Lightweight Bipedal
Walker Equipment

CFRP Lightweight Bipedal Walker Equipment

Using the unique qualities of CFRP to develop the knee-ankle-foot orthosis for people with spinal cord injuries.

C-FREX is walking equipment made with CFRP to help people with spinal cord injuries maintain physical faculties.
We are developing equipment with a goal of launching an absolutely new product for people with spinal cord injuries to move around much like a healthy person without using any outside motorized power.

The C-FREX development concept:

  • Applying CFRP to the lower leg socket reduces weight and activates elastic energy.
  • Knee joint flexion with no power―realization of stretching action
  • Fulfilling user needs through a sophisticated design not seen in other equipment.

Fellow developer:

Noritaka Kawashima,
Chief of Neuromuscular Function System Research Laboratory
Research Institute of the National Rehabilitation Center for Persons with Disabilities

Development History

  • 2014 - 2016

    T1 Model

    Realization of the lightness and elastic energy inherent in CFRP

    Using the basic structure of ARGO (advanced reciprocating gait orthosis), the current powerless leg orthosis, as the foundation, and adding CFRP material to lighten, strengthen and make more elastic the thigh and lower leg sockets, we address the problems with current equipment, namely its weakness and heaviness.
    Activate the elastic energy using the spring plate in the foot's CFRP plate to get a forward thrust that previous polycarbonates could not produce.
    After a walk test, the results expected from CFRP – “It felt like I was touching the ground.”, “The leg movement was smooth.” – became a reality.

  • 2015 - 2016

    N1 Model

    Wheelchair and brace-compatible model

    The N1 model is compatible with wheelchairs and walking braces. Even if we develop good equipment, if we don't consider the use environment and accessibility along walking routes, the technology will not lead to benefits for the user.
    That's when we derived a concept model from C-FREX and developed a mobility device that was integrated into the wheelchair.

    JEC World 2016 Award

    The N1 model received the Innovation Award at JEC (Journals and Exhibitions on Composites) World 2016, the world's biggest trade fair for the composite material industry, held in Paris in March 2016.
    A mobility device integrated into a wheelchair was called an innovative invention unparalleled in the world, which led to the award.

  • 2017 - 2018

    T2 Model

    Knee joint flexion - start to develop an extension mechanism and trial of a 3D printer part with continuous carbon fiber

    In conventional equipment, because the knee joint is fixed, it is difficult to preserve the clearance on the floor. That sort of restriction on movement can become a physical burden. The T2 model does not use any outside motorized power, and the knee joint can bend and stretch as it aligns to the walking cycle. We aim to develop a product that will allow for movement close to that of a healthy person.

    Installation of a 3D Printer with Continuous Carbon Fiber

    The specialty of a 3D printer is its low-volume production, and its ability to produce a variety of customized sizes and shapes.
    Among those printers, the 3D printer with continuous carbon fiber from Mark Forged Inc. makes it possible to make stronger molds, reduce development times, according to independently carried out strength tests and evaluations.

  • 2018 - 2019

    T3 Model

    Prototype for walking test with knee joint flexion and weight-loading function

    The joints of the hips, knees, and feet in bipedal walking perform flexion and extension movements in each phase of the walking cycle, and the combination has a regular pattern. Utilizing this periodicity, we have developed a "knee joint flexion-extension mechanism" that allows the knee to be held in the extended position during the stance phase and flexion-extension during the swing phase. It is possible to smoothly swing out the legs without using a sensor or battery.

    Exhibited at REHACARE 2019

    We exhibited for the first time at REHACARE, international trade fair for rehabilitation and care held in Düsseldorf, Germany from September 18 to 21, 2019. About 50,000 people with disabilities to people from the medical, welfare, and nursing industries visited the venue. We received a lot of response from wheelchair users and sales agents in each country.

  • 2019 - 2020

    N2 Model

    Final prototype for assumed of product models

    Developed the N2 model that follows the design of the function prototype that has been developed so far. This is the final prototype that implements all the conventional concepts of 1) CFRP, 2) flexion and extension of the knee joint, and 3) design. We will continue to test and improve it for practical use.

    Exhibited at CES2020

    We exhibited C-FREX (N2 model) for the first time at CES2020, a home electronics trade fair event held in Las Vegas, USA from January 7th to 10th, 2020. Approximately 200,000 visitors came to the venue to demonstrate walking by person with spinal cord injury . We received a lot of response from local reporters and research institutions.