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Novel Drive Wheel System Based On Spinning Sphere
An anonymous reader writes "A Bradley University student has built a mobile robot that uses a hemispherical omnidirectional gimbaled, or HOG, drive wheel. It consists of a black rubber hemisphere that rotates like a spinning top, with servos that can tilt it left and right and forwards and backwards. The HOG system delivers an amount of torque directly proportional to the tilt of the hemisphere, allowing the robot to move incredibly fast nearly instantaneously."
How about making a robot with four legs. The foot on the bottom of each leg would be a wheel like this. Servos which control the attitude of the legs would also control the direction the wheel operates in.
http://michaelsmith.id.au
My biggest concern is how much control you have over the accuracy and precision. The friction between the power and pavement surfaces is dependent on how much that wheel is worn down. While driving the response you get as the wheel ages will change.
---jstlook ---For that is the way of Elves, for they say both yes AND no, and mean every word of it. --- J.R.R.T.
It's a cute idea. It assumes a single point of contact with the ground, and thus requires a flat, hard floor. This is limiting.
The various "omni-wheel" designs, with wheels composed of little wheels arranged around a big wheel, have a similar problem. The size of the little wheels, not the big one, determines the terrain-handling limits of the vehicle.
1980s robots tried to do everything by wheel odometry. Back then, most of the software was too dumb to plan moves given steering limitations, so omnidirectional drives were popular. Robots got a lot better when people stopped building robots with complex wheels and no suspension, and went to more ordinary wheels with off-road type suspensions.
The video embedded in TFA contains the engineer who created this saying that it was invented about 100 years ago, but nothing came of it and the tech was forgotten. He did rediscover it independently, however.
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the innovation by the student is great and shows the university has the talent to polish and show to the world.
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So, the funky cars they used in the iRobot movie with Will Smith, this re-invention now makes them possible? I am curious to know how well it works on rougher surfaces, like potholes, sand, or gravel.
You might want to check your meds and then re-read the article. The word "Novel" is here used to mean "new". It has no relation to the company "Novell", which went bankrupt a few years after partnering with Microsoft and sold themselves to a private company - Attachmate sans their patents that went to... an IP consortium Microsoft had a controlling interest in. NVM. Maybe it's me that needs to check my meds.
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It seems interesting but I have a few concerns (some have been stated in other posts but I would like to get them in one place).
1. Uneven surfaces; With such a small surface contact it is easy to lose traction.
2. Control. It seems that one can change direction at will but it seems difficult to do it accurately and more difficult to stop the device.
3. Soft surfaces; if the hemisphere is going at a constant speed would it dig into a sift surface when stopped? Sure you can stop the motor but that means you would have the same acceleration characteristics of a conventional wheel.
I would have liked to see it on bare concrete doing a slalom and stopping at a designated point.
Another cool drive mechanism coming soon to your local robotics competition, alongside dozens of other ways I would never have dreamed to make a robot haul across the competition floor. You definitely won't be seeing on it a car because it's too inefficient, wears quickly and can't handle rough roads.
Then it's not funny.
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Looking forward to when this is the last thing that I see before the whirring blades eviscerate me.
This has already been turned into a personal vehicle some years ago. It won the 1988 Toyota Olympic Ideas competition and ran on perpetually spinning Chinese woks. The best link I can find is
http://books.google.com/books?id=1M3e82yGmZMC&pg=PA27&lpg=PA27#v=onepage&q&f=false
Perhaps someone can find a better picture or video.
It is not a novel idea, he mentions it himself at 1:07: an almost 100 year old idea that everybody has forgotten :-)
Quite cool idea though. Looking back at those first "automobile like" designs; cars with legs, monowheels etc. it is not surprising - they were good at thinking outside the "4 wheels on a box" box back then. Probably because the "car" idea was not established yet.
1. Why keep the motor running at constant rpm? Sure, those peelouts are fun but they cause tire wear and won't work too well on loose surfaces. And in the video, the wheel bounces off the ground when going from forward to reverse. That depends on the power-to-weight ratio and won't be so much of a problem in production vehicles, though.
2. The video doesn't show how the system behaves at low speeds (ie with the wheel at an angle approaching 90 degrees). I suspect that at those angles, the direction of the drive force will start varying because even small imperfections in the floor will change the position where the wheel makes contact with the floor, so your course becomes erratic.
WTF is a "gimbaledl"?
Oh, janitors all over the world are gonna hate this guy. A spinning rubber hemisphere touching the freshly waxed floor all over the place will not only wreak havoc with the floor wax but may eventually damage the tile.
Spinning top, you ever played with these toys? What happened to them when they hit a curb like a book or something? Right, they bounce off. Why? Because all of sudden it gains traction with what can be thought of as a wheel.
This ball wheel works as an infinite gear because by tilting it, the controller decides exactly how large a wheel (a ball is an infinite number of circles/wheels, each a bit smaller/larger then its neighbour, stacked on top of each other) contacts the floor. If the ball is spinning direction is parallel to the floor (if the ball doesn't deform) it wouldn't move because there is no forward motion. Tilt it and you are essentially making contact with an ever larger wheel. If the RPM remains the same, the larger the wheel the greater distance must be travelled. That it works is clear and predictable. It makes perfect sense.
But a bump on the road would suddenly cause a far greater wheel to make contact, greater wheel means greater speed and BAM, you got a difficult to control vehicle.
This thing doesn't just need a flat surface, it must also avoid any curbs. And what if it hits a crack in the surface, what if its gets grip on its on opposite sides of the spinning ball?
Doesn't mean this won't have its uses but they will be limited.
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I loved the link! Couldn't have happened to a better person.
Cant wait for him to test drive the first HOG wheeled vehicle!
Voith schneider propeller. Much like the spinning rubber hemisphere in this robot the propeller can spin up to speed with the vehicle stationary and quickly move the vehicle in any direction by rotating a series of underwater hydrofoils:
http://www.voithturbo.de/de-pua-marine-vspropeller-demprogramm.php
Well, if they just covered that grate in the floor, Mike wouldn't have to carry him in.
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i haven't had points since my first kid was born. if i had points, i'd mod you up.
i very nearly whooshed, then i lol'd.
I visualized a spinning black hemisphere scuttling about by tilting itself. From the article I learn that it's just a drive wheel.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
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assuming the spokes could be strong enough to support the vehicle and its rider.
Telescoping tubes work a lot better in cartoons than in real life.
I have seen one robot with a deforming wheel design which transitions from a wheel to a flat tracked drive. Their slogan is "wheels when possible, tracks when necessary.") It was fast, agile, showed up once at one trade show, and hasn't been seen much since. Nice mechanical engineering.
This guy made an awesome battle bot using the principle. The spinning weapon and "wheel" are on the same axle. Independent raising/lowering the rear wheels does steering. Bot only uses one motor for weapon and drive. Video: http://www.youtube.com/watch?v=R0_tARpOo6g&NR=1
Believe it or not, I had been working on the HOG wheel for months when I met this guy last year - Geen at Mecha Mayhem in Chicago. I was blown away that we both came up with this concept using totally different approaches. He helped me put together the first HOG wheel prototype the same day. His combat bot One Fierce Dragonfly is incredibly powerful since it uses two lightweight servo motors to actuate the wheels and one giant weapon motor to spin the blade and to drive whith - really fun to watch it destroy stuff.
I was just about to say!
"Exterminate!!"
Good news is, if you run up a flight of stairs they're screwed.