@ Matt Well I'll read between the lines that this will work for me. It will be a bit heavier but it wont have the hard starts and stops. Thank you for putting the rubber to the road. :thumb:
Hi Rural-
Let me clarify my "warranty" statement above. We absolutely stand behind every product we sell. If there's ever a problem that you encounter with our products - let us know and we'll do everything we can to make it right.
What I said (above) was specifically directed @ W9GFO because we know him pretty well - he's always trying to break what we make!
So if you do decide to build a robot using our MMWK, let us know what you think, and post pictures of your projects so that we can all see what you've done - Welcome to the community!
@ Matt. I know you guys are behind all your stuff. I have a few of your products already. I am using the BS2 for another project so this robot I am talking about is going to use a netbook and interface board with it.
Will the HB25 run these motors?
Look around and answered my own question. so Now I have to order the drive and two HB25.
I'll post some pictures once I get through to Christmas. My wife said I can order the stuff but I can't have it till Christmas
Well, we could run them at elevated voltage/current, but that's not fair, because they would/should never be subjected to that in the wild.
However, in the wild it is not unreasonable to encounter a situation where the motor is stalled. I think this is the only question I have left about these motors. Do they shut down when overheated, or will they be damaged?
If they do shut down (like some motors that look similar) then that will save me having to monitor their temperatures.
@ erco, I found the same thing at Princess Auto for 30 bucks. But with the same problem as yours. They are a5/16 shaft and short so I was having a hard time finding a sprocket for them. That is why I am looking at the unit from Parallax.
However, in the wild it is not unreasonable to encounter a situation where the motor is stalled.
Good call W9, hence:
Test #4: Full motor stall with full complement of recommended battery power
Test Conditions:
Ambient temp: 74 degrees
Battery: Dual, 12v, 7.5ah SLA in parallel = standard configuration of a full Eddie or MadeUSA platform
12.6 volt beginning charge level
4.0 amp current draw (single motor) under full stall conditions
Beginning motor housing temperature = 74 degrees.
Looking good. Curious that you're only getting 121 degrees after 20 minutes of full stall. That's not very hot. In an earlier post, Rich was reporting "too hot to keep your finger on" after 10-15 minutes of no load.
Rich was reporting "too hot to keep your finger on" after 10-15 minutes of no load.
So did I in post #23.
I'll bet the big diff is that a locked motor doesn't generate heat in the worm drive. Another delta is that that earlier test was powered via benchtop supply.
This last test was "real-worldly" - two SLA batteries in parallel, hb25 controller, full motor stall for over an hour. - with no worm drive action, not as much heat generation is my guess at this point.
Real-world, dual-battery powered MadeUSA with motors completely locked up did not fail after a 1 hour plus test. We just drained the batteries a bit, and warmed my office up a little (it's cold and wet here today, and I ain't got no heat down here)...
-MattG
Are you taking voltage readings right at the output of the HB-25 where it goes into the motor? The reason I ask is that I've had some poor quality jumper cables that had a fairly high resistance and would limit the current going to each motor. Not noticeable during a quick bench test when the motor is moving but you can definitely tell when the motor is stalled.
Good call as usual RobotW :thumb: -
I just re-ran the test with 12gauge wire - a lot less voltage drop this time, and during this process, we have come up with the definitive answer that W9 is looking for...
Yes, was a destructive operation.
These motors contain a thermally activated safety. Probably some sort of bi-metallic strip (shown above as the red chicklet thingy). Run too much current through it (by stalling the motor) and it opens. after about 10 seconds or so, it resets. I cycled it at least a dozen times - it's non-destructive in its operation. Let the motor cool, and everything goes back to normal operation.
A word of caution: Do not open up your own motors, as "things pop out all over" when you do, and getting them back in would be a brutal challenge - just trust me :-)
Bottom line...motors, if stalled will protect themselves internally. (of course if you're applying power and the encoder ain't seeing anything then you'll know you're stalled - any good programmer would do that naturally, right? ).
Glad to see that it has overload protection. Now you can add that to the product page!
