Reverse stationary skate/shoe

[Baccus]

Hi helpful folks..

I am proficient in software design, but to even call my self a "tinkerer" in terms of electrical or mechanical engineering would be a stretch, so I'm a bit out of my element with this project concept that has been a splinter in my brain for the last several weeks.
I would like to design and prototype a powered "skate" of sorts, but not for forward propulsion. Instead, I envision a shoe with two large wheels on the sides, which would allow the sole of the foot to remain very close to the floor. These wheels, (by way of accelerometers or sensored motors?) would sense foot speed or force, and would be powered in the reverse direction, letting the wearer essentially walk or jog in place, akin to a treadmill.
The idea would be that these shoes, or skates, would assume the role of a treadmill for apartment dwellers, like myself, who don't have space for an entire treadmill setup.
My problem is that aside from the concept and some rough ideas as far as aquiring physical parts (the wheels, supporting toe and heel rollers, etc.), I'm a little overwhelmed as far as what electronic components I should consider.
First, would you recommend an accelerometer sensor, or a kind of sensored motor for this application? Or both? Second, what kind of motor system should I look into? How much torque will be required to move the feet of someone underneath them, while keeping them in one place?
Any and all advice is much appreciated. Thanks!

 

[zeusfaber]

Does it need to be powered at all? After all, the objective is to absorb energy, not inject it into the runner. Couldn't you do everything you need to with a brake? Either a simple friction device, or something where the resistance increases with speed (and there's all sorts of options for doing that without needing a power supply).

A.

 

[Baccus]

Thanks for the reply!

Perhaps due to my limited mechanical engineering knowledge, I'm not quite clear how I would accomplish this without some sort of powered counter-rotation on the wheel. Much like walking forward with roller skates on, you could move your legs in an unnatural way to come close to running in place on skates, but you would still be moving forward. That's how I see it, but you probably know more about it than I do.
What kind of "brake" or friction device would you recommend I research?

Thanks again!

 

[SwinnyGG]

If you're not familiar with the concept of a free body diagram, google it and draw one- this idea won't work.

The short version is that if you are applying force to the floor in either direction, whatever is applying that force is going to move.

 

[waross]

Put brakes on the wheels and use a tummy strap to anchor yourself to the bathroom door.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[zeusfaber]

Do treadmills not normally have some sort of bar for you to push against? It's hard to envisage any sort of natural "running against resistance without moving" action without something at the body end of the muscles that are doing the work to react the forces.

Once you've got the idea of clinging onto a towel rail and pushing against the wall as you run, it's easier to picture yourself running against a brake.

Thinking about it a bit more, one of the difficulties you're going to have to solve is getting rid of the energy absorbed by your brakes without the shoes getting scorchingly hot. An active system (like the one you originally described) would have the advantage that you would be pumping much of that waste energy into the National Grid, rather than just storing it on your feet.

Two other things you'll have to overcome.

You'll need to watch the amount of mass you attach to people's feet - otherwise you're going to start damaging their knees.

I don't think I'd like to live underneath anybody who had one of these things.

A.

 

[SwinnyGG]

Do treadmills not normally have some sort of bar for you to push against? It's hard to envisage any sort of natural "running against resistance without moving" action without something at the body end of the muscles that are doing the work to react the forces.

No.. the belt moves, you run on the belt.

 

[Baccus]

Thank you.

 

[Baccus]

Strange... I had a reply posted above, I came back this evening and the entire post is gone with the exception of "thank you". I hope I didn't offend anyone.

I'll try again.

Thank you Zeusfaber, those are good points to consider. I had considered the noise problem and and figured the only ways to possibly mitigate it would be by using rubber tires on the wheels, and perhaps a rubber mat. I also considered the tethered belt/roller skate solution previously, but traditional 2x2 skates are heavy because of the large trucks and add too much height. Inline skates can be lighter, but still add height, and are unwieldy to attempt to use in any kind of natural walking motion. I was hoping that side-mounted wheels would not only bring the foot closer to the floor and offer stability, but could be possibly lighter as well. But yes, the weight of the system will also be a struggle.

 

[KoachCSR]

Rather than using wheels, you could try to incorporate a belt or track system to each shoe - basically modularize the treadmill. A belt system on each shoe could be designed to move freely without the need for motors or brakes, though you'd still want to push against something.