Struct Thermostat 

pub struct Thermostat { /* private fields */ }

A hysteresis (bang-bang) controller for a single on/off actuator.

This is the controller behind “keep a temperature”. It switches a cooler or heater on and off to hold a reading near a setpoint. A deadband around the setpoint - the hysteresis - stops the output chattering when the reading hovers at the threshold, which protects relays and compressors that have a limited number of switching cycles in them.

Examples

use pamoja_kit::Thermostat;

let mut fridge = Thermostat::cooling(4.0, 0.5);
assert!(fridge.update(5.0)); // above the deadband: the cooler runs
assert!(fridge.update(4.2)); // inside the deadband: it holds its state
assert!(!fridge.update(3.4)); // below the deadband: the cooler stops

Implementations

impl Thermostat

pub fn cooling(setpoint: f32, hysteresis: f32) -> Self

Creates a thermostat that drives a cooler, such as a fridge.

The output turns on when the reading reaches the top of the deadband and off when it reaches the bottom.

Arguments

• setpoint - the target reading. One that is not a number never switches.
• hysteresis - half the deadband width; its magnitude is used, and one that is not a number is taken as zero.

Returns

A thermostat whose output starts off.

pub fn heating(setpoint: f32, hysteresis: f32) -> Self

Creates a thermostat that drives a heater.

The output turns on when the reading reaches the bottom of the deadband and off when it reaches the top.

Arguments

• setpoint - the target reading. One that is not a number never switches.
• hysteresis - half the deadband width; its magnitude is used, and one that is not a number is taken as zero.

Returns

A thermostat whose output starts off.

pub fn update(&mut self, reading: f32) -> bool

Updates the controller with a reading and returns whether the output is on.

A reading that is not a finite number, such as the NaN a failed probe reports, is ignored and the output stays as it was: a heater that was on stays on. A node that must fail safe checks the reading itself and decides what off means for its plant.

Arguments

• reading - the latest measured value.

Returns

true if the cooler or heater should be running.

pub fn is_on(&self) -> bool

Returns whether the output is currently on.

Returns

true if the most recent update left the output running.

Trait Implementations

impl Clone for Thermostat

fn clone(&self) -> Thermostat

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Thermostat

impl Debug for Thermostat

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Thermostat

fn eq(&self, other: &Thermostat) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Thermostat