Interesting test results. So it seems that the worm drive creates more heat than the motor itself? I would not have expected that but it does fit with the results. This would mean that the main source of heating is coming from friction... and of course you know that leads to more questions.
How long will it last? Could it be that it needs to be "broken in"? Hmm, probably not, 7.5 hrs should have been enough time to break it in.
What would Jamie and Adam do? They wouldn't stop until something blew up.
I would Chalk the worm gear creating more frictional heat as negligible and not likely in this case ...
Now if you said that more heat was generated inside of the motor due to the reduction of IR drop in the wires carrying current to the motor such as on the last test, I would completely agree.
Another question: With the motor stalled, using 12-gauge wire, what's the peak current and what's the effective duty cycle? If that thermal fuse pops after one second of stall current, then opens for 10 seconds, then the average current is pretty low. Much of the heat is generated inside the fuse, and that's why the overall motor temp is lower in this stall condition.
Certainly there's a fair amount of friction in a worm drive, but no way sufficient to generate finger-burning heat at no load. My guess is that it's mostly motor heat from the 100% duty cycle at no-load. Again, that's 1.5 A no-load current, that's 18 watts of mostly heat output.
The no-load test (technically not no load since it had the wheel on there, but very low load) the motor was direct connected to the power source.
In the load test (spinning with 60# of stuff) it was running through the HB-25s, so there is another possible factor in the temp diff.
In any case, the use that these motors were designed for is either car power windows or windshield wipers, and in both of those cases I would expect them to have good stall handling (as they do). I would also expect them to handle more abuse than any of us are likely to throw at them with bots.
In any case, the use that these motors were designed for is either car power windows or windshield wipers, and in both of those cases I would expect them to have good stall handling (as they do). I would also expect them to handle more abuse than any of us are likely to throw at them with bots.
I've been very happy with these drive motors on my large robots and would definitely recommend them. The only issue I've had was with the intelligent encoder board but that can be fixed with a firmware update or by adding a relay to keep the drive power off until the position controllers are initialized.
I think Matt has performed more abuse on these than we should ever run into when properly using them on a robot.
I'm having a problem with my motor kit and HB25 motor drivers. I send a command to go forward and it works fine, but when set it to go backwards, it doesn't get to the set position and a high pitched sound comes for the motor drivers. Is this a result of incorrect assembly of the the motor kit, a problem of the motor drivers or something else?
Comments
No warranties expected.
Torque measurements:
http://forums.parallax.com/showthread.php?117744-Help-ke-km-an-R-value-of-Motor-Mount-and-Wheel-Kit-%28-27971-%29&p=857912&viewfull=1#post857912
Started robot platform: (Also what started the Torque measurements)
http://forums.parallax.com/showthread.php?118861-Homebuilt-Robotic-Platform-AKA-Retrobot&p=873514&viewfull=1#post873514
Finished robot platform: (just an FYI .. did the robot ever get finished?)
http://forums.parallax.com/showthread.php?127631-RC-Car-BOE-Bot-style-with-Tilt-steering
Let me clarify my "warranty" statement above. We absolutely stand behind every product we sell. If there's ever a problem that you encounter with our products - let us know and we'll do everything we can to make it right.
What I said (above) was specifically directed @ W9GFO because we know him pretty well - he's always trying to break what we make!
So if you do decide to build a robot using our MMWK, let us know what you think, and post pictures of your projects so that we can all see what you've done - Welcome to the community!
-MattG
Edit: Excellent backfill Beau, thanks!
Will the HB25 run these motors?
Look around and answered my own question. so Now I have to order the drive and two HB25.
I'll post some pictures once I get through to Christmas. My wife said I can order the stuff but I can't have it till Christmas
-MattG
However, in the wild it is not unreasonable to encounter a situation where the motor is stalled. I think this is the only question I have left about these motors. Do they shut down when overheated, or will they be damaged?
If they do shut down (like some motors that look similar) then that will save me having to monitor their temperatures.
Cheap, but no specs and you're on your own connecting to that short splined shaft.
