#robotics Logs

Jan 10 2015

01:32 RifRaf started a new canadian postal service rue?
01:41 rue_house they seem to be romising things get to people faster
01:41 Hyratel weird, erratic behavior: for ADC input range 000..0x7FF, when the input is reading across 0x003 and 0x004, the LED I have on PWM is flickering at full brightness. anyone got any ideas? This is with a Cypress PSoC 4200 series chip
01:41 rue_house than I have ever seen
01:42 rue_house Hyratel, your adc inputs are mixed up
01:42 rue_house your really reading a pin adjacent to the one you think you are
01:42 Hyratel nope
01:42 rue_house and the stray capacitance has it follow for the most part
01:42 Hyratel it's flickering only at value 003 to 004
01:42 rue_house ground out all unused adc channels and try again
01:43 Hyratel it's a SOC, all pins are explicitly created and assigned
01:43 Hyratel all ADC inputs are explicitly created
01:43 rue_house ah, if its not an avr I'm not sure
01:43 rue_house its because your soc is junk
01:43 rue_house :)
01:43 Hyratel I doubt it
01:44 rue_house obviously it is, the adc circuit is folding over
01:44 Hyratel mainly because I'm not seeing the fluttering on the console output
01:44 Hyratel instead, it looks like it's a weird in the PWM circuit
01:44 A4K Where is your analog input coming from? A pot?
01:44 Hyratel yep
01:44 rue_house maybe the pwm is junk, no buffering
01:44 Hyratel tried 3 different pots, left handed and right handed
01:44 Hyratel all give the same behavior
01:45 rue_house is the pwm buffered like on an avr?
01:45 A4K You may be having mechanical noise from the pot... You need a 'turnless' (infinite turn) pot to avoid that... If that IS the problem.
01:45 Hyratel i don't think it is
01:45 Hyratel I'm going to mess with the PWM
01:46 rue_house A4K, he's just gonna reject anything we say
01:46 Hyratel rue_house, actually
01:46 rue_house see?
01:46 A4K Life of a roboticist, do you expect any less?
01:46 Hyratel I've been trying to see if it' sthe ADC or pot for hours
01:46 rue_house :)
01:47 Triffid_Hunter Hyratel: race condition writing to the timer register
01:47 rue_house A4K, are you hiding under a secret name or are you someone new?
01:47 Hyratel Triffid_Hunter, hmm
01:47 A4K rue_house, I'm new. Just googled robotics IRC.
01:47 rue_house ah cool
01:47 rue_house A4K, as to happy hour, people have to show up for it!
01:47 Triffid_Hunter Hyratel: if you can, only update the timer register when the timer overflows. still possible to get races but they should be significantly rare
01:48 Triffid_Hunter rarer*
01:48 A4K It's a shame there isn't a larger community
01:48 rue_house the sad part is that this channel covers most of the world
01:48 Hyratel Triffid_Hunter, put this in a PM to me so I can check it later
01:48 rue_house A4K, where are you from?
01:48 A4K Yeah, it was basically the only still active channel. I am from Australia. You?
01:48 rue_house canada
01:49 rue_house RifRaf, theBear and GuShH are also in australia
01:49 A4K Ah cool. Are you guys mostly professionals or enthusiasts?
01:49 RifRaf hi A4K
01:49 A4K Hello RifRaf
01:49 RifRaf GuShH, is NOT from au silly
01:49 rue_house option C, hobbyist
01:50 RifRaf he is AR
01:50 rue_house GuShH, if he would stop damn well moving I could keep track
01:50 RifRaf just finished a new printer rue, solid aluminium i3
01:50 rue_house ah yes
01:50 rue_house did he post pics?
01:50 RifRaf no i did
01:50 rue_house hah
01:51 rue_house I take it he had some help then?
01:51 RifRaf about to start calibration
01:51 rue_house ooh I see where Imixed up
01:51 rue_house heh
01:51 rue_house you gonna use it or sell it?
01:51 RifRaf want to use it as main one, and sell the old one, replaceing bearings and making it look nice
01:52 rue_house heh, just a few last upgrades
01:52 RifRaf the solid frame should handle triple extruder better
01:52 rue_house or even a quad!
01:52 RifRaf or hex
01:52 RifRaf well the hex needs a bigger frame, is a project in a short while
01:53 rue_house maybe use a nema42 on the Y axis
01:53 anonnumberanon Are those cheap USB logic analyzer of any use?
01:53 RifRaf nema23 should do the job
01:54 rue_house anonnumberanon, never used one
02:18 joga anonnumberanon, for stuff like looking at i2c etc. they're okay and cheap
02:19 anonnumberanon Maybe my Analog Discovery can do it.
02:19 anonnumberanon I just got it.
03:44 anonnumberanon http://www.nasa.gov/multimedia/nasatv/#.VLDtEYdXaFY
03:45 anonnumberanon launch
03:54 joga when?
