[Mike Copioli]

Originally Posted by Uberbots

i assume your coprocessor is doing some fairly complex vector operations to get an angle out of the encoders?

We use the co-processor as an interrupt driven encoder tick counter. It also performs all of the floating point math for calculating arc-length and theta. Arc length is simply the sum of the ticks of each encoder divided by 2. We then calculate the difference in arclenghth of each encoder. Since we know the distance between the two encoders (robot diameter) we can calculate theta. Using an external processor guarantees that no encoder ticks will be missed due to program flow latency or high priority interrupts like the ones used on the RC. We are using 128 bit quadrature encoders that are measured on both the rising and falling edge of each pulse. This gives an effective resolution of 256 ppr.