#robotics Logs
Aug 22 2018
#robotics Calendar
12:00 AM gaze__: noice
12:04 AM gaze__: so more specifically
12:04 AM rue_mohr: its 80-100lbs of ugh for me
12:04 AM gaze__: is it worth preloading skateboard bearings?
12:04 AM gaze__: if you need them to have minimal play
12:04 AM rue_mohr: depends some of them are pretty sloppy
12:04 AM rue_mohr: what you using the bearings on?
12:04 AM rue_mohr: and what software are you controlling the winder with?
12:04 AM rue_mohr: not gcode...
12:04 AM gaze__: eh maybe the question I should ask is if you know of a cheap source of good bearings in preloaded pairs
12:04 AM gaze__: I was thinking of hacking up a hard drive
12:04 AM gaze__: and using the head bearings
12:04 AM gaze__: but I don't know much about them
12:04 AM rue_mohr: give me an application
12:04 AM rue_mohr: I use a combo of thrust and skate that preload
12:04 AM orlock: gaze__: preload depends specifically on the load i think?
12:08 AM gaze__: pulling and pushing on the translating and rotating rod in the coil winder
12:08 AM rue_mohr: gaze__, what is the screen grid made from on that, I dont ahve one on mine
12:08 AM orlock: gaze__: for linear bearings, then one's that i've seen have a slit so you can adjust the clamping force on them to remove slop
12:08 AM * orlock liberally applies alchohol
12:08 AM orlock: ants around my new desk
12:08 AM rue_mohr: drat, I have to got to bed
12:08 AM orlock: so i'm using these handy spray packs of alohol to get rid of them
12:08 AM gaze__: https://www.youtube.com/watch?v=Mvk6q_gT7Xo
12:08 AM gaze__: there's these bearing cartridges
12:08 AM gaze__: i'd love to know if they're preloaded/angular contact
12:14 AM rue_bed: oik
07:36 AM nineties: hey guys, i would like to track rc cars on the floor to make computer-controlled vehicles for racing, it's a hobby project, and i though about some lights on the cars (i just need position and orientation) and a camera on the ceiling, what do you guys think of that idea?
07:39 AM nineties: the idea is to place lights of different color and in some shape i can easily identify the orientation
07:40 AM durrf: the PSVR uses domes of coloured light for positional tracking of the headset/controllers
07:40 AM nineties: the problem is that i'd need some high resolution low latency video input into the computer
07:40 AM nineties: durrf: yep, that's more or less the idea
07:40 AM nineties: it's a hobby project so i can't really get some pricey camera
07:41 AM durrf: you dont need a pricey camera
07:41 AM nineties: and i can place bright lights on the vehicles so exposure can be low
07:41 AM durrf: the pseye (ps3 camera) works
07:41 AM durrf: and you can find those at pawn shops for 2 bux
07:41 AM nineties: durrf: i think they're too low-resolution
07:41 AM durrf: it works for tracking the psmove via software called psmoveservice
07:42 AM durrf: i have dabbled in using psvr on pc
07:42 AM nineties: yeah, but the problem is i need to identify not only the position but the orientation of the individual vehicles, they're like 10cm on a 10m area
07:42 AM nineties: i'll need some detail to get the orientation
07:42 AM durrf: you would require more then one point and/or accelerometers/gyroscopes on the cars
07:43 AM durrf: you could use a psmove for that sort of stuff but it will add weight to the cars
07:43 AM z64555: thought that 2 axis IMU's were cheap these days
07:44 AM durrf: https://github.com/cboulay/PSMoveService this stuff does it in real time pretty well, but requires at least two cameras for proper 3d positioning, but i got 3x cameras for a grand total of 15 bux
07:44 AM z64555: decent
07:44 AM durrf: i know that people also use the microsoft kinect
07:44 AM durrf: that has 2 cameras built into it
07:45 AM z64555: it also has a lidar, if I'm not mistaken. which probably wouldn't be all that helpful in this application
07:46 AM durrf: does it have lidar? i thought it only used those IR dots
07:47 AM robotustra: morning
07:47 AM nineties: ok guys, so you don't recommend getting the orientation from the image input?
07:49 AM robotustra: nineties, what is your idea?
07:50 AM robotustra: or project?
07:50 AM nineties: robotustra: i need to track rc cars on the floor, i just need position and orientation so i was thinking that maybe something like a gopro on the ceiling would do (and opencv)
07:50 AM nineties: and some lights on the cars
07:51 AM nineties: with special shape to detect the orientation properly
07:51 AM veverak: hi robo!
