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BrianG · 12.01.2006, 03:29 PM

Seperate motors on each wheel would take a different type of controller, or at least some type of signal adaptor. Since each wheel would have to spin at different rates when steering (which is normally taken care of with a diff) the controller would have to adjust the pulsewidth of the signal to the slower wheel based on the steering adjustment. So basically, if you are going straight, both motors get the same power. When turning left, the left wheel has to spin slower, so the controller would have to somehow factor the steering signal into the throttle signal to know that the left wheel is to spin slower. I guess basically how a tank controller operates.

So, the easiest way to do this would be to use a controller with two throttles and use that for steering and throttle control. Not very intuitive compared to a typical pistol-grip controller.

The other way to do this would be to feed the throttle and steering signals from the Rx into another "box". This box would then have two throttle outputs. The signal on these would be a processed signal based on the input throttle and steering.

I've done some thinking on this already. A typical output singal of a receiver is a series of square wave pulses at a frequency of 50-60Hz. The actual frequency really doesn't matter as long as it is consistent and not too far from these values. The positive part, or "on" portion, of the square wave pulses range from 1ms at min throttle/full left turn to 2ms at max throttle/max right turn. Steering center/neutral throttle is 1.5ms. So, a circuit would have to be designed to create two 50Hz squarewaves for each throttle signal whose pulsewidth is equal to the single input throttle pulse except when the steering is engaged. If turning left, the left throttle channel signal would be reduced in proportion to the steering pulsewidth. The same for the right side. I think this can be done relatively simply with some cheap linear analog circuits (op-amps, transistors, etc).

Maybe if I have time this weekend, I'll try to breadboard a couple of ideas. Might be a neat thing to market...

	(#22)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	12.01.2006, 03:29 PM Seperate motors on each wheel would take a different type of controller, or at least some type of signal adaptor. Since each wheel would have to spin at different rates when steering (which is normally taken care of with a diff) the controller would have to adjust the pulsewidth of the signal to the slower wheel based on the steering adjustment. So basically, if you are going straight, both motors get the same power. When turning left, the left wheel has to spin slower, so the controller would have to somehow factor the steering signal into the throttle signal to know that the left wheel is to spin slower. I guess basically how a tank controller operates. So, the easiest way to do this would be to use a controller with two throttles and use that for steering and throttle control. Not very intuitive compared to a typical pistol-grip controller. The other way to do this would be to feed the throttle and steering signals from the Rx into another "box". This box would then have two throttle outputs. The signal on these would be a processed signal based on the input throttle and steering. I've done some thinking on this already. A typical output singal of a receiver is a series of square wave pulses at a frequency of 50-60Hz. The actual frequency really doesn't matter as long as it is consistent and not too far from these values. The positive part, or "on" portion, of the square wave pulses range from 1ms at min throttle/full left turn to 2ms at max throttle/max right turn. Steering center/neutral throttle is 1.5ms. So, a circuit would have to be designed to create two 50Hz squarewaves for each throttle signal whose pulsewidth is equal to the single input throttle pulse except when the steering is engaged. If turning left, the left throttle channel signal would be reduced in proportion to the steering pulsewidth. The same for the right side. I think this can be done relatively simply with some cheap linear analog circuits (op-amps, transistors, etc). Maybe if I have time this weekend, I'll try to breadboard a couple of ideas. Might be a neat thing to market...