sphere bot
 

Wouldn't it be the scariest thing ever, if you set your robot down on the playing field. And another team comes up. With a big ball. You ask, what is that?? They say, our robot. It emits a blue glow, their team color. It rolls. It rolls over things. Wouldn’t that be AWESOME?

I personally think it would be worthy of applause if a team makes a sphere bot that can roll over other robots. Come on, you can make up to a 30” sphere. I am just wondering if any team has made a sphere bot before, and if so how they accomplished it.

Making a 30” hollow sphere that is light and strong must be a pain in the… Yea, if you have any ideas on how to make a sphere bot, please feel free to post here.

A related topic:

If one were to make a sphere bot, it would probably need a polycarb shell on the outside and inside. So… how would on go about covering a sphere with curved polycarb?

I have a few ideas, like milling a giant mold and melting plastic into it. But that’s expensive. Also, one could make a curved piece of sheet metal, lay flat polycarb onto it, and heat it up so the polycarb forms to the curve. If anyone has done this before (making a polycarb sphere), any advice would be greatly appreciated.

Thanks,
Veselin Kolev

Re: sphere bot
 

You can always buy a premade polycarb dome here:

http://www.globalplastics.ca/domes.htm

Yeah.. We talked about making/buying one of our freshman a hamster ball to run around Atlanta in when we were looking for covers for our dome and I stumbled upon this site.

We were gonna buy two of these size balls here that is covering the salad bar and attaching them together somehow

http://www.globalplastics.ca/micashop1.jpg


edit: Ok, back to the subject at hand - enough ranting.
As for bending polycarb, there are a few good ways to do it, and a million bad ways.
In 2002 we had a polycarb formed cover on our robot as seen HERE.
It wasn't a sphere, yet was as smooth as a baby's rear end.
I believe this was achieved by a length or heated up material of some kind that was in the shape of a bow. It was used to form the curves on the robot's cover, and the cover held up all year. (Remember, this was the year that our robot was attacked continually by soccer balls)
I regret not knowing what the actual material that was used to bend the polycarb on this robot's cover was, but maybe I will see it one of these days.
I know it was a very simple device, that was like maybe a heated filament of some sort, and the lexan was bent around the material.

Re: sphere bot
 

You mean like this? Okay, so this one has a yellow glow instead of blue, but close enough.



This particular version of the Tumbleweed rover is wind-driven. But there is another variation built by a former FIRST student that now works at Johnson Space Center in Houston that is made entirely of FIRST-legal parts, and is actuively driven/controlled.

-dave

Re: sphere bot
 

my guys have discussed the idea in the past -especially considering the times we got Gyrochips in the kits - but other than roll around we couldn't figure out how it would play the game.

See if you can find the old toy called the Bumble Ball- it may give you some ideas on how to make this thing walk around. There are a number of cat toys that work on similar acentric cams and such.

If you do decide to build one I would certainly love to see how you do it....

WC

Re: sphere bot
 

Yeah, the idea is cool, but it would pretty much ruin the mobility of your robot if you were to put out any appendages to actually manipulate something in the game.

Thinking about it though, Stack Attach might have worked with this. If you could get some actual power.

Re: sphere bot
 

that would be aweosme...actually just having a sphere bot would be awesome...if i was going to build one, i'd jsut use 1" square moly tubing and bend it to make a frame, and then just cover that in sheets of aluminium that have been run through an english wheel a abunch of times, or something like 22-gauge sheetmetal....but i have no idea how this would effect the weight issue

Re: sphere bot
 

This is Roboball, it was designed , built and tested within about 6 weeks. most components are FIRST legal though I had to swap out a few things in order to fit under my weight limit of about 20 Kg ( 44 lbs). First ran about this time last year. It is capable of about 20 mph and will run for about an hour before the motors over heat or the battery for the IFI EDU controller dies. The ball material is a 50 inch diameter big-ins ball similar to the ones that have been used in a few FIRST competitions in the past. the little green wheels are just there in case the pendulum arm impacts the ground while traveling over bumpy terrain. It is inflatable and yes can travel across water.

