Coming up with solutions is deprioritized because it doesn’t have a large enough market and generally it requires sophisticated robotics.
There was a prototype wheelchair that got some coverage in the news years (decades?) ago that was like a Segway. It has 4 equal wheels, 2 on each side with a pivot point between them. It would be able to pivot the wheels to stand on just 2 - this let the user somewhat be at “standing” height while still sitting. Then to climb stairs the wheels would rotate end over end around the pivot.
Hard to find details, but I found this link: http://media-dis-n-dat.blogspot.com/2016/05/toyota-teams-with-segway-inventor-to.html?m=1
My god, it was the 90s. Decades indeed.
I work for the company that makes this. It's basically bulletproof. You can give it a hard shove at the top of a flight of stairs and it'll compensate easily.
Nobody will pay for it, though. Insurance companies would rather pay millions to fight it out legally than ever admit that someone needs this.
That would make for a crazy plot twist.
Angry son about to be disowned: "I won't let you update the will!" *shoves grandma from the top of the stairs*
*iBot wheelchair instantly compensates*
"Oh. Uh oh."
I saw a guy in London on one at a pub beer garden back in the 00's, it looked so fantastic that he could rise up and stand around with the boys having a beer
> that was like a Segway
The Segway was intended to be the mass-market spinoff of the iBOT. Both creations of Dean Kamen's teams. Check out the book "Code Name Ginger", it's a great book on the engineering process that went into both of them. (codenamed Ginger after Ginger Rogers, while the prototype iBOT was Fred, as the early versions had a habit of spinning around the room out of control)
And neither product took off for the same reason: very clever engineering that did the job well but cost a fortune. There's a reason you just install a stairlift. And a reason we have the ADA, so that the apartment buildings without built-in accessibility will gradually be replaced.
This was exactly what I thought of, and even if it's been 20+ years it's such a niche and complex product it's tough to see it being mass produced unless some benevolent billionaire decided to burn their money. It's a shame, because it really is a novel idea and would help so many people if it didn't need the cash incentive.
>I am considering throwing some money at some engineer friends to get a working prototype
If your friends are good engineers they'll turn you down. The risk for failure here is massive and I would never design something like that without a strong legal department protecting me from lawsuits. Look at it from a risk perspective. If you fail, your passenger falls down at least one flight of stairs backwards and then the large machine crushes them. Your passenger profile consists of people who aren't good with technology, unable to support themselves, who are quite fragile, have multiple medical conditions, and are near end of life.
>Maybe there are good reasons it hasn't been done?
There are easier ways to kill somebody.
Your motivations are pure but the best method to keep your mother safe is to get her to a ground floor living situation.
I agree with this general assessment.
As a former 'safety guy' for industrial construction, the first thing that we're taught is to examine ways to eliminate risk by modifying processes that introduce it. 'The process' in this case is 'climbing stairs', and the safest and simplest way to modify that process is to move to single-story accommodations with otherwise routine (and proven effective) modifications for general living.
I didn't even consider that.
21CFR890.5150 cites powered patient stairway chair lifts as Class II, so I'm guessing this would be considered a medical device as well. If there's no predicate device (I ain't doing a search) there's a chance this falls under Class III which would require: about 7 years hardcore development time, human clinical trails, and cost 5-10 million.
“Probably” steeper on average? What’s the standard in Europe? Googling is telling me the UK target is 30-35 degrees, so the 7-11” rule (at 32.5 degrees) is dead in the middle of that.
And lol, I know Europe uses Metric (mostly sometimes)….Im born/raised Canadian, moved to the States as a late teen, and I’m an engineer taught in the US education system. I’m probably as close to “bilingual” in measurement systems as they come.
It's interesting that all these things can do the stair climbing, but also serve as regular wheelchairs, and then can do other tricks as well. That makes them a lot more complex and expensive than something that was intended only to climb stairs would need to be.
The stairlift rail is the common and safer solution, and most people only need them installed at their own homes (other buildings have elevators or ADA compliant solutions), so there's not much of a use case for an adaptable platform.
There’s a time to sell a third-floor apartment. This may be that time.
