Legged Robots
 

Were any legged robots actually been made by a team and competed with? I believe that it is a very good form of robot locomotion. There are 1, 2 , 4, 6 legged robots that I know of, even Leg/Wheel Hybrids like the RoboTrac. How come they were never really attempted by any teams? I completely understand the cost of the robots, but 1 competition is like 6k, I can make a decent sized 6 legged robot with that budget, just by not going to 1 regional.

RoboTrac:


The Epicest 4 legged robot in the world:
http://www.youtube.com/watch?v=cHJJQ0zNNOM

People can say that it is unstable... But you only need 3 points of contact to the ground minimum to be stable, the Hexaped robots are highly stable.
http://www.youtube.com/watch?v=-Soq9qpK5Ac

Re: Legged Robots
 

Maybe I'm missing something. Can you list some advantages you see to a legged robot over a robot with wheels for FIRST applications?

I'm not even going to get into the disadvantages I see until I figure out what the benefits are.

Re: Legged Robots
 

Stability (6 Legged Robots)
Adaptability
Maneuverability
Innovation

Re: Legged Robots
 

how does it be more maneuverable than a regular wheeled robot?

Re: Legged Robots
 

You can literally walk over the bump, Not really affected by height change, You can even jump if you get that far, I applaud you. IDK but Dogs can go anywhere, they have 4 legs.

Re: Legged Robots
 

So you are suggesting that a legged robot that has 3 contact points at a given time is more stable than a wheeled robot with 4 or more contact points?

I have never seen a video of a legged robot I would consider more maneuverable than a drop-center 6 wheel FRC drivetrain, not to mention something like a mecanum or swerve drive.

Adaptability may be debatable, I don't know enough about legged robots to say whether they are more or less adaptable to different terrains (assuming that is what you mean).

Innovation is definitely an advantage of a legged robot. If that is one of the goals of your team that should definitely factor in. Personally I don't value innovation for innovation's sake in this competition for teams I work with. I always work to have us design the best robot to play the game we can, if that means that some parts are tried and true, boring things then so be it; if it means that we need to go somewhere teams haven't gone before than that's fine too.

I definitely understand and respect teams that try each and every year to come up with something completely innovative. I think that's really cool. It's just not for me.

Re: Legged Robots
 

If we're going to be loose with our definition of "legged," I would consider Beatty's 2002 machine to be a "crawler" of sorts. Check out some of their videos on TBA, it's really an elegant mechanism. However, they weren't champions in 2002 because of the qualities you indicated. In fact, their machine was simply very slow and powerful, but guaranteed a victory if they could snag all 3 goals at the start of a match.

Their mechanism was simply two sets of one-way shoes which slide forward on the carpet. In this sense, the robot could easily be pushed forward, but impossible to stop if you were pushing backward. It would take a minute to get where it needed to go, but the simplicity of the design (469's mechanism reminded me of this this year) was just phenomenal.

Re: Legged Robots
 

team 71 in 2002 oe 2001 i cant remember. but any ways they would flip down garb the goals and crawl over to the other side of the field. call it the game breaker bot that year if you like. but they used legs to get across if i recall. so legs can be used for power when speed is not needed.

Re: Legged Robots
 

This big dog thing creeps me out every time I see it walking....

I can't think of a game it would be good for.

Re: Legged Robots
 

Wasn't it team 71 (correct me if im wrong) who had a walking bot a while back???

Someone beat me to it

Re: Legged Robots
 

Its the giant one that has the 2 big arms? Dang, thats pretty epic, but so slow:ahh:

Re: Legged Robots
 

Definitely no...
(at least from my experiences working with Chiara and Nao robots).

Re: Legged Robots
 

As a design rule of thumb, legs should only be used where wheels won't work. Legs are more complicated, slower, less powerful, and difficult to program. Wheels are simple, fast, and reliable.

There aren't many places where wheels or tracks won't work.

That said, it would still be cool to see a fast legged robot in a FIRST competition. Not saying it can't be done, it's just not for rookies.

Re: Legged Robots
 

;) We will see next year in the LA regionals who's team has the Fully Autonomous Possibly legged robot... I am going more toward wheel, but a wheel/leg hybrid sounds cool

Re: Legged Robots
 

Actually, if you know ahead of time that you'll be walking on a flat floor (where wheels work well), you can do a fairly simple mechanical linkage (one motor on each side driving three legs) hexapod that will scoot around and look impressive. It might not win a competition, but it might get a design award!

Re: Legged Robots
 

Or some weird robot with a wheel based drive system but also with legs on the outside. That would be so awesome.

