#robotics Logs

Apr 15 2018

02:08 AM polprog: rue_mohr: i made a laptop yesterday out of two.
02:11 AM polprog: AND it works!
02:25 AM rue_mohr: :)
06:56 AM z64555: rue_mohr: i've seen several scholarly papers that mention the use of jacobian matrices, PD controllers, and a quadratic problem solver (among other things)
06:57 AM z64555: I haven't come across anything that uses quaternions, instead of the jacobian (or transpose jacobian, for that matter)
11:01 AM rue_bed: hmm
11:41 AM rue_bed: !!
11:42 AM rue_bed: I dont have to put the motors on the ends of the flip-cards, I can probably use fishing line and have the motors twist it
12:49 PM rue_mohr: drat, I think, current limit on MC1488 is 10mA, thought it was 20
12:53 PM rue_mohr: eek, this motor pulls 60mA
12:53 PM rue_mohr: hmmmm
12:54 PM mrdata: tiny
12:55 PM mrdata: oh but way more than 10mA
12:55 PM mrdata: you can drive it with a 2n3904
12:56 PM rue_mohr: I wanted to use chips for drivers, save space
12:56 PM mrdata: uln2003a is plenty powerful
12:56 PM rue_mohr: I'm up into the fet driver range now
12:56 PM rue_mohr: I need a totempole driver
12:56 PM rue_mohr: its a vibrator motor
12:57 PM rue_mohr: I'm using it to flip segment cards in a large display
12:58 PM rue_mohr: I dont know of a fet driver thats ganged
12:58 PM rue_mohr: 7 motors per display
12:58 PM rue_mohr: its getting large
01:00 PM rue_mohr: hmm
01:00 PM mrdata: totem pole, you mean an H-bridge?
01:00 PM rue_mohr: half an H bridge
01:00 PM rue_mohr: tho
01:00 PM rue_mohr: hey
01:00 PM mrdata: there are half-bridge chips iirc
01:01 PM rue_mohr: if I run a square wave on half a H bridge, I can play with sync to get motor polarity
01:01 PM rue_mohr: and use 1 bridge for every 2 motrs
01:01 PM rue_mohr: or fet drivers
01:01 PM mrdata: IR2018 is a half-bridge
01:02 PM rue_mohr: then I dont have to play with level conversion on the control stuff
01:02 PM rue_mohr: mrdata, dont have time to order parts I dont have
01:02 PM rue_mohr: and its low budget
01:02 PM rue_mohr: AOP605 is something I do have
01:03 PM rue_mohr: which needs driving, but
01:03 PM rue_mohr: oh drat, its a full votlage gate
01:05 PM rue_mohr: too bad I dont have a whole bunch of opto-fets
01:18 PM rue_mohr: CD4066 cant take 60mA
01:27 PM mrdata: check the data sheet for the IR2018
01:28 PM mrdata: err, IR2108
01:28 PM rue_mohr: 2113?
01:28 PM rue_mohr: problem being, their pricey and I do NOT have time to order for this project
01:28 PM rue_mohr: I have a time limit on this one
01:29 PM rue_mohr: and no more budget
01:34 PM rue_mohr: 8-| wait
01:34 PM rue_mohr: whats the current limit on the output of a 555
01:35 PM rue_mohr: Output can source or sink 200 mA
01:35 PM rue_mohr: OH YEA!
01:36 PM rue_mohr: so, the cheapest those driver chips get is 50c ea
01:36 PM rue_mohr: 6.50 for 50pcs 555
01:36 PM rue_mohr: and I have lots
01:43 PM rue_mohr: halarous
01:44 PM rue_mohr: yup, ya lock the thres and trigger togethor and its a buffer
07:26 PM mrdata: https://gizmodo.com/experts-sign-open-letter-slamming-europe-s-proposal-to-1825240003
07:45 PM LuminaxWork is now known as LuminaxWk
08:18 PM rue_mohr: media sure has an interesting nature latley
08:30 PM Tom_L: rue_mohr, how did robot class go this weekend?
08:36 PM rue_mohr: subdued, which is good for that kid
08:37 PM rue_mohr: :)
08:37 PM rue_mohr: we worked on the 3d printer
09:46 PM rue_shop3: so, one valve pulls about 80mA
09:47 PM rue_shop3: about 188 valves
09:47 PM rue_shop3: only half of which can be active at the same time
09:48 PM rue_shop3: so, with some room, about 8.5A
09:48 PM rue_shop3: of 80V
09:48 PM rue_shop3: comming from a 12V supply
09:48 PM rue_shop3: if @ 100% eff, is ~60A
09:48 PM rue_shop3: :S