5 ms·

yes, it's been common knowledge in biomechanics that wheeled vehicles win on flat surfaces, hands down (ha). legs are good for the 99.9% of earth's land that is

yes, it's been common knowledge in biomechanics that wheeled vehicles win on flat surfaces, hands down (ha). legs are good for the 99.9% of earth's land that isn't nearly as predictable. the general utility of accessing that 99.9% is relatively dispersed though (and hard to build a business on).

Robotbeat 6y ago
Simply using big wheels or tracks work for non-flat surfaces, too, and are cheaper & more efficient (especially the wheels). Legs allow you to climb, ie a ladder, very steep stairs ( more than 45 degrees), a tree, or an extremely steep rough slope (think: mountain). A tracked vehicle or large-wheeled vehicle can go almost anywhere a legged robot can go with a large efficiency and cost advantage. However, you can run into space constraints. Bipedal robots are good for navigating human-scale environments while still having a tall and stable robot. But generally, tracks or big wheels are way cheaper and more efficient and can do the same thing.
- clairity 6y ago
  sure, bigger wheels and tracks can get you some greater percentage of navigable land, but nowhere near 100%. most terrestrial animals uses legs and not wheels for a reason (and it's not because it's not evolutionarily possible). but yes, bigger wheels and tracks probably cover a greater percentage of the commercially viable landscape.
  - Robotbeat 6y ago
    It is close to evolutionarily impossible to do a wheel and axle biologically. If the whole animal rolls, sure, but not a full wheel and axle (macroscopically). That is probably the main reason we see zero macroscopic animals with that configuration.
    - clairity 6y ago
      biology on an evolutionary timescale is exceedingly clever, more ingenious than us humans. you don't need an axle, just something roundish (eyeballs or even pearls, for example).
      - thombat 6y ago
        The organism will need something like a fluid rotary union so the nervous and circulatory system can reach the rotating part, or that part will be limited to very low metabolic levels (basically diffusion). That will certainly be ingenious.
        clairity 6y ago
        certainly, but biology is amazing. our muscles are basically chemical ratchets interconnected throughout a mosaic of levers (ignoring the complex control and feedback mechanisms, as well as the energy and waste systems, for a moment). also, your point is why i mentioned pearls--not all tissue needs to be activated or enervated similarly, or at all. we should have no doubt that biology would find a way given enough time.
        Robotbeat 6y ago
        It has found a way! Through engineering. We invented wheels, and we’re a result of evolution. Dung beetles have engineered something similar, although no axle (yet).
      - Robotbeat 6y ago
        And yet it hasn’t happened! So I think that means there are fundamental reasons why it’s difficult for evolutionary processes.
      - squarefoot 6y ago
        That would be really really hard to achieve in nature. What about a millipede? To me they're the closest thing to a legged and a tracked-like creature. https://www.youtube.com/watch?v=xysbNbvUDZA https://www.youtube.com/watch?v=xysbNbvUDZA
    - ggm 6y ago
      Not to invoke fiction as proof, but Philip Pullman hypothesized animals with a shiny claw which co-evolves with a tree making wheels. The claw evolves to be the axle and the tree evolves to make the wheels for co-benefit.
  - bsder 6y ago
