Smartphone Machine Remote Control

The problem. On fogging and spraying equipment, non-crane machines and vehicle-mounted equipment, the operator wants to stay away from the machine (chemicals, noise, visibility). Classic RF remotes are limited by channel count, one-way and have no display; they get lost, their batteries run out, and every machine needs its own transmitter. The mobile-app approach brings app-store processes, phone-model and cloud dependencies; above all, if the safety logic is left to the phone, the machine can keep running when the connection drops.

The solution. An ESP32 control unit is fitted to the machine; it opens its own access point (and can also join the existing plant network) and serves the interface to the phone as a captive-portal page. The interface talks to the unit over WebSocket; the unit passes the relay mask to the STM32 safety relay board over a 115200-baud UART. Momentary commands such as direction and start are active only while a finger is on the screen and fall back to a safe state through three separate timeouts (phone 800 ms, connection, daughterboard 500 ms). Start works only with the ignition on, for at most 5 s and once per ignition cycle; opposite directions are never energized together; the chemical pump runs only with the ignition on. Operating hours and the serial number are stored in the unit.