Test #4: Full motor stall with full complement of recommended battery power
Test Conditions:
Ambient temp: 74 degrees
Battery: Dual, 12v, 7.5ah SLA in parallel = standard configuration of a full Eddie or MadeUSA platform
12.6 volt beginning charge level
4.0 amp current draw (single motor) under full stall conditions
Beginning motor housing temperature = 74 degrees.
[video=youtube_share;vthPPHyZhxA]
Results to follow...
-MattG
[video=youtube_share;-RwBHnl81kc]
We'll let this test go for a total of one full hour under a full stall condition.
-MattG
I'll bet the big diff is that a locked motor doesn't generate heat in the worm drive. Another delta is that that earlier test was powered via benchtop supply.
This last test was "real-worldly" - two SLA batteries in parallel, hb25 controller, full motor stall for over an hour. - with no worm drive action, not as much heat generation is my guess at this point.
Real-world, dual-battery powered MadeUSA with motors completely locked up did not fail after a 1 hour plus test. We just drained the batteries a bit, and warmed my office up a little (it's cold and wet here today, and I ain't got no heat down here)...
-MattG
I just re-ran the test with 12gauge wire - a lot less voltage drop this time, and during this process, we have come up with the definitive answer that W9 is looking for...
Yes, was a destructive operation.
These motors contain a thermally activated safety. Probably some sort of bi-metallic strip (shown above as the red chicklet thingy). Run too much current through it (by stalling the motor) and it opens. after about 10 seconds or so, it resets. I cycled it at least a dozen times - it's non-destructive in its operation. Let the motor cool, and everything goes back to normal operation.
A word of caution: Do not open up your own motors, as "things pop out all over" when you do, and getting them back in would be a brutal challenge - just trust me :-)
Bottom line...motors, if stalled will protect themselves internally. (of course if you're applying power and the encoder ain't seeing anything then you'll know you're stalled - any good programmer would do that naturally, right?
Interesting test results. So it seems that the worm drive creates more heat than the motor itself? I would not have expected that but it does fit with the results. This would mean that the main source of heating is coming from friction... and of course you know that leads to more questions.
How long will it last? Could it be that it needs to be "broken in"? Hmm, probably not, 7.5 hrs should have been enough time to break it in.
What would Jamie and Adam do? They wouldn't stop until something blew up.
...all together now...
"The world may never know..."
-MattG
And they're paid to do exactly that. We've reached the limits of characterization and destructive testing on these motors.
Now if you said that more heat was generated inside of the motor due to the reduction of IR drop in the wires carrying current to the motor such as on the last test, I would completely agree.
Another question: With the motor stalled, using 12-gauge wire, what's the peak current and what's the effective duty cycle? If that thermal fuse pops after one second of stall current, then opens for 10 seconds, then the average current is pretty low. Much of the heat is generated inside the fuse, and that's why the overall motor temp is lower in this stall condition.
Certainly there's a fair amount of friction in a worm drive, but no way sufficient to generate finger-burning heat at no load. My guess is that it's mostly motor heat from the 100% duty cycle at no-load. Again, that's 1.5 A no-load current, that's 18 watts of mostly heat output.
In the load test (spinning with 60# of stuff) it was running through the HB-25s, so there is another possible factor in the temp diff.
In any case, the use that these motors were designed for is either car power windows or windshield wipers, and in both of those cases I would expect them to have good stall handling (as they do). I would also expect them to handle more abuse than any of us are likely to throw at them with bots.
Roy
You just need some beeps and LEDs...
I've been very happy with these drive motors on my large robots and would definitely recommend them. The only issue I've had was with the intelligent encoder board but that can be fixed with a firmware update or by adding a relay to keep the drive power off until the position controllers are initialized.
I think Matt has performed more abuse on these than we should ever run into when properly using them on a robot.
Robert
And on that note, I concur Robert :thumb:
I'm having a problem with my motor kit and HB25 motor drivers. I send a command to go forward and it works fine, but when set it to go backwards, it doesn't get to the set position and a high pitched sound comes for the motor drivers. Is this a result of incorrect assembly of the the motor kit, a problem of the motor drivers or something else?
What circuit are you using to drive the motors, the HB-25, or another H-bridge circuit?
...and Welcome to the Forums :-)
-MattG