---
title: "SD-04 | UC-04: Detect Side Obstacles"
---
sequenceDiagram
    actor OS as Obstacle Sensor (HW)
    participant LS as left:ObstacleSensor
    participant CTR as :Controller

    OS->>LS: detect()
    activate LS
    LS->>CTR: reportObstacle(LEFT)
    activate CTR
    CTR-->>LS: ack()
    deactivate CTR
    deactivate LS