03:55 joga k, 10min
03:55 joga ...or not
04:07 anonnumberanon http://www.nasa.gov/multimedia/nasatv/#.VLDtEYdXaFY
04:07 anonnumberanon 30 seconds
04:10 joga heh... "vlc media player"
04:16 rue_bed did a launch go wrong?
04:20 deshipu again?
04:22 anonnumberanon it launched fine
04:23 anonnumberanon now we're waiting for the landing attempt on the sea barge...!!!
04:32 deshipu barbaric!
04:34 deshipu it should be forbidden
04:34 deshipu forever
06:11 ShH waves to Ri
06:11 GuShH rue_house: dude I moved 40-50KM from where I was hahah
08:07 codepython777 can anyone tell me how to calculate the payload capacity of a truck like this: https://www.servocity.com/html/nomad_4wd_off-road_chassis.html ?
08:08 deshipu what do you mean by "payload capacity" exactly? how is it distributed
08:09 deshipu also, what do you want the car to do while under that payload -- there is no hard edge at which it just stops running, but it will degrade slowly
08:10 deshipu the axles are the usual suspects for giving up first
08:13 Veverak nah
08:13 Veverak friend of mine showed me ninja printer plate
08:14 verak is againg battling the battle: have to convince myself that I don't nee
08:14 deshipu Veverak: it's for a plate that you use to print ninjas, right?
08:14 Veverak deshipu: more or less? :)
08:15 Veverak http://printinz.com/printer-plates/
08:16 codepython777 deshipu: I want to put 3kg of load on it and then run it on grass/roads
08:16 deshipu codepython777: on it == on that platform in the middle?
08:18 Veverak just by looking at it
08:18 Veverak codepython777: have you thought about RC Crawler?
08:18 Veverak (just asking)
08:19 codepython777 Veverak: not yet, can you show me a link
08:19 codepython777 deshipu: yes, i will probably screw a ply on that platform top and then screw in the weights
08:19 Veverak codepython777: http://farm4.static.flickr.com/3448/3400778870_8e30f06f93_b.jpg
08:19 Veverak for example
08:20 Veverak many companies sells these.. I suppose "axial" is one of them
08:20 Veverak but you can find much more I suppose :D
08:20 Veverak and community around these specific RC Cars got ... big sense in DIY them
08:20 Veverak so I suppose it's easy to build one
08:20 codepython777 Veverak: Does anyone have a flat surface on top that i can screw some things on?
08:21 codepython777 Veverak: The one i am looking at, its easy to customize.
08:21 Veverak I don't say it's better option, didn't dive into details, just asking :D
08:21 Veverak codepython777: everything can have flat surface on top if you add it :P :D
08:21 deshipu codepython777: I would check how much the axles on those parts that rotate with the wheels can take
08:21 deshipu codepython777: they look like the weakerst spots
08:22 deshipu codepython777: then the wheel axles
08:22 deshipu codepython777: and also the power of the motors
08:25 codepython777 deshipu: how does one convert the 4 motor kgf-cm to payload?
08:27 deshipu codepython777: take the diameter of the wheel as the cm
08:27 deshipu sorry, radius
08:28 deshipu basically divide by the wheel radius
08:28 Veverak hmm
08:28 deshipu that tells you how much weight it can carry over a bump
08:29 deshipu of course you want to have a margin ther
08:29 deshipu e
08:29 Veverak hmm
08:29 Veverak deshipu: can I ask you ?
08:30 Veverak how can I calculate "how much weight it can carry over a bump" given that I know max-power in wattage and max-RPM ?
08:30 Veverak also know the volts...
08:30 Veverak + I can modify the calc given that I know the gearratio
08:31 deshipu Veverak: you would need to know it's mechanical power, not the electrical -- the difference is efficiency
08:32 Veverak nah, don't know that :/
08:34 codepython777 Motors: 4.5 kgf-cm
08:35 Veverak deshipu: but given that I know it...
08:35 Veverak deshipu: I calculate actual mechanical power and divide mechanical power / rpm ?
08:36 codepython777 5.4" diameter wheels
08:36 Veverak nah, given this view it ... RC Cars motors/esc sucks for robotics
08:36 codepython777 deshipu: https://www.servocity.com/html/313_rpm_hd_precision_planetary.html - this is the motor
08:37 codepython777 how do we calculate payload now?
08:37 deshipu divide the torque by the radius of the wheel
08:38 deshipu but use the same units
08:38 deshipu I recommend ISO units
08:38 deshipu as they are somewhat more consistent
08:38 deshipu radius is half o diameter
08:44 codepython777 4.5kgf-cm/6.858cm?
08:44 codepython777 deshipu: .7 kgf per wheel? whats the payload then?
08:46 deshipu how did you get 0.7?
08:47 deshipu well, how many wheels do you have?
08:59 codepython777 oops
08:59 codepython777 4.5/6.8 = 0.6561679790026247?
