pH neutralisation

pH neutralisation — CSTR with acid, buffer and base streams.

Action space	Box((1,)), all actions in [-1, 1]
Observation space	Box((3,))
Tracked variable(s)	pH
Episode length	300 steps (1500 s at 5 s per step)
Import	from target_gym import PHNeutralization, PHParams
Cite as	ph_neutralization-v1

Action space

Actions are normalised to [-1, 1] and mapped onto the plant's real actuator range inside the environment.

#	meaning	min	max
0	base flow	-1	1

Observation space

3 values. Indices (0,) carry the tracked variable(s) that the reward scores.

Rewards

pH tracking minus a small reagent cost.

Every environment in this suite scores on one contract: the reward is (tracking terms, multiplied) x (1 - weighted costs), bounded in [0, 1], and reaches 1 only while the target is held exactly. See Reward shaping.

Starting state

reset samples the initial condition and the target; state has 7 fields.

Episode end

Termination. See check_is_terminal.

Truncation. After 300 steps.

Baselines

A tuned PID ships with this environment.

Arguments

parameter	default
delta_t	5
max_steps_in_episode	300
V	2900
q1	16.6
Wa1	0.003
Wb1	0
q2_nominal	0.55
q2_noise_std	0.35
q2_min	0
q2_max	2.5
Wa2	-0.03
Wb2	0.03
q3_min	10
q3_max	22
…	9 more, see the params dataclass