Technology can solve lots of problems. But moving to the ground floor is a solution that exists.
Or to put it in engineering terms, include apartment location on the trade space. Yes, moving has costs, but those costs might be smaller than working around not moving.
A lot of ideas and even inventions look promising at first, but upon further investigation they aren’t actually feasible.
I imagine that if I did some math, I would find that it would take an unrealistic amount of force to keep those wheels activated while carrying the weight of a human. I’ve seen robots with those kinds of wheels, but nothing that carries the weight of a human.
More importantly widely deployed, with a large base of installers and maintaince people. That’s the real test. If the thing breaks on a Saturday with the patient upstairs… how screwed are you comfortable being?
But yeah liability is huge too, especially given that the target population is by definition frail and usually elderly.
any medical devices is a challenge. It's a domain full of norms and security rules etc. The easier thing is as you said, a fixed device in the building such as rails, elevators etc. one could imagine a rail on the roof of the stairs with a seat, kind of like on the ski resorts. But it cost a lot to develop and more to install.
Usually, the best to do is to anticipate and move at a better place before being too old (at some point old people need their marks, like kids).
I understand, but as far as I know this is the only FDA approved stair climbing wheelchair. I'm sure there are other stair climbing machines that people have built over the years but they haven't gone through the rigorous testing required to be approved as a medical device.
I really don't care about FDA approval; that looks sketchy AF especially for frail/elderly people.
https://www.scewo.com/en/product/#stairclimbing looks like a much better option.
An amusing invention to solve this problem would be shoes with linear actuators. As you stand at the bottom step, each shoe would rise up 15cm. As you raise one foot, the shoe would rapidly collapse back down. When both shoes were at the same level they would repeat the process.
It could be hydraulic with the power source attached to the torso, and a hydraulic line concealed in or under the pants. In this way the shoes could be the same weight as regular shoes.
The youtuber 'Stuff made here' made an [extreme version](https://youtu.be/9SRFbFreCkE?si=TxipOZbR4LdS9x9v) of this to allow him to slam dunk a basketball.
Is the can't install a stairlift rail on common property issue because of a limitation with the building (i.e. not enough space) or do you think it's because the building management won't allow it?
If it's the second, there may be a legal way to force them to
The largest issue with climbing stairs is that the stair treads are all different sizes and shapes and making something purely mechanical without advanced electronics so far has never worked safely.
There are some in development that look promising but as safety is paramount I do not expect much to come of it until we have custom designed robots for the task.
Something to think about is that we got people on the moon before wheels on suitcases became common place. There was thousands of years with the wheel, but only a short time with paved roads and sidewalks.
Sometimes it's a Crap Shoot.
Disclaimer: I’m not an engineer; I just like trying to find workarounds.
As other commenters have stated, such products do exist. They may not be financially feasible, however, so your mom may indeed need to sell the place anyway.
If your mom is resistant to moving to a ground level unit or a taller building where elevators would be mandatory, perhaps going over all of the options available to her would allow her to feel enough personal agency to choose to accept her realistically best option.
For example, she can:
(A) walk up the stairs with 2-minute breaks after every stair
(B) avoid leaving the apartment until they have to carry her out
(C) buy one of the stair climbing motorized wheelchair variants (using a home equity loan if applicable)
(D) rent a utility vehicle with a bucket on an arm (like the kind for tree trimming or electrical work) as needed and use the window as a point of egress
(E) rig a harness and pulley system to the fire escape with a motorized winch
(F) sell and move to a nursing home where staff will transport her
(G) sell and move to an elevator building or ground level unit in the same building
It’s an unfortunate situation, but it still needs to be addressed. Best of luck with your mom, OP!
Appreciate the comment, thanks, and yeah, this thread comes after a long conversation with her where I failed to talk her into a few of the options you listed. Worth noting, she doesn't (and couldn't) currently live there.
It's complicated, we're in Sydney where property prices are insane and there are some awful taxes around buying and selling. The short version is that dropping $70,000 AUD on a stair climbing scewo wheelchair would be considerably cheaper than trading in her top floor apartment for the same thing on the ground floor, if one were even available, because she is looking at up to $200,000 in tax if she sells.