Re: sphere bot
 

That's awesome! :D

Question though... is it able to turn? It's hard to tell from the pictures. (Being only two. And I'm an idiot programmer nerd who ignores the peasants who build the robot. ;))

Re: sphere bot
 

Definately able to turn, the pendulum interal to the deveice is leaned over at any angle you want and it will cause the sphere to lean over as well and as long as it is traveling forward it will turn, much like a motorcycle when you lean. Similarly the ball can lean so far over that it places the metal disks on the sides of the ball onto the ground and literaly turn on a dime. Though its nearly unstable if you try and turn at full speed. Tends to make the ball flip over, always a fun thing to see.

Re: sphere bot
 

I've always thought about it, never have proposed it to my team, but I've thought about it.

There is no 'might have' with a sphere bot and Stack Attack. It would have been a champion bot just for the defensive capability and manuverability. I can see it knocking stacks of boxes down by 'bowling' into them and becoming king of the hill by rolling on top another bot or just evading them.

On a side note, why did I instantly think Samus when I saw this thread?



Source: Nintendo.com

Re: sphere bot
 

http://downloads.solarbotics.com/PDF/kit6.pdf http://www.chiefdelphi.com/forums/sh...ighlight=robot
Oddly enough this has been talked about before. It just was in the chitchat forum. Of course the robot discussed there pushed the definition of robot to the extreme.

Re: sphere bot
 

Please excuse me double posting but I figured it would be better than starting another thread on the same topic. Aparently there is a patent on a spherical robot. It was really quite random on how I discovered it because I was searching for the person's name. If anyone actually recognizes the name then you probably would know why I was curious.
Shperical robot patent

Re: sphere bot
 

i just noticed. if you can have the spherical robot folded at the start and it folds out so the starting height limit is a little below the centerline of the sphere, then as much as other teams push you (assuming other teams robots only push from below the height limit), then they will not be able to push you (well they would, but) if you have a high traction, you can roll right over them no problem. anyone understand what im trying to say? please rephrase this then.

Re: sphere bot
 

How would you change the size of the sphere? If it were somehow inflateable, it seems too easy to pop. I can't see any other expansion method being robust enough to work consistently.
:confused:

Re: sphere bot
 

Another idea commonly passed around before was the idea of the hoverbot which would be cool to see but i haven't looked in the rule book for a while to see if it would be allowed

Re: sphere bot
 

It's perfectly legal, but even if you made it work you'd drain almost all of your resources (weight, power, fabrication time) doing it and in the end have a pretty useless bot.

Oh, btw, I fence foil, and I've challenged Max Lobovsky to a duel if we go to nationals...

Are you strictly saber?

Re: sphere bot
 

If it is a sphere bot, then it is as wide as it is tall....and the width and length starting dimensions are much smaller, so it would have to be folded a lot or inflateable which probably wouldn't be to efficient because it would take a while to inflate anything strong enough to be on a FIRST field.

Re: sphere bot
 

When you say Sphere bots, not only do I think of Samus, but I think of a omni-directional robot that can change position and direction at any time. Any propulsion ideas?

Re: sphere bot
 

Omni wheels. Set them at 45? to the sides of a square bot, and by changing the power to each wheel, you could theoretically control how fast and which direction the bot moved. If you wished to add an arm, then you could build a platform around the sphere at about 'waist' height. You could put the controls on the outside and have a pole sticking up and in to the exact center of the sphere above it. If you make the cord from this tower to the motors on the inside just a little bit longer than the shortest path around the sphere from the bottom to the tower, then the cord would roll itself around to the top side when needed. you may find a need to have a retractable cord (ie some sort of spring loaded winch) so that the length of the cord is not too long. the outer platform could be supported by teflon skids, or casters. Or, if you want to control the direction that the arm is pointing, then put omni wheels on the outside and power them, too. That would enable the outside to turn as well, but sort of ruins the idea of sphere propulsion. :rolleyes:

i apologize for the disorganization of my thoughts, they usually happen that way :D . I've been working on this type of idea for about a year, on and off, but my team doesn't like it much. So, good luck to anyone who wants to try it, and tell me if works!