    > most terrestrial animals uses legs and not wheels for a reason (and it's not because it's not evolutionarily possible). Actually, I suggest its for exactly that reason. Rotary motion is sufficiently more efficient that if there was a way to evolve it, it probably would have. Rotary motion has lots of difficult issues: how do you power it, how do you communicate with it, how do you lock it in place, how do you reverse it? None of these are problems for stabilized linear actuators (aka muscles).
    - clairity 6y ago
      that's exactly the limited engineering perspective to be wary of. biology doesn't consider those things, it just finds a way in a staggeringly multidimensional space of real consequences (also, muscles are just one, amazing, component of a holistic locomotory organism). rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. for a potential analogue/precursor, consider the rotary joints we have in our bodies. legged locomotion has evolved to be quite efficient in certain ways too. human legs, for instance, evolved for walking/jogging long distances efficiently (we have 2 gait-dependent locomotory efficiency points at two different speeds). but we can also climb and run and kick and hop and swim and more when required, unlike rollers.
      - bsder 6y ago
        > rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. Unlikely. Something that has the possibility to be so staggeringly more efficient would have found some niche even in present day. At least one spider makes itself into a wheel to roll down sand dunes faster than a predatory wasp can follow. When something as complicated and calorically expensive as vision can evolve multiple times, the fact that rotary power hasn't evolved says that there is a block somewhere. And, rotary power has evolved in some flagellar creatures. However, what evolved was a cellular ratchet. The system can go one direction only, and there was effectively no fine control for exactly the reasons I mentioned. > for a potential analogue/precursor, consider the rotary joints we have in our bodies. And those joints have complicated musculature and are relatively easy to permanently damage.
- somewhereoutth 6y ago
  Our built environment has been designed for the human form, so a general purpose robot will necessarily be humanoid. Essentially we would leverage the existing interface between humans and structures/machines - instead of having to create a new interface for robots to interact with their environment.
  - jtsiskin 6y ago
    Many humans are already on wheels, and the ADA tries to ensure accessibility.
    - Robotbeat 6y ago
      This is a hugely important point and much of the reason I chose a wheeled or tracked robot over a legged one for a project I’m working on. My workplace is supposed to be accessible, and to the degree that it isn’t, my workplace is federally required to fix it. So in some ways adding a tracked/wheeled robot to the mix could also help us find ways to make our workplace more welcoming for wheelchair users. As a mobility platform, a wheeled/tracked platform is more efficient, more open (less overhead), probably more robust (doesn’t fall over of power is lost mid-stride), an order of magnitude less costly, and it may even enhance workplace accessibility. Win-win.
      - somewhereoutth 6y ago
        Indeed! And by digging up some wheelchair accessibility specs you will know exactly the form your robot needs to take to take advantage of that interface.
renox 6y ago
I think that eventually robots will get both wheel and legs: wheel are more efficient where they are usable.