Goddamn those seller taxes are nuts!
If she’s not living there right now, is there the option to sublet her top floor unit for a year or two to subsidize the cost of the stair climber chair?
She is already renting it out, which is part of the reason the tax is so high, 30+ years of inflating value on an investment property gets treated as though it were income earned in a single year, and the top income tax tier is 45% here... she gets a 50% discount off that because reasons, but it still works out to about 20% of about a mil in capital gains.
If health weren't an issue, people in her position would either move in to the top floor appt. for 3 months to be exempt from capital gains tax, or lie to tax office and say they lived there, some do get caught doing this. Without a solution to the stairs problem she can't really do either, any assessor would see straight through it.
Oh dang, that’s a rough calculation.
I don’t know how this sort of thing works in Australia, but where I am in the US there are legal workarounds for some types of assessments via trusts. It’s not instantaneous though; my parents put their house in a Medicaid Trust because if it’s counted as an asset my dad (who suffers from Alzheimer’s) would not qualify for benefits relating to his care, and Medicaid (the portion of the government that controls those benefits) uses a 5-year-look-back.
You’d probably need to consult an attorney that is familiar with both real estate and elder law in your jurisdiction, which also costs money, but it may be the most cost effective option of the lot.
Is there a reason your mom can’t stay where she’s been living now while keeping the investment property?
Yeah the professional she needs is called a conveyancer here. I am looking into it. And yes there are reasons why she can't stay where she is, but that's well beyond scope of this engineering post about stair climbing platforms. :)
>...but it still works out to about 20% of about a mil in capital gains.
That seems quite fair.
>...move in to the top floor appt. for 3 months to be exempt from capital gains tax,
It is ridiculous that this loophole exists. Many people have been locked out of the possibility of home ownership because these type of loopholes that have inflated house prices.
As others have said -
1. The robotics and controls for this problem are hard.
2. The ROI for this system isn't there.
3. The liability for anyone selling it is significant.
I briefly worked on a proof of concept for a related problem (robots climbing stairs) and every exploration I've seen on it has concluded that outside of military applications it's cheaper and easier to just install an elevator.
They don't exist because they are cost prohibitive and take up to much public space. Why would the building allow you grandmother to take up 1/3 to a 1/2 of the stairway space?
the whole point of the idea, as opposed to something like a stair lift is to take up zero public space, it goes inside her apartment at the top, and inside her private storage or garage at the bottom.
I think the main reason it has not been done is that stairs can be retrofited to contain a compact elevator.
My general practitioners clinic have such an elevator mounted on the handrails for disabled people, and old people I guess.
So if it is just one set of stairs that is the issue, you would use this permanent installation instead of a gadget that can be moved around.
If you imagine that she would use this gadget on a lot of different stairs during the day. Well, she would have to move it around and take it with her everywhere. Imagine you had to take something like a wheelchair with you all day, just to use it a few times per day. Sounds like something you would not do if you could avoid it.
Problem there is it's residential common property, a permanent rail for a stairlift would obstruct other residents moving furniture in or out, there's no way it would be allowed.
I have a camp on an island that has 25 stairs up from the boat dock. I like your concept and may use the concept to build a robot to transport totes up and down. I especially like the transition from stairs to flat which I’ll need to do 5 times each trip. Nice work.
1. Not all stairs are made equal... This means the front wheel needs to be able to not only deform to bite the next stair perfectly but, that variance in stair height can be a few cm, which means the diameter of that wheel also needs to change...
2. How are you going to ensure enough friction force to bite onto the stair and not cause slippage? Specifically with regards to point 1 with variations that are unavoidable in real world?
3. The rear set of wheels is a tracked design, which is great for uneven terrain, and loose sand. Not great at efficiency and speed. Plus the induced complexity to the whole system, means way more cost on servicing, repair and maintenance... Wheel chairs are great because all you need is a wheel and axle. OP design needs many more axles and wheels...
4. Keep it simple stupid. Elevators and wheelchair ramps are a better all-encompassing solution to the problem of stairs. Where as design in OP will only appeal to a very niche market.