Squirrel

Re: sphere bot
 

i was kinda thinking maybe a folding the shpere in eight peices. cutting it into 4 from each "side" of the box. then kinda swinging it in.. if there was a good strong light easy reliable way to do this with say,,, sheet metal, and cover the outside with some treads as to fit in the rules, maybe, but then again that just might not be strong enough. well a honeycomb structure sandwiched between two sheetmetal shperes. tediously welded together or sumthing.. mebe. but theres the lexan and heatgun idea again too. and for propolsion. probably try to have a thing inside the sphere that is independant of the shpere and rolls inside an easy omnishperical robot can be like

................______
............/....omnis...\
.........../.......[]........\
..........|........[].........|
...........\.......[]........./
.............\....omnis.../
................--------
comprehende?

my idea is, you need easy access inside the sphere obviously, so why not just have it expand out from an open to a closed more stable structure.

Re: sphere bot
 

:ahh:
Run awaaaaaaaay!

Re: sphere bot
 

Sorry about bringing back an old topic. But.....

Since the build season is over with, I've been toying around with ideas to make an "off-season" bot strictly for fun. One ideas that I sorta devolped on was a sphere-bot, using 3 "wheels" which would really be custom made plastics that would fit around the frame and be powered by a CIM motor. All three of them would work off of the same motor, going in the same direction. The steering would be comprised of a pendulum sort of device that shifts the spheres center of gravity to one side or another to allow it to angle in and turn. I'm posting some sketches and Inventor models I made to help visualize this...... Any ideas or improvements would be greatly appricaiated!





Another idea I had was a belt driven spherebot. Where there would be 4 belts (driven independtly by 4 CIM motors) that control the direction and speed. I made a rather detailed Inventor model here:

Re: sphere bot
 

Looking at lbridgwater's robot it may be possible to place a blower inside that central pole and have the pole open on one end and drill venting holes below where you place the blower, such that when the blower was run it would pull air into the pole and exhaust it out into the robot thru the venting holes. Now all you have to do is figure out how to wire that motor. Not to sure if that could easily be done but thats an idea.

Re: sphere bot
 

ill take you up on that idea and have one done before AZ Regionals...i'm full of ideas for this project...thanks for the idea...

Re: sphere bot
 

Care to share?

Re: sphere bot
 

Today I was messing around with a new frame shape.... Tell me what you think....

Re: sphere bot
 

One problem with a sphere is that if the weight is not exactly centered, or not much weight is low, and you are nudged a bit from the side, you could get beached. I have seen little sphere-bots that you can buy in a kit (at radio shack I think). It was kind of like a tank drive, but the wheels conformed to the sphere shape and between the wheels there was a little space below. Unfortunately, while cool, they were cheep, so they didn't drive straight, but they did get I kid that I know in the 6th grade interested in robotics.

Re: sphere bot
 

I was pondering that eariler today, and figured that if you made the center wheel flat, it would help keep it centered when upright. Also, having a "bar" stick out from the sides would help when turning to keep it from rolling over itself...... It would take a lot of precision to keep the CM in the middle.... but I think its possible. Maybe have a gyroscope help keep the weight under control? I'm not experienced in using them, but maybe if it senses it out of balence, it can adjust the weight (using a large weight on a slider) to compensate for the angle? Would require a lot of calculations though.....

This is an image I threw together in CAD showing the "flat bottom" center wheel and the bars on the side to help it when turning..... The red dots symbolize the CM.....

Re: sphere bot
 

The model is very complicated and while there isn't a specific weight limit, you still don't want to be too heavy. Only the outer shell needs to be sphereical, not the frame inside. If you use tread like shown, then the tread on the sides would need to slip in order to go. this could create problems with driving and wear and tear. By putting a bar outside, and by making part of the sphere flat, you almost defeate the purpose of having a sphere bot.

I worked with Squril Rock (sp?) on this idea and we think the best thing would be to have a 1/2 structure withat has like omniwheels at the bottom. you could drive in any direction and if properly ballanced, the sphere would roll and the bot inside would stay upright.

