#robotics Logs
Aug 08 2017
#robotics Calendar
12:07 AM rue_shop3: zhanx, the cad drawing of the first piece will take me a bit, it turns out that openscad cant actually make 2d dxf's from stl files 8|
12:09 AM zhanx: rue, i got 1 torn down, so the race is one then
12:09 AM rue_shop3: I have most of the first peices drawing, I have to slog out some labour for the final bits of it
12:09 AM anniepoo: zhanx, you on?
12:09 AM rue_shop3: wood block with 4 holes, not to, sorry
12:09 AM zhanx: yes
12:09 AM anniepoo: kk, read pm
12:11 AM zhanx: rue size?
12:11 AM zhanx: i have some 1/4 wood or is it 3/8?
12:13 AM anniepoo: well, you should have snailishness in a few days
12:14 AM zhanx: cool
12:14 AM zhanx: kids are gonna love this
12:14 AM rue_shop3: 1/2"
12:15 AM rue_shop3: each peice from about 4"x2.5" peice
12:15 AM rue_shop3: piece
12:16 AM zhanx: i can do that
12:16 AM rue_shop3: oh I know you can do it, I just have to locate the other two holes
12:17 AM rue_shop3: +-, right now I have to go to bed
12:18 AM anniepoo: should go good with a small RC toy
12:26 AM rue_shop3: https://www.aliexpress.com/item/Free-shipping-5PCS-AS5600-ASOM-AS5600-SOP8-magnetic-encoder-With-magnet-NEW-ORIGINAL/32806731050.html
03:46 AM Jak_o_Shadows: Recently been getting into https://optimizationcodes.wordpress.com/ at work
03:46 AM Jak_o_Shadows: cool stuff
05:40 AM Jak_o_Shadows: and I found a pdf somewhere
05:40 AM Jak_o_Shadows: not sure where
08:43 AM SpeedEvil: google sometimes indexes pdfs, so simply search words inside
08:50 AM robotustra: http://i.imgur.com/TwlRCkI.png
09:23 AM rue_more: yea, I also need a way to disable that stupid thing in the top right corner about privacy settings
09:24 AM deshipu: F11
09:24 AM deshipu: oh, sorry, they changed it ctrl+shift+i
09:24 AM rue_more: "Control your Google privacy settings. Take a quick Privacy Checkup." NO
09:42 AM rue_more: YAY, finally worked out how to block the google privacy popup!!!!
09:42 AM veverak: hmm
09:42 AM veverak: found out I can't do quaternions
09:42 AM rue_more: hopefully it holds
09:42 AM rue_more: why not?
09:43 AM rue_more: on what?
09:43 AM veverak: my math is wrong
09:43 AM rue_more: so fix it
09:43 AM veverak: need to orient 3D disk in space
09:43 AM veverak: so it reflexs given axis ([0,0,1])
09:44 AM robotustra: veverak: use euler angles instead?
09:44 AM rue_more: is the disk 2d or 3d?
09:44 AM veverak: disk is 2d in 3d space
09:44 AM rue_more: ok
09:44 AM rue_more: poly or infinate?
09:45 AM veverak: don't understand?
09:46 AM veverak: robotustra: I need to provide quaternion for visualization
09:46 AM rue_more: is it made of polygons?
09:46 AM veverak: but can create it from euler angles
09:46 AM veverak: rue_more: does not matter
09:46 AM veverak: I provide 'quaternion' for library, it displays the disc
09:46 AM veverak: can't get the quaternion right
09:46 AM rue_more: sure it does, you have to know where the disc starts... dont ya?
09:47 AM rue_more: or its always a 'normal disc'
09:47 AM veverak: ah
09:47 AM veverak: default: disc axis is aligned with 'x' axis
09:47 AM rue_more: ah
09:48 AM rue_more: so, you could just rotate it on the Y by 90, but your trying to do it with a quat
09:48 AM veverak: "quaternion_about_axis()" is not the function I want maybe
09:48 AM veverak: rue_more: I need to provide quad
09:48 AM veverak: I can create it from eulers
09:48 AM veverak: :)
09:49 AM rue_more: going to work, bye!
