Design calculations
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Maximul speed
Motor has 5600 RPM at 6V no load. Gearing is 9.68:1 Wheel diameter is 6cm.
This gives a max speed of 5600/60/9.68*0.06*Pi = 1.8m/s
Encoder calculations
The encoder has 48 ticks per revolution. This gives 48*9.68 = 464.64 ticks per wheel revolution, or Distance per tick = pi*0.06/464.64 = 0.40568 mm/tick
Speed calculation
Speed is calculated based on time between encoder ticks
At max speed there should be approx 4.48 encoder ticks per ms, or 223 us between tics The timing base is pt. 10us, so velocity resolution is rather bad at high speeds. This is be improved by averaging if time between encoder is smaller than sample time.
Sample time is (pt.) 1ms.
Parameter estimation
Pololu say that at 6V stall current is 2.2A, or R_A = 2.7 Ohm
On this robot the total anchor resistance is estimated to 3.3 Ohm (including H-bridge and wires) from current step responce.
