For anyone who wants to know more:
This is an application of Jansen's linkage: https://en.wikipedia.org/wiki/Jansen%27s_linkage
There are other similar linkages but Jansen's is quite good.
For anyone who doesn't have an idea why something like this matters or is inspiring beyond art, legged vehicles have many downsides but one big upside is that you can theoretically avoid the rubber/microplastic particulate emission associated with tires and wheeled vehicles if you can make legged vehicles as good as wheeled ones.
Even an electric battery vehicle with an electric motor charged by a solar/wind/nuclear power plant still emits pure poison into the air and waterways through friction between tires and the road.
Good alternatives would be biocompatible tires (Nitinol mesh tires like SMART Tire company's initial prototype that lacked the rubber coating) or legged vehicles.
Wouldn't a legged vehicle still have that problem if it can achieve the same speeds and weights that regular cars go at?
Scale up a human for example to the weight and speed of a car. Crazy powerful and big legs, big feet, big shoes. The rubber must hit the road either way and push down with a force to propel the weight of this car-heavy legged human at speeds of 100km/h. It would still wear rubber away just like tires do.
Legged vehicles aren't a replacement for regular vehicles if tire particulates are your concern.
Couldn't you do away with rubber and shoes since for legs you don't need flat, smooth roads either (so metal legs of a multi-ton vehicle won't have anything to damage too bad).
For comfort, you could have springs and air and hydraulic dampeners.
The metal itself would damage the ground that is walked on though no?
Yes, but walking on rough terrain would still keep it a rough terrain.
How does keeping rough terrain rough help with that?
My implication is that you want rubber for nice asphalt/road surface to avoid damaging it — for comfort, other suspension components can help out instead.
If you don't care about preserving the terrain (which you can when it's rough to begin with), you can just go with large surface metal feet and you should not get any rubber/microplastics, though you will get metallic dust.
I believe the main issue is the rubber and chemicals from the nice road surfaces. So your argument seems like a problem looking for a solution?
That's wrong: the problem is the rubber on the wheel (or feet in case of legs) being spent due to the traction and emission of rubber microparticles as it is.
Yes sorry I wasn't clear enough. Rubber and chemicals from tires on the nice road surfaces. That's what that should have said.
But the legs are still a solution in search of a problem.
Sure, the original article is about a legged movement, and the entire thread is about microparticle (plastics/rubber) emission comparison between wheels and legs.
Wht do you think mountain bikes have rubber tires? Or one of these? https://en.wikipedia.org/wiki/All-terrain_vehicle Or a dune buggy?
Pretty clearly the worry about the road surface is not the only cause of using tires.
Also, if you don't care for either preserving the surface or comfort (use something else for comfort) then... use metal wheels. Or ceramic wheels, or tracks or something.
Rough terrain with less and less purchase, until it just turns into a pile of dry dust / wet mud (depending on weather). A legged vehicle as heavy as a car would wear away stone, tear roots… I don't think there's any surface that could withstand heavy traffic, except maybe something ridiculous like a fast-growing woody grass.
For some reason, I was imagining a machine with legs like a footstool. Any realistic machine like this would have large, wide feet. With proper suspension, the pressure might be low enough to not completely destroy the ground.
Though, I'm struggling to see how this would be better than a wheeled vehicle: you've still got static friction between the feet and the ground… I guess maybe they're flexing less?
Yeah, large feet would reduce the pressure on the ground, though it would still suffer some effects for sure — but the goal is to avoid rubber and microplastics, so metal feet it is :)
Anyway, I agree that a wheeled vehicle is probably going to win on efficiency just the same, though wheels do require better roads than legs do (eg. common example is stairs).
A bicycle can do stairs just fine. They're tricky, but not much more than a similarly-steep hill would be. (Of course, that's ignoring wear on the tyres from going over the edges of the steps.)
With wheels, it depends on the size of the wheel what unevenness in the terrain it can cover.
Eg. a monster truck can handle more of it, but it's impractical for a bunch of other reasons.
Similar holds for legs, but legs can usually do jumps too.
if the wheels were metal and the roadway was also metal, but arranged into parallel small roadways, then we could avoid using rubber and not have the problem of rubber particulates.
Seems like in that case, you could just use cogwheels and racks, and avoid the complexity of legs.
like, trains?
Yes, specifically cog railways.
Metal particles are more reactive and toxic than rubber particles.
It’s been a hot minute since I learnt rolling friction in high school physics but (iirc) a very interesting and unintuitive aspect of it is that there’s always an opposing/slowing force on a (rubber) wheel. Only a slippping wheel will not experience a slowdown. Static friction is different from rolling friction, and (I think) can offer zero wear in ideal conditions - but rolling wear is always non-zero.
How do you square this idea with the fact that my running shoes wear out? I'm a legged vehicle, and it's clear that the soles of my shoes wear down over time and the lost mass of the rubber went somewhere.
