What Passive Mechanism is Used in Ergonomic Exoskeletons?

Are there any others you care to highlight or just this one?

I don't understand why these exoskeletons are so expensive?
https://www.ergosanteweb.fr/exosquelette-fabrique-en-france-ergosante-technologie/420-shiva-exo-exosquelette-france.html

Custom made lightweight high strength alloy parts + R&D costs for several years + advertising and company overhead...

The answer to the question can be obtained by purchasing one and studying it.

Its $5000 and not available to purchase by general public.

_Deleted.

https://www.airpower-usa.com/2020/03/17/levitate-in-the-news/

"The Airframe exoskeleton from Levitate Technologies is powered mechanically and does not require electricity. Instead, it uses a patented system of pulleys to support its users’ upper bodies.

The Airframe exoskeleton prevents upper body fatigue. This makes it easier and safer for workers to use their arms to perform work, especially when they are working with their arms over their heads or are doing repetitive motions. The exoskeleton actually reduces the exertion workers need to use to do their jobs by as much as 80 percent.

How does it work? It takes the weight of users’ arms off their necks, backs, and shoulders and transfers it to their cores. The energy that workers expend becomes more evenly distributed, which reduces strain and stress on the muscles and joints.

The Airframe responds to the user’s arm motions to provide the right amount of support that is needed at every moment. The mechanical pulley system provides an increasing amount of support as the user raises his or her arm. When the arm is lowered, the exoskeleton gradually releases its support. With machine and human working together, a worker’s arm motions feel natural, but they are far less tiring."

You have a spring mounted arm that connects to the hip and transfers the weight from your arms to your hips...makes your arms feel nearly weightless...

https://www.levitatetech.com/2018/01/28/how-do-exoskeletons-work/

https://www.levitatetech.com/patents/

What passive counter balancing device did they use? I found their patent info here:

USP 9,205,017

https://patents.google.com/patent/KR100911269B1/en?q=A61H1%2f0274

USP 9,737,374
https://patents.google.com/patent/US9737374B2/en

https://www.vulcanspring.com/constant-force-springs/

https://www.vulcanspring.com/variable-force-spring/

You want the force to increase slightly as the arm goes up...

The patent, (USP 9,205,017) says

"a spring element coupled to the arm bar and the shoulder bracket, the spring element being the exclusive energy source applying an offsetting force to the arm bar to at least partially offset a gravitational force acting on the arm as the user moves and the arm support follows the movement of the user's arm."

Patents are intentionally written as vague as possible, but apparently, it's a spring to counter the weight of a person's arm and power tool. A similar principle is used on garage doors to counter the weight of the door and allow it to be opened with less force.

Where I can buy this mechanism?

As far as I understand, a linear actuator pushing the arms from behind against the gravity (when arms raise up); but how the pushing force changing continuously with changing the weight in arms and where the linear actuator getting the energy to push if its passive mechanism?

There is no linear actuator in this mechanism...it's powered by springs and pulley's...

ok, so how its pushing the arms from backside?

Springs and pulleys....what part do you not understand?

Ok, where to buy these parts?

You have to design it first...you need proper specification of individual parts...a lot of the parts will need to be made specifically for this application....

If you want to work with just off the shelf parts and modify where necessary that will take some time, and might not work as well...

So you have to build what's called an engineers model to begin with, that will be proof of concept...

On the other hand if you have deep pockets you can contract out the work to a company that specializes in exoskeleton devices...but you still need the specifications of what force where at what angles etc...

So before you can begin you need a theory of operation, what movements do you want to support, and how much support you need for each operation, then you need to design the mechanism that provides that support at each degree of movement that will be within the scope of this application...

They used the following arm counter balancing mechanism:

https://www.youtube.com/watch?v=OdmpYBSMWzM

Yes but we probably want a three section device, one for each section of the arm including the wrist...can we get that all from one spring?

If we include the elbow joint, then we need two systems for two fulcrums (shoulder & elbow joint).

What about support for the wrist? Isn't this the problem area?...or I guess you could tie a holder to the forearm support that was then just controlled by the hand....or not

It depends that what kind of work or job a person performs and which joint they use more. Those who keep their hands above the shoulder (like electrician or automotive workers etc), they need support for their shoulder joint (Levitate is designed for them). Some people do repetitive work at elbow joint (dentists or dental hygienist, assistants etc). Some factory workers use wrist joint a lot. Its difficult to make one device which works for all upper extremity joints.

Well if it was easy, it wouldn't be so valuable...we don't choose to do things because they are easy, we choose to do things because it is hard...the hardest path leads to the greatest rewards...philosophically speaking of course...

"Its $5000 and not available to purchase by general public."

They do sell support vests for photography that might be adaptable for use...at least some components as a framework...pretty cheap too....

$710.

https://www.adorama.com/iarmt03sv.html?gclid=CjwKCAiAzNj9BRBDEiwAPsL0d4JFvvT7Kn4o9jYDJWbdmRzYDcZ6ODOKBJ28FE2sIDJFOd9nhk-aERoCW5IQAvD_BwE&utm_source=adl-gbase

Wow, the price is very reasonable, but it seems like quite heavy.

A spring. Or an elastic band.

What do you think about this one:
https://www.youtube.com/watch?v=6ukInFjlgTQ

Looks kind of buggy still....no shoulder support....this just adds weight to the shoulder instead of relieving the weight....this then adds additional stress to the back...don't think that will work as a stand alone...

It's not designed for shoulder. It assists only elbow joint.

What good is helping one joint and adding stress to another?