paper: Shooter Wheel Speed Control

[John]

Originally Posted by Ether

- what motor(s)

- total gear ratio from motor to wheel.

- Jag or Vic?

- coast or brake mode?

- voltage ramp rate?

2 FP 0968-9015 motors. About a 3:1 reduction. Victors, coast. No voltage ramp (Does it need one?).

- what encoder model, and where mounted

- what language

- 1x 2x or 4x decoding?

- Counter or Encoder class?

- to measure RPM, are you measuring the time between consecutive counts, or are you dividing the counts by the delta time?

- if dividing counts by delta time (see above item), how are you computing the delta time

- what execution cycle update rate?

- what wheel rpm value were you trying to control

- please elaborate a bit more on the nature of the oscillations: amplitude, frequency, etc

This might be the problem. We are using a light sensor and a single strip of reflective tape to determine rate (one count per revolution). We used the Counter (labview) to determine rate by measuring time between counts. The execution rate was 20ms. I tried commanding wheel speeds between 2600 and 3600 rpm (the extremes of our shooter during competition). 20ms*(2600rpm * (1minute/60000ms)) = .867 rev/cycle. If the speed updates less often than the power command, would that throw it off? Thanks