LinuxCNC Gantry Robot System

A large high-precision 3-axis gantry robot system using LinuxCNC, integrated with Mesa Electronics interface cards and igus® dryve D1 motor controllers.

The system was developed from our LinuxCNC motor control testbed, which ensured the main components of the system were able to work reliably.

The repository includes a custom calibration solution that leverages an existing OptiTrack motion capture system in the installation room to measure and compensate for errors in the gantry movement. Using this solution the gantry robot can achieve sub-centimeter precision across the entire work envelope.

Key Features

• 3-Axis Control: X, Y, Z linear axes.
• Large Work Envelope: 5.3m (X) × 5.2m (Y) × 1m (Z) working volume.
• Real-time Coordination: Precise real-time motion using LinuxCNC with MESA interface cards and igus® dryve D1 motor controllers.
• Closed Loop Control: High-precision encoder feedback for accurate positioning using closed loop control.
• Visual Status Indicators: Custom LED status indicators.
• Positioning calibration: Software to analyze OptiTrack measurements and custom LinuxCNC kinematics module for compensation of positioning errors.
• Heavy Duty: Built with igus® self-lubricating linear units enabling lifelong operation of the moving parts without external lubrication.

Documentation

The following documentation is provided in this repository:

• Technical Documentation: Sphinx documentation sources of the system documentation in docs/. The documentation has been prepared to be built in HTML and PDF formats. To build the documentation follow the instructions below:

  1. Prepare the environment:

     cd docs
     uv venv && uv sync && source .venv/bin/activate

  2. Build the documentation:

     • HTML: make html

       The HTML documentation index file will be saved in docs/build/html/index.html.

     • PDF (requires a LaTeX installation with LuaLaTeX): make latexpdf

       The PDF file will be saved in docs/build/latex/linuxcnc_gantry_robot.pdf.

• Electrical Installation: KiCAD electrical schematics in electrical_installation/schematics/.

Positioning calibration

The gantry robot can be calibrated to compensate for positioning errors using an existing OptiTrack motion capture system in the installation room. For this, the repository provides the following software:

• Custom calibxyzkins LinuxCNC Kinematics Module in linuxcnc/components/linuxcnc_calibrated_xyz_kins/: compensates for the positioning errors in real-time
• Calibration Analysis Software in calibration/: Python scripts for processing the OptiTrack data and generating the calibration parameters

Hardware Components

Component	Model	Quantity	Function
Control Computer	PC running LinuxCNC	1	Real-time motor coordination
Motor Controllers	igus® dryve D1	4	Individual motor control
Main Interface	MESA 7I96S	1	Ethernet-LinuxCNC bridge and stepper motor control
I/O Expansion	MESA 7I77	1	Analog control for brushless motors and I/O signals
X-Axis Motor	igus® MOT-EC-86-C-I-A	2	NEMA 34 brushless with 1000 PPR encoder
Y-Axis Motor	igus® MOT-EC-86-C-I-A	1	NEMA 34 brushless with 1000 PPR encoder
Z-Axis Motor	igus® MOT-AN-S-060-035-060-M-C-AAAC	1	NEMA 24 stepper with 500 PPR encoder
Emergency Stop	Push-button with NO/NC contacts	1	System safety shutdown
Limit Switches	igus® proximity switch	4	Position boundary detection
48V Power Supply	MEAN WELL SDR-960-48	3	Brushles motors power
24V Power Supply	MEAN WELL SDR-240-24	1	Stepper motor power
24V Power Supply	Generic power supply	1	igus® Drive D1 logic and MESA 7I77 field power
5V Power Supply	MEAN WELL MDR-20-5	1	MESA 7I77 field I/O logic power

System Architecture

Repository Structure

gantry-robot/
├── README.md                    # This file
├── assets/                      # Pictures and videos
├── docs/                        # Technical documentation
├── igus-dryve/                  # igus® dryve D1 configuration files
├── linuxcnc/                    # LinuxCNC configuration files
│   ├── configs/                 # Machine configurations
│   └── components/              # Custom LinuxCNC components
├── calibration/                 # Calibration code and measurements
│   ├── src/                     # Python analysis and calibration tools
│   └── measurements/            # Gantry robot and OptiTrack measurements
└── electrical_installation/     # Electrical documentation
    ├── schematics/              # KiCAD electrical diagrams
    └── photos/                  # Electrical installation photos

License

This project contains multiple components with different licenses.

General License (unless otherwise specified)

LinuxCNC Gantry Robot System © 2025 by Tomás Domínguez Bolaño, Valentín Barral Vales, Carlos José Escudero Cascón, and José Antonio García Naya (CITIC Research Center, University of A Coruña, Spain) is licensed under Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0). To view a copy of this license, see the LICENSE file or visit https://creativecommons.org/licenses/by-sa/4.0/.

Documentation License (docs/)

Copyright © 2000-2022 LinuxCNC.org
Copyright © 2025 Tomás Domínguez Bolaño, Valentín Barral Vales, Carlos José Escudero Cascón, and José Antonio García Naya.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

Software Licenses

• LinuxCNC Components (linuxcnc/components/): GPL v2 or later
• Calibration Source Code (calibration/src/): MIT License

Acknowledgments

This work has been supported by grant PID2022-137099NB-C42 (MADDIE) and by project TED2021-130240B-I00 (IVRY) funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR.