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On Screw Linear Interpolation for Point-to-Point Path Planning

Anik Sarker 1 Anirban Sinha 1 Nilanjan Chakraborty 1
Stony Brook University 1
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ScLERP based motion planning algorithm can implicitly satisfy few tasks constrains (such as pure translation, pure rotation etc.) without explicitly defining them.

Overview

Robot motion is controlled in the joint space whereas the robots have to perform tasks in their task space.

Many tasks like carrying a glass of liquid, pouring liquid, opening a drawer requires constraints on the end-effector during the motion. The forward and inverse kinematic mappings between joint space and task space are highly nonlinear and multivalued (for IK). Consequently, modeling task space constraints like keeping the orientation of the end-effector fixed while changing its position (which is required for carrying a cup of liquid without dropping it) is quite complex in the joint space.

We show that the use of screw linear interpolation to plan motions in the task space combined with resolved motion rate control to compute the corresponding joint space path, allows one to satisfy many common task space motion constraints in motion planning, without explicitly modeling them. In particular, any motion constraint that forms a subgroup of the group of rigid body motions can be incorporated in our planning scheme, without explicit modeling. We present simulation and experimental results on Baxter robot for different tasks with task space constraints that demonstrates the usefulness of our approach.

Example applications of the ScLERP based motion planner

Video showing advantages of Screw Linear Interpolation (ScLERP) in maintaining complicated task space constraints without explicitly encoding them.

IROS Presentation:

Talk about a simple method of dealing with constraints on hand motion during manipulation of objects. Constraints on hand motion that arise when operating a man-made object with mechanical joints can be handled easily with this approach. Examples include opening a drawer (prismatic joint), opening a hinged door (revolute joint), screwing/unscrewing a light bulb (screw joint) . More technically, this talk is about showing that screw linear interpolation along with resolved motion rate control allows us to plan motions for manipulation where the constraints on the motion of the hand(s) are constrained to a sequence of or combination of subgroups of SE(3) (the group of rigid body motions).

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BibTeX

@INPROCEEDINGS{9341651, author = {Sarker, Anik and Sinha, Anirban and Chakraborty, Nilanjan}, booktitle = {2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)}, title = {On Screw Linear Interpolation for Point-to-Point Path Planning}, year = {2020}, volume={}, number={}, pages={9480-9487}, doi={10.1109/IROS45743.2020.9341651}}