Robotbeat 6y ago

Simply using big wheels or tracks work for non-flat surfaces, too, and are cheaper & more efficient (especially the wheels). Legs allow you to climb, ie a ladder, very steep stairs ( more than 45 degrees), a tree, or an extremely steep rough slope (think: mountain). A tracked vehicle or large-wheeled vehicle can go almost anywhere a legged robot can go with a large efficiency and cost advantage. However, you can run into space constraints. Bipedal robots are good for navigating human-scale environments while still having a tall and stable robot. But generally, tracks or big wheels are way cheaper and more efficient and can do the same thing.

clairity 6y ago
sure, bigger wheels and tracks can get you some greater percentage of navigable land, but nowhere near 100%. most terrestrial animals uses legs and not wheels for a reason (and it's not because it's not evolutionarily possible). but yes, bigger wheels and tracks probably cover a greater percentage of the commercially viable landscape.
- Robotbeat 6y ago
  It is close to evolutionarily impossible to do a wheel and axle biologically. If the whole animal rolls, sure, but not a full wheel and axle (macroscopically). That is probably the main reason we see zero macroscopic animals with that configuration.
  - clairity 6y ago
    biology on an evolutionary timescale is exceedingly clever, more ingenious than us humans. you don't need an axle, just something roundish (eyeballs or even pearls, for example).
    - thombat 6y ago
      The organism will need something like a fluid rotary union so the nervous and circulatory system can reach the rotating part, or that part will be limited to very low metabolic levels (basically diffusion). That will certainly be ingenious.
      - clairity 6y ago
        certainly, but biology is amazing. our muscles are basically chemical ratchets interconnected throughout a mosaic of levers (ignoring the complex control and feedback mechanisms, as well as the energy and waste systems, for a moment). also, your point is why i mentioned pearls--not all tissue needs to be activated or enervated similarly, or at all. we should have no doubt that biology would find a way given enough time.
        Robotbeat 6y ago
        It has found a way! Through engineering. We invented wheels, and we’re a result of evolution. Dung beetles have engineered something similar, although no axle (yet).
    - Robotbeat 6y ago
      And yet it hasn’t happened! So I think that means there are fundamental reasons why it’s difficult for evolutionary processes.
    - squarefoot 6y ago
      That would be really really hard to achieve in nature. What about a millipede? To me they're the closest thing to a legged and a tracked-like creature. https://www.youtube.com/watch?v=xysbNbvUDZA https://www.youtube.com/watch?v=xysbNbvUDZA
  - ggm 6y ago
    Not to invoke fiction as proof, but Philip Pullman hypothesized animals with a shiny claw which co-evolves with a tree making wheels. The claw evolves to be the axle and the tree evolves to make the wheels for co-benefit.
- bsder 6y ago
  > most terrestrial animals uses legs and not wheels for a reason (and it's not because it's not evolutionarily possible). Actually, I suggest its for exactly that reason. Rotary motion is sufficiently more efficient that if there was a way to evolve it, it probably would have. Rotary motion has lots of difficult issues: how do you power it, how do you communicate with it, how do you lock it in place, how do you reverse it? None of these are problems for stabilized linear actuators (aka muscles).
  - clairity 6y ago
    that's exactly the limited engineering perspective to be wary of. biology doesn't consider those things, it just finds a way in a staggeringly multidimensional space of real consequences (also, muscles are just one, amazing, component of a holistic locomotory organism). rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. for a potential analogue/precursor, consider the rotary joints we have in our bodies. legged locomotion has evolved to be quite efficient in certain ways too. human legs, for instance, evolved for walking/jogging long distances efficiently (we have 2 gait-dependent locomotory efficiency points at two different speeds). but we can also climb and run and kick and hop and swim and more when required, unlike rollers.
    - bsder 6y ago
      > rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. Unlikely. Something that has the possibility to be so staggeringly more efficient would have found some niche even in present day. At least one spider makes itself into a wheel to roll down sand dunes faster than a predatory wasp can follow. When something as complicated and calorically expensive as vision can evolve multiple times, the fact that rotary power hasn't evolved says that there is a block somewhere. And, rotary power has evolved in some flagellar creatures. However, what evolved was a cellular ratchet. The system can go one direction only, and there was effectively no fine control for exactly the reasons I mentioned. > for a potential analogue/precursor, consider the rotary joints we have in our bodies. And those joints have complicated musculature and are relatively easy to permanently damage.
somewhereoutth 6y ago
Our built environment has been designed for the human form, so a general purpose robot will necessarily be humanoid. Essentially we would leverage the existing interface between humans and structures/machines - instead of having to create a new interface for robots to interact with their environment.
- jtsiskin 6y ago
  Many humans are already on wheels, and the ADA tries to ensure accessibility.
  - Robotbeat 6y ago
    This is a hugely important point and much of the reason I chose a wheeled or tracked robot over a legged one for a project I’m working on. My workplace is supposed to be accessible, and to the degree that it isn’t, my workplace is federally required to fix it. So in some ways adding a tracked/wheeled robot to the mix could also help us find ways to make our workplace more welcoming for wheelchair users. As a mobility platform, a wheeled/tracked platform is more efficient, more open (less overhead), probably more robust (doesn’t fall over of power is lost mid-stride), an order of magnitude less costly, and it may even enhance workplace accessibility. Win-win.
    - somewhereoutth 6y ago
      Indeed! And by digging up some wheelchair accessibility specs you will know exactly the form your robot needs to take to take advantage of that interface.

renox 6y ago

I think that eventually robots will get both wheel and legs: wheel are more efficient where they are usable.