4KARE (Knee Joint Exoskeleton)




The knee joint is one of the strongest and most important joints in the human body. It allows the lower leg to move relative to the thigh while supporting the body’s weight. Movements at the knee joint are essential to many everyday activities, including walking, running, sitting and standing.

The product is completely a pure mechanical structure designed to reduce the load on knee joint. The main purpose/ problem which our idea will solve is that it will transfer partial amount of force from the upper leg i.e. thigh to the lower leg i.e. shin through an external structure mounted on leg Thus the force/load on knee is reduced.

The external structure is made up of four bar mechanism and the benefits of using four bar mechanism are-

I. Gives combination of rotational plus translational motion i.e. it exactly traces the complex motion of the knee

II. Follow trajectory of knee curve (J-curve) i.e. it exactly traces the motion of the leg.

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Step 1: 4 Bar Mechanism Check

The working of the four bar mechanism was checked by making a wooden model and by tying on the leg. The motion was thus verified by stretching, walking and running.

Step 2: Scaling, Dimesioning & Sketching

the dimensions of the link for scale 1.0, 0.9,0.8, 0.7 & 0.6 were calculated and the exterior structure of the four bar mechanism was cut on a cardboard for each scaling. It was then tied on the leg with the help of the thread as shown in the figure.

The number of clamping required to properly transfer the load and to prevent it from getting loose and sliding down were then decided. Clamping is very important when it comes to hold the product tight with the leg. After doing a research on the type of clamping with the help of Velcro and the number of clamping, we finally decided to go with three clamping on the thigh part of the exoskeleton and two clamping for Shin part.

A circle is marked covering the entire patella.Taking the midpoint of the circle marking were done on each side of the knee. The height of the top and bottom edges depends on a person’s height. This exoskeleton has been designed for a person of height 6’16”. A length of 3.5” were marked on the thigh and shin. Top most and bottom most edges for the structures were marked at a height of 8.5” on the thigh and 6.5” on the shin. We than had 5” on the thigh and 3” on the shin for clamping the exoskeleton.

The rough sketch was then prepared in order to imagine a picture of the targeted product.

Step 3: Modelling

Taking the original dimensions of the leg the product was then modelled in Fusion 360.

Step 4: Simulation and Shape Optimization

The 3D model was then simulated and its shape was the optimised by applying load on the required points and the final design was obtained.

Step 5: Final Design and Assembly

Step 6: Prototype

The Prototype has been made through 3D printing in ABS plastic.

Step 7: Testing Video of Prototype 1.0

The Video of the testing was recorded with first Prototype(1.0) of the product but the Images of the prototype shown in the previous steps are of the second prototype(2.0)



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    13 Discussions

    Surya Vignesh

    1 year ago

    Nice work.Have you published any Journal regarding your product? Do you think ABS plastic is strong enough to hold the body weight?


    1 year ago

    in your project ,do you store the energy from the upper leg? how do it in your project?

    Thank You Steel.
    I am not sure. The mechanism used for this if this concept would work for elbow.
    The four bar mechanism used in the Exoskeleton has specifically been derived for knee joints.


    1 year ago

    Can you tell me how much power we can reduce by or how many% and have formula calculated?

    1 reply
    Mandeep Singh KapoorHuyT60

    Reply 1 year ago

    Hi HUY T60,
    There is no as such calculated formula for calculating the load transfer. We used Strain Gauges on the links to calculate the amount of load transfer. The research and development of the project is still under process so I won't be able to tell you the amount of load transfer. But may be very soon.


    1 year ago

    Nice one, forum and function 4 link does work well for this sort of desigin

    1 reply
    Mandeep Singh Kapoordlyall

    Reply 1 year ago

    This length oh this four bar mechanism is really unique. This four bar mechanism is specially been derived to exactly trace the motion of the knee.
    So this mechanism in this exoskeleton even works better.

    Great design. This looks like it would be just as functional as any other kind of knee support that I have seen.

    1 reply

    Thank You DIY Hacks and How Tos !!

    Yes it is definitely functional. Infact it is much more efficient and better compared to any other knee braces available in the market because they uses a pin joint mechanism but 4KARE uses a 4 bar mechanism which exactly traces the motion of the knee.


    1 year ago

    Wow; thanks for sharing pictures of your simulations to give context for your design geometry. :)