#robotics Logs

Nov 06 2011

01:15 rue_house - things to have if it happens again
01:15 rue_house - things to stop it from happening again
01:17 rue_house this could be explained by a boiler pump failure
01:18 rue_house wonder how I can detect a line bursting
01:18 rue_house flow sensors I suppose
01:20 rue_house hmm I wonder what fault detection time is acceptable
01:20 rue_house 4 seconds too long?
01:20 rue_house I'm gonna take longer than that
01:21 rue_house by about 2 seconds if I'm not in bed
01:57 tinyClark Im trying to be able to write 127,255,255 into the console of the arduino and i want to split the 3 serperate numbers to use for the RGB led how would i go about doing this
06:57 mindw0rk Hey Tom_itx, remember that free devkit you posted a link to (I think it was a Cortex M3)?
08:45 Tom_itx mindw0rk yes
08:46 mindw0rk can you give me it again?
08:46 Tom_itx i think the offer is over now
08:46 mindw0rk ah, crap. Well thanks anyway.
08:47 Tom_itx it wasn't on there the last time i visited the site
08:47 Tom_itx you can get them thru normal channels i think but they're like 15-20 or so
08:48 Tom_itx http://www.st.com/internet/evalboard/product/252419.jsp?WT.ac=p2_bn_sep11_stm32f4discovery
15:38 KongfuPanda Hello robotics people :)
15:57 coppermine is there a guideline for the size of the flat robot platform? is 5 inch diameter wheels and 16"x21" good? thats what i have so far
15:57 coppermine wheels are 1 inch wide
16:01 home KongfuPanda, hai
16:06 KongfuPanda hi home, how are things?
16:19 rue_shop 3 line ruptures, the exchanger is empty, thats about 40gal of antifreeze/water mix lost
16:19 rue_shop the holding tank is full
16:21 KongfuPanda oh no!
16:26 rue_shop no thats good
16:26 rue_shop the bottom end of the exchanger is holding water, this is also good
16:27 rue_shop ok.. well, its holding it as well as it ever did, but thats another story
16:31 KongfuPanda I see
16:31 KongfuPanda :D
16:39 rue_shop seems I found a spot on one of the pipes that I had this problem with before, I had used electrical tape to "patch" it...
16:39 rue_shop :/
17:11 rue_shop part of the firebox is significantly warped, but I'm not worried about it
17:23 Tom_itx damn electricians think tape will fix anything
17:30 amphistatic Who else is looking forward to the singularity?
17:37 zhanx where i spent my weekend
17:37 zhanx https://lh4.googleusercontent.com/-sR8Y-xbgawk/TrXl2O_OCCI/AAAAAAAAC7s/jEr3Z1bHrmY/s320/2011-11-05%25252013.07.03.jpg
17:47 rue_shop zhanx, I blowed up the boiler
17:47 zhanx SWEET
17:47 rue_shop LOTS of steam and hot water everywhere
17:48 rue_shop its not so serious, the poly pipes all came apart
17:48 zhanx you flooded your house!
17:48 rue_shop lost about 30 or 40 gal of antifreeze mix
17:48 rue_shop no, the boilers outside
17:48 zhanx darn
17:48 rue_shop I have a lot of safety improvements I thought of after
17:49 rue_shop its a good thing I added all the shutoff valves I did
17:49 rue_shop for just that kinda situation
17:49 zhanx they auto shut off?
17:49 zhanx ie via water sensors?
17:49 rue_shop yea, I need one of those
17:50 rue_shop I added valves on the in and out of everything, as much for if a line burst as being able to work on it without having to drain a tank
17:50 rue_shop ok! but I have 6 hours left of weekend for ME
17:50 rue_shop I'm gonna play
17:52 rue_shop so, I was at the thriftstore and saw a LED calculator, for a dollar, so I bought it
17:53 rue_shop shall I put a scope on it to see how they mux the numbers?
17:53 Tom_itx yes
17:53 rue_shop freq, duty, etc?
