Creating High-quality Roadmaps for Motion Planning in Virtual Environments Roland Geraerts and Mark Overmars IROS 2006

Requirements The roadmap –is resolution complete –is small –contains useful cycles –provides high-clearance paths res. complete, smalluseful cycleshigh-clearance paths

Outline Reachability Roadmap Method (RRM) –Resolution complete roadmap –Small roadmap Adding useful cycles Adding clearance to the roadmap Experiments Conclusions & current work

RRM – Criteria Coverage –Each free sample can be connected to a vertex in the graph Maximal connectivity –For each two vertices v’,v’’: If there exists a path between v’ and v’’ in the free space, then there exists a path between v’ and v’’ in the graph

Reachability Roadmap Method Paper –R. Geraerts and M.H. Overmars. Creating small roadmaps for solving motion planning problems. MMAR 2005, pp Outline of algorithm –Discretizes the free space –Computes small set of guards –Guards are connected via connector –Resulting roadmap is pruned

Adding Useful Cycles Paper –D. Nieuwenhuisen and M.H. Overmars. Useful cycles in probabilistic roadmap graphs. ICRA 2004, pp Useful edge –Edge (v,v’) is K-useful if K * d(v,v’) < G(v,v’) v’v

Adding Useful Cycles Useful node –Node v is useful if there is an obstacle inside the cycle being formed v’ v’’ v

Adding Useful Cycles Algorithm –Create RRM roadmap –Add useful nodes –Create a queue with all collision-free edges Queue is sorted on increasing edge length –Add edge from the queue to the graph if edge is K-useful RRMuseful nodesfinal roadmap

Providing High-clearance Paths Paper –R. Geraerts and M.H. Overmars. Clearance based path optimization for motion planning. ICRA 2004, pp Retract edges to the medial axis –Retraction of a sample d d

Providing High-clearance Paths Paper –R. Geraerts and M.H. Overmars. Clearance based path optimization for motion planning. ICRA 2004, pp Retract edges to the medial axis –Retraction of an edge

Experimental Setup Field House Office Quake

Experimental Results Field Graph statisticsPath statistics resolutiontechniquetime (s)|V||E|SPFavg query (ms) 94 x 94RRM RRM* RRMRRM*RRRM

Experimental Results Field Clearancetime minavgmaxs RRM* RRRM RRMRRM*RRRM

Experimental Results Office Graph statisticsPath statistics resolutiontechniquetime (s)|V||E|SPFavg query (ms) 130x80RRM RRM* RRMRRM*RRRM

Experimental Results Office Clearancetime minavgmaxs RRM* RRRM RRMRRM*RRRM

Experimental Results House Graph statisticsPath statistics resolutiontechniquetime (s)|V||E|SPFavg query (ms) 57 x 20 x40RRM RRM* RRMRRM*RRRM

Experimental Results House Clearancetime minavgmaxs RRM* RRRM RRMRRM*RRRM

Experimental Results Quake Graph statisticsPath statistics resolutiontechniquetime (s)|V||E|SPFavg query (ms) 57 x 20 x40RRM RRM* RRMRRM*RRRM

Experimental Results Quake Clearancetime minavgmaxs RRM* RRRM RRMRRM*RRRM

Conclusions High-quality roadmap –resolution complete –small –short and alternative paths –high-clearance paths –fast query times

Future Work Corridor Map Method –Creating high-quality paths within 1 ms Paths are smooth, short or have large clearance –Method is flexible Paths avoid dynamic obstacles

Future Work Corridor Map Method –Creating high-quality paths within 1 ms Paths are smooth, short or have large clearance –Method is flexible Paths avoid dynamic obstacles Smooth pathShort pathPath avoiding obstacles