2.4 The PEAS Framework (BT104CO)
1. What is PEAS?
In the framework of Russell and Norvig, PEAS is the first step in designing any AI. Before writing code, you must specify the task environment using these four headings.
Performance
The objective criteria for success. What the agent is trying to maximize (the "goal" or "reward").
Environment
The external world or setting where the agent operates (roads, patient, image database).
Actuators
The "tools" the agent uses to perform actions and change its environment (steering, display, tags).
Sensors
The inputs the agent uses to perceive the environment and gather data (cameras, keyboard, LIDAR).
2. PEAS Examples (Case Studies)
To master PEAS for an exam, you should be able to break down any AI system into these four categories.
Case A: Automated Taxi Driver
| Category | Description |
|---|---|
| Performance | Safety, speed, legal driving, passenger comfort, profit. |
| Environment | Roads, other traffic, pedestrians, weather, customers. |
| Actuators | Steering wheel, accelerator, brake, signal, horn, display. |
| Sensors | Cameras, LIDAR, GPS, speedometer, engine sensors. |
Case B: Medical Diagnosis System
| Category | Description |
|---|---|
| Performance | Healthy patient, minimized costs, avoiding malpractice. |
| Environment | Patient, hospital staff, medical database. |
| Actuators | Display of questions, tests, diagnoses, treatments. |
| Sensors | Keyboard/Touchscreen (symptoms, lab results, history). |
Case C: Satellite Image Analysis
| Category | Description |
|---|---|
| Performance | Categorization accuracy, speed, minimized false positives. |
| Environment | Downlink from satellite, image database, weather. |
| Actuators | Tagging images, sending alerts, re-ordering database. |
| Sensors | High-resolution cameras, infrared sensors. |
3. The Relationship Between PEAS and Rationality
A Rational Agent is defined relative to its PEAS. An action is rational if it follows this logic: