Pebble

A home robot that maps the space with LiDAR and senses what happens around it through radar and ranging instead of cameras. I built the first complete robot alone in four months, then formed the team that builds its software.

What Pebble is

Pebble is a small autonomous robot that lives in a home. It maps the space with LiDAR, drives itself and senses what is happening around it without cameras or wearables. It uses mmWave radar, time-of-flight and ultrasonic ranging, plus a “Hey Pebble” voice interface. For people who are deaf or hard of hearing, it signals with light and vibration.

What I built

I built the first complete robot on my own in four months: the 3D-printed chassis and drivetrain, the motor-control electronics, a custom PCB and the sensor suite. Then I brought together a five-person team for mapping, voice, cloud and sensor data. I still own the hardware and every robot build.

• Drivetrain: two GM25-370CA DC gear motors with Hall-effect quadrature encoders, controlled by an ESP32.
• Power: a custom PCB with a dedicated motor supply rail and a separately regulated 3.3 V logic rail.
• Sensing: a VL53L0X time-of-flight sensor and two ultrasonic sensors for near-field ranging, a microphone and IMU, and a Raspberry Pi with LiDAR for mapping.

Key decisions

• One motor driver per wheel. On the bench, a single shared DRV8871 current-limited both motors under load. Giving each motor its own driver fixed it.

Where it is now

Five units are in build for a pilot study.