A 3D-printed carbon fiber robotic arm

It all began with LEGO. Development engineer Radu Florin Burcea always wanted to build things. Especially robots. And so, he built one for his master thesis: a robotic arm for automated testing of electronics.

A 3D-printed carbon fibre robotic arm – made by Radu
Hands holding tablet on blurred automation machine as background

We’re welcoming Radu Florin Burcea, new development engineer at Data Respons R&D Services. His master thesis project is rather spectacular and although he graduated a year ago it is well worth presenting. Not least because it illustrates the challenges of embedded technology: Making hardware and software work seamlessly together, taking into consideration the restraints of the physical world, and merging materials, mechanics, and algorithms.

Robotics engineer from UiO

Radu graduated as a robotics engineer from the University of Oslo in 2020. All the way through his studies he chose to focus on robots, in theory as well as in practise.
However, the practical side of robotics turned out to be difficult. Because even when you’re studying Robotics and Intelligent Systems at university that doesn’t necessarily mean you’ll get to work with real robots and get hands-on experience building them. In fact, initially Radu was a bit disappointed by the lack of opportunities to actually build robots as part of his education. Most of the robotics courses at university were entirely theoretical.
Still, he wouldn’t give up on his plan to learn as much as possible about constructing robots, and not only the software and programming part of that effort, but getting to know the strengths and limitations of actual materials, and components like servomotors, grippers etc.

3D revelation

He even experienced a kind of revelation, when he decided taking a university course in 3D modelling and rapid prototyping.
– I liked it so much I worked 10 hours a day. I realized I could build what I wanted. I just had to design it and upload it to the 3D printer. At university they had this very expensive Markforged 3D printer that could print stuff in carbon fibre composite material. You have continuous lines of carbon fibre in the print, and with that material you can print components, which are much better than aluminium. Unlike aluminium, when it bends under stress it just bends back into shape again.

Master thesis

Radu decided to focus his master thesis on customizing an off-the-shelf robotic arm to make it stronger and more precise.
– I was inspired by a company that builds robots for NASA. They are using this composite instead of aluminium and they’ve redesigned their robots, for instance reducing the number of parts by 91%.
– I wanted to try to push the boundaries of low-cost robotic arms, and make them cheaper, lighter, and stronger, Radu says, and he found the perfect use case at the electronics company he was working for as a student assistant.
– They needed to test a chip to see if the software downloaded on it was working correctly. It was dull and time-consuming work. You had to take the chip, put it in a test unit, close the lid, wait for a few minutes for the test to be completed, open the test unit, remove the chip, and start again. A few seconds of work and a lot of waiting. I wanted to have a robot do it instead of a human.

Parts from CrustCrawler

As a starting point he decided to use off-the-shelf robotic arm parts from the manufacturer CrustCrawler.
– In my opinion it was not very good quality. It was a bit shaky, not especially precise, and made of cheap aluminium that would bend under stress.
Radu chose to redesign the links of the robot and 3D print them using carbon fibre.
– I must admit that my instructor wanted me to focus on programming the robot. He wanted me to use a special algorithm called Inverse Dynamics Control which calculate the exact amount of power needed to perform a specific motion, based on inertia, acceleration, speed and gravity. That was OK, and I did that. But I also wanted to exploit the potential of the Markforged printer and this material. And so I did, and I managed to redesign parts of the robotic arm to make it stronger and more precise than the original. At the same time, I was able to reduce its weight by 50 per cent and its price by 60 per cent.

If you want to see Radu’s robot at work, please take a look at this short video showing it performing the PCB test mentioned earlier.

Hardware based engineering

Radu’s interest in hardware has now led him to work as a development engineer for Data Respons.
– I chose Data Respons because it allows me to focus on hardware based engineering and embedded systems. Here we work directly on the hardware, and that is what I want to learn about. I want to learn as much as possible about low-level interaction with the hardware.
– When I did my thesis, I realized that I couldn’t control it the way I wanted. The software was high level, so I couldn’t program the robot the way I wanted due to lack of tweaking flexibility of the motion planning framework used. I realized I had to learn to write my own software from scratch to make it work properly. So, I needed to learn how to do that.

The dream is alive

Learning the software is part of Radu Florin Burcea’s great plan for the future. Sometime in the future he wants to build his own robot.
– My biggest dream is to have my own robot company. I’m not talking about expensive industrial robots, but low-cost robots that would make life easier for normal people, in their homes, to automate cleaning or cooking for instance. Currently you can buy small hobby robots online. I want to take that approach a step further and design cheap but strong robots that are good at performing advanced tasks. To keep the price down you could 3D print some of their parts yourself, maybe in carbon fibre composite. But the most important part of that plan is learning to create my own software so I can easily make changes to improve the robot and have better control over what it does. To program such a robot properly requires a lot of knowledge.
However, Radu’s first assignment for Data Respons is developing world class video conferencing systems at Cisco.