Battlebots FAQ

Robotics, battling robots, trains and similar Futaba Equipment uses

• Information on receiver/servo operation with and without radio control
  
  
• Information on digital servos
  
  
• Using an aircraft 6+ channel radio
  
  
• Futaba sponsorship
  
  
• Tank-style control with 2 sticks both centering automatically?
  
  
• How can I set up "inverted driving" on a 2-motor/2-wheel bot?
  
  
• How do I make my 2-motor model go forward/backward/turn on a single stick?
  
  
• How can I use an RC radio system to control my train?
  
  
• Can you tell me what the maximum stalled current is on (insert name here) servo is?
  
  

I did not find the answer to my question here. How do I get further assistance?

The signals that go from the receiver to the servo are in the same format whether using AM, FM or PCM. The signals may differ in the length of the frame, number of channels, etc, but the FORMAT is the same. These are ANALOG signals in PULSE-POSITION modulation. Each CHANNEL within every frame may vary in length anywhere from about 1000 microseconds to 2000 microseconds, with center usually being around 1500 microseconds. Most servos are analog, but now DIGITAL servos are making their way into our industry. Please see http://www.futaba-rc.com/servos/digitalservos.pdf

Frame lengths vary depending on the number of channels. Futaba typically can be anywhere from 19-22 milli-seconds. In any frame, the channels are bundled together at the BEGINNING. Any extra room in the frame it will come at the END.

The voltage of the pulses will vary depending on the voltage of the DC power source to the Rx, with an absolute minimum operational voltage usually in the 4.0V range.

The rotation of the servo output IS directly proportional to the width of the respective pulse (channel). The minimum width of any pulse (channel) will be about 1000 microseconds, never 0 seconds. The maximum width of any pulse (channel) will be about 2000 microseconds.

PCM modulation ONLY refers to how signals are converted to digital when sent out of a transmitter, then decoded and converted back to analog by receiver.

The receiver draws only the current it needs to operate, as do the servos.

Additional helpful information:

http://www.futaba-rc.com/servos/digitalservos.pdf

If you wish to utilize an RC aircraft radio with 6 or more channels to operate a Battle bot, you must do so utilizing a ground (75MHz) legal frequency and PCM modulation. For more information on frequency use please visit:

If you are seeking battlebot sponsorship, regrettably the U.S. sponsorship program is full at this time and we are not currently accepting applications.

http://www.futaba-rc.com/faq/product-faq.html#q181

Using a 9C, the radio we strongly recommend for this task, the following programming is required:

1. Motor drives via channels 1 and 6
2. Activate flaperons
3. Activate elevator to flap mix, and assign it to your upright/invert switch (ex sh H) (off when inverted, on when upright)
4. Mix elevator to flap 100% on when inverted
5. Mix elevator to aileron -100% on when inverted
6. Mix aileron to aileron -100% on when inverted
7. Mix aileron to aileron -100% on when inverted
8. Mix ail to flap -100% on when inverted
9. Mix ail to flap 100% on when inverted

You will need to use the elevon programming in your 6X, 7U, 8U, 9C, or 9Z to set up single stick control which gives you 2 motors forward = forward, left/right gives one motor forward the other reverse, and back = both motors backwards.

We do not have extensive experience using RC systems for train applications. The information provided here is as much as we have available to offer you, to give you some starting ideas.

Before we begin, one important note—trains are ground control models and MUST be operated on the designated 75MHz, 50MHz (HAM license required) or 27MHz frequencies. It is against FCC regulation and potentially dangerous to use model aircraft frequencies in the 72MHz range or any other frequencies not specifically designated to models.

1. The minimum radio that is needed is a simple 2 channel radio system. Either a 2 channel stick or 2 channel pistol grip, it's your choice.
2. For throttle/motor control, a speed control is needed (for a basic system something like the C-50 from Great Planes number GPMM2050).
3. One channel on the transmitter can be used to drive a servo (which is included with the radio system). The servo can drive a three position toggle switch (forward - off - reverse) which will control the forward and reverse of the engine. You would have to make up the linkages for this but it should be fairly easy to do..

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