Brushless drive ESC

[shakesc]

All brushless esc's have a delay, even the sensored ones. You can't trow a brushless in reverse like a brushed motor. It has to be stopped. The only thing you can have is a minimal delay.

It will take a lot of practise to get the best from the new tech.

Agree with the practice but I need that regardless but its a slight change in driving style

The availability of brushless motors and esc is improving. The accuracy that sensored brushless gives is not really necessary in our applications where some wheel slip is acceptable. Where sensored does score is the startup of the motor. Sensorless controllers have challenges during motor start-up, as no back EMF is present when the motor is stationary and therefore need to bump the motor initially to determine position on powerup. The motor can become out of sync when running with the position the ESC believes it in. Improvements in ESC s/w should minimise this.
Its going to take some experimentation in building drivetrains for fighting robots and testing them in competition.

[overkill]

All brushless esc's have a delay, even the sensored ones. You can't trow a brushless in reverse like a brushed motor. It has to be stopped. The only thing you can have is a minimal delay.

It will take a lot of practise to get the best from the new tech.

If there is a delay on my brushless drives, its too short to detect. I also find that the sensored brushless drives have better torque and control at low speeds than the brushed system I was using. Perhaps a short video will convince the doubters? There are also few problems with the sensors being delicate. The sensors are three small surface-mount hall switches on a well protected PCB; the only thing I worry about is the sensor cable and its tiny connectors.

BTW: the 2nd Hobbyking ESC mentioned looks ideal to me; I have two of the 150A controllers on the way for testing.

[maddox10]

I tried the NTM28-36 motors. Start torque ain't what is needed. It drives, but not what we want.

[overkill]

What gear ratio did you use? With sensorless motors, you need plenty of reduction and/or a fairly large motor. By comparison the 540 size sensored motors I use have very similar performance to drill motors.

[knightrous]

There is some testing I did with NTM 42-38 with a 12:1 gearbox (video description is wrong), 15kg of steel dumped on top.
http://www.youtube.com/watch?v=HKg-FZft0Wc

I'm hoping to have some 19:1 gearboxes shortly to test with to see if the start up torque is enough to smoke the tires

[maddox10]

6-1 gearratio to 90mm wheels on 3S.

I have 42-35's 750 KV as backups, but implementing those is another matter.

[overkill]

Its hard to smoke a Colson - just breaking traction at low speed is a very good sign the motors are adequate. A 19:1 gearbox and a higher KV motor should do even better. Its good to see us Aussies leading the way on brushless drive!

[maddox10]

In Nebelwerfer 2 the Frankensteined Gimson GR02's 24/1 with HK 2838 2850 KV inrunners mated to the Trackstar 25A sensorless speedo's work fine. And that's with large, soft 130mm RC wheels. And that one is standing by for months now. On the other hand, that's a 6 kg raptor.

And yes, it's the starting speed that is a problem with the current Calliope drives. Once it goes, it goes well.

[Daniel]

http://youtu.be/2Aa4Qx_iEB0

NTM 42-38's with Trackstar 80 controllers on a 4-cell battery. 10:1 onto 100mm wheels but the total setup is only 6kg and has problems with the chains and can't afford to rebuild it yet.
This is a sensorless setup and as you can see the delay isn't noticable.

I also forgot this older test with the same brushess motors/ESC but with 25:1 onto 250mm wheels. It was a 10kg setup. Video was origionally posted 12 months ago and I still keep reading that sensorless outrunners won't work. Really wish I could afford to build the new robot the drive was origionally brought for.
http://youtu.be/bRkM_OzetfM

[cavecrusher]

I'll just post this link again. Maybe someone is interested in some.

http://vedder.se/2014/01/a-custom-bl...or-controller/

[Mouldy]

That esc looks bang on Tim- shame there not sold pre-built.

[leorcc]

So far our test results are promising, but like Mario said in Caliope we married a too small a motor with too small of a gear ratio. I'm convinced that with a dual stage gearbox the drive would have been fine. But as it is it is not taking off and stopping fast enough. The Brushless drive in de raptor performs really well, similar performance as the Scarifier video from Daniel.

[daveimi]

Aren't Botbitz a brushed ESC originally?

[overkill]

No, the TZ85 is originally a brushless plane ESC that Steve reprogrammed to be a bi-directional bot ESC. Its a little ironic that the same people are now leading with brushless drive motors.

[Eventorizon]

In my process for designing a machine for live events I was looking at these as a combination:

http://www.hobbyking.com/hobbyking/s...grammable.html

http://www.hobbyking.com/hobbyking/s...tor_730KV.html

Running on 4S, 73mm wheels with two 3:1 belt reductions (9:1 total) it would be able to do just over 10mph.
Looking at the PDF, the ESC is capable of Forwards/Brake/Reverse and Forward/Reverse:

http://www.hobbyking.com/hobbyking/s...7X53414X36.pdf

Unless the ESC can take the large back currents during braking/soft breaking it may have to be run in simple Forward/Reverse.

The alternative would be to get a large diameter outrunner with lots of torque to help compensate for the lower starting torque. But from the vids and other combinations people have done it may not be necessary.

Thoughts?