#robotics Logs

Aug 04 2015

02:15 deshipu !
12:43 ats I am using two of this (http://www.dfrobot.com/image/data/ROB0055/RP6%20motor%20TFK280SC-21138-45.pdf) motor in my rover 5. These motors are rated 7.2v with 2.5A stall current. I need a 2 channel motor driver. I found L293D. Can it handle two motors under maximum pressure?
12:46 Hyratel !A per channel
12:47 Hyratel so no. not even if you doubled up the L293D
12:47 Hyratel https://www.sparkfun.com/products/9557
12:47 Hyratel this, however, would work
12:48 Hyratel er
12:48 Hyratel wrong one
12:48 Hyratel here - https://www.sparkfun.com/products/9479
12:51 ats thank you Hyratel
17:07 rue_school well, I need to really brush up on my AC electrical math
17:08 m_itx gives rue_school a scrub b
17:09 Tom_itx why you in skook now?
17:09 rue_school 3rd year skool for sparkies
17:10 Tom_itx gettin smarter?
17:10 rue_school well, it looks like I need more experience with RLC circuits :)
17:10 rue_school in the context of applying sine waves to them anyhow
17:20 Tom_itx rue_school will this further your job?
17:21 Tom_itx gonna be a power co lineman?
17:24 rue_school no
17:24 rue_school the only thing I come out with after this is being another year up
17:25 rue_school same job, same pay
17:25 Tom_itx no more pay?
17:25 Tom_itx boss paying for the edu?
17:25 rue_school I'm already paid more than I should for my level cause I run 1/3 of the company
17:25 rue_school no, I'm paying
17:25 rue_school I think this will cost me about $8000 when done
17:26 Tom_itx my kids 2 cad classes are around 3.5k
17:26 rue_school why are they studdying the canadian dollar?
17:26 rue_school ;)
17:27 Tom_itx good q
17:55 rue_school so, I'm looking at a scope trace, one on voltage, the other on a current probe to a load, it shows Vp (not pp, just p) as 100V and Ip as 10A, its at 60Hz, how do I work out the value on the R and L
17:55 rue_school oh, and the current is lagging by 60 degrees
17:55 rue_school this is bugging me cuase I should know it
17:56 Tom_itx you should know it more than me
17:56 rue_school heh
17:57 Tom_itx i've picked up enough to get by
17:57 Hyratel current lags on Inductive laods, IIRC, and leads on cpacitive
17:58 Hyratel loads
17:58 ace4016 hrm, i need ideas for a mission set my aquatic bot will perform...
17:58 Hyratel ace4016, how big?
17:58 Tom_itx ace4016, chase russian subs
17:58 ace4016 Hyratel, depends on the mission set i decide on; as long as it's affordable
17:59 Tom_itx measure the depth of your bath tub
17:59 Hyratel retrieve an object ; negotiate a ravine ; loiter against a current
18:00 ace4016 hrm...
18:01 Hyratel hold position against turbulence
18:01 Hyratel locate a vision target
18:01 Hyratel collect a sample object
18:01 Hyratel (ie, marble)
18:01 Hyratel different from retrieve a debris
18:02 Tom_itx take core samples of the ocean floor
18:02 SpeedEvil ace4016: Catch tuna
18:02 Hyratel that's kinda what I was thinking, in simpler for with the grab a marble
18:02 Hyratel grab a marble from a pipe
18:03 rue_school Hyratel, yes, but this is a real world exampls
18:03 ace4016 hehe, think the wild life ranger will be unhappy with me for spear fishing with a sub?
18:03 ace4016 :P
18:04 rue_school 2 channel scope, channel 1 on the voltage into a complex load, channel 2 on a current probe. CH1 shows Vp at 100V, channel 2 shows 10A, there is a 60 degree latency on the current
18:04 Hyratel ok
18:05 rue_school SO, given 60Hz, whats the resistor/inductor value
18:05 ace4016 hrm...time to rack-n-stack some of those :P
18:05 Hyratel ace4016, retrieve a marble on flat sand; on gravel; from inside a shallow pipe; from inside a deep pipe
18:05 rue_school the inductor itself is 90 degrees, the resistor pulls it to 60
18:05 Hyratel pipe about 2-3 times the diameter of the marble
18:07 rue_school Hyratel, you know how you blow into a cup to get something out and it comes back in your face?
18:07 Hyratel yes
18:07 rue_school 8-|
18:08 rue_school I have to work on my almost real world problem
18:08 Hyratel rue_school, so stick a proboscis down the pipe and jet water in with a catch bin
18:25 ace4016 hrm...wonder if i should go with propeller driven or one of the "natural" swimming motions
18:25 ace4016 the former is "easier" and the latter is more fun
18:46 sector_0 What's the speed of a pneumatic muscle in relation to human muscles?
18:47 sector_0 most demonstration i've ever seen of pneumatic muscles are really slow
18:53 ace4016 pnuematic pistons used as muscles, or the ones that are in that mesh to be muscle like?
18:58 sector_0 ace4016, the "bladder wrapped in mesh" ones
19:01 ace4016 ah, never really seen those used outside of hobby/college research stuff
19:03 sector_0 ace4016, ok so what about the pneumatic pistons?
19:03 ace4016 they can be pretty dern fast :P
19:04 ace4016 they're used industrially; iirc pick-n-place machines are pneumatic (may be hydraulic though...not sure)
19:05 sector_0 ace4016, ok
19:06 sector_0 ace4016, but what about the load carrying capacity, are pneumatic actuators stronger than a motor attached to a joint?
19:09 ace4016 i'm not entirely sure, but i'd imagine if you needed more accuracy/repeatability and speed, you'd go with an electric motor over pneumatics
20:51 rue_school "its not a mouse, but it doubles as an eraser"