09:49 AM robotustra: horces die from work
09:49 AM veverak: I see
09:50 AM veverak: the code for quaternion_about_axis is bullshit
09:50 AM veverak: well
09:50 AM veverak: let's do it by myself
09:51 AM rue_more: how is the result being applied?
09:52 AM veverak: dunno
09:52 AM rue_more: is the disc being specified by normal, position, and radius
09:52 AM rue_more: ?
09:52 AM veverak: just position and orientation
09:52 AM rue_more: 2v+s?
09:53 AM veverak: more like
09:53 AM veverak: disc is static 3D element
09:53 AM rue_more: 2 vectors and a scalar?
09:53 AM veverak: you just set where you want to position it in space
09:53 AM veverak: by specifiing x,y,z coordinate and orientation
09:53 AM robotustra: hyroscope?
09:54 AM veverak: http://imgur.com/nYTwEJM
09:56 AM veverak: it works as fancy control of each joint
09:56 AM veverak: :)
09:57 AM veverak: differen approach
09:57 AM veverak: I have 'v1' as start state
09:57 AM veverak: 'v2' as end state
09:57 AM robotustra: do you do IK task?
09:57 AM veverak: (both, [x,y,z] coordinates)
09:57 AM veverak: define v1 -> v2 using quaternion
09:57 AM veverak: len(v1) == len(v2)
09:57 AM veverak: robotustra: IK is next layer
09:58 AM robotustra: what CAD do you use?
09:58 AM veverak: openscad
09:58 AM veverak: (thing on picture is not CAD)
09:58 AM robotustra: you did draw it in OpenGL?
09:58 AM veverak: what?
09:59 AM veverak: why would I? :D
09:59 AM robotustra: what is this?
09:59 AM veverak: ros.org -> rviz
09:59 AM veverak: 3D visualization tool
09:59 AM robotustra: ok
09:59 AM robotustra: you just put your model inside?
09:59 AM veverak: yep
09:59 AM robotustra: nice
09:59 AM veverak: now I want it to show "interactive markers"
09:59 AM veverak: (the circles)
10:00 AM veverak: which can be interacted using the interface
10:00 AM veverak: to directly controll joints
10:00 AM robotustra: I got rid of the idea to put my robot inside visualizer
10:01 AM veverak: hmm
10:01 AM veverak: Python version of 'tf' library (lirbary that has math to do this things)
10:01 AM veverak: got few functions
10:01 AM veverak: but!
10:01 AM robotustra: do you want your robot to be able to flip upside down?
10:01 AM veverak: the C++ got a lot of it
10:01 AM veverak: robotustra: not sure
10:02 AM veverak: I want it to walk eventually
10:02 AM robotustra: different giats?
10:03 AM robotustra: do you have the real leg and body position feedback?
10:03 AM veverak: not in this phase
10:03 AM veverak: I just fake it
10:03 AM veverak: (bachelor thesis)
10:03 AM veverak: (next thesis will have proper feedback)
10:03 AM veverak: robotustra: I do not think in terms of feedback
10:03 AM veverak: robotustra: I think in 'state of the robot'
10:03 AM veverak: I can lineary change the state a little
10:04 AM veverak: so I search for "sequence of little state changes that make me arrive into goal state"
10:04 AM veverak: using Graphs, and "finding shortest path in graph"
10:11 AM robotustra: veverak: what is one leg is broken?
10:45 AM SpeedEvil: https://www.theguardian.com/technology/2017/aug/08/self-driving-autonomous-vehicle-man-dressed-up-as-car-seat-arlington-virginia-tech-university?CMP=fb_gu
11:20 AM veverak: robotustra: ??
11:23 AM deshipu: https://voltera.io/
12:57 PM robotustra: veverak: will your robot change the giat if one of the leg is broken?
01:05 PM veverak: should be definetly possible
01:05 PM robotustra: will you put it into the code?