17:53 Tom_itx absolutely
17:53 rue_shop ok, then maybe I can work on my air muscle
17:54 Tom_itx i'll think of something else for ya by then
17:54 rue_shop so I have a box of reel to reel audio tapes to convert for the museum
17:54 rue_shop and 3 boxes of 1" reel to reel video tapes, along with 2 players, which weigh about 50lbs ea
18:06 coppermine i read somewhere to take abotu 1/4 of the stall current which is 5A
18:06 coppermine i read somewhere to take abotu 1/4 of the stall current which is 5A
18:06 coppermine oops
18:06 coppermine with these specs how do I find out what max amperage at 12vdc I can run it safely without burning it? http://www.pololu.com/catalog/product/1103
18:06 coppermine thats my question
18:07 orlok hmm
18:07 orlok amperage.. it will draw what it needs
18:08 Tom_itx figure your drivers for stall current then the motor will use what it needs
18:08 orlok you dont run something at a certain amperage, it draws what it needs and you try to keep up
18:09 coppermine it wont burn it?
18:09 coppermine if my motor controller can handle it its ok?
18:09 orlok yup
18:09 coppermine cool
18:09 Tom_itx if you stall it, it will
18:09 coppermine stall meaning it stops adn cant get out
18:09 coppermine then it will go over 5A
18:09 coppermine and burn?
18:10 coppermine so stall current means its max?
18:10 Tom_itx yeah, it's awesome to watch
18:10 coppermine haha
18:10 coppermine what blows up first?
18:10 coppermine the battery
18:10 coppermine or motor
18:10 orlok depends where the limiting factor is
18:10 coppermine the motor controller should shut it down
18:10 coppermine detect > 5a
18:10 Tom_itx use fuses silly
18:11 coppermine so that means i can run it at 4A x 12v = 48W
18:11 coppermine and 4 of these
18:11 coppermine 200W
18:11 coppermine lots of power
18:11 coppermine would drain a 200WH battery in 1 hour
18:12 Tom_itx http://tom-itx.dyndns.org:81/~webpage/largebot/largebot2.jpg
18:12 coppermine how many AH is that battery? 7.2AH?
18:12 Tom_itx yup
18:13 coppermine and the rating of the motors?
18:13 coppermine RPM/TORQUE
18:13 orlok coppermine: the stall current is what the motor will draw if its jammed and not moving.. you want to be able to provide that much current for a short period of time, as it will draw close to that much when it starts moving from a standstill as well with a heavy load
18:14 coppermine in short burts i hope
18:14 coppermine thats 60W
18:14 coppermine short meaning a few seconds?
18:15 orlok yeah, enough for it to either get moving or break traction
18:15 coppermine im designing my robot for 20lbs payload
18:15 coppermine 4 motors
18:15 orlok my big robot has two motors
18:15 coppermine 12vdc 8kg/cm 350rpm
18:15 coppermine 5a stall
18:16 orlok a single motor, taking off from a standstill draws 13A@12v
18:16 coppermine orlok: how much payload can it handle?
18:16 orlok 8kg/cm isnt actually _that_ much...
18:16 coppermine yeah but 4 of them
18:16 coppermine for 20 lbs
18:16 coppermine is enough
18:16 coppermine isnt it?
18:16 orlok dunno.. i use metric
18:17 orlok :P
18:17 coppermine 110 oz-in
18:17 coppermine oh metric
18:17 orlok depends on the size of your wheel
18:17 coppermine 4 7/8 inch
18:17 coppermine i used a calculator
18:17 coppermine to calculate
18:18 coppermine acceleration 1/m/s
18:18 coppermine 1m/s
18:18 coppermine max include 20 degrees
18:18 coppermine etc
18:18 coppermine *incline
18:18 coppermine im actually over the requirements
18:18 coppermine it only needs 150rpm
18:18 coppermine and i have 350
18:18 coppermine the torque needs 8kg/cm
18:19 coppermine and i have exactly 8kg/cm per motor
18:20 orlok did that include wheel size?
18:20 coppermine yes
18:20 coppermine radius
18:20 coppermine so 2.5inches
18:20 orlok smaller wheel = slower, more torque
18:20 coppermine cool
18:21 coppermine 5 inch isnt that big
18:21 orlok well, consider..
