Kumar UtkarshRobotics · ROS 2

MechaBot, a self-docking AMR

HardwareNov 2025 – Apr 2026· Solo project

I designed MechaBot as the robot learners build in AMR Mastery, so every part of it had to be explainable. It maps, localises, patrols and docks itself on real hardware: Nav2 gets it close, a QR marker aligns it, and LiDAR tells it when to stop.

What it does

  • Maps a room with slam_toolbox and localises with AMCL.
  • Navigates and patrols waypoints with Nav2.
  • Watches its battery, cancels navigation when it runs low, and returns to the dock.
  • Finds the dock with a camera and a QR marker, and stops on LiDAR about 15 cm away.
  • Docks and undocks on real hardware.

How it is built

Hardware
Two-wheel differential drive, encoder DC gear motors, L298N driver, Raspberry Pi, ESP32, RPLiDAR, MPU6050 IMU, ultrasonic sensor, camera, 16×2 LCD, 3D-printed chassis designed in Fusion 360.
Firmware
ESP32 with a PID loop per wheel and interrupt-driven quadrature encoders.
ROS 2
A custom C++ ros2_control hardware interface (real and Gazebo), diff-drive controller, twist_mux, joystick teleoperation.
Navigation
Nav2 with the Smac 2D planner, Regulated Pure Pursuit, layered costmaps and a custom behaviour tree; a multi-threaded executor for docking.
Tooling
Gazebo worlds including a QR maze built in Blender; Docker packaging.
MechaBot CAD model
The CAD model
MechaBot chassis with LiDAR and Raspberry Pi during assembly
Coming together, Apr 2026
Inside MechaBot: Raspberry Pi, LiDAR and wiring
Inside the robot

The hard part

Docking. Nav2 alone gets the robot near the dock but not reliably onto it, so docking runs in stages: Nav2 drives to a pre-dock pose, a proportional controller aligns on the QR marker from the camera, and the LiDAR decides when to stop.

I didn't sit down and "learn SLAM" as a subject one weekend. I learned exactly the SLAM I needed the day my robot couldn't reliably find its way back to its charging dock.From my post on the MechaMind Labs blog

Status and limits

  • Docking and undocking work on real hardware and succeed most of the time. I haven't published a measured success rate.
  • The battery publisher that triggers return-to-dock is not in the public repository.

Learners who rebuilt it

Naman Arora built the full autonomy stack in simulation; Dipanjan Bakshi and Dhrutidhara Behera built their own physical versions. Their posts are on the home page.

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