sphere bot

[phrontist]

Originally Posted by Levin571

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

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?

[tkwetzel]

Originally Posted by greencactus3

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.

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.

[Joe Matt]

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?

[Squirrelrock]

Originally Posted by JosephM

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?

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.

i apologize for the disorganization of my thoughts, they usually happen that way . 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

[greencactus3]

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.

[Mike]

Originally Posted by Elgin Clock

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.

Run awaaaaaaaay!

[MConte05]

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:

[scitobor 617]

Originally Posted by phrontist

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.

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.

[Herbie698]

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...

[MConte05]

Care to share?

[MConte05]

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

[Daniel Brim]

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.

[MConte05]

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.....

[jdiwnab]

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.

[MConte05]

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?