on November 27th, 2020

Hendrik van Heerden is a skilled Mobile Crane Specialist and is also currently studying EIT’s Bachelor of Science (Mechanical Engineering) through our online delivery mode. For his final year project, Hendrik literally got ‘hands-on’ with his endeavors. Inspired by the intertwining of the biomedical and mechanical engineering fields, he has created a 3D printed prosthetic arm that can be controlled via an electronic glove.

Hendrik Van Heerden and his 3D printed robotic arm
Hendrik and his 3D printed robotic arm project

Considering his career trajectory, a biomedical engineering project was perhaps the last thing anyone expected Hendrik to select. He proved, however, that bringing together two seemingly disparate disciplines can attain one of engineering’s primary goals: the betterment of human beings.

Hendrik’s career began in 2006 when he qualified as an electrician upon completing his trade test at the Department of Labour in South Africa.

Soon afterward he was employed by Sandvik (SMC) at Finsch Diamond Mine. His duties were to maintain, repair, and diagnose failures in the electrical components of Sandvik’s mining machinery.

In July 2008, Murray & Roberts Cementation employed Hendrik. The company is a market leader in shaft sinking, tunneling, raise drilling, engineering, design and contract mining. He worked in their Wessels Mine as an Artisan Electrician. In 2009, he qualified as an Automotive Electrician.

In September 2010, he began working as an expat outside of South Africa as a Drill Rig Electrician. He was employed by Barrick Gold Corporation, at the Bulyanhulu Mine in Tanzania. By 2012 he had joined the First Quantum Minerals PLC Group, at the Kansanshi Open Pit Copper Mine in Zambia, as a Mobile Crane Specialist. He has been working in that role for the last eight years. There are very few specialists in this field in the country, which renders Hendrik unique and in demand.

The transition to EIT

In 2014, he was looking to further develop his knowledge and continue sharpening his engineering skills. His search led to EIT where he was able to work alongside his study; he enrolled in the online 52810WA Advanced Diploma of Mechanical Engineering Technology.

“My studies through EIT fulfilled my needs and worked very well for me. For practitioners like us working between 11 to 12 hours per day, the studies enable me to continue my full-time work and study after hours,” Hendrik explained.

He successfully completed the Advanced Diploma and in 2016 and re-enrolled, this time into the online Bachelor of Science (Mechanical Engineering) – with credit from his previous studies. This year is Hendrik’s last year before he graduates from the degree; his capstone project is one of the final hurdles before he completes his current studies.

This culminating experience of the students’ engineering program is to provide them with an opportunity to work individually, in a situation similar to one that may be found in an industrial or commercial environment.

An ode to prosthetic technological development

Hendrik’s capstone project began by highlighting how two disciplines of engineering could come together for the betterment of human beings. Hendrik pointed out that engineers, along with doctors, have been trying to improve disabled people’s lives for centuries. He set out to prove that he could take what he had learned in his career and apply it to making his own prosthetic.

“I wanted to do something unique. Bio-robotics is something I am very interested in, I wanted to challenge myself with it. I found the robotic field when integrated with the medical field was interesting and came up with the idea,” Hendrik explained. He said that a range of different prosthesis technologies have been tried, ranging from the older body-powered prosthetic, to one powered electronically, to the brain-powered prosthesis.

“We all know how to hold a pen, or a piece of paper. However, what if a simple task like putting on your trainers is not so simple anymore?” Hendrik asked.

He worked to consolidate all his accumulated mechanical and electrical engineering knowledge and skills, bringing them to his capstone project: a 3D printed prosthetic arm and hand, controlled by an electronic glove.

Individual components were sketched and then 3D printed. They were then connected with metal rods and an elastic cord. Hendrik 3D printed 57 individual components utilizing white 1.75mm PLA filament. Over a period of 3 weeks (or 504 hours) of non-stop printing, he produced enough components to assemble the arm. He used 2 and a half roles (a total length of 630 meters) of PLA filament to print all of the components at a hundred percent infill.

Hendrik says he is fascinated by how advanced the prosthetics industry is becoming. He says that robotic arms are now being hooked up to humans’ nervous systems utilizing electro arrays that enable sensor feedback from the prosthesis to the human’s brain – effectively returning the sense of touch to someone fitted with a prosthetic device.

Hendrik, in his final presentation of his 3D printed prosthetic arm, pointed out that the index, middle, ring, and little finger each have four degrees of freedom. The degrees are the minimum number of independent movements required to define the position or motion of the system. The human thumb has five degrees of freedom. He had to engineer something that could mimic these natural movements.

“The fingers are actuated with a braided line which serves as the artificial tendons for the fingers and the elastic cord mimics the retraction of the muscles in the fingers. The fingers are actuated with DC servo motors via a pulley system that is located in the robotic forearm,” Hendrik explained. He then hooked up the system to a wireless controller system, so a user could manipulate the robotic arm using a glove.

“The robotic arm was designed to be controlled with a glove with flex sensors on each finger on the glove itself. Once the user puts the glove on and starts operating the glove, the robotic hand will mimic the functions coming from the user’s glove,” he continued.

Hendrik tested the robotic hand by putting it through an assortment of grip patterns. One had it gripping a gun-shaped video game controller, then it completed a grip around (and lifting of) a cylinder, a tennis ball grip and a cuboid test. Lastly, he used a Coca-Cola bottle to demonstrate a cylindrical grip with the total weight of a full 500ml bottle.

Hendrik asserted that through putting the robotic arm through its trials he noted its errors; he believes there is room for improvement. He will be continually improving the build to mimic the movement of human hands.

Hendrik hopes to continue his studies once he has graduated – he plans to embark on a Master of Engineering (Mechanical). He also notes that he will continue working on his 3D printed prosthetic arm and see how he can accomplish more finger and thumb actuation and get it to a more realistic level of functionality.

“Going forward with this project in the future, some changes on the mechanics of the fingers can be made,” Hendrik concluded.

His project has been applauded by his peers, his lecturers, and staff at the Engineering Institute of Technology.

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