Quote:
Originally posted by wysiswyg
Hear is a stupid question if the victors rely on pwm exactly like other esc's for radios then why do can't you use a radio to control the esc's or can you???
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Well, yes and no...
That's
exactly what they were originally designed to use, but they tweaked it for Robot Controller use... However, read on. We may be able to fix that.
Many BattleBot competitors use IFI hardware with their basic RC controls and no computer in the middle.
HOWEVER, IFI makes two versions of the Victor 883, an IFI Robot Controller version, and a Radio Control version for BattleBot and others to use.
First off, check out the IFIRobotics site, another entry to the same company we call "InnovationFIRST":
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http://www.ifirobotics.com/
You'll see a bunch of BattleBots there.
Now check out their products area:
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http://www.ifirobotics.com/products.htm
You'll see the bigger THOR 883 modules, which are TWICE the current capacity of the Victor 883's (120A continuous! Whoof!)
Compare these monsters:
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http://www.ifirobotics.com/victor_883.htm
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http://www.ifirobotics.com/thor_883.htm
NOW... According to the Victor 883 datasheet above the IFI version of the 883
we use "does not come with a signal driver". I'll
betcha it means the PWM signals need to be 12V square waves for our version, instead of 5V. If so, that means you'll only need a simple opamp or transistor driver to level shift the voltage from the RC control's 5V up to 12V square waves. That's EASY...
HEY... LET'S CHECK IT!!! 
Here's a test for someone with a working robot: Put an oscilloscope on the signal leads between the Robot Controller and the Victor, and read off the square wave amplitude.
Settings: "DC coupled", "5V/division", zero = any convenient line below the centerline.
Connections: Tie the scope ground to the BLACK lead, and probe the WHITE lead.
Test: Measure the amplitude of the square waves and report it back here. (If you wish, take a digital pic of the scope's trace and either post it or email it to me...)
(I can't do it because I'm now starting up my second rookie team in two years, and we don't have hardware in hand yet...)
BTW, If someone want to make one HECK of an RC car out of: an RC system, a thrown out Fisher Price kid's riding jeep with the front wheels changed to castors, a spare FIRST robot battery, and a spare pair of Victor 883s, I'll betcha it'll probably only take a buffer amp to do it!
(It sounds like a good team exercise to me!) If someone wishes to do that, I'll help you make the signal driver for it...
FYI, some of us in my town's robotics club are making Autonomous Jeep Sumo bots for parking lot battle now with: thrown away kid's jeeps, home grown MOSFET drivers in place of the Victors, and whatever micros we each have on hand to drive them (i.e. Mindstorms RCX bricks, Stamps, PICs, Amtels, Palm Pilots, etc...). But that's a separate thread for another time and forum...
Somebody let me know what you find about about the waveforms, and I'll tell you what you need to use a Victor with an RC system!
- Keith