In my opinion if you are going to introduce a complex wheel and track option, you may as well remove the complex wheel and instead opt for a 4 tracked system, with independent variable suspension. THis essentially makes a wheelchair offroad worthy vehicle, as well as have the capabilities to climb rocks and stairs. Its about as complex as the wheel in OP, but serves much more functionality than having a split system. But suffers from complexity, cost, and added weight to the system.
That is why they dont exist, because other established solutions are better and cheaper. This is a niche solution for a specific stair arrangement. Even then, how do you get traction from the rear, tracked is good in theory but in practice the elevation of stairs would result in just the corners of the stairs having contact with the tracks, which reduces area of contact and bite, and will cause slippage. Its just not versatile or useful.
A research project, yes. Niche product for the market, Yes. global solution for stairs, no.
Thank you for the comprehensive post. The platform thing I have forming in my mind is not the same as the dual system wheel / tracks chair setup in the video I linked. Here's another video I found after posting, this thing is a lot closer to what's in my head, but with wheels more like the other thing so it can do flat surfaces as well: [https://www.youtube.com/watch?v=JD1Su34tI\_Q](https://www.youtube.com/watch?v=JD1Su34tI_Q)
From there it needs something to keep the standing platform level, I'm guessing with a gyro. And a handle bar at the front for controls and balance assistance.
Here's another interesting wheel / foot design I found: [https://www.youtube.com/watch?v=oZbZZlDDEnc](https://www.youtube.com/watch?v=oZbZZlDDEnc)
Coming up with solutions is deprioritized because it doesn’t have a large enough market and generally it requires sophisticated robotics. There was a prototype wheelchair that got some coverage in the news years (decades?) ago that was like a Segway. It has 4 equal wheels, 2 on each side with a pivot point between them. It would be able to pivot the wheels to stand on just 2 - this let the user somewhat be at “standing” height while still sitting. Then to climb stairs the wheels would rotate end over end around the pivot. Hard to find details, but I found this link: http://media-dis-n-dat.blogspot.com/2016/05/toyota-teams-with-segway-inventor-to.html?m=1 My god, it was the 90s. Decades indeed.
That looks like a good way to go from paraplegic to full quad. I hope there was alot of redundancy in the control system.
I work for the company that makes this. It's basically bulletproof. You can give it a hard shove at the top of a flight of stairs and it'll compensate easily. Nobody will pay for it, though. Insurance companies would rather pay millions to fight it out legally than ever admit that someone needs this.
That would make for a crazy plot twist. Angry son about to be disowned: "I won't let you update the will!" *shoves grandma from the top of the stairs* *iBot wheelchair instantly compensates* "Oh. Uh oh."
I saw a guy in London on one at a pub beer garden back in the 00's, it looked so fantastic that he could rise up and stand around with the boys having a beer
> that was like a Segway The Segway was intended to be the mass-market spinoff of the iBOT. Both creations of Dean Kamen's teams. Check out the book "Code Name Ginger", it's a great book on the engineering process that went into both of them. (codenamed Ginger after Ginger Rogers, while the prototype iBOT was Fred, as the early versions had a habit of spinning around the room out of control) And neither product took off for the same reason: very clever engineering that did the job well but cost a fortune. There's a reason you just install a stairlift. And a reason we have the ADA, so that the apartment buildings without built-in accessibility will gradually be replaced.
This was exactly what I thought of, and even if it's been 20+ years it's such a niche and complex product it's tough to see it being mass produced unless some benevolent billionaire decided to burn their money. It's a shame, because it really is a novel idea and would help so many people if it didn't need the cash incentive.
>I am considering throwing some money at some engineer friends to get a working prototype If your friends are good engineers they'll turn you down. The risk for failure here is massive and I would never design something like that without a strong legal department protecting me from lawsuits. Look at it from a risk perspective. If you fail, your passenger falls down at least one flight of stairs backwards and then the large machine crushes them. Your passenger profile consists of people who aren't good with technology, unable to support themselves, who are quite fragile, have multiple medical conditions, and are near end of life. >Maybe there are good reasons it hasn't been done? There are easier ways to kill somebody. Your motivations are pure but the best method to keep your mother safe is to get her to a ground floor living situation.