Re: sphere bot
 

For the sphere-bot plan that I came up with, I wasn't planning on it having a full and complete range of motion, such as being able to move left, right, forward, backwards, and still be able to roll. It would mainly be one big wheel that can tilt and turn as well...... if that makes sense?

Re: sphere bot
 

Hey, just throwing you this simple idea.

I currently have one of this sitting in my closet:

The Motor Ball

This RC ball just has 2 half-sphere shaped wheels. The black bands are like giant rubber bands. These wheels are also hollow and connected by one bolt each. As a matter of fact you have to take off one wheel to change the battery.

The battery and motors are mounted very low to keep a low center of gravity similar to the weight on a Segway.

The black antenna has a wheel on the end of it so when you "hit the gas" it keeps the whole motor mechanism from spinning around inside the ball. So in other words it is connected to the motorized mechanism and when you make it move forward the wheel hits the ground thus making it move forward.

If you made your wheel with a very low center of gravity you may not need this wheel/antenna combination.

This RC can do 360's and can pretty much do anything, however, it is very hard to control.

Re: sphere bot
 

While nice, the problem is that you can't move any direction, like sidways, without turning. If I want to build a ball bot, I want it to be able to turn left, right, forward, and back without having to turn.

Re: sphere bot
 

How about this idea then?

I just thought this up.

Do all the of the controlling from inside the ball rather than outside.

Of course you are going to have to make this a two piece bolt together on the outside though.

The 2 upright omni wheels shift the weight forward or backward.
The 2 sideways onmi wheels shift the weight left or right.

This combination thus moves this ball in any direction.

The problem with any ball is once you get it moving how do you stop without the ball rolling???

(Just realized you can probably eliminate the sideways omni wheels as the forward moving omnis will just spin them on a dime, well hopefully anyway.)

I think this idea would work; I really have not put much thought into it.

Re: sphere bot
 

team222badbrad had the same idea.


I had pretty much the same idea. Use two sphere halves, and mount them so they can spin freely of a center part holding your electronics and motors. Use an adjustable ratchet type setup to move the sphere halves, so that when the motors engage they move the sphere halves, but if you slow down, the ratchet won't let the sphere take off spinning with your motors and everything else. stopping is still to be determined, except just letting it roll. But if your center of gravity is low enough, the center portion of your bot will stay pretty much level, and you can mount a small arm to it. Wheely bars just in case.

Re: sphere bot
 

THat is very similer to what Squirrel Rock and I thout up. Onlywe had many more omniwheels for stability. all you need to do is to keep the weight low and turn the ball on the outside.

Re: sphere bot
 

I kind of wish I had one of these. Well, on second thought I really have no idea what I would do with it. It sure is interesting to watch to say the least.

If someone here can actually duplicate that, I'll eat my hat.

Re: sphere bot
 

Oh wow you guys brought up my dead thread. oh well heres what i have to say.

Me and a few of my friends actually designed all of the stuff for it. With an arm too.. believe it or not. Heres how:

The sphere was basically a robot with 4 wheels at 90 degrees to each other, which rests inside the sphere outer frame made of fiberglass. The wheels rested exactly on the "x" and "y" axis, exactly halfway up the sphere. This means that you can go sideways, and any other direction, without using omniwheels at all. The sphere was designed so it comes apart in halfs with the removal of 8 bolts, and had two large 3" holes on opposite sides. As for the arm, it was an arm similar to 254's arm last year, which extends out of one of these holes. Yes we would have sensors to align the hole with the arm. Retract the arm and start roling again. To get the most effective "roll power", we put all our weight at the bottom of the robot, calculated that it would give us a 12 inch lever arm.

Warning: sphere bots involve lots of physics calculations.
We had to use mad physics skills to calculate the maximum acceleration the sphere would undergo until the "robot" inside it would flip over. painful

on a side note, to insure that your sphere bot does not die when the inner robot actually does flip, ball castors are used to keep the robot constantly centered. yes. enought talk i go to sleep now.

regionals tomorrow!!!

:D