01:13 PM veverak: I don't have to explicitly
01:13 PM veverak: :)
01:27 PM robotustra: veverak: https://www.youtube.com/watch?v=tQqJGwjm6Xs
01:28 PM robotustra: https://hackaday.io/project/8843-mr-runner
01:34 PM robotustra: http://i.imgur.com/V3vk51H.gifv
01:42 PM rue_shop3: damnit, Farnsworth was right again, keeping little coloured bits of wire in a drawr is a damn good idea
01:43 PM SpeedEvil: Also, tying ear-defenders so they hang at the operating position of noisy machines
02:00 PM veverak: well
02:00 PM veverak: "shortestArcQuat(v0,v1)"
02:00 PM veverak: is it
02:00 PM veverak: creates shortest quaternion to change from v0 to v1
02:01 PM veverak: http://imgur.com/HqXqV8Y
02:06 PM veverak: last task
02:07 PM veverak: I have Quaternion q1
02:07 PM veverak: which is original rotation
02:07 PM veverak: Than I have quaternion q2
02:07 PM veverak: which is actual rotation
02:07 PM veverak: I know axis abouw which it should rotated
02:07 PM veverak: I should be able to get the angle of rotation
02:09 PM anniepoo: yes, you want quaternion to axis-angle
02:10 PM anniepoo: are you using some package to do the math?
02:10 PM veverak: I try to, but it's range of operations is limited
02:10 PM veverak: but I have proper C++ package, rewriting some methods into python
02:10 PM veverak: :)
02:11 PM anniepoo: ok, well, angleaxis is the representation you want
02:11 PM veverak: yeah
02:11 PM veverak: but!
02:11 PM veverak: hmm
02:11 PM veverak: have to thing about how to do this
02:11 PM veverak: axis I know and axis of each quaternion
02:11 PM anniepoo: https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#Recovering_the_axis-angle_representation
02:11 PM anniepoo: 8cD
02:11 PM veverak: could be completely different thing
02:12 PM veverak: anniepoo: I can calculate shortest angle between two quaternions
02:12 PM anniepoo: well, there is some rotation in some axis between any two unit vectors
02:12 PM veverak: theoretically, it's the thing, except that I am missing sign
02:12 PM anniepoo: the axis is going to be the cross product
02:13 PM anniepoo: right hand rule
02:18 PM z64555: and the w component is the dot product
02:18 PM z64555: iirc
04:45 PM anniepoo: @zhanx your box went out this morning, should be there friday
04:47 PM veverak: finally got my math right!
04:52 PM anniepoo: whoot
04:52 PM anniepoo: 8cD that great feeling when the math's right
04:53 PM veverak: except
04:54 PM veverak: that I have to use multiply on place
04:54 PM veverak: where I should not :)
04:59 PM anniepoo: instead of divide?
05:17 PM veverak: nah, repaired that bug
05:18 PM veverak: one last thing remains
05:18 PM veverak: decent way to detect if vectors are in same direction or opposite direction
05:40 PM veverak: https://youtu.be/-obcyxlUoX8 <3
05:46 PM deshipu: why does the servo rotate together with the horn?
05:47 PM veverak: minor details!
05:47 PM veverak: :D
05:47 PM veverak: deshipu: I am more triggered by STL bugs to be honest
05:49 PM veverak: anyway
05:49 PM veverak: I will provide similar interface in front of "IK"
05:50 PM veverak: really 3 arrows at tip of the leg
06:38 PM * anniepoo attaches herself to a ginormous servo and drives it with an arduino that sends random positions every 500msec
06:38 PM anniepoo: 8cD
06:41 PM anniepoo: veverak, what software's this from?
08:14 PM rue_more: did you get the quatermions worked out?
08:26 PM ace4016: quarterminions? (quaternions)
08:40 PM z64555: alright! finally got the little bastard apart
08:41 PM z64555: jackshaft is in rough shape, needs to be rethreaded. got mad at the pulley so it's out of commision
08:41 PM z64555: but the bearing block is in usuable state. which is the main thing
08:58 PM robotustra: https://www.youtube.com/watch?v=u5OCyOfTdnQ
10:00 PM rue_shop3: yea, like the violin better than the origional
10:01 PM trojan is now known as synja
11:26 PM Luminax-Work is now known as LuminaxWk