Development of lower extremity support parts with Markforged 3D printer

3D printers are gaining traction not only for industrial purposes, but also for academic purposes. One example is the development of a peristaltic pump using Markforged's Mark Two by the Nakamura Laboratory at Chuo University. In the Nakamura laboratory, the Markforged Mark Two is mainly used for the development of peristaltic pumps. A peristaltic pump mimics the movement of the large intestine and is a soft robotic technology that can transport and mix objects simultaneously.

The Nakamura Laboratory at Chuo University conducts research with the key words "biological robots" and "soft robotics." Soft robotics refers to robot systems that utilize flexible mechanisms.

Most of today's devices are constructed on the premise that they are driven by a rotating system centered on a motor. However, it can also lead to bulkiness and inefficiency, and in some situations a flexible function like a mollusk muscle is more suitable. Such a "flexible drive mechanism" is called soft actuation.

Structural flexibility means that simple systems can be configured without the need for exaggerated sensors and controls for the surrounding environment. Furthermore, it seems that it will be possible to build a robot system like human musculoskeletal, such as ``hard when working'' and ``soft usually''.

Lower extremity power assist device under research and development

Background of introduction: Parts with complex shapes can be manufactured and weight can be reduced

Originally, the Nakamura Laboratory at Chuo University used 3D printers for research and development purposes. Mr. Kurumatani, an assistant professor at the organization, said, "Since it is a part that supports the human lower leg from the back, it draws a three-dimensional curve that follows the shape of the thigh and calf. It also needs parts to attach belts and fasteners. Since it is difficult to create such a complicated shape by other methods, we originally used a 3D printer.

However, the material (acrylic) that I had used before was not without problems, so it was not the best choice. is being talked about. Also, considering the function of power assist, the heavier it is, the more burden it will be on the wearer, and there was also the problem of strength, such as cracking from time to time.

Therefore, we introduced the CFRP-compatible Markforged Mark Two.

Operation method and effect: realization of weight reduction

Smart Actuation in Nakamura Laboratory

3D printer used: Markforged Mark Two

Usage: Mainly auxiliary parts for lower limb power assist devices

Effect: Significant weight reduction while maintaining strength.

Thigh parts Lower leg parts

Old model 203g 149g

Mark Two 110g 87g

Weight reduction -93g (46% reduction) -62g (42% reduction)

Mr. Kurumatani, an assistant professor at the organization, said, "The problem of strength has been resolved, and the weight is obviously lighter. To ensure durability, carbon fiber is sandwiched between the moldings. There is, but it seems that it can be made even thinner than it is now.However, it is still functioning well at present, so we are not pursuing further thinning.However, light and thin means a power assist device As a valid point, it is wonderful to have potential."

In addition, it was said that it is good that it does not need to be painted later. "Even though it's on top of the clothes, it's a part that comes into contact with the human skin, so I wanted to make it smooth. It doesn't have the roughness of the layers that are typical of layered 3D printers, and it's wonderful that it can be used as a part of an assist suit without additional machining. think."

Lower leg (back of thigh) support parts sample

Comparison with previous material

Future prospects

‍Currently, the Nakamura Laboratory at Chuo University is creating general male data as a sample. However, according to Mr. Kurumatani, an assistant professor at the organization, they are considering creating separate versions for women in the future. In addition, he said, "Currently, we are only 3D printing the support parts for the lower limbs, but we are thinking about 3D printing the parts that support the lower back."

3DPC supports not only industry but also manufacturing for research purposes.

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