Three legged robot..lil help pls

[puremobi]

hey ,
I have a competetion coming up..n i have to make a three legged robot..which should
1)walk like a human i.e lift its leg up and down.
2) make a right or left turn

it could even be two legged.

i have checkd online..hey use a gui to calibrate the movement and serial cable

can we write the entire program on a chip which doesnt require calibrating.?
i was thinkin of using the components in my bluetooth mouse for the control.

what would be the basic requirements?.i have knowledge in atmel 89c51/89c52programming.
pls suggest ideas...thank you very much.

 

[blueroomelectronics]

Sounds very difficult for a beginner. Wheeled robots are much easier.

 

[puremobi]

hi blueroom,
I have a doubt with PWM and servo,
Should i continously send 20ms delay with 1ms to get clockwise rotation?..
what about the 90 degrees?..it says 1.5ms
so should pulse be continous to the motor?..or for a define number of cycles?

 

[Nigel Goodwin]

The pulse has to be continuous.

 

[The Mad Professor]

Am curious as I am sure so are many others who have viewed this thread,
how have you or intend to solve the problem of making it balance?

 

[puremobi]

hi,
thanks for reply..
iam sorry ,
iam using two threads for the same doubt.
professor,i didnt get ur question at all..

 

[The Mad Professor]

Equilibrium - it's a question of balance

Are all three legs to be moved independently using servo motors ?



True three legged robots are notoriously difficult to get right, consider the classic robot of science fiction the 'Tripod' from HG Wells novel 'War of the Worlds'. Paramount film studios have twice thrown a great deal of money at this problem once in 1953 and again in 2005. The BBC special effects people also had a look at the problem for the series 'Tripods' in 1984 and said no way it can be done.

The problem is the moment you try to lift one leg up it falls over in that direction, bipedal (two legged) robots get around this by leaning over thus shifting weight to the stationary leg while the other one moves. With a tripod however the arrangement of legs means that the center of gravity is always going to be in the wrong place for walking.

Now if you could devise a way to change the center of gravity, the same way high wire walkers do , then it could amble along quite nicely.

 

[puremobi]

nice..three legs gonna be big flop then..
had a tough time with two legged robot..my friend had bought a lynxmotion robo with expandable accesories..
great issue with weights..
iam goin with the six hexa pod now..
requirin at least 12 servos i guess..

 

[The Mad Professor]

Don't abandon hope

Don't abandon hope, the idea is not flawed but the technology is.
The small geared servo motors just cannot move fast enough to beat the pull of gravity.

As Thomas Edison famously said:
Build A Better Mousetrap And The World Will Beat A Path To Your Door

The same could be said of servo actuators, you can get high speed ones but they are large, use lots of power and typically found in industrial machine tools. Amateur robot builders meanwhile are stuck trying to make do with a geared servo mechanism whose design has changed little in over two decades.

 

[duffy]

Wait - don't give up - three legged robots are BITCHIN'!!! Look at this page -
Swashbot

That doesn't look too hard to build, and wins points for style, if not speed.

 

[The Mad Professor]

Scuttle and Stride

STriDER - Can you run faster than it ?

STriDER Tripedal Dynamic Experimental Robot: Science Fiction in the News

 

[Torben]

Wait - don't give up - three legged robots are BITCHIN'!!! Look at this page -
Swashbot

That doesn't look too hard to build, and wins points for style, if not speed.

Wow! Definitely not a speed demon but so much personality. (Jeez. I think becoming a father has made me into a hopeless cheeseball). It's guys like that who make me sad that movies are headed so firmly toward CGI instead of animatronics. Maybe he can get a job at Disneyland.


Torben

 

[Torben]

STriDER - Can you run faster than it ?

STriDER Tripedal Dynamic Experimental Robot: Science Fiction in the News

Seeing as the makers were impressed that it managed one step, I could probably outrun it, yes. But a fully debugged unit would be fun to watch. A thousand of them running over a hill toward me would scare the bejeezus out of me.

For some reason the motion of that thing made me think of this:

**broken link removed**

I hope STriDER's programmers take this into account.


Torben

 

[puremobi]

well,it definetely seems possible n more interesting than the six legged..
iam clearin out some questions with runnin a servo..when its done..i will march forward..

strider ....they can get scary ,jus so if u watched other videos of strider.;s

 

[puremobi]

in the swashbot..the 'shapelock plastic ' used is pretty cool..best fast solution

 

[duffy]

It's also goes by the name "Friendly Plastic" on some sites.