A proportional-integral-derivative (PID) controller.
Features
- Visibility into individual contribution of P, I, and D terms which often
need to be logged for later analysis and parameter tuning.
- Output limits on a per term basis.
- Mitigation of integral windup using integral term limit.
- Mitigation of derivative kick by using the derivative of the measurement
rather than the derivative of the error.
- On-the-fly changes to
kp/ki/kd.
- Mitigation of output jumps when changing
ki by storing the integration of
e(t) * ki(t) rather than only e(t).
- Generic float type parameter to support
f32 or f64.
Assumptions
- Measurements occur at equal spacing. (
t(i) = t(i-1) + C)
- Output limits per term are symmetric around 0 (
-limit <= term <= limit).
Todo
- [ ] Three-term output limit:
MAX(p + i + d, global_limit).
- [ ] Helper for (auto-)tuning by detecting frequency & amplitude of
oscillations.