Autonomous Garden Management System

## Project Story

The Autonomous Garden Management System, or GMS, is my in-progress autonomous garden maintenance rover. The goal is to build a practical low-cost outdoor robot that can mow, water plants, aim a hose, and eventually support modular garden tools.

## Current Progress

The project is currently in progress.

Completed or mostly complete:

• Drivetrain mechanical build
• Front mower module
• Rope-based mower lift mechanism
• FOC mower motor controller wiring
• Front section of the robot
• Worm-gear rotating turret base for the first hose turret degree of freedom

In progress:

• Rear section of the robot
• 2-DOF hose turret
• Second hose turret axis for up/down hose angle
• Base-station hose attachment interface
• ESP32-P4 high-level control software
• STM32 F103 low-level control firmware
• Control box layout
• Wiring documentation
• Test procedures

Planned:

• Autonomous hose attach/detach at the base station
• Plant-targeted watering
• Controlled liquid application module, tested with water first
• Outdoor navigation and obstacle handling
• Field test logs
• Final BOM and cost documentation

## High-Level System Structure

GMS uses a distributed microcontroller architecture:

• ESP32-P4: high-level controller for autonomy logic, subsystem coordination, docking behavior, and overall robot behavior.
• 2x STM32 F103 Blue Pill boards: low-level controllers for timing-sensitive tasks such as encoder reading, motor PWM, BTS7960 control, and sensor I/O.
• BNO085 IMU: orientation and motion sensing.
• Low-cost ODrive-style FOC controller: BLDC mower motor control.
• 36V battery system: main robot power bus, with lower-voltage regulation for logic electronics.

The control split is designed so the ESP32-P4 can make high-level decisions while the STM32 boards handle real-time motor and sensor work.

## Mechanical Design

The chassis is built from around 16 feet of aluminum channel from Lowe's. I chose aluminum channel because it is inexpensive, easy to cut and modify, and strong enough for an early outdoor robot frame.

The robot is split into two main physical areas:

• Front section: drivetrain, mower module, mower lift, battery placement, and mower electronics.
• Rear section: hose turret, base-station hose interface, and future modular garden tooling.

The front section is mostly complete. The rear section is currently being developed around the hose turret and docking system.

## CAD Organization

The CAD folder is organized by subsystem so each part of the robot can be developed separately:

• Turret system: rotating hose turret and worm-drive base.
• Mower subsystem: mower mechanism, blade mounting, protection, lift parts, and frame interfaces.
• Drivetrain: wheel, motor, axle, gearbox, and drive mounting parts.
• Outer frame: chassis pieces, brackets, mounting rails, and exterior support parts.
• Electronics holder: trays and mounts for electronics, wiring, sensors, and power distribution.
• ODrive holder: mount for the mower motor FOC controller.
• Computer holder: mount for the ESP32-P4/high-level control hardware.
• Full robot: top-level assembly combining the complete rover.

## Mower System

The mower module uses a C6374-class BLDC motor on a 36V system. The mower motor is controlled by a low-cost ODrive-style FOC controller. The hardware has high peak capability, but normal cutting should be much lower than the peak rating.

The mower lift uses a custom rope-based mechanism. The goal is to raise and lower the mower without needing a heavy linear actuator or expensive mechanical stage. The mechanism is built, but it still needs repeated load testing, repeatability checks, and safety validation.

## Drivetrain

The drivetrain uses DS3240 servos repurposed as low-cost drive motors. The mechanical drivetrain is built, and the next step is low-level control using the STM32 F103 boards for encoder reading, PWM, motor driver control, and sensor input.

## Hose Turret and Watering

The rear turret is planned as a 2-DOF hose aiming module. Phase 1 is the worm-gear rotating base for the first degree of freedom. The second degree of freedom will raise and lower the hose angle.

The longer-term plan is for the robot to park at a base station, attach or detach a hose, and aim water toward plants. A small pump or container module may also be added later for controlled liquid application. Any liquid testing will start with water.

## Roadmap

Phase 1: Mechanical platform

• Build aluminum-channel chassis
• Complete drivetrain mechanical assembly
• Complete front mower module
• Complete rope-based mower lift mechanism
• Mount major front-section hardware

Phase 2: Low-level control

• Wire drivetrain encoders
• Test STM32 F103 encoder reading
• Test BTS7960 motor control
• Send low-level motor and sensor data to the ESP32-P4
• Validate drivetrain movement feedback

Phase 3: Mower control

• Test C6374-class BLDC mower motor control
• Validate ODrive-style FOC controller behavior
• Add safe enable and disable logic
• Add emergency cutoff behavior
• Test mower lift control under load

Phase 4: Rear hose turret

• Complete worm-gear rotating base
• Test first turret degree of freedom
• Build second hose elevation axis
• Add hose mount
• Add base-station hose interface

Phase 5: Base station and watering

• Build hose docking station
• Add controlled water flow
• Add docking alignment sensors or guides
• Test autonomous hose attach/detach behavior
• Test hose pointing repeatability

Phase 6: Autonomous operation

• Add navigation sensors as needed
• Add basic path following
• Add obstacle detection and stop behavior
• Add docking behavior
• Add plant-targeted watering behavior

Phase 7: Field testing

• Test on flat ground
• Test on grass
• Test slope handling
• Test mower height repeatability
• Test watering turret aiming
• Measure runtime, reliability, and thermal behavior

## Safety Notes

This project includes a 36V electrical system, high-current motor controllers, drive motors, rotating mower hardware, and liquid handling. I treat every subsystem as experimental until it has been tested safely.

My safety plan includes:

• Testing drivetrain behavior with the mower disabled first.
• Keeping people and pets away during powered tests.
• Using fuses, a main disconnect, and emergency shutoff behavior.
• Keeping high-current wiring separated from logic wiring where practical.
• Testing liquid systems with water first.
• Logging failures and updating the design before increasing speed or power.

## What I Want To Improve Next

The next major work is to finish the rear section, continue wiring cleanup, bring up the ESP32-P4 and two STM32 F103 control layers, and test the drivetrain feedback loop. After that, I want to validate the mower lift under load, test the first hose turret axis, and keep documenting the CAD and BOM as the design changes.