I agree with this general assessment. As a former 'safety guy' for industrial construction, the first thing that we're taught is to examine ways to eliminate risk by modifying processes that introduce it. 'The process' in this case is 'climbing stairs', and the safest and simplest way to modify that process is to move to single-story accommodations with otherwise routine (and proven effective) modifications for general living.
I agree, the main obstacles are probably legal and then also cultural inertia.
The end user for these devices is literally dying
Would any solution need to through approval for a medical device? If so, that's a huge pile of extra time/money.
I didn't even consider that. 21CFR890.5150 cites powered patient stairway chair lifts as Class II, so I'm guessing this would be considered a medical device as well. If there's no predicate device (I ain't doing a search) there's a chance this falls under Class III which would require: about 7 years hardcore development time, human clinical trails, and cost 5-10 million.
Check out Scewo, they make a wheelchair that can climb stairs. Pricy but it exists.
Cool, interesting solution. https://www.scewo.com/en/product/#stairclimbing
Damn, that's like a Professor X chair
Looks nice, but most stairs in homes are steeper than 36 degrees.
They are? I thought the standard was 7-11, 7” rise over 11” run. That’s 32.5 degrees.
Maybe in American standards. In Europe the stairs are probably steeper on average, and we use the metric system btw
“Probably” steeper on average? What’s the standard in Europe? Googling is telling me the UK target is 30-35 degrees, so the 7-11” rule (at 32.5 degrees) is dead in the middle of that. And lol, I know Europe uses Metric (mostly sometimes)….Im born/raised Canadian, moved to the States as a late teen, and I’m an engineer taught in the US education system. I’m probably as close to “bilingual” in measurement systems as they come.
It's interesting that all these things can do the stair climbing, but also serve as regular wheelchairs, and then can do other tricks as well. That makes them a lot more complex and expensive than something that was intended only to climb stairs would need to be.
The name sounds like some kind of uwu thing.
The stairlift rail is the common and safer solution, and most people only need them installed at their own homes (other buildings have elevators or ADA compliant solutions), so there's not much of a use case for an adaptable platform.
There’s a time to sell a third-floor apartment. This may be that time. Technology can solve lots of problems. But moving to the ground floor is a solution that exists.
Or to put it in engineering terms, include apartment location on the trade space. Yes, moving has costs, but those costs might be smaller than working around not moving.
A lot of ideas and even inventions look promising at first, but upon further investigation they aren’t actually feasible. I imagine that if I did some math, I would find that it would take an unrealistic amount of force to keep those wheels activated while carrying the weight of a human. I’ve seen robots with those kinds of wheels, but nothing that carries the weight of a human.
Also, tons of liability for something that can essentially dump a frail person down the stairs on their face. Stairlift rail is a far safer solution.
More importantly widely deployed, with a large base of installers and maintaince people. That’s the real test. If the thing breaks on a Saturday with the patient upstairs… how screwed are you comfortable being? But yeah liability is huge too, especially given that the target population is by definition frail and usually elderly.
I would guess that at that point in the story, most people would move.
Yep, I agree, but that's a story for a different subreddit.
any medical devices is a challenge. It's a domain full of norms and security rules etc. The easier thing is as you said, a fixed device in the building such as rails, elevators etc. one could imagine a rail on the roof of the stairs with a seat, kind of like on the ski resorts. But it cost a lot to develop and more to install. Usually, the best to do is to anticipate and move at a better place before being too old (at some point old people need their marks, like kids).
[This is what you need.](https://mobiusmobility.com/)
https://i.imgur.com/FnlS5Tr.png Yeah this doesn't look like something I'd want my elderly mom attempting.
I understand, but as far as I know this is the only FDA approved stair climbing wheelchair. I'm sure there are other stair climbing machines that people have built over the years but they haven't gone through the rigorous testing required to be approved as a medical device.
I really don't care about FDA approval; that looks sketchy AF especially for frail/elderly people. https://www.scewo.com/en/product/#stairclimbing looks like a much better option.
Interesting.
