HB-25 Application
As part of a multi-step process with a new all-girls robotics team (called The Rover Girls) we are building an RC "Mars Rover" based on a hacked RC truck.· The first step is a mini-bot based on an RC transmitter/receiver and continuous rotation servos.· Purpose is to have success in building and controlling something.
Next step is the hacked RC truck.· Problem is motor control because the toy was originally intended to be crashed into rocks and trees and dirt at "high" speeds rather than deliberated controlled remotely with an on-board camera/transmitter and remote sight and sound monitor and a model airplane transmitter.
Motor was oritinally made to run at a nominal 19.2 VDC.· I doubt the original setup ever reached that with low-end batteries and charger.· I have installed a Ryobi battery "socket" from an unused flashlight that runs at 18 VDC nominal.· Actually varies between about 19 VDC and 17 VDC.· Probably lower after some runtime.· Motor works fine down to 12 VDC, but, less torque.· Obviously.
It looks like the HB-25 would nearly work.· Certainly ample headroom on the amperage.· "Nameplate" on the controller of 16 VDC makes me wonder·if I should rig up some sort of voltage divider to apply less than full battery voltage to it.· I know you can run anything at any voltage, provided you can live with the run time at overvoltages.· If I can make it work, the HB-25 would function on this second-generation rover; and when combined with a second controller would also work on the autonomous "Mars Rover" we are aiming at.
Any thoughts, suggestions, or real-world experiences?
Thanks.
Steve K.
Next step is the hacked RC truck.· Problem is motor control because the toy was originally intended to be crashed into rocks and trees and dirt at "high" speeds rather than deliberated controlled remotely with an on-board camera/transmitter and remote sight and sound monitor and a model airplane transmitter.
Motor was oritinally made to run at a nominal 19.2 VDC.· I doubt the original setup ever reached that with low-end batteries and charger.· I have installed a Ryobi battery "socket" from an unused flashlight that runs at 18 VDC nominal.· Actually varies between about 19 VDC and 17 VDC.· Probably lower after some runtime.· Motor works fine down to 12 VDC, but, less torque.· Obviously.
It looks like the HB-25 would nearly work.· Certainly ample headroom on the amperage.· "Nameplate" on the controller of 16 VDC makes me wonder·if I should rig up some sort of voltage divider to apply less than full battery voltage to it.· I know you can run anything at any voltage, provided you can live with the run time at overvoltages.· If I can make it work, the HB-25 would function on this second-generation rover; and when combined with a second controller would also work on the autonomous "Mars Rover" we are aiming at.
Any thoughts, suggestions, or real-world experiences?
Thanks.
Steve K.
Comments
It's no different than any other team. Very few people want to coach a team (or rather, are willing to put in the huge amount of effort), and you take whoever is willing regardless of gender.
@Steve
I wouldn't try to run the HB-25 at more than it is rated for. If you have an extra $50 then you can always experiment, but it probably won't work. Anyway, I have a robot that uses an RC car base. I think the RC car that I used was designed to run at on 7.2v battery packs, but it still goes really fast (a slow walk) even on a minimum speed. For you setup I would just experiment with what you have, and see if it works. There is something to be said for throwing theory out the window and getting your hands dirty.
Another option would be to replace the motor with something that works at a lower voltage.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Powered by enthusiasm
www.acroname.com/robotics/parts/R220-MD22.html
www.acroname.com/robotics/parts/S24-15A-30V-HBRIDGE.html
www.lynxmotion.com/Product.aspx?productID=623&CategoryID=10
www.lynxmotion.com/Product.aspx?productID=565&CategoryID=10
www.lynxmotion.com/Product.aspx?productID=562&CategoryID=10
So.... if anyone at Parallax is listening, I can clearly state what the HB-25 has always lacked/included that has made it a less than ideal choice for my projects:
- at such high amps, it can be highly desirable to run 24v systems, which the HB can't handle
- I don't want a fan, esp. one that is not under host control
If they ran 24v and had no fan, they'd probably be all I'd use, given price, Parallax quality and support, etc. (Although regenerative charging is a serious consideration as well.)
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST
1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php
John Abshier
Zoot· -· Like you, I stick with Parallax when I can.· Support is, um, unparalleled.· There, I said it!· Will most likely use a controller from Pololu that will run 2 motors at variable speeds and 1 at a single speed.· That one can be used for the next step in the sequence as well.
MasterC· -· I took your comment in exactly the tone you intended, good natured fun.· If you don't have a sense of humor you definitely do not want to coach any team in any endeavor, regardless of gender!
SRLM· -· I didn't expect anyone to have actually tried running the HB overvoltage intentionally, but you never know.· I am still trying to get my mind around that concept - "an extra $50".· I'm afraid that's up there with visualizing a 4-dimensional cube.
Will post pix as we progress.· Thanks for your input.
Steve K.
The new Jaguar is rated 24V @ 40Amp continuous current, 100Amp peak...
www.luminarymicro.com/jaguar
Unfortunately they seem to be out of stock though...
search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-25445-ND
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Living on the planet Earth might be expensive but it includes a free trip around the sun every year...
Experience level:
[noparse][[/noparse] ] Let's connect the motor to pin 1, it's a 6V motor so it should be fine.
[noparse][[/noparse] ] OK, I got my resistors hooked up with the LEDs.
[noparse][[/noparse]X] I got the Motor hooked up with the H-bridge and the 555 is supplying the PWM.
[noparse][[/noparse] ] Now, if I can only program the BOE-BOT to interface with he Flux Capacitor.
[noparse][[/noparse] ] I dream in SX28 assembler...
/Bamse
What is the model of the RC truck that you are using?
You should be able to get replacement gears and pinions easily in order to gear it down AND replacing the motor with an inexpensive, lower voltage should be quite easy. Since you have no need for racing speeds I would go that route and use a 12 volt (or less) battery pack.
Rich H
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
The Simple Servo Tester, a kit from Gadget Gangster.
However· -· I·am going with a Sawtooth that is vast overkill for this project, but will be exactly right for my next ground-up project, and will have voltage and amperage headroom for most anything I build in the near future.
First club meeting is tomorrow.· I will post at least pix, maybe video if I can be referee/coach/triage nurse/short-order-cook/cameraman at the same time.
Steve K.
Steve K.
Looking forward to hearing how your club is getting along. Hacking a R/C truck or car is something I have been wanting to do for a long time. Parallax opens up a so many opportunities.
Keep us informed.
Tex
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Of all the things I have lost...
I miss my mind the most.