07:52 AM robotustra: I think we already discussed this thing, yeah, the camera + LED possibly should work ok
07:52 AM robotustra: veverak, hi
07:52 AM robotustra: nineties, are you getting the stream from gopro?
07:53 AM nineties: robotustra: nope, i didn't buy anything yet because i don't know if latency is good since most of these cameras buffer for quite a while and convert the stream too
07:54 AM veverak: I had reasonable latency with rpi and it's camera
07:54 AM nineties: the downside is that i need quite a bit of definition to detect the orientation
07:54 AM robotustra: nineties, define what precision do you need
07:54 AM veverak: yup
07:54 AM robotustra: and latency
07:55 AM robotustra: you can put 3 leds stationary to define the camera position
07:55 AM robotustra: so you will read 4 leds
07:55 AM robotustra: 3 for coordinate system and 1 for the car
07:56 AM robotustra: or even put 2 leds on a car to know the direction were it goes
07:56 AM nineties: well, the cars are like 10-15cm on a 10x12m area, and i need latency and framerate enough for a speed of like 20km/h (sorry metric system)
07:56 AM robotustra: 5 m/c
07:56 AM nineties: i don't think only 2 leds are enough for orientation unless they're different shapes
07:56 AM robotustra: it's a lot
07:57 AM robotustra: different colors
07:57 AM robotustra: you can install many leds to define the trak for instance
07:57 AM nineties: well yeah... i was thinking of different colors per vehicle, but cameras can detect many colors :P
07:58 AM robotustra: it is
07:58 AM nineties: the camera will be stationary so i don't need to detect the track though
07:58 AM robotustra: it will solve the problem of camera position
07:58 AM z64555: even then it would be difficult to discern the different shapes of the LED's
07:59 AM z64555: I recommend having 4 LED's in a T
07:59 AM robotustra: I myself came now to the task of detectins special points on the frames of binocular vision
08:00 AM robotustra: I think 4+
08:00 AM z64555: 2 LED's at the top bar of the T, and 2 LED's in the column
08:01 AM nineties: the problem on relying on colors is that i don't know to what extent ambient lighting will affect that
08:01 AM nineties: needless to say i need a camera that allows you to disable white balance and such
08:02 AM robotustra: you can compose different shapes like L shape, + shape, etc
08:02 AM robotustra: of group of leds
08:03 AM durrf: yeah this is how the PSVR detects headset orientation (along with the accel/gyro data)
08:03 AM durrf: the front/back of the headset has different patterns of light
08:04 AM durrf: you can get the psmoveservice to track just a sphere of light, an LED in a pingpong ball for example
08:04 AM durrf: all other positional tracking systems im aware of use other shit (like the htc lightboxes or whatever they are called)
08:05 AM durrf: which i assume is similar to the tech used in nolovr
08:05 AM durrf: is it outside? can you use GPS? lol
08:05 AM nineties: lol
08:05 AM robotustra: indoor
08:06 AM nineties: it sounds like a plan :) ... so i need a low latency video stream, do you guys recommend any camera for that? i'd need control over exposure too ofc
08:07 AM nineties: most consumer grade cameras are very limited on that regard
08:08 AM durrf: the pseye has very low latency and 60fps
08:08 AM durrf: i dunno about the range that it can track at
08:08 AM durrf: but thats whats used for psvr on pc quite often
08:09 AM durrf: https://www.youtube.com/watch?v=kKevIGRe-gE
08:09 AM durrf: to show the latency/setup/tracking
08:09 AM durrf: thats using 2x pseye cameras
08:10 AM durrf: (and modified drivers)
08:12 AM nineties: looks great... i'm not sure if the resolution is enough though, but i guess i could use multiple cameras
08:12 AM nineties: covering different areas of the track
08:13 AM nineties: what are those ps4 dual cameras?
08:16 AM durrf: the original ps4 camera has the stereoscopic cameras
08:16 AM durrf: but in the vidoe the guy uses the ps3 pseye cameras
08:16 AM durrf: you *can* set it up using one but it cant get proper 3d positionning with only one
08:18 AM nineties: i don't need 3d positioning, the floor is flat and the camera position will be fixed, from the image i can easily calculate the actual position on the floor
08:18 AM nineties: and i'm thinking about pointing the camera straight down so the transformation is even easier
08:36 AM nineties: ok, say i'll need 4 pseye cameras, should i expect trouble connecting them to the computers and getting+processing the streams?