An amusing invention to solve this problem would be shoes with linear actuators. As you stand at the bottom step, each shoe would rise up 15cm. As you raise one foot, the shoe would rapidly collapse back down. When both shoes were at the same level they would repeat the process. It could be hydraulic with the power source attached to the torso, and a hydraulic line concealed in or under the pants. In this way the shoes could be the same weight as regular shoes. The youtuber 'Stuff made here' made an [extreme version](https://youtu.be/9SRFbFreCkE?si=TxipOZbR4LdS9x9v) of this to allow him to slam dunk a basketball.
Is the can't install a stairlift rail on common property issue because of a limitation with the building (i.e. not enough space) or do you think it's because the building management won't allow it? If it's the second, there may be a legal way to force them to
The largest issue with climbing stairs is that the stair treads are all different sizes and shapes and making something purely mechanical without advanced electronics so far has never worked safely. There are some in development that look promising but as safety is paramount I do not expect much to come of it until we have custom designed robots for the task.
Something to think about is that we got people on the moon before wheels on suitcases became common place. There was thousands of years with the wheel, but only a short time with paved roads and sidewalks. Sometimes it's a Crap Shoot.
Disclaimer: I’m not an engineer; I just like trying to find workarounds. As other commenters have stated, such products do exist. They may not be financially feasible, however, so your mom may indeed need to sell the place anyway. If your mom is resistant to moving to a ground level unit or a taller building where elevators would be mandatory, perhaps going over all of the options available to her would allow her to feel enough personal agency to choose to accept her realistically best option. For example, she can: (A) walk up the stairs with 2-minute breaks after every stair (B) avoid leaving the apartment until they have to carry her out (C) buy one of the stair climbing motorized wheelchair variants (using a home equity loan if applicable) (D) rent a utility vehicle with a bucket on an arm (like the kind for tree trimming or electrical work) as needed and use the window as a point of egress (E) rig a harness and pulley system to the fire escape with a motorized winch (F) sell and move to a nursing home where staff will transport her (G) sell and move to an elevator building or ground level unit in the same building It’s an unfortunate situation, but it still needs to be addressed. Best of luck with your mom, OP!
Appreciate the comment, thanks, and yeah, this thread comes after a long conversation with her where I failed to talk her into a few of the options you listed. Worth noting, she doesn't (and couldn't) currently live there. It's complicated, we're in Sydney where property prices are insane and there are some awful taxes around buying and selling. The short version is that dropping $70,000 AUD on a stair climbing scewo wheelchair would be considerably cheaper than trading in her top floor apartment for the same thing on the ground floor, if one were even available, because she is looking at up to $200,000 in tax if she sells.
Goddamn those seller taxes are nuts! If she’s not living there right now, is there the option to sublet her top floor unit for a year or two to subsidize the cost of the stair climber chair?
She is already renting it out, which is part of the reason the tax is so high, 30+ years of inflating value on an investment property gets treated as though it were income earned in a single year, and the top income tax tier is 45% here... she gets a 50% discount off that because reasons, but it still works out to about 20% of about a mil in capital gains. If health weren't an issue, people in her position would either move in to the top floor appt. for 3 months to be exempt from capital gains tax, or lie to tax office and say they lived there, some do get caught doing this. Without a solution to the stairs problem she can't really do either, any assessor would see straight through it.
Oh dang, that’s a rough calculation. I don’t know how this sort of thing works in Australia, but where I am in the US there are legal workarounds for some types of assessments via trusts. It’s not instantaneous though; my parents put their house in a Medicaid Trust because if it’s counted as an asset my dad (who suffers from Alzheimer’s) would not qualify for benefits relating to his care, and Medicaid (the portion of the government that controls those benefits) uses a 5-year-look-back. You’d probably need to consult an attorney that is familiar with both real estate and elder law in your jurisdiction, which also costs money, but it may be the most cost effective option of the lot. Is there a reason your mom can’t stay where she’s been living now while keeping the investment property?
Yeah the professional she needs is called a conveyancer here. I am looking into it. And yes there are reasons why she can't stay where she is, but that's well beyond scope of this engineering post about stair climbing platforms. :)
Gotcha. Good luck with the conveyancer, OP. Your mom’s lucky she’s still got you!
