Petar Crnjak's PAROL6 Is an Industrial
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Petar Crnjak's PAROL6 Is an Industrial

Jun 20, 2023

Roboticist Petar Crnjak is hoping to bring industrial-style robot arms to a wider audience with an open source 3D-printable six-axis design dubbed the PAROL6 — offering support for an impressive 2.2lbs payload.

"PAROL6 is a high-performance 3D-printed desktop robotic arm," Crnjak explains of his creation. "The design approach of PAROL6 was to be similar to industrial robots in terms of mechanical design, control software, and usability. Control software, GUI [Graphical User Interface], and [the] robot's STL files are open source."

The robot's design is an evolution of earlier work by Crnjak, including on a three-axis design and a smaller six-axis variant. PAROL6, though, is considerably more powerful: according to Crnjak's specifications, the STMicro STM32F446-driven arm when built as-described can handle a 1kg (around 2.2lbs) payload capacity, reach 400mm (around 15.7") with its standard gripper, and offers a 0.08mm (around 0.003") repeatability from its stepper motors and precision planetary gearboxes.

Other features of the robot arm include the choice of open- or closed-loop control using limit switches and stepper drivers or magnetic encoders respectively, two each of isolated inputs and outputs, two CAN buses, two pneumatic connectors, and USB connectivity to a controlling PC — where it can be driven from Crnjak's own PAROL6 Commander software, via an application programming interface (API) from Python, C++, or MATLAB, or using the Robot Operating System (ROS).

"[The] PAROL6 control board has multiple ways to interact with outside world," Crnjak adds. "Communication with high level code running on a PC is done with USB, but on top of that you can use other features like I/O [Input/Output pins] or CAN to communicate. [The] CAN bus will allow you to control external grippers and additional axes."

More information on the PAROL6 is available in the project documentation, with source code, design files, and STL files for 3D printing available on the PAROL6 GitHub repository under the reciprocal GNU General Public License 3 — though published with the warning that the project is "still a work in progress and is being constantly updated," with weekly changes to be expected.