with the link 1 collision body
Fig. 2: Corresponding state in the hardware. The gripper is clear of the link 1 body.
Workaround
Manually move the robot out of collision (deactivate the hardware to do so). Then motion planning succeeds.
Solution
Model a collision body that is both simple (few triangle) yet models the changing diameter to avoid the collision state after homing.
Problem
The link 1 body is modelled as a constant cylinder mesh with the maximum diameter from its base. This simple shape had been chosen to simplify the mesh. However the actual link body reduces in diameter towards the top. The simple mesh does not take this into account.
While this approach is generally acceptable for collision checking and performant it has a problem:
After the robot has been homed, the gripper can be rotated in a way that it appears collides with the collision body (1), while the hardware is clear of the body (2). The robot is hence in a collision state and any motion planning fails since the start state is invalid.
Fig. 1: Collision with the link 1 collision body
Fig. 2: Corresponding state in the hardware. The gripper is clear of the link 1 body.
Workaround
Manually move the robot out of collision (deactivate the hardware to do so). Then motion planning succeeds.
Solution
Model a collision body that is both simple (few triangle) yet models the changing diameter to avoid the collision state after homing.