Summary of HACKADAY PRIZE 2023: PAROL6 – A GPL DESKTOP ROBOTIC ARM
Parol 6 is a 3D-printed six-axis robot arm by Petar Crnjak that uses NEMA17 stepper motors, metal planetary gearboxes (10:1 and 20:1), belt drives on multiple axes, and a pneumatic gripper. A custom STM32F446-based controller PCB with TMC2209 stepper driver modules and RS485 transceivers handles motion; software uses Arduino with STM32 HAL and AccelStepper. The project shows good repeatability, work-in-progress KiCad files, gerbers, and a BOM, and has an active community on Discord.
Parts used in the Parol 6:
- 3D-printed structural parts (robot arm components)
- Pneumatic gripper
- NEMA17 stepper motors
- Metal planetary gearboxes (20:1)
- Metal planetary gearboxes (10:1)
- Belt drives (used on four axes)
- Inductive sensors
- Mechanical microswitches
- Custom controller PCB based on STM32F446 microcontroller
- Modular stepper driver boards using Trinamic TMC2209
- RS485 driver chips
- Power supply and wiring (implied by electronics and motors)
- Gerber files and Bill of Materials (documentation artifacts)
Parol 6 is a 3D-printed six-axis robot arm created by [Petar Crnjak] as a combination of the principles from a few previous projects. Aside from a pneumatic gripper, each axis is driven by a stepper motor, with at least a few of these axes being driven through a metal planetary gearbox for extra precision and torque.
From what we can glean from the work-in-progress documentation, there are some belt drives on four of the relevant axes and a mix of NEMA17 format steppers driving either 20:1 or 10:1 reduction boxes. There appears to be a mix of inductive sensors and traditional microswitches used, but it’s not so easy to work out where these are placed.
The controller PCB is a custom design based around the STM32F446 microcontroller, with modular drop-in boards for driving the motors, using the Trinamic TMC2209 for super smooth and quiet motion. The KiCAD project seems to be missing at the moment, with only gerbers and BoM for reference, but we expect that to appear at some point. There are some RS485 drivers on there, which is a sensible addition to providing an isolated interface if correctly implemented. There isn’t much detail on the electronics yet, but it all looks pretty standard fayre. The software stack looks like Arduino with a smattering of STM324xx HAL being used directly. The standard AccelStepper library is used, which is a good choice as it’s quite mature.
From the video logs in the project page, the robot looks complete, with some pretty good repeatability numbers, but we would like to see some data on absolute positioning accuracy as well, that said it’s a great project with an active Discord behind it, so let’s see how this develops.
Source: HACKADAY PRIZE 2023: PAROL6 – A GPL DESKTOP ROBOTIC ARM
- What type of motors drive Parol 6?
Parol 6 uses NEMA17 stepper motors to drive each axis. - Does Parol 6 use gear reduction?
Yes, some axes use metal planetary gearboxes with 20:1 or 10:1 reduction. - Are any belt drives used in the robot?
Yes, belt drives are used on four of the relevant axes. - What kind of gripper does the robot use?
The robot uses a pneumatic gripper. - What microcontroller is the custom controller PCB based on?
The controller PCB is based on the STM32F446 microcontroller. - Which stepper driver chips are used for quiet motion?
The modular driver boards use Trinamic TMC2209 chips. - Is there any communication interface on the controller board?
Yes, the board includes RS485 drivers for an isolated interface. - What software stack is used to control Parol 6?
The software uses Arduino with some direct STM32 HAL code and the AccelStepper library. - Are the KiCad files for the controller available?
No, the KiCad project is missing at the moment; only gerbers and a BOM are provided. - How does the robot perform in terms of repeatability?
The project video logs report pretty good repeatability numbers, though absolute positioning accuracy data is not provided.