09:01 deshipu yeah
09:02 deshipu so you can lift and hold that much per wheel when going over a vertical obstracle
09:02 deshipu obstacle
09:02 deshipu it's a simplification, of course
09:03 deshipu because in practice the two back wheels will be on ground, and the weight will be somewehre in between
09:03 deshipu so you will have a lever
10:28 Veverak https://cloud.veverak.org/public.php?service=files&t=d27b06047be5fb1c3230fbfb8e5a11ab finally nice idea for robot frame
10:29 deshipu hmm, that's quite a low suspension
10:29 Veverak max. I can get for that size of the wheels
10:30 Veverak hmm, but I didn't involved the thickness of the tracks in the calculations
10:30 deshipu Veverak: I mean, the yellow things that hang well below the acles
10:31 deshipu Veverak: they will hit obstacles on the floor and make the vehicle "hang" on them
10:31 Veverak yeah, I get your point
10:33 deshipu there was a brilliant video about making robots that can go around your room forever
10:33 deshipu let me find it
10:33 Veverak well
10:34 Veverak point is that suspension allows only 17mm of "movement"
10:35 deshipu the point is to not have any part of the chassis stick out beyond the wheels
10:36 Veverak well... practically I am ok with that?
10:37 Veverak deshipu: airless wheel suspension -> suspension by pressing the wheel
10:37 Veverak actually it's made so the yellow-frame is on the level of wheels axis
10:37 deshipu I mean the yellow stuff sticks out beyond the shape of the wheels in front
10:38 Veverak in front ! :D
10:38 deshipu let me get my tablet
10:38 Veverak yeah, I get the point for that
10:40 deshipu http://paste.sheep.art.pl/c77a51fb-83af-4b96-835d-02f4eba97b04
10:41 deshipu Veverak: also, think about obstacles that are narrower than the body, and come between the tracks
10:42 deshipu Veverak: I would make the body as high as possible, offset by stability issues
10:42 Veverak well, point is that I prefer stabillity over ... obstacles?
10:42 Veverak :D
10:43 deshipu there surely is some sweet spot
10:43 deshipu that gives you maximum clearance with maximum stability
10:43 Veverak yeah, I suppose I got it now...
10:44 Veverak axis of that wheels -> doesn't move with suspension
10:44 Veverak actualy level of the chassis -> that of axis of suspension
10:44 Veverak but I suppose I will add some ... changes for front/back
10:46 Veverak deshipu: actually when you would got only wheels and press the robot to it's maximum... I suppose the chasses would barelly touch the floor
10:46 Veverak so there is some reserver with "tracks" for maximum pressed suspension
10:48 Veverak *some reserve
10:48 Veverak deshipu: I won't got hill-climbing with that :)
10:51 Veverak https://cloud.veverak.org/public.php?service=files&t=a17944d0a471ab1dc9d3a79def0a17f3
10:51 Veverak I suppose you mean something like that?
10:54 deshipu yes
11:12 Veverak https://cloud.veverak.org/public.php?service=files&t=01fa105e198db3e6916846e2ae6df870 "done" so far
11:12 Veverak but chassis -> in progress
11:12 Veverak gearbox -> heavy in progress
11:12 Veverak tracks -> track mounting in progress
11:15 Tom_L you want tank tracks?
11:15 Tom_L this is how you do it: http://www.users.qwest.net/~kmaxon/page/side/robot1_137.htm
11:16 Veverak nah, different level..
11:19 Tom_L http://www.users.qwest.net/~kmaxon/page/side/robot012_137.htm
11:21 Veverak yeah
11:21 Veverak looks like some thing I've got
11:22 Veverak just mine is more complicated in shape
11:23 Veverak https://cloud.veverak.org/public.php?service=files&t=bff614cad1d682e4970aa99ae4df5457
11:24 veinofstars man
11:25 Tom_itx Veverak, that guy built an injection mold machine just to make those
11:26 Veverak yeah, I am not that into it :)
11:26 armyofevilrobo-1 Don’t see much posted by him anymore, but he’s amazing.
11:26 Tom_itx me either
11:57 deshipu Tom_itx: ugh, that website, so many gifs O.o
11:58 deshipu and all the images not loadin
11:58 deshipu g
12:01 Veverak yeah
12:01 Veverak his robotics skills are awesome
12:01 Veverak not so great with webdesign though
12:01 deshipu https://www.youtube.com/watch?v=dd8sIbxN4Zc <-- this is quite cool, robots building things
12:03 Veverak deshipu: awesome
16:43 Tom_itx deshipu, yeah he needs to fix some of it, it's been up for a long time and i think he changed hosts at least once or twice
23:24 e_shop4 stret
23:52 rue_shop4 fixing up this cnc will be precarious
23:53 rue_shop4 I wonder if it'll take less time to reverse engineer the harness or to find the diagram