---
title: "Cybernetics"
summary: "The science of steering."
date: 2026-11-01
links:
  - "https://en.wikipedia.org/wiki/Cybernetics:_Or_Control_and_Communication_in_the_Animal_and_the_Machine"
  - "https://aesv.io/device-asset-sync"
  - "https://aesv.io/receipt-ocr-pipeline"
  - "https://aesv.io/conversational-robot"
  - "https://aesv.io/jev-mario"
  - "https://aesv.io/pianito"
---

<!-- DRAFT copy: Axel to confirm -->

## What cybernetics is

Cybernetics is the study of steering. Anything that holds a course does the same four things over and over. It senses where it is, compares that to where it wants to be, acts on the difference and senses again. A thermostat does it with a room. A cook does it by tasting a sauce and adding salt. A driver does it every time they nudge the wheel back into the lane.

```mermaid
flowchart LR
  G([the goal]) --> C{compare}
  S[sense] --> C
  C -->|the difference| A[act]
  A --> W[the world]
  D([a push from outside]) -.-> W
  W --> S
```

The word comes from the Greek kybernetes, the steersman of a ship. Norbert Wiener named the field in 1948 with his book [Cybernetics: Or Control and Communication in the Animal and the Machine](https://en.wikipedia.org/wiki/Cybernetics:_Or_Control_and_Communication_in_the_Animal_and_the_Machine). His point was that machines and living things steer the same way, by feedback, so one set of ideas describes both.

Feedback is what keeps a thing on course when the world pushes on it. Take a room kept at 20 degrees. After hour 4 the outside drops from 8 degrees to 0. A heater left at one setting slides toward 13, the lower line. A thermostat senses the drop, turns the heat up and brings the room back toward 20, the upper line.

```mermaid
xychart
  title "A room after a cold snap, degrees by the hour"
  x-axis [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
  y-axis 10 --> 22
  line [20, 20, 20, 20, 20, 18, 16.5, 15.4, 14.5, 13.9, 13.4, 13.1, 12.8]
  line [20, 20, 20, 20, 20, 18, 18.7, 19.1, 19.3, 19.5, 19.6, 19.7, 19.8]
```

## What a cybernetician does

A cybernetician designs and tunes those loops. The work is choosing what to sense, what counts as on course and what to do about a difference, so a system corrects itself instead of drifting until somebody notices.

## Where it shows up in my work

Some of what I build is a loop like this.

- In [Device Asset Sync](/device-asset-sync), each computer checks its own record in the inventory and corrects what differs, so the inventory would stop drifting.
- In the [Receipt OCR Pipeline](/receipt-ocr-pipeline), each receipt's own arithmetic checks the reading, and a reading that fails is flagged for a person to check.
- The [Conversational Robot](/conversational-robot) keeps listening while it talks, and stops when someone talks over it.
- [jev-mario](/jev-mario) tries each move from a snapshot, measures where Mario ends up and lets Jev choose before playing on.
- [pianito](/pianito) listens to each string, compares it to the target pitch and guides the tuner toward it.