PR2 navigation with wheeled object(s) - ROS.org · 2010. 9. 13. · PR2 navigation with wheeled...
Transcript of PR2 navigation with wheeled object(s) - ROS.org · 2010. 9. 13. · PR2 navigation with wheeled...
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PR2 navigation with wheeled object(s)Jon Scholz
Georgia Tech
Willow Garage Intern Presentation, 8/19/2010
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Introduction• How can we improve on
the hackathon results?•What are the main
criteria for a good planner?
• Starts to get interesting when we add cart params
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Considerations for good planning
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TextText
• “optimality” (??)
•Soundness •Completeness
<- It’s tough to get both ->
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The Task• Amounts to solving the following core problems:• Perceiving the state of the cart• Articulating the cart with both arms• Checking the cart and robot for collisions• Combining everything in a new local planner
• And solving these would be nice too:• Visualization (publish cart models, footprints, etc.)• Robot+Cart teleop• Utils for setting up runs (pose saver and teleop)
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Quick overview of the NavStack• Plugin-based architecture that alternates between
two modes• Global planning: Search a map for a path• Local planning: Issue robot commands to follow path
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I focused mainly on this
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The Cart Hackathon Approach
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Is it Sound?
Is it Complete?
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First improvement: Articulation
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• Added a method for articulating rigid bodies with both arms
• Created a local planner that picked cart poses from the global plan and sent along to the cart controller
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Cart Pushing 0.1: havoc!
Is it Sound?... obviously not
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More improvements•Collision detection for the cart•Velocity control of cart (smoothness)•Global plan pruning (no more spin-offs)•Combined velocity filtering (better waypoint
tracking)
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Trajectory Rollout
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Filtering and Obstacle Avoidance
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Cart Pushing Final
Is it Sound?
Is it Complete?
No!? ...so what did we get?
Sort of... more like “safe”
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Conclusions•We can push holonomic (hackathon) carts
through buildings with fairly high confidence
•Traded a little soundness for completeness• Solution: cart global planner
•What about other carts, chairs, etc?• cart_local_planner is a base class for deriving
pushing-type controllers
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The problem with other carts
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•Same idea, but different constraints are different...
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Related Work•pr2_pose_saver
$ savepose hackathon_cart_ready$ setpose hackathon_cart_ready.pps
•pr2_cockpit_teleop
• rxplot
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rxplot: 3D plotting
$ rxplot --mode=3d Pose2D/x:y:theta
$ rxplot --mode=2d Pose2D/x:y:theta
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Thanks!•With special acknowledgment to Bhaskara
and Sachin for their feedback and assistance
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