#robotics Logs

May 19 2018

04:10 AM Jak_o_Shadows: veverak, were you the one with the hexapod with the linear actoators?
04:14 AM Jak_o_Shadows: PLease keep us informed on how that is going. I will want to scale my quadrapod up at some point, and that seems like it might be nicer
04:14 AM veverak: nope
04:14 AM Jak_o_Shadows: aha.
04:14 AM Jak_o_Shadows: oh well
04:28 AM veverak: I've got into deep C++ levels to code the thing
04:28 AM veverak: :)
04:29 AM veverak: just now: decomposition into convex hull
04:31 AM veverak: or
04:31 AM veverak: to be more precise, conversion of 3D triangular mesh into a set of 3D simplexes, that represent the 3D shape of the mesh
04:32 AM veverak: somehow I believe I need decomposion of the surface mesh into a set of convex hulls
04:32 AM veverak: as tetrahedralization of convex hull is simple
04:40 AM rue_: mesh to mesh conversion?
04:41 AM veverak: surface triangle mesh -> set of 3d simplexes
04:42 AM rue_: for layering rendering?
04:43 AM veverak: need to mark all voxels of space, that are in collision with the 3d shape
04:43 AM rue_: oooh
04:43 AM veverak: not just the ones that are in collision with the surface
04:43 AM rue_: binary trees
04:43 AM rue_: stl to binary tree
04:43 AM veverak: octal :)
04:43 AM rue_: same difference
04:44 AM veverak: P.S: assimp is awesome
04:45 AM veverak: rue_: anyway yeah, I have octal tree where nodes are voxels
04:45 AM rue_: I recall
04:45 AM rue_: and the tree solves the problem of needing to allocate n^3 voxels
04:46 AM veverak: yup
04:46 AM veverak: because it can prunne itself
04:46 AM rue_: what is the voxel library used for?
04:46 AM veverak: so it's size is based more on the level of detail of environment, rather than the environment size
04:46 AM veverak: rue_: motion planning
04:46 AM rue_: ah ok
04:46 AM rue_: slam
04:47 AM veverak: do want SLAM
04:47 AM veverak: in todo to learn
04:47 AM veverak: anyway, SLAM's and the octree work well together
04:47 AM veverak: proer OcTree has "propability that something is in the voxel" assigned to each node
04:47 AM veverak: that represents if the voxel is empty or not
04:48 AM veverak: that works well with sensors AFAIK, not tested by myself yet
04:48 AM rue_: adjust the hit % that cuases a voxel to exist?
04:48 AM veverak: I do
04:49 AM veverak: 11.92% - 971%
04:49 AM veverak: 11.92% - 97.1%
04:49 AM rue_: hah, I'm tired, but it IS 2am
04:49 AM veverak: (numbers from the article on the topic)
04:49 AM rue_: I would assume if a voxel is >50% hit it should be created
04:50 AM rue_: but the resolution thing, so hmm
04:50 AM veverak: nah, it is created always
04:50 AM veverak: it's just that once a voxel has 11.92/97.1 prob. it is prunned
04:50 AM veverak: (it's children are dropped)
04:51 AM veverak: (with a caveat: only in cases where all children are leafs)
04:51 AM rue_: how is the size of the root voxel determined?
04:51 AM veverak: it's autoscaled
04:51 AM veverak: rue_: it starts with small voxel (depends on use case)
04:51 AM veverak: that determines the lower bound
04:51 AM rue_: to the specified 11.92-97.1%?
04:51 AM veverak: each time you insert something into tree
04:51 AM veverak: it scales the roop up in case it would not fit in
04:52 AM rue_: but if your taking an stl and voxelizing it
04:52 AM rue_: via intersections
04:52 AM veverak: I do, I may have pic somewhere
04:52 AM rue_: 2am I need sleep
04:53 AM rue_: the input of a TTL gate pulls up @ about 1ma
04:53 AM rue_: I think thats enough current to trip a transistor to drive 5ma
04:53 AM rue_: which means my new matrix keyboard controller is plausable
04:54 AM veverak: rue_: nice thing is that you can create 'anytime' collision detection
04:54 AM veverak: as you don't have to go to the leafs of the tre
04:54 AM rue_: but a ttl gates pullup is not enough to trigger a 2803 input
04:54 AM veverak: but stop in 1/2 of it's depth
04:55 AM rue_: gnight
04:55 AM veverak: gnight rue_
06:58 AM ad is now known as adddd
06:58 AM adddd is now known as AchiestDragon
11:42 AM rue_: so I have _one_ 8x8 led matrix
11:42 AM rue_: if I want to make a rom with it, I have to get it right the first time
12:40 PM SpeedEvil: what?
12:41 PM SpeedEvil: Just use 64 diodes
12:51 PM mrdata: 64 diodes to do what again?
12:52 PM mrdata: voltage drop? stand off?
02:14 PM z64555: LED matrix
05:04 PM rue_: diode rom
06:24 PM z64555: but
06:24 PM z64555: what would you do with 8 bytes of data