Whether legs or wheels, there are going to be contact patches that have to endure some quantity of sheering force when the vehicle is doing anything other than remaining stationary. It's this sheering force that grates the particulates away from tires, and I presume a legged vehicle would need a tire-like compound on the surfaces it uses to contact the road. So why would legs be different in this regard?
You could wear wooden clogs or something. It would be uncomfortable but if you were a robot you wouldn't care. They would still wear out, but sawdust is less permanent than microplastics.
most wooden clogs come with rubber soles nowadays to make them bearable to wear for more than an hour
Or, we should stop paving road surfaces so wooden clogs work again as intended without being painful after a while.
Paving is a solution to a much worse problem of huge maintenance costs of non paved roads and paths. Unimproved dirt doesn't stand up well and gravel needs more maintenance than paving as well.
Before there was asphalt/tarmac/blacktop there was "macadam", which was tarmacadam without the tar. But it used to kick up huge amounts of dust, so it was normal to pour water on the roads in hot weather.
Doesn't seem like that would be significantly better to walk on compared to modern paved surfaces with all wood clogs as mentioned in this thread though. Never worn them though so maybe it would be.
Before they used wooden tires
Isn't another advantage of legged vehicles being more applicable to uneven/unstable terrain? (Like in this case the constantly shifting water/mud/sand boundaries of a beach)
If you wanted to build a similar contraption that is powered by wind but moves on wheels, I imagine there is a much larger chance of it getting stuck.
Sure, but on the other hand legs produce a LOT more force/weight per square inch, which can lead to them sinking more easily.
Which is why what the military uses for unstable terrain is treads like you see on tanks. Same for construction equipment that operates on soft soil.
Makes sense. I suppose the additional constraint here is "with minimal damage to the environment".
Like, some caterpillar-type vehicle could move fine on that beach, but you'd definitely see the trace of its movement afterwards...
So legs are not a useful movement mechanism for tanks, but they might be for delivery bots, etc.
I also wonder about the energy expense. The strandbeests seem to be powered by nothing else than a number of sails and the movement mechanism has little enough resistance that the wind force is enough to pull the vehicle along.
It feels as if a caterpillar would have more resistance, though I don't have the numbers. I guess you could in theory make a wind-powered caterpillar vehicle by using a turbine - but the vehicle would probably be slower, I.e. less efficient?
It says these are made of plastic pipe. Doesn't the pipe wear down where it contacts (or even slides in the video) the ground, creating microplastics?
Also, it already slides some of the time in the videos. Not sure what the advantage is over a simple slide dragged by a sail.
Strandbeest is just one legged vehicle. But I was just going on a tangent about an important aspect of legged vehicles in general.
That’s a dumb reason. A reason for reasons sake.
These matter because they are beautiful and make people happy. They’re also appreciable technical achievements.
(Emphasis mine)
The OP acknowledges that these are beautiful, and then explains other reasons why this work may be interesting or important.
There's nothing dumb in that.
Are any companies doing r&d for drop in tire replacements that don't have as much of an issue with micro plastics?
SMART tire company
So many people dont know this - the tire muck that comes from theforever chemicals used in all tire manufacture is horrifically bad - to the point where one eco guy I was listening to basically gave up when he learned just how bad the chemicals from tires are. (ill try to find the podcast) -- and he notes how Humans tried to make reefs out of tires for Ocean Life.
In dystopian Dark Mirror Humor, I bemused myself with the day dream thought that Michelin Star restaurants, whom are awarded 3 stars for the distance one should be willing to drive is greatest with more stars - meaning that you should be willing to make a journey to the off-beaten path to visit and eat this food (which has yet to be em-poisoned with the forever chemicals our Tires have put into all the densely populated environments, thus this Elite Food is Clean.
There are tire particulate matter capture devices out there, in research at least [0]. This solution plus having a heavy vehicle weight-dependent tax could help (i.e. encouraging more 2 (or 3) wheeler transportation regardless of whether motorized or not).
[0] https://www.imperial.ac.uk/news/195595/worlds-first-device-c...
Yes indeed - Jansen's machines are applications of Jansen's linkage :)
I feel like your choice of phrasing downplays the fact that the strandbeest is created by the guy the principle is named after.
If your goal is to replace rubber tires, then how about going whole hog and turn the entire road system into a railway system? Tires made of steel, parallel tracks, lots of switching, perhaps regional control systems to guide computerized vehicles along the fastest route keeping safe distances between cars, and cars that automatically link and unlink to create dynamic trains along shared routes. I think that would be a very cool system (although outrageously expensive to realize).
There's a question of course about why we're not using legged machines but I think you're way over-thinking this. Strandbeests are just a cool and beautiful art project and there is no more justification that they need than that. Art has a utility all of its own without having to inspire engineering works.
Besides which strandbeests are made of plastic tubing which kiind of weakens your argument about environmental friendliness.
You seem to posit that legged vehicles doing 100+ km/h for hundreds of thousands of kilometers do not have as much wear and tear as rubber tires do. What is that based on? And does it have the same or better friction / energy efficiency?
(I know the answers, I'm just trying to provoke you into thinking about your comment)