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Open source robotics hardware
branikita 
posted an update 3 days ago
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2688
Robonine (Educational Robotics) completed a structural optimization of our 6-DOF robotic manipulator after a structural optimization study. By increasing structural rigidity through topology optimization and design refinement, we reduced end-effector deflection by over 60% (from ~1.05 mm to ~0.41 mm) and improved motion stability. The final configuration delivers higher precision and reliability for industrial applications.

Article: https://robonine.com/increasing-the-structural-rigidity-of-the-manipulator/
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branikita 
posted an update 7 days ago
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1689
Our engineer Alan from https://robonine.com/ (Educational Robotics) integrated Feetech STS3250 and STS3215 servo motors into the prototype and completed the first test run of a 6-DOF semi-SCARA manipulator.

During motion, the structure demonstrates high stiffness with no visible backlash or mechanical play. The kinematic chain remains stable throughout the test trajectory, confirming the rigidity of the mechanical design and joint assembly.

The next stage includes full assembly with all actuators operating in backlash compensation mode, followed by quantitative measurement of positioning accuracy and repeatability.
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branikita 
posted an update 17 days ago
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2887
Our engineer Alan from https://robonine.com team has assembled the mechanical frame of our 6-DoF manipulator prototype - without servo motors for now. At this stage we are evaluating how easy the structure is to assemble, checking for any mechanical play, and validating the kinematics.

Good news: the structure feels solid and Alan reports no detectable backlash so far.
branikita 
posted an update 21 days ago
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Open-source parallel gripper for SO-ARM100/101 released!

We’ve published the full open-source parallel gripper design for SO-ARM100 and SO-ARM101.

Includes:
- Mechanical specs and documentation
- Step-by-step assembly guide
- Full BOM with sourcing links
- STL/CAD files for FDM printing (tested on Bambu Lab A1 mini, Prusa MINI+, ≥180×180 mm bed)

The gripper supports an interchangeable camera holder compatible with common research cameras:

- IMX335 (USB RGB, 5 MP)
- GC2093 (USB RGB, 2 MP)
- Orbbec Gemini 2 (RGB-D)
- Intel RealSense D405 (RGB-D, close-range)
- Intel RealSense D435 / D435i (RGB-D, general purpose)
- Intel RealSense D455 (RGB-D, long-range)

~30–45 min assembly, fully 3D-printable, ready to integrate with SO-ARM.

Github repo: https://github.com/roboninecom/SO-ARM100-101-Parallel-Gripper
branikita 
posted an update 26 days ago
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2050
We tested the maximum dynamic payload of the SO-ARM101 with our parallel gripper and a base servo replaced by a Feetech STS3250. The maximum load before failure was 630 g, at which point the Feetech STS3215 in joint 3 failed — its large brass output gear was completely worn down.

The Feetech STS3250 in the base with a metal gear train withstood a significantly higher load.
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branikita 
posted an update about 1 month ago
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2141
Next week, we will release full documentation for the SO ARM 101 with a parallel gripper, featuring leader and follower arms and support for widely used stereo cameras.
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branikita 
posted an update about 1 month ago
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2074
Update: Our engineer Alan has received a batch of components for the manipulator assemblies — including clamps and metal bracket parts. Prototype assembly is planned for the beginning of next year.
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branikita 
posted an update about 2 months ago
branikita 
posted an update 2 months ago
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1273
Publishing our research on dual-motor backlash compensation for STS3215 servos. To complete our arXiv submission, we need a quick endorsement from someone who has published in robotics (cs.RO/eess.SY).

If you can help, here’s the code: L64QM3
Thank you!
branikita 
posted an update 2 months ago
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3277
Proud to share the results of our engineering team’s recent work at
Robonine :

• Together, we applied advanced topology optimization to redesign critical brackets of the manipulator, achieving a 57–76% reduction in structural deflection.

• Our updated model also demonstrated a major stress decrease — from 93 MPa down to 25 MPa — all while staying within the allowed weight increase.

• Although we didn’t fully reach the target tip deviation of 0.3 mm (best achieved: 0.41 mm), the project gave us valuable insights and a solid foundation for the next design iteration.
branikita 
posted an update 2 months ago
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2135
We tested the mechanical backlash of the Feetech STS3250 servo.
Using an 86 mm lever arm, we measured a tip displacement of 0.64 mm, which corresponds to an angular backlash of approximately 0.43°.

According to the datasheet, the maximum allowable backlash is 0.5°, so our measured value of 0.43° falls within the specified limit.
branikita 
posted an update 3 months ago
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2924
In November, with
Robonine are starting work on the next version of the SO ARM 102 manipulator. The version will be open source and agreed upon with @therobotbuilder the creator of the original manipulator.

We are planning to:

- increase positioning accuracy by approximately 2x using Feetech STS 3250 motors
- increase working payload from 200g to 300g
- increase rigidity using parametric design optimization and stiffer plastic
- increase length to 550 mm
- increase folding angles
- use ISO 9409-1-50-4-M6 mounting standard for the gripper
- use a parallel gripper in the default version
- update the mounting plate for different camera types, M3 grid with 12.5 mm pitch
- add table mounting standard 80x80 M8

The number of degrees of freedom and basic kinematics will remain the same.

