Motor Mount and Wheel Kit with Position Controller on my new bot
I am just getting started in building a new bot its going to be stingray style. its going to be bigger and heavier. I am looking at around as a high guess around 50lbs or so. What I was wondering is would the Motor Mount and Wheel Kit with Position Controller part number 27971 be big enough to drive this bot with no problem? The bot will be driving on carpet and tile flooring.
Thank you for any help everyone.
Thank you for any help everyone.
Comments
I believe that Ken once stated that the motor mount wheels could handle up to 50 lbs. I have a pair and they are very sturdy and are presently supporting around 35 lbs with no trouble. You might be able to find cheaper motor drives on eBay or Craig's list though.
Regards,
TCIII
I am currently awaiting a response from tech support regarding the motors running hot after being run for more than ten minutes while not under load. I think it is normal but I want verification that my use is "approved", especially since I plan to make other similar robots.
50# no problem.
We did some internal tests about a year ago, and we were able to drive our machinist around with no problem. He weighed about 190#.
That's NOT to say that the MMWK is rated to run at that load, but it did, although we don't guarantee it.
The weak link (if you want to call it) that is our caster wheel kit. It failed during the test because of the machinist losing his balance and putting all of his weight on the front end of a Madeusa platform.
We're currently out of stock because we're changing over the kits to include our new high resolution quadrature encoder (#29321).
Should be in stock soon!
Easy Cheesy... I drive mine in an open field in the dirt, grass, and mud. No problem-o
-MattG
PS: (you'll have to get in line, i get one of the new ones first ;-)
-MattG
Thanks Matt, my question to tech support also asks if my application is an approved use of the motors. I need to know because if it's not, then I need to source a different system for my customer.
I also asked if the motors have protection from overheating.
I need to make sure that the motors can drive around an 80 lb robot for three to four hours in an office environment. I have no idea how many of these I will be making but I am starting on the second one which will be designed with small scale production in mind.
I figure that the robot will be pushing about 80lbs now with the 35ahr battery I will be putting in it. With the heat that you are getting off them W9 I will put a fan in it to help that. This kit seems the best way for me to build my first robot from scratch.
Thanks for the help guys:thumb:
If I was building an 80-lb bot (which might end up a 100-lb bot), I'd look for a bigger gearmotor using spur gears. A higher voltage motor uses less current for the same power output, which would run cooler too. If you were making a 4WD bot, I'd suggest using four of my favorite $10 24V gearmotors (using a different wheel) which was just on sale for $3.50. Yes, for real!
http://forums.parallax.com/showthread.php?117280-Nice-10-Gearmotor&highlight=%2410+gearmotor
I don't have same reservations with worm drive motors since they are very commonly used in electric wheelchairs. However, I have noticed that for the smaller motors they tend to get hot quickly, not just the Parallax ones. At least some of the window regulator motors will shut down automatically when they get too hot. I still do not have an answer to whether or not the Parallax motors have any protection from overheating. They did say that 80lbs is outside the range that they recommend.
If it turns out that the Parallax motors shut themselves down when they get too hot then I will continue to use them. If not, I guess I have to find another source.
W9 I thought Matt ment they are not rated for a 190lbs. I'll have to keep looking around to figure out what I need then I guess.
Thank you for all the advice.:thumb:
Edit: just saw 1.5A @12V no load for those motors. 18W no load, no wonder they're getting hot. Put a light load on 'em and fry an egg! That's a lot of power any way you look at it. For comparison, those little gearmotors' no load current is just 50 mA @24V. Stall current is only 1A.
In a mobile robot, motor efficiency and battery life are everything.
No way with just 2 motors. Four, maybe. Six? Sure. Make a Mars Rover rocker bogie and you're good.
The wheels on those little motors are not real strong. For a 15-20 lb, 2-motor robot they're OK. But plan to replace them for a heavy bot. My motors (got 'em LONG ago) came with different, uber strong gray/green wheels. Soild nylon or delrin. The newer ones have thinner black ribbed wheels. But there are tons of motors out there, look around before you commit $300!
