Plan path with minimum clearance.

Hey all,

I am trying to plan a path using RRT for a robot manipulator using matlab.

Currently I am using manipulatorRRT as a planner, however i cannot find any way to change the minimal clearance of the planned path.

Due to safety of he application, I need a certain distance to all environment objects.

Is there any way to set the clearance in manipulatorRRT, or what can i use alternatively to achieve a path with a certain clearance?

Thank you very much for your help!

Yours,

Lukas

Answer 1

[Karsh Tharyani]

Hi Lukas,

You can't specify a safety clearance in the planner. However, if your environment comprises of meshes (even if it isn't you can convert them to a collision mesh using convertToCollisionMesh), you can simply scale up the meshes in the environment and that should create a safety clearance for you.

Here's how you scale a mesh:

groundvehiclemesh=collisionMesh(stlread('groundvehicle.stl').Points);

% Show the original collision mesh

subplot(1,2,1)

show(groundvehiclemesh);

xlim([-150,150])

ylim([-150,150])

zlim([-60,60])

title("Original Mesh");

% Scale the mesh by a scaling factor

scalingfactor=2.5;

groundvehiclemesh.Vertices=scalingfactor*(groundvehiclemesh.Vertices);

% Show the scaled collision mesh

subplot(1,2,2);

show(groundvehiclemesh);

xlim([-150,150])

ylim([-150,150])

zlim([-60,60])

title("Scaled Mesh " + string(scalingfactor) + "X")

Then you can simply pass the scaled mesh to the planner "manipulatorRRT" during its creation.

Hope that helps,

Karsh

[Lukas Schroth]

Thank you very much, that helped!!

Answer 2

[Image Analyst]

I suggest you get a mask of your objects then enlarge them with imdilate to create the safety buffer zone around them. Then see Steve's blog to get the shortest route:

Exploring shortest paths – bwdistgeodesic

[Karsh Tharyani]

The posts which you link are only relevant for 2D point like robots. The OP is asking about manipulatorRRT which uses a rigid body tree and involves collision checking for poses in 3D.