Post on 23-Feb-2016
description
On Improving the Clearance for Robots in High-Dimensional Configuration Spaces
Roland Geraerts and Mark OvermarsIROS 2005
Outline• Related work• Retraction algorithm• Algorithmic details• Experiments• Conclusions
Related Work• Preprocessing techniques
– Extract path from graph with cycles– Create path along the medial axis
• Post processing technique– Retract path to the medial axis (MA)
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Related Work• Preprocessing techniques
– Extract path from graph with cycles– Create path along the medial axis
• Post processing technique– Retract path to the medial axis (MA)
Related Work• Preprocessing techniques
– Extract path from graph with cycles– Create path along the medial axis
• Post processing technique– Retract path to the medial axis (MA)
Initial path Retraction to MA Retraction to ridges
Retraction Algorithm
Algorithmic Details – Metric
Algorithmic Details – Vector
Algorithmic Details – Validate
maximumstep size
Experimental Setup• Pentium 4 (2.66GHz)• Comparison of retraction techniques
– Workspace (1 run)– Configuration space (100 runs)
• Environments / paths
planar (2 dofs) hole (6 dofs) manipulator (6 dofs)
Experimental Results
min avg timeinitialworkspaceC-space
0.351.801.79
2.844.494.47
0.01.5
15.0
initial paths workspace C-space
n.a.
Clearance
min avg timeinitialworkspaceC-space
0.210.441.27
1.553.374.69
0.01.5
50.0
min avg timeinitialworkspaceC-space
0.01 n.a.0.16
0.13 n.a.0.33
0.0 n.a.60.0
Conclusions• Clearance along paths is improved
– No complicated data structures are needed– The algorithm can handle robots with an
arbitrary amount of DOFs• Running times are too high for online usage
– Does not matter for high-cost environments– Smarter implementation decreased the running
times by an order of magnitude
Current Work• Retraction of a roadmap yields online performance
Reachability roadmap Retracted roadmap
Current Work• Retraction of a roadmap yields online performance
Reachability roadmap Retracted roadmap