08:42 AM speedevil: USB processing can be a problem - cameras don't always share what bandwidth there is well.
08:42 AM speedevil: You may need one motherboard root port per camera.
08:44 AM nineties: speedevil: well, so for 4 cameras on modern motheboards i don't think it'll be a problem right?
08:46 AM speedevil: no.
08:46 AM speedevil: Note that USB3 doesn't help at all here, unless you have cameras that can do superspeed.
08:48 AM durrf: other then it being a seperate host
08:48 AM speedevil: (the camera saying it is USB3 is not an indication)
08:48 AM durrf: vs the usb2 ports
08:50 AM nineties: but are these pseye cameras usb3? o_O
08:50 AM durrf: nope
08:51 AM durrf: the ps3 pseye is usb2 and the ps4 camera uses its own fucked up connector
08:51 AM nineties: and can you control exposure and white balance and such?
08:51 AM durrf: but its just usb
08:51 AM durrf: yeah i think so
08:51 AM nineties: great... i think the pseye is indeed a good option
08:51 AM durrf: theres an option in the psmoveservice configuration app that lets you tweak the camera settings and whatnot
08:52 AM durrf: https://www.etr.fr/articles_images_1/359834-psmoveservice_psvr_9.png
08:52 AM durrf: dont see white balance there actually
08:53 AM durrf: but theres a lot of changes to the UI between versions so it might be there now i dunno
08:56 AM speedevil is now known as SpeedEvil
09:26 AM SpeedEvil: https://www.ebay.co.uk/itm/3D-Mini-Photograph-Stereoscopic-Camera-Lens-for-Cell-Phone-Tablet-MB-Universal/153005673535
09:26 AM SpeedEvil: There are also hacks.
09:26 AM SpeedEvil: This avoids many of the normal 3d vision problems - matching white balance, frame sync, ...
09:29 AM rue_mohr: I got one of those
09:29 AM rue_mohr: need to line it up with the ccd orientatin well
09:31 AM nineties: hey guys, what about DSLRs, can some of them stream video to the computer at low latency?
09:31 AM durrf: many of them have HDMI out but i dunno about latency
09:31 AM rue_mohr: why do we suddenly have a flood of computer vision people?
09:32 AM durrf: nor duration that they can remain on for
09:32 AM rue_mohr: most of the latency is the software on things that handle it, lots of coders like to receive a full frame before they start to send it
09:33 AM rue_mohr: put a few layers of that between you and your camera and you get a 500ms latency
09:33 AM rue_mohr: regardless of processor speed
09:33 AM nineties: oh boi... half a second is absurd...
09:33 AM rue_mohr: waitng for a full frame to come in before you start to send it is obsurd
09:34 AM nineties: indeed
09:34 AM rue_mohr: requiring a web browser to have 256bit encryption for viewing public content is obsurd
09:34 AM nineties: but even though good cameras can capture a frame in 1/16000 of a second
09:34 AM rue_mohr: obsurd is the new normal
09:34 AM rue_mohr: and new software can delay a video stream 60 frames
09:35 AM nineties: yeah, software these days sucks :P
09:35 AM rue_mohr: but even 15 frames is trouble
09:35 AM durrf: so much overhead
09:35 AM nineties: indeed
09:35 AM rue_mohr: a web browser that needs to use 64bit addressing to handle the memory its using is obsurd
09:36 AM nineties: not if you consider that they often use many gigs of memory
09:36 AM nineties: but that fact is absurd :P
09:37 AM rue_mohr: I love that you can turn the cache off, and it does anyhow
09:37 AM weyland|yutani: 1.8gig atm running 30+ tabs
09:38 AM rue_mohr: and that having a program that deletes the cache every few minutes increases performance due to the fact its not taking so long checking the cache content to see if its up to date
09:38 AM rue_mohr: cause it actaully takes less time to redownload the content then to check the cache
09:38 AM nineties: yeah... i'm kinda ok with firefox these days though
09:39 AM nineties: so there's no newer alternative to the pseye with a little bit better resolution?
09:42 AM nineties: what about say the rpi camera module?
09:44 AM durrf: the kinect works too, pretty sure oyu can use any camera
09:45 AM durrf: but the reason they use the pseye is the low latency i think
09:46 AM rue_mohr: when will people learn to use sheer plane for depth perception rather than stereo vision?
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10:21 PM mrdata-- is now known as mrdata_