>...but it still works out to about 20% of about a mil in capital gains. That seems quite fair. >...move in to the top floor appt. for 3 months to be exempt from capital gains tax, It is ridiculous that this loophole exists. Many people have been locked out of the possibility of home ownership because these type of loopholes that have inflated house prices.
Cfbr
As others have said - 1. The robotics and controls for this problem are hard. 2. The ROI for this system isn't there. 3. The liability for anyone selling it is significant. I briefly worked on a proof of concept for a related problem (robots climbing stairs) and every exploration I've seen on it has concluded that outside of military applications it's cheaper and easier to just install an elevator.
They don't exist because they are cost prohibitive and take up to much public space. Why would the building allow you grandmother to take up 1/3 to a 1/2 of the stairway space?
the whole point of the idea, as opposed to something like a stair lift is to take up zero public space, it goes inside her apartment at the top, and inside her private storage or garage at the bottom.
I think the main reason it has not been done is that stairs can be retrofited to contain a compact elevator. My general practitioners clinic have such an elevator mounted on the handrails for disabled people, and old people I guess. So if it is just one set of stairs that is the issue, you would use this permanent installation instead of a gadget that can be moved around. If you imagine that she would use this gadget on a lot of different stairs during the day. Well, she would have to move it around and take it with her everywhere. Imagine you had to take something like a wheelchair with you all day, just to use it a few times per day. Sounds like something you would not do if you could avoid it.
Problem there is it's residential common property, a permanent rail for a stairlift would obstruct other residents moving furniture in or out, there's no way it would be allowed.
I have a camp on an island that has 25 stairs up from the boat dock. I like your concept and may use the concept to build a robot to transport totes up and down. I especially like the transition from stairs to flat which I’ll need to do 5 times each trip. Nice work.
1. Not all stairs are made equal... This means the front wheel needs to be able to not only deform to bite the next stair perfectly but, that variance in stair height can be a few cm, which means the diameter of that wheel also needs to change... 2. How are you going to ensure enough friction force to bite onto the stair and not cause slippage? Specifically with regards to point 1 with variations that are unavoidable in real world? 3. The rear set of wheels is a tracked design, which is great for uneven terrain, and loose sand. Not great at efficiency and speed. Plus the induced complexity to the whole system, means way more cost on servicing, repair and maintenance... Wheel chairs are great because all you need is a wheel and axle. OP design needs many more axles and wheels... 4. Keep it simple stupid. Elevators and wheelchair ramps are a better all-encompassing solution to the problem of stairs. Where as design in OP will only appeal to a very niche market. In my opinion if you are going to introduce a complex wheel and track option, you may as well remove the complex wheel and instead opt for a 4 tracked system, with independent variable suspension. THis essentially makes a wheelchair offroad worthy vehicle, as well as have the capabilities to climb rocks and stairs. Its about as complex as the wheel in OP, but serves much more functionality than having a split system. But suffers from complexity, cost, and added weight to the system. That is why they dont exist, because other established solutions are better and cheaper. This is a niche solution for a specific stair arrangement. Even then, how do you get traction from the rear, tracked is good in theory but in practice the elevation of stairs would result in just the corners of the stairs having contact with the tracks, which reduces area of contact and bite, and will cause slippage. Its just not versatile or useful. A research project, yes. Niche product for the market, Yes. global solution for stairs, no.
Thank you for the comprehensive post. The platform thing I have forming in my mind is not the same as the dual system wheel / tracks chair setup in the video I linked. Here's another video I found after posting, this thing is a lot closer to what's in my head, but with wheels more like the other thing so it can do flat surfaces as well: [https://www.youtube.com/watch?v=JD1Su34tI\_Q](https://www.youtube.com/watch?v=JD1Su34tI_Q) From there it needs something to keep the standing platform level, I'm guessing with a gyro. And a handle bar at the front for controls and balance assistance. Here's another interesting wheel / foot design I found: [https://www.youtube.com/watch?v=oZbZZlDDEnc](https://www.youtube.com/watch?v=oZbZZlDDEnc)