Gimme some test conditions you want to see covered...
-MattG
Sounds good. I'd like to see a time lapse video of you sitting on a MadeUSA while it continuously spins in place for a full 60 minutes.
+1. If it's 60RPM or better for the whole video, I'll buy a pair of motors, plus more pumpkin pie for Matt.
1st its the long weekend. There is turkey to be eaten. Everything else can wait till next week.
If you are testing it. Could you try putting 100# on it and run it just above a resonable speed and see if it will do that for an hour on and an hour off and on again.
Please..
If you feel they take that kind of beating and still be reliable then I will take you word on it and go ahead and order a set for my bot.
I need the motors to last at least a few years for this bot. I know the weight won't increase, but the run time might run as high as how long the battery holds out. It might get to that run time point for testing times. But it will be running in my house at a resonable speed to be safe, and on carpet and tile flooring.
So I guess that is as close to my running parameters I can give.
@ Matt. If you feel that these motors will fit the bill for my set up I'll take a set when they are back in stock.
Thank you for all your advice for a rookie.
Happy Thanksgiving.
Right you are Rural Geek :thumb: - Since this IS "next week" check this out:
Additional notes:
WE DO NOT RECOMMEND THIS under any circumstances - this is an extreme test for what it was originally designed for, but it was fun to see what MadeUSA could do.
This is me, plus two 12v,6.5ah SLA batteries, plus an upper deck, additional standoffs, the base platform, a couple of HB25's and a BS2 BOE. (Total load was approx 200# +/-)
And after talking with our Sales Manager (JimC) - nobody here can recall ever replacing a single 'burned out' motor for any customer - I've damaged some, but only during "rough prototyping" episodes.
The motor duration/heat/full-speed test is currently in process - will update that soon...
-MattG.
Actually, the Cye website used to have that feature. Anyone could log on and drive Cye around the office. That would be a cool Eddie implentation at Parallax so we could keep an eye on Matt, Jen & Ken.
http://www.personalrobots.com/spycye/testdrive.html
Thank you for the info it works for me.
[video=youtube_share;y70SUkRWqIE]
-MattG
-MattG
[video=youtube_share;NAk7GezvyAk]
Additional test conditions:
Ended up running just 10 minutes shy of 8 hours continuous operation, before it was turned off (intentionally - It was time to go home ;-)
The Blue Plastic bumper (attached to my workbench) helped to keep it in the same spot for hours and hours because I did not implement any encoder feedback. Kinda like "bumper-bots".
The constant "slinging" of the load back and forth added to the stress of the unit, but there was no noticeable degradation, in spite of this to the any parts of the machine at all.
Unless you'all can think of something else (that I did not cover in these tests), I'd say this is pretty conclusive of the MadeUSA Robot Platform's reliability (with a 60# load).
I'm convinced that, if the load were evenly distributed, and the terrain was flat, and you programmed the machine to accelerate and decelerate, that even larger loads could be accommodated. However, we're not going to suggest that your application won't push it beyond what it can handle - it's up to you to determine whether or not MadeUSA is capable for your application.
Speaking for myself, I'm convinced that it'll carry this load reliably - and beyond - in fact, I'm gonna go off-road with my own machine this winter - mud and all :thumb:
-MattG
Another thought: It's interesting to note that the first test (static, full on motor) resulted in a motor temperature of about 170 degrees, whereas the fully loaded final test only produced a temperature of 120 degrees or so.
The two variables that I can think of that might explain this are:
1) Semi-intermittent on vs. full on
2) air circulation because of machine movement
But even with those variables, that's a 50 degree drop from a "test bench does nothing but spin in free air" to a "real-world, 87# (60# payload plus full MadeUSA base platform, batteries, etc.)
-Robot Torturer
If the motors were reversed every few seconds without ramping then it seems that there was no time that current was not applied, and at stall current for a moment every cycle. I can't see how that would be easier on them.
Did you measure the temp of both motors or just one?
-Dr. Thermo
No warranties are implied by these comments ;-)
-MattG