ESC's and Motors

Does anyone have a good ESC solution for each of the following motors or would muy current ESC...

http://www.technobotsonline.com/saberto ... or-rc.html

be up to the task?

I intend to use 4 of whichever I choose, simply because the design has always had 4 motors and I want the robot to have some considerable push!

And can anyone suggest a suitable solenoid or ESC to drive a Speed 900 motor?

http://www.cornwallmodelboats.co.uk/aca ... _6373.html.


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For the full rant, see below...

Hi All

Despite all my hard reseach it seems that I am going to have to replace 2 critical parts of my first robot, the motors and as a result of changing the motors, the electronic speed controller as well.

The current set up is 4x 919D 50:1 metal gear box motors*, 2 for each side, linked to a Sabertooth dual 12A ESC**. I know from various tests and many hours of run time for my university demonstrations that this set up works perfectly well for about 30/45 minutes before I run my batteries flat.

But now after talking to Robo-challenge and a few others on this Forum that the motors are woefully inadequate. I have found an alternative for myself and been shown 2 other but these motors as well as being more robust are considerably more power hungry, or ampage hungry at any rate.

The options are€¦

1: http://www.technobotsonline.com/re-975d ... x-4-1.html

A planetary version of my current motors but with a bigger motor.

2: http://www.ebay.co.uk/itm/JAGUAR-XJ40-X ... 20be5252b7

Bosch 35w motors, I know very little about these.

Or 3: http://www.gimsonrobotics.co.uk/GR01_pl ... motor.html

Again knowledge is limited above what is given on the data sheet.

For option 1 it may be possible to keep my current ESC but only run 2 motors, though I would prefer to run 4 as the design has always fitted 4. For 2 I have no idea what voltage or current they require and for 3, with theoretical peaks of 70A, the Sabertooth would become a singed electrical mess in no time at all.
I know that ESC€™s are expensive but what options do I have regarding a replacements for each motor option?


* http://www.technobotsonline.com/re-540- ... -50-1.html

** http://www.technobotsonline.com/saberto ... or-rc.html

i don't like the sabertooth contolers for anything abouve antweight really, they have blown up on me too many times, 30a electonize is your best bet probably, or 4 15a ones, one per wheel

Re Sabertooth I have used one (25A) in featherweight robots and in Pilgrim the big walker (This has two 250W 24V motors to run it, even when I get it to dance the speedo dose not get warm),for a long time and had no problems with it at all. I know a lot of Roboteers that find these speed controllers fine. Most problems seem to occur when you try to run 2 motors off one channel but if you steer clear from that they seem to work fine.

Sabertooth's (Saberteeth?) are very nice controllers. Small, compact, silent, feature full (fail safe, lithium mode, mixing built in) and a good price.
But for some reason they do just seem to break down for no good reason... Some people have never had a problem, whereas other like myself have had them fail without the robot having ever been in combat!
On the plus side their customer service is very good and are very willing to help/replace faulty good. On the downside they are based in America so postage takes a while plus the USPS loses pretty much every package it has to deal with!

What motors do you plan on using?

The 12amp model is about as common as the 25amp one in FWs, it all depends what sort of current you think you'll draw, which can be tricky to figure out.
25amp is a lot, so go for the bigger one if you want to be safe. You should fuse the expensive parts of your robot anyway if the current does go wild for any reason.

Just remembered With regards to these speed controllers.
I always Hot glue gun the capacitors together and then to the terminal block To hold them steady as they seem to be left swaying in the breeze! if your robot gets flipped by the floor flipper the thin conductors connecting them to the board can become detached giving you an intermittent fault. :uhoh:

I used the singal syren version, and that works fine, it even has a high current cut out, which is pretty useful...

Ah so the USPS is the bottleneck in that case, have an order from dimension with a sabertooth that never got here.
But yeah as you said they have a very good seervice.

I am leaning towards 4 of the GR-1 motors. In testing with the motors I have at the minute they were drawing 0.5A each when unloaded which is normal but spiking to 3A each when loaded.
The GR-1 motors say the stall current is 70A, does that mean I need an ESC that can take peaks of 70A?
As far as I am aware you match the ESC to the loaded draw current of the motor, and then get a more powerful ESC if you are being more conservative with your design...

Quote:

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Originally Posted by PJ-27

You should fuse the expensive parts of your robot anyway if the current does go wild for any reason.

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How do you fuse the parts? Is it as simple as using appliance fuses, like in your kettle or toaster, in a box or are there special trip switches like you get in your fusebox at home? And where in the system do they go?

Better to compare to the fuzebox of a moped or motorcycle. A lot smaller than household or industrial fuzes.

Also, any DIY shop with a small automotive rack has fuzes and holders.

I have seen people using a 50A blade fuze as removable link.

Technobots do a standard fuse up to 40A this should be enough, and a 4 fuse holder one for each motor if you wanted.

Generally with drive motors you shouldn't ever reach a stall condition, the wheels should spin before this happens. The reason fuses are often put in line with the motors (between the motor and speed controller, on either of the two leads) is to protect against this exceptional stall condition, which might occur if a wheel gets jammed due to damage for instance. This differs to the main power fuse some robots have after the battery which is often to protect against electrical faults (e.g. shorts).

Specifically to the GR01 I wouldn't expect normal running as drive in a featherweight (with wheels up to 125mm) to exceed 20A average with ~30A peaks (of course there are more variables). A current-protected controller around the 20-30A range would be ideal (Scorpion XXL or Sabertooth 25) or a non-current protected controller with in-line fuses (e.g. Electronize 30A).