Module pid 

A discrete-time PID controller for closed-loop budget regulation.

The DCC uses this to drive GORNA’s global budget multiplier so that the measured frame time tracks a setpoint (the heuristic-suggested latency), replacing the old static thermal/battery lookup. The controller is a pure scalar algorithm — no engine state, no allocation — so it lives in khora-core and is unit-tested in isolation.

It implements the practical refinements that matter for a noisy, saturating, discrete-actuator plant:

• Derivative on measurement (not on error) — no derivative kick when the setpoint jumps (it jumps every time the thermal state or phase changes).
• Filtered derivative — a first-order low-pass on the derivative term tames frame-time noise; the filter time constant is (Kd/Kp)/N.
• Back-calculation anti-windup — the output saturates to [output_min, output_max]; the integrator is unwound by Kb·(saturated − unsaturated) so it never accumulates against a limit (the steady ceiling at output_max when running with headroom is the most common windup case here).
• Setpoint weighting — the setpoint is weighted by b in the proportional term to curb overshoot without hurting disturbance rejection.
• Output clamping — to a configurable [output_min, output_max].

Structs

PidConfig

Tuning and limits for a PidController.

PidController

A discrete-time PID controller with filtered derivative-on-measurement and back-calculation anti-windup. See the module docs for the rationale.