Are there other things missing for working with SO ARM 100?

- Any standard inputs/outputs, for example?
- Status indicators?
- Perhaps some types of mounting for third-party grippers are more preferable?
- Anything else?
branikita 
posted an update 3 months ago
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2303
FEETECH STS3250 Stall Torque and Repeatability Tests

We recently tested the FEETECH STS3250 servo, comparing actual performance with the official specifications. While the datasheet lists a stall torque of 50 kg·cm at 12 V, our real-world measurements showed:

- 25 kg·cm sustained torque after protection activation
- Up to 48 kg·cm peak torque for a split second

Although the built-in protection limits continuous stall torque, the servo demonstrated excellent stability and control precision.

Precision and Repeatability:
- Repeatability tolerance: ±0.02 mm at the end of a 95 mm arm
- Smooth motion response with PID control and 12-bit (4096-step) magnetic encoder
- Reliable performance for high-accuracy robotics and automation applications

#Feetech #STS3250 #ServoTest #Robotics #Engineering #PrecisionControl #HardwareReview
branikita 
posted an update 3 months ago
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Load test conducted on the Feetech STS3250 servo motor.

With a 2 kg load on a 100 mm arm, the motor operated near its limit. At higher acceleration settings, lifting performance decreased noticeably. The temperature increased from 40 °C to 70 °C within 8 minutes.
The test highlights the torque and thermal constraints under sustained load conditions.

#Robotics #Engineering #ServoMotor #Testing #Feetech #Automation #Mechatronics #Hardware
branikita 
posted an update 3 months ago
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At
Robonine , we applied topology optimization to enhance the stiffness and efficiency of a robotic manipulator. Using HyperMesh with the OptiStruct solver, we defined the design space where each element had a pseudo-density coefficient (0–1) controlling stiffness. This allowed the algorithm to continuously redistribute material toward regions with higher strain energy — much like how a fluid naturally flows to balance pressure.

Results:
- Aluminum bracket: displacement reduced by 0.16 mm
- Steel bracket: displacement reduced from 1.05 mm → 0.63 mm
- Steel clamp: displacement reduced by 0.14 mm
- Final structure: optimized geometry with improved load distribution and reduced deformation

This project highlights how advanced structural optimization can significantly improve performance while minimizing material usage — shaping the next generation of robotic design.
branikita 
posted an update 3 months ago
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With
Robonine team we recently verified the rotational speed of the Feetech STS3250 servo motor (12 V, 50 kg·cm torque, magnetic encoder) to compare measured performance with the official specification.

According to the datasheet:
- Rated speed: 0.133 s per 60°

Calculation:
- 0.133 s × 6 = 0.798 s per full rotation
- 1 / 0.798 = 1.253 revolutions per second
- 1.253 × 60 = 75.2 RPM

This confirms the official specification of approximately 75 RPM at 12 V under no load.

Our measurement:
- Encoder output: 5,300 values per second
- Encoder resolution: 4,096 counts per revolution

Calculation:
- Revolutions per second = 5,300 ÷ 4,096 = 1.294 rev/s
- RPM = 1.294 × 60 = 77.6 RPM

Result:
The measured value differs by only about 2–3% from the datasheet specification, confirming that the STS3250 performs very close to its rated no-load speed. This close agreement validates both the servo’s performance and our measurement approach.

Video: https://youtube.com/shorts/_O_mVZvYQlQ?feature=share

#servo #robotics #automation #motioncontrol #mechatronics #Feetech #STS3250 #engineering #datasheet #precision #hardwaretesting #roboticsengineering
branikita 
posted an update 3 months ago
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Robonine team created a HEX mesh and started analyzing our 6DOF robotic arm model's stiffness. Our goal is to achieve a maximum displacement of 0.3 mm under full load!
branikita 
posted an update 3 months ago
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We’re preparing an in-depth review of the Feetech STS-3250 servo motor — exploring its performance, features. One of the top serial bus servo for hobby robotics compatible with SO-ARM 100 manipulator.
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branikita 
updated a Space 3 months ago
branikita 
posted an update 3 months ago
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2594
With
Robonine team we released an open-source 3D-printed parallel gripper designed for robotics applications, compatible with popular budget servos like Feetech STS3215 and Waveshare ST3215.

This precision gripper offers parallel jaw movement, real-time monitoring, and positioning accuracy of ±0.1°, making it ideal for both robotics enthusiasts and professionals. Complete build cost: Just $69.45–$74.45, with all components available for purchase on Amazon. Direct links are provided in the Bill of Materials on GitHub.

Check out the project on github: https://github.com/roboninecom/3D-Printed-Parallel-Gripper-for-Robotics-Arms

We encourage you to Watch, Fork, and Star the repository to support our open-source initiative and stay updated on future developments. Your feedback is also welcome!