Configuration Space/ Joint Space

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Dheenu
Posts: 7
Joined: 15 Apr 2017, 01:29

Configuration Space/ Joint Space

Post by Dheenu » 19 Jul 2019, 03:34

Hello,

I have a confusion in configuration space for a robotics arm.

I know C-space have the dimension of number of joints in a robot. for example 7-DOF robot will have 7-D C-Space.

So when we implement motion planning algorithms like RRT, PRM or any other planning algorithms in C-Space, if choose a random point in C-space (say for example 5.5) how does a single random point corresponds to 7-D C-space. I mean don’t we need to specify a vector 7 different random points to denote a point in C-Space?

Thanks in advance

coppelia
Site Admin
Posts: 7330
Joined: 14 Dec 2012, 00:25

Re: Configuration Space/ Joint Space

Post by coppelia » 19 Jul 2019, 13:58

Hello,

this question does not seem to be directly linked to V-REP.
When you mean a
single random point
, you probably mean a single random node. A node represents a configuration in the configuration space of the robot and is often used in randomized path planning algorithms.

Cheers

fferri
Posts: 396
Joined: 09 Sep 2013, 19:28

Re: Configuration Space/ Joint Space

Post by fferri » 21 Jul 2019, 18:04

Dheenu wrote:
19 Jul 2019, 03:34
I know C-space have the dimension of number of joints in a robot. for example 7-DOF robot will have 7-D C-Space.
Dheenu wrote:
19 Jul 2019, 03:34
if choose a random point in C-space (say for example 5.5)
How can 5.5 be sampled from C-space? You just said C-space had 7 dimensions...

By the way, this has nothing to do with V-REP.

FYI, in actual motion planning algorithms, C-space is never computed explicitly. Instead, collisions are computed lazily, on the sampled points. That's why sampling-based motion planning algorithms are successful, even in high-dimensional spaces, despite the problem being PSPACE complete (at least as hard as NP-complete).

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