#robotics Logs

Apr 04 2017

12:18 AM rue_house: na
12:25 AM Anniepoo_: evening rue
12:36 AM Guest26609 is now known as CrazEd
12:36 AM CrazEd is now known as Guest16044
12:55 AM rue_house: haha, its brilliant!
12:55 AM rue_house: you use lasers to generate eddy currents in the metal, that attract the atomized particles to it, which are thermallly fused byt eh lasers
12:56 AM rue_house: hahaha
12:58 AM Anniepoo_: how does the laser induce eddy currents?
01:01 AM Anniepoo_: or are you talking with somebody I muted?
01:08 AM mrdata: no one muted that i can see
01:10 AM Anniepoo_: thanks
01:36 AM Guest16044 is now known as CrazEd
01:37 AM CrazEd is now known as Guest7776
01:45 AM rue_house: no
01:45 AM rue_house: its concentrated high freq wave
01:49 AM Anniepoo_: hf as in radio
01:50 AM rue_house: as in 850nm
02:37 AM Guest7776 is now known as CrazEd
02:37 AM CrazEd is now known as Guest79175
03:38 AM Guest79175 is now known as CrazEd
03:38 AM CrazEd is now known as Guest39925
10:11 AM rue_house: I think I figured out the problem with my nc spooler, I was sending the lines with \r\n on them, which I think is generating a dual "ok" which screws up the transactions
10:16 AM rue_house: ahhhh
10:16 AM rue_house: click
10:17 AM rue_house: when you send ?<cr> you get an OK
10:17 AM rue_house: the ? is responded to right away, the <cr> generates the OK
10:19 AM deshipu: I just soldered 22 servo shields \o/
10:19 AM deshipu: and I soldered the chip backwards only on one of them
10:19 AM rue_house: I hope you didn't apply power with it backwards
10:20 AM deshipu: I did, my usb port shut down
10:20 AM rue_house: ah
10:20 AM rue_house: I wonder if it killed the chip
10:20 AM rue_house: what chip youuse?
10:20 AM deshipu: nah, there is also a polyfuse on the mcu board
10:20 AM rue_house: 4017? 595?
10:20 AM deshipu: pca9685
10:20 AM deshipu: the led driver
10:20 AM rue_house: oooh, the "I promise you 12 bits, but for servos only deliver 7"
10:21 AM deshipu: leds don't complain
10:21 AM rue_house: no
10:21 AM rue_house: resolution sucks for servos tho
10:21 AM deshipu: depends on how sucky servos you have, I guess
10:22 AM rue_house: no
10:22 AM rue_house: you see, the servo pulses are at 20ms
10:22 AM rue_house: they are up to 2ms long
10:22 AM rue_house: so, your duty is, at best
10:23 AM rue_house: 10%, which for 12 bits (4096) is 409 counts
10:24 AM deshipu: yeah, I know, I wrote the driver for that thing
10:24 AM rue_house: so, for 12 bits, you get less than 9
10:24 AM rue_house: opposed to my code, thats gives you 16000 counts
10:24 AM rue_house: which nobody wants
10:24 AM deshipu: I wonder why :)
10:25 AM rue_house: cause they dont care about jitter and resolution
10:25 AM deshipu: I also have my own 20-channel shield with an atmega328p, but I'm not confident enough in my code to be selling it
10:25 AM deshipu: I sold the 3 prototypes I made, no complaints yet, though
10:26 AM deshipu: I suspect they just lie at the bottom of some drawer
10:26 AM rue_house: I think most stuff gets put on a shelf and forgotten
10:26 AM rue_house: yea
10:26 AM deshipu: with a non-programmable chip I can always claim factory defect :P
10:27 AM deshipu: right now I'm waiting for the chips for this: http://paste.sheep.art.pl/234aeb51-9b37-4bed-aa50-a334a86855c3/+inline
10:27 AM rue_house: 2x 4017 and you have 20 channels
10:27 AM deshipu: rue_house: but your code has to be driving them
10:27 AM rue_house: timers would conflict, so there would be jitter, but, as stated, nobody cares
10:28 AM rue_house: my code is port direct, no external chips
10:28 AM deshipu: the whole point is that you just tell the driver what the position should be, and forget about it, do other stuff in your code
10:28 AM rue_house: mhm
10:29 AM deshipu: it also lets you modularize your projects and debug each module separately
10:29 AM rue_house: yup
10:29 AM rue_house: I just lothe that nobody cares about the jitter caused by controllers with bad timing
10:30 AM deshipu: depends on your use case
10:30 AM rue_house: which all started when rifraf was trying to make things with the prycon avrlib servo library
10:30 AM rue_house: all his robots and camera controllers had the shakes
10:30 AM deshipu: 90% of use cases out there is "swing that distance sensor around"
10:30 AM rue_house: and then buzz back and forth a bit cause of 0.1ms controller jitter
10:31 AM deshipu: I think that most servos have a dead band
10:31 AM rue_house: yup, and lots of the controllers are so bad their jitter exceeds it
10:32 AM rue_house: its just a sore point with me
10:32 AM rue_house: BUT I have my own controller with rock steady, high resolution timing
10:32 AM rue_house: AND and I'm really interested in going farther with hobby servos
10:33 AM rue_house: I have this whole torque and position thing to play with
10:40 AM deshipu: yeah, shame that current sensing is difficult to mux
10:41 AM deshipu: easier to just add a wire inside the servo
11:12 AM rue_shop3: yup, it looks like the whole problem was /r/n instead of /r
11:12 AM rue_shop3: no, the current sensing is not hard to mux, cause its just a digital pulse
11:17 AM deshipu: if it's so easy, why don't everybody do it already?
11:18 AM rue_shop3: for the same reason nobody makes servo controllers with good timing, nobody really cares
11:18 AM rue_shop3: but I do
11:18 AM rue_shop3: and I'm interested
11:19 AM SpeedEvil: So start selling some
11:19 AM SpeedEvil: Or measuring existing ones
11:19 AM rue_shop3: yea, I'll put it on the selling pile
11:19 AM rue_shop3: (which is big)
11:19 AM deshipu: rue_house: ever tried Tindie?
11:19 AM rue_shop3: no time, too busy playing and working
11:19 AM deshipu: well, if that's how much you care :)
11:21 AM deshipu: most people will probably not want to have their MCU digital pins connected to their servo power line, which is usually even at a different voltage
11:22 AM rue_shop3: $2.50 slave pro mini
11:22 AM rue_shop3: ~done~
11:22 AM rue_shop3: did you see the way I do the boards up for my arms?
11:23 AM rue_shop3: http://ruemohr.org/~ircjunk/robots/arm9/p1080399.jpg
11:23 AM rue_shop3: I couldnt maintain an SSC protocol tho :(
11:24 AM rue_shop3: the last 4 pins are used to carry power, their ganged up
11:24 AM rue_shop3: gtg 2 work, bbl!
12:49 PM * anniepoo imagines rue's pins flashing gang signs and playing loud rap music
06:29 PM rue_house: ?
06:30 PM Tom_L: confused?
06:31 PM Tom_L: this code is working nicely now
06:45 PM justanotheruser is now known as unmelanated_iris
06:51 PM rue_house: so is mine
06:51 PM rue_house: self.CommPort.write(string + "\r\n") -> self.CommPort.write(string + "\n")
06:52 PM rue_house: cause /r/n causes duplicate OKs
07:00 PM unmelanated_iris is now known as justanotheruser
09:07 PM Tom_L: continuing to add and modify...