Re: Legged Robots
 

im pretty sure team 71's beast robot in 2002 was a hybrid of the two, with wheels to speed up to the goals then the one way super legs crawl it to the end zone with all three goals.

innovation, legged robot, world champion

Re: Legged Robots
 

another advantage of legs would be if the terrain was incredibly bad a legged bot like this would be really slick

http://www.youtube.com/watch?v=wIuRVr8z_WE

now thats maneuverability

Danny B

Re: Legged Robots
 

It's a very cool idea, but there's a lot of reasons no to.
Bumpers have to be 10-15 inches off the ground, and they can't be moving. You only have so many motors to power everything.
Legged robots would have a problem with balls going into their frame perimeter.
Legged robots would probably be slower.
Obviously, as 71 showed, there are games here legged robots are masterful and great. However, this game just isn't the one for it.

Re: Legged Robots
 

Our team (1648) looked at walking robots last year. It seemed a perfect application on the slick regolith surface. We would have used the slick wheels as feet, and even did a very interesting prototype with a VEX kit. The VEX version walked very well on the slick surface and pulled a trailer with no trouble. It walked well, with enough speed, and could turn easily. The video we shot looks like a big insect plodding along.

As said above, we had to throw it all out because of the bumpers. They can't move up and down and have to stay inside the bumper zone. Otherwise, we would have had a really neat walking robot.

Sometimes, it seems, the rule makers want conformity rather than innovation. Either that or it's the Law of Unintended Consequences butting in.

Dr. Bob

Re: Legged Robots
 

Does anybody have a video of 71 that year? I would love to see it!

Re: Legged Robots
 

Re: Legged Robots
 

my $.02

what happens to your robot's legs when a 6WD comes over and rams the bolts out of you? :eek:

of course, i'm thinking of the legs being fairly long rather than thick logs that don't have much of a vertical component.

I'd love to see legged robots in FIRST, but i don't see it happening unless there is a "double" terrain, where legged robots can go, but if your robot has only wheels it might not be able to traverse that area.

Re: Legged Robots
 

You bring that up, so I will ask this, will the wheel's torque go up if you use multiple motors to power the same wheel?

Re: Legged Robots
 

Being somewhat interested in FIRST history as well as legged robots, i can think of 2 off the top of my head:ahh:

71 from 2002
and 190 from '01. The mechanism was retractable and was scrapped fairly early in the competition season.
See picture here

Re: Legged Robots
 

For those who are interested in 71, here are a couple more videos to check out:

http://www.youtube.com/watch?v=h4slv...eature=related
(Just a match with some really nice close-ups)

http://www.youtube.com/watch?v=lAmAnkYDUQM
(A pretty incredible pushing match between 71 and 60, another goal-grabbing robot)

Re: Legged Robots
 

Legs aren't practical.

In battlebots they give a 100% weight bonus* for walking, and it still isn't worth it. :(

However, they are awesome, and I'm all for cool stuff.

The main problem is that we don't have enough powerful motors in the kit to make an effective omni-directional walking machine. Which means, that instead of "legs" what we really need to build are linkages (which can turn with regular tank style steering).

I've tossed around a mechanical spider linkage DT, but have never gotten around to designing it.

Why build it? Because you'd be famous instantly! Everyone at champs would come and see it!

If my team had more machining skills I'd gladly sacrifice winning for fame :D



*I've suggested FIRST adopt the same bonus in the "design the game threads"

Re: Legged Robots
 

Well, some of the most successful robots in Battlebots history (namely one of the first Son Of Whyachi variants) were walkers. Then they changed the definition of a "walker" to make building one that could work too impractical for the weight.

I guess I don't see the point in doing something "cool" like legs, when wheels appear to be ideal solutions for pretty much any robotics game there ever will be.

Re: Legged Robots
 

It's a pretty cool concept, legged robots can move pretty quickly. I still think wheels could move faster in the FIRST robotics world because it's a concept that we have developed and been working with for some time now. Just my two cents.

Cass

Re: Legged Robots
 

The Klann linkage is good if you need to climb-over things such as steep inclines like this year, or vertical walls, like '04, however it doesn't provide the most stable platform and you would have to be careful to make sure the oscillations don't move your bumpers out of the bumper zone.

A Jansen mechanism would keep the platform much more level, if engineered properly, and uses the same number of legs and motors as Klann. Also, slopes aren't a huge deal for them either, the mechanism was originally used for kinetic sculptures that ran on beaches, which are sloped, While Jansen mechanisms may not be able to take on this years bumps, I believe the ramps from '03 would be fine with the proper foot design.