Motivation: Rethinking Autonomous Ag-Bots

I needed a small implement carrier for agricultural use—a vehicle that demands high torque, steady ultra-low speeds (< 1m/s), and excellent off-road capability. But there's a catch: it must be battery-powered and affordable enough for makers in developing countries to replicate.

The "No-GPS" Philosophy

I intentionally avoided GPS. Why? Because true autonomy shouldn't depend on third-party satellite infrastructure. I want a machine that works anywhere, independently.

The Prototype: A Fusion of Leftovers and Innovation

This 1:2 scale prototype was born from parts I had on hand, resulting in a somewhat "unusual" build. The primary goal was to test a concept often dismissed in EV design: Using stepper motors for traction. By equipping them with Field Oriented Control (FOC) drivers, I aimed to turn high-pole-count motors into high-torque, precise drive units.

Early Success & Evolution

The initial tests were surprisingly positive. This encouraged me to expand the scope:

Drive System: Testing FOC-stepper performance in the field.

Navigation: Implementing a "Wall-Follower" logic using 8 ultrasonic sensors to navigate obstacles and corners without GPS.

Mechanical Innovation: Evaluating a Rocker-Differential-Suspension. I believe this system will allow even small wheels to tackle tough off-road terrain.

Note: Due to weather conditions, extensive field testing is still ongoing. Documentation of the suspension's off-road performance will follow soon.

🔹 System Overview

This project is an experimental autonomous off-road carrier designed for operation on agricultural terrain such as fields, meadows, and farmland.

Key characteristics:

  • Stepper motors integrated directly into the wheel hubs

  • Field-oriented control (FOC) for high torque at very low speed

  • Dual-MCU architecture

    • Motion MCU: real-time motor control

    • Control MCU: high-level behavior, planning, and sensors

  • Rocker-differencing kinematic suspension for terrain adaptation

  • Four-wheel steering using high-torque MGR946R servo motors

  • Open-source firmware (GPLv3)

The goal is not maximum speed, but reliable, controllable motion with high torque in rough terrain.