Life Support PID Control Loop Tuner

PID Gains — CO₂ Scrubber

Proportional K_p 0.90

Integral K_i 0.20

Derivative K_d 0.40

Cabin & Crew

Setpoint 3000 ppm

Crew CO₂ production 700 ppm/min

Live Telemetry

STABLE

Cabin CO₂

3000 ppm

Error

0 ppm

Scrubber output

0 ppm/min

Sim time

0.0 s

How it works

The cabin CO₂ concentration C(t) obeys a mass balance between crew metabolic production P and the scrubber's active removal rate u:

dC/dt = P − u(t)

u(t) is generated by a real discrete PID controller acting on the error e = C − setpoint (positive when the cabin is above target, so a larger u increases scrubbing):

u(t) = Kp·e + Ki·∫e dt + Kd·de/dt
u(t) clamped to [0, u_max]

K_p reacts to the present error — too low and the loop drifts, too high and it overshoots.
K_i accumulates past error to erase steady-state offset — too high causes slow oscillation ("integral windup").
K_d reacts to the rate of change, damping fast swings but amplifying sensor noise if pushed too far.

This is the same feedback-control pattern real ECLSS (Environmental Control and Life Support System) hardware uses to keep an amine-bed or metal-oxide CO₂ scrubber running just hard enough to hold the cabin near its setpoint without over-cycling the actuator. The scrubber fan blades spin faster as u increases; the drifting particle cloud shows live CO₂ density; the ribbon graph plots C(t) against the setpoint line over the last two minutes of simulated time.

CO₂ molecules Setpoint line C(t) trend

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