18:21 coppermine i wanted 4 originally but they didnt have in stock
18:21 orlok 8kg@1cm
18:21 coppermine that match my hubs
18:21 coppermine and 6cm shaft
18:21 coppermine 6 mm
18:21 orlok 5"=12.5cm
18:22 coppermine my specs as is is 1 meter/second
18:22 coppermine thats pretty fast
18:22 coppermine for a 20lbs robot
18:22 coppermine so it has power
18:22 orlok .. i'm not sure how to work out the torque@12.5cm
18:22 coppermine ill show you
18:23 coppermine http://www.robotshop.com/dc-motor-selection.html
18:23 coppermine just plug the values in that
18:23 coppermine it will tell you
18:23 orlok is it a straight conversion, so 1kg@8cm?
18:26 coppermine are you using pololu controllers for 2 motors in parallel?
18:26 coppermine 2 motors per controller
18:26 orlok one single controller
18:27 orlok it supports 2 bidirectional motors plus a single unidirectional
18:27 coppermine what does gear ratio 1:29 mean
18:27 coppermine for dc motors
18:27 coppermine you can have 50:1
18:27 coppermine 29:1
18:27 orlok it means its reduced so for every 29 turns the motor itself makes the output shaft turns once
18:27 coppermine i chose it for to match my specs
18:27 orlok the higher the ratio, the slower the motor turns but the more torque
18:28 coppermine i know the ratio changed the specs
18:28 coppermine so for 20lbs load i should use a higher ratio?
18:30 coppermine after checking now
18:31 orlok hmm 9kg..
18:31 coppermine a 50:1 would be better for me
18:31 coppermine 12kg-cm
18:31 coppermine 200rpm
18:31 coppermine instead of 29:1
18:31 orlok i would say yes.. also, look at cheap hardware supplies
18:31 orlok cordless drills, etc
18:32 coppermine which the 50:1 i can haul 30lbs
18:32 coppermine at the sam speed
18:32 orlok top speed will be lower, but it will get there faster
18:33 coppermine cool ill change my order
18:33 coppermine encoders are to track distance right?
18:33 orlok movement/distance.. yeah
18:38 coppermine the output shaft is only 0.61" long
18:39 coppermine and the wheel is 0.8"
18:39 coppermine wont work
18:39 coppermine damn
18:40 coppermine what kind of quality wheel can i put with this
18:40 coppermine http://www.pololu.com/catalog/product/1104
18:40 coppermine i wanted banebots or colson
19:23 rue_shop damnit, he alwasy leaves before I have a chance to answer
19:23 Tom_itx that's what logs are for
19:24 Tom_itx got pics of your fiasco?
19:24 rue_shop yea, post them tonight
19:24 rue_shop well I have pics of the aftermath
19:25 rue_shop I was too busy closing valves and unplugging things at the time to take pics
19:28 rue_shop each column get 40us of a .7ms scan time
19:28 rue_shop they are driven at 2.4V/270R
19:30 zhanx great my sister is on crazy mode again
19:32 rue_shop hmm
19:33 rue_shop air muscle
19:57 SerpentX someone blow me timbers
19:59 zhanx umm no
21:00 Tom_itx http://earthquake.usgs.gov/earthquakes/dyfi/
21:02 Tom_itx felt 1 out of ~26
21:53 LoRez Tom_itx: I was in south OK. didn't notice.
21:55 Tom_itx it shook the house here pretty good last night
21:55 LoRez nice.
21:56 Tom_itx first for everything i guess
21:56 Tom_itx i figured OKC would have gotten damage
22:36 LoRez my place seems fine
22:46 rue_house and then why might I ask is your neighbours bathtub in your kitchen and your coffeetable on your cieling?
22:53 LoRez you don't know what you're talking about.
22:58 rue_house :)
22:58 rue_house as you say that I'm trying to work out how to operate a reel to reel tape player
22:58 rue_house they did it wrong, you have to take the tape out of the cassette to play them
22:58 rue_house siiily sily