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Originally Posted by Al Skierkiewicz
Dan,
What are you trying to do? There's more than one way to skin a cat.
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Alright, I'll explain a little bit what I'm trying to do. I'm basically working on algorithms to control a vehicle with 4 independantly-steerable wheels... full-blown omnidrive if you will... for one of my classes. Before we build a full-scale prototype, I just made a small rectangular platform with four servos on each corner, each rotating a multispeed-motor, just to test the positioning/speed algorithm (basic theory behind omnidrive for the interested - when you make a turn, the wheels need to turn at different speeds, otherwise you get slippage and inefficiency/wasted energy. A car accomplishes this with a differential. I'm trying to write an algorithm that given the turning radius, calculates the most efficient wheel rotation and speed for each wheel). Long story short, the way I modelled my algorithm I need about 180 degrees of rotation out of each wheel to be able to do every type of turn (a bit less, actually, depending on the length/width parameters of the car, but 180 simplifies the math).
I chose to go with the IFI controller because I'm not yet at the point where I can program my own microcontrollers to do all the radio transmitting overhead, plus its just a really clean package with all the integrated inputs and outputs, and getting this done fast is a priority.
Anyways, so the last two days I've been learning how to program my own microcontrollers, and I've gotten one to make the RC PWM pulses. Turns out you CAN make a servo do the full 180 degrees it is mechanically capable of by changing the pulse length... I was able to get the max mechanical range out of my Hitec HS755HB's with .6ms and 2.35ms pulses. In fact, the circuitry tries to match higher and lower pulses, its just that the servo begins to whine and make bad noises.
I think what I'll try doing now is try and program the IFI controller to make my own length PWM pulses. Anyone have any ideas on how to go about doing that?