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[CS686] Paper presentation 1
KAIST School of Computing
Generation of Dynamically Feasible and Collision Free Trajectoryby Applying Six-order Bezier Curve and Local Optimal Reshaping
Liang Yang et al.
IROS 2015
Heechan Shin
2017.04.27
CS686
[CS686] Paper presentation 1
KAIST School of Computing
Contents
• Problem of the paper• Backgrounds• Framework• Methods• Result• Summary• Limitation• Quiz
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[CS686] Paper presentation 1
KAIST School of Computing
Problems of the paper
• UAVs(or other robots) can follow a path, which is designed by previous path planner, with relatively slow speed.
• Piecewise linear paths are generated by RRT, RRT*, etc.
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[CS686] Paper presentation 1
KAIST School of Computing
Backgrounds
• Curvature
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[CS686] Paper presentation 1
KAIST School of Computing
Backgrounds
• Curvature
• Why is the curvature important?• Non-holonomic robots can’t go through piecewise linear path with high speed
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Low speed High speed
[CS686] Paper presentation 1
KAIST School of Computing
Backgrounds
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• G2-Continuity
• End point• Tangent• Curvature radius
[CS686] Paper presentation 1
KAIST School of Computing
Backgrounds
• Bezier curve• Using Bernstein polynomial• N-1 order Bezier curve with N points• Continuous curvature at joint of two curves
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[CS686] Paper presentation 1
KAIST School of Computing
Framework
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[CS686] Paper presentation 1
KAIST School of Computing
Framework
• Path planner : Guiding Attraction based Random Tree(GART)• Attraction to the goal & Repulsion by the obstacles
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[CS686] Paper presentation 1
KAIST School of Computing
Methods
• Bezier curve based path smoothing
• Dangerous region finding
• Local optimal reshaping
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[CS686] Paper presentation 1
KAIST School of Computing
Methods – Bezier curve based path smoothing
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Six-order → 7 points
From path planner
From interpolation
[CS686] Paper presentation 1
KAIST School of Computing
Methods – Bezier curve based path smoothing
• How can we get interpolation points?
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[CS686] Paper presentation 1
KAIST School of Computing
Methods – Bezier curve based path smoothing
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• Tuning Rotation(TR)• Turning adjacent node until smooth
enough• Making the curve be consistent
[CS686] Paper presentation 1
KAIST School of Computing
Methods – Dangerous region finding
• “UAV simulations with dynamics show that the dangerous region”
• Performing fast simulation
• Obtaining dangerous regions (collision-expected)
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[CS686] Paper presentation 1
KAIST School of Computing
Methods – Local optimal reshaping
• Nodes near dangerous region should be reshaped
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Path length Curvature(1)
(1) Minimum distance from center of object𝒅𝒅𝒔𝒔𝒔𝒔𝒔𝒔𝒔𝒔 = 𝟒𝟒𝟒𝟒
(2),(3) Redistribution region
(2)
(3)
(4) Bezier curve
(4)
[CS686] Paper presentation 1
KAIST School of Computing
• Curvature within maximum curvature after smoothing and reshaping• Not enough to their target curvature 0.1
Result
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[CS686] Paper presentation 1
KAIST School of Computing
Result
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• After Tuning Rotation, curvature becomes lower than 0.1
[CS686] Paper presentation 1
KAIST School of Computing
Result
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• With speed disturbance 0.2m/s magnitude of WGN
[CS686] Paper presentation 1
KAIST School of Computing
Summary
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Guiding Attraction based Random Tree(GART)Six-order Bezier curve and Tuning RotationForward simulation to find dangerous regionLocal Optimal Reshaping
[CS686] Paper presentation 1
KAIST School of Computing
Limitation
• No mention about computational time
• No dynamics
• No difficult obstacles
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[CS686] Paper presentation 1
KAIST School of Computing
QnA
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THANK YOU
References• Generation of Dynamically Feasible and Collision Free Trajectory by Applying Six-order Bezier Curve and Local Optimal Reshaping (IROS 2015)• Guiding attraction based random tree path planning under uncertainty: Dedicate for UAV (IROS 2014)
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