Drive motor options

[Daniel]

I don't notice any pause when switching directions. Maybe someone else who is a lot more anal would but I felt it was the same as an IFI. I'll find the instructions and post what setting I used once I remember.
I also think it's the future and surprised I hear people saying outrunners won't work for drive.

[Ellis]

Thanks for the info Daniel! Is there really no delay between FWD/REV? I guess it's quite like having a braking function on brushed motors, but that gets bypassed (I believe) if you're ramming back and forth, and the polarity just switches. With brushless there must be an extra delay to allow the motor to stop completely before continuing in the opposite direction?

Would you say it's responsive enough for a robot which is all about drive control - i.e., a design something like Sewer Snake's, where being the dominant driving force in the arena is kinda crucial?

Could be the future of this sport!

edit: I mentioned Hot Stuff a page back, I am now fairly confident that that is running four of these: http://www.hobbyking.com/hobbyking/s...tor_730KV.html - spotted the red and black motor cans in one of his videos. That's a lot of power!

[Daniel]

Hi guys. I notice my robots are being talked about.
I have been building a brushless drive feather and I did take it into combat but failed. The brushless motors and controller worked perfectly, it was the lack of money that forced me to make a dodgy drive train that was the problem. Sprockets slipping, chains coming apart, motors falling off, stuff like that. The 4WD test platform does work reliably, as show in the videos.
I used the 80A Trackstars as they were the biggest car brushless controllers on Hobbyking last year. That was fine with me as I think that the NTM 42-38 750kv motors are the biggest you will need for a feather weight drive, but that is just a personal opinion. I do run a 4 cell LiPo to try to get the most of the 750W the motors are claimed to out put. When working they produce a very simalar driving experiance to running 2 x 300W scootor motors in a feather weight, and since I know a 300W scooter motor can output closer to 500W, then a 750W brushless motor is probably closer to 500W when used for drive. But that is just eye-balling the robot driving around, so who knows.
The 150A Trackstar is a new product on Hobbyking, but it looks the same. I didn't need to spend too much time mucking around with setting on my 80A controllers and they robot drives the same as the old scooter motor / Victor 883 setups I used to use. If I ever get a job I'd like to try the new 150A Trackstar and a NTM 50-50 on 6 cells to drive an axe. An all brushless Avenger.

[leorcc]

I have that ESC in one of my truggies. It works great, just keep away from water. For the function you need, you need to program it with the transmitter. The programming card will not set the reversing correctly.

[Ellis]

Am skeptical but only because it's in my nature, wish you both good luck! If you manage to get decent response times from biggish brushless motors like those then you'll be paving the way for many.

(just don't expect the gimsons to handle 1.6hp for long!)

[Liftoff]

We're seriously considering the brushless drive, my brother is in contact with a local roboteer who successfully used a similar setup on his spinner at last year's event. So as soon as he's confident its doable I'll start sourcing the parts... We're looking at these motors and esc... they do look like an overkill but what the heck, as long as they fit inside !
Will be testing the gimson gearbox, if it survives good, if not then there should be alternatives me thinks

motors
http://hobbyking.com/hobbyking/store...0KV_1295W.html

and escs
http://hobbyking.com/hobbyking/store...s_Car_ESC.html

[maddox10]

We use the 18A trackstars for the experiment, neat little speedo's.

[Liftoff]

Wouldn't this esc be better suited to those brushless motors? Its unsensored, like the motors are, and it can take up to 6s lipo if I understood correctly....reading through the feedfack on this esc one guy mentioned that it can also control a brushed motor... don't know if it's possible at all.
http://hobbyking.com/hobbyking/store...s_Car_ESC.html

I'm really tempted

[plargen]

This Australian build thread shows a machine with brushless drive, but there isn't much detail: http://robowars.org/forum/viewtopic....=asc&start=615

if you look further back he also made this
https://www.youtube.com/watch?v=bRkM_OzetfM

[Ellis]

You have to match them. Sensored motor needs a sensored speedo, and vice-versa.

[Liftoff]

Does it make any difference if you use an unsensored motor on a sensored esc?

[Ellis]

States on the thread that the wheels are 100mm. Believe that ESC is rated for just 3s, so at 10:1, that's 10mph top speed. Over 1hp potential drive power. Pretty nice, and as per the video, drives quite nicely. Doesn't quite look like 10mph, though. Might be running 2s.

Either way, it proves the point that it's viable. Just for high power drives, the speedos are behind a bit.

That said, I believe the American machine "Hot Stuff" (a 60lber) uses brushless drive, too. Very powerful. No idea on actual specs, but it's running some Turnigy Trackstar motors into Dewalt gearboxes, and cheapo Chinese motor controllers. Might be worth trying to find out more. There are several videos on the builder's channel of tests: http://www.youtube.com/user/dtrobotics/videos

[leorcc]

We are testing with brushless drive as well but in a lower weightclass. Still there is no reason to assume the drive will be any different with the larger ones than the results we've had with the smaller ones. One thing about the Trackstar ESC's, the programming card is quite useful but one of the settings is not available on that card. You would need to use the transmitter programming option for that.

[Eventorizon]

This Australian build thread shows a machine with brushless drive, but there isn't much detail: http://robowars.org/forum/viewtopic....=asc&start=615

He recently put this info up (Directly and indirectly)...

ESCs: Trackstar 80A brushless car controlers

Motors: NTM Prop Drive 42-38 750Kv (Picture matched and found here: http://www.hobbyking.com/hobbyking/s...arehouse_.html)

Reduction: 10:1

Wheel Dia: 102mm (Taken from ebay. Same width, hex and scale so I am assuming the OD matches too. http://www.ebay.com/itm/4PCS-17mm-Hu...-/360669106232

Provided the ESC's work off the shelf, this should be easy enough to reproduce and modify. I have to say that guy has some serious skills. Check the 43rd page, all those designs!

Or here: http://i34.photobucket.com/albums/d1...psba4b0087.jpg

[maddox10]

As low as needed, but each stage adds weight, complexity and size.

It also depends on what gear-ring you have available.