Lab 8 — Payload Servo + ThingsBoard Mission Dispatch

Duration90 minutes

Depends onLab 7

MilestoneDashboard sends mission → car executes → payload release

StatusOutline — to be written

Practical focus

Add a simple servo release mechanism; connect the car to ThingsBoard; report vehicle state; receive pickup and destination; implement mission states.

Infrastructure to arrange before this session

TODO — instructor, all of these block the lab if unresolved:

• ThingsBoard instance — hosted at thingsboard.cloud or self-hosted? URL?
• Device provisioning: one device per car, with access tokens issued in advance.
• Campus WiFi. ESP32 WiFi commonly cannot join enterprise WPA2-Enterprise networks (eduroam-style) without extra configuration. Test this on the actual network before the session, or provide a dedicated AP.

Objectives

1. Drive a servo to release a payload at a commanded moment.
2. Connect the ESP32 to WiFi and to a ThingsBoard instance.
3. Publish vehicle telemetry (state, position, battery, sensor readings).
4. Subscribe to mission commands containing pickup and destination.
5. Implement the mission as an explicit state machine.

Procedure outline

TODO — expand.

1. Mount and test the servo standalone. Find the open and closed angles.
2. Connect to WiFi. Confirm with a printed IP address.
3. Publish one telemetry key and watch it appear on the dashboard.
4. Receive one RPC command and act on it.

5. Build the state machine:

   IDLE ──► MISSION_RECEIVED ──► DRIVING_TO_PICKUP ──► AT_PICKUP
                                                          │
                   ┌──────────────────────────────────────┘
                   ▼
         DRIVING_TO_DESTINATION ──► AT_DESTINATION ──► RELEASING ──► IDLE
   

Make the state visible

Publish the current state name as telemetry and show it on the dashboard. When a car misbehaves in Lab 9, the state readout is how you find out why without stopping it.

Servo current on a shared rail

A stalled servo draws far more than its idle current and can brown out the ESP32 mid-mission. Confirm the servo is powered from the battery rail, not the ESP32's regulator.

Deliverable

Dashboard sends mission → car executes → payload release.