01 Overview

Otto is an open-source bipedal robot platform capable of walking, dancing, and obstacle avoidance.

This project uses an ESP32-series MCU as the main controller, with servo drivers for motion control.

Wi-Fi or Bluetooth connects to XiaoZhi AI / Tuya AI for voice interaction and remote control.

The board provides four servo channels for 180° servos like SG90, making it suitable for education, makers, and AI interaction prototypes.

This is not a general-purpose dev board but a dedicated controller optimized for the Otto robot, with tightly coupled hardware and firmware.

02 Hardware

Main MCU: ESP32 series (exact module per schematic, typically ESP32-WROOM-32).

Power: 5 V for servos, 3.3 V logic, USB or battery input.

Servo outputs: 4 PWM channels for 180° servos such as SG90.

Sensors: optional HC-SR04 ultrasonic module for obstacle avoidance.

Other: buttons, status LEDs, UART debug header.

Power management: watch servo stall current; the 5 V rail needs sufficient headroom, consider separate supply or bulk capacitors.

Layout: servo headers near board edge for wiring; ultrasonic header position per schematic.

03 Software flow

Flash the matching firmware over USB, targeting the ESP32 on the schematic. Confirm serial logs before applying 5 V to the servos.

At boot, four PWM channels follow an action table for walk, dance, and similar sequences — change gait by editing the table first.

If ultrasonic range drops below the threshold, interrupt the current sequence and switch to obstacle avoidance; do not fork a second servo driver.

Wi-Fi or Bluetooth to XiaoZhi / Tuya maps voice commands onto that same action table.

During bring-up, test each servo angle individually before combining sequences to avoid mechanical conflicts.

Firmware updates via OTA or UART, see schematic and accompanying docs.

04 Core points

Motion core: servo PWM generation and action sequence management.

Servo PWM frequency and pulse width must match SG90; different servos have different specs, so do not copy settings across chips.

The action table is the core data structure; modify gait by editing the table, not rewriting the driver.

Obstacle avoidance should be an extension of the action table, not a separate system, to keep code unified.

Power stability: servo stalling can drop the rail and reset the ESP32; pay attention to supply design.