pic: Robo-one legs

[[527]phil]

[cdm-description=photo]21930[/cdm-description]

[Arefin Bari]

I must say that this is one of the coolest project I have seen around in this forum. But I do have questions for you...

In the picture you are using 11 servos... if you are adding a body with arm and a head, you would add atleast another 5 servos. How are you planning on powering 16 servos to work the same. What kind of controllers would you use and why? Do you think you will need more than one controller? what kind of battery are you going to use? Don't you think it will weigh a lot which may cause it to tip over?

The legs look cool. Great job man.

[santosh]

That looks pretty awesome. Nice job.

[mechanicalbrain]

very nice!

[spears312]

Cool. I tried something like that once (but w/ Lego's, needless to say, it never really "worked", per say). Have you given it a test yet and will it have a gyro sensor to detect and compensate for balance? It really want to see this thing walk! :D

[mechanicalbrain]

http://www.etek.chalmers.se/~almir/ this is also pretty cool and very similiar. i highly recomend the movie.

[Arefin Bari]

http://www.etek.chalmers.se/~almir/ this is also pretty cool and very similiar. i highly recomend the movie.

That is one cool robot. Definitely check out the video. It's one of the very intelligent robot I have encountered in my FIRST career. After watching the video all I could think or say was "I wanna make one of those."

[[527]phil]

We'll I've already tested it and it walks fine. I'm using a lynxmotion BASIC atom pro 24 pin module and their mini Atom bot board. I'm going to have to purchase their servo controller though because I need to control (ready for this) 19 servos. I didn't really design it to walk up stairs but it can. And I'm not using any gyros (yet), it just takes about 400,000,000,000,000,000 tries before I get the servo placements and timings right so it doesn't fall over. I plan on putting up a video of it walking, but first I have to program it. If you plan on building something like this DON"T but the BASIC atom pro + bot board, it can control 20 servos, but only 1 at a time. So lets say i want the legs to crouch and both motors need to move an equivalent of lets say 800, I have to divide it by a big number and then move each one back and forth.

IE.
SERVO 1, 5
SERVO 2, 5
SERVO 1, 5
SERVO 2, 5
etc.

O, and for the batteries, I'm just using a 9 volt battery because the BASIC atom board can take up to 9 volts and convert it to 5 volts for the micro controller and the servos.

[Andrew Rudolph]

Ive seen videos of these kinda robots they are really impressive to watch move.

[mechanicalbrain]

yeah i was specifically impressed with the logic programming on that robot.

[[527]phil]

I'm having trouble with the programming though, if anyone knows how to put voltage through a pin in order to keep a servo from moving, or if you know how to make more than one servo move at a tine, OR if you know how to sue the pulsout command, please help!!

[mechanicalbrain]

you tell the servo the angle you want it the potentiometer inside it will keep it at that angle and as long as power runs to the servo it will "lock" it at that angle. i recomend Robot DNA building Robot Drive Trains. its a must.

[mechanicalbrain]

i did a sumo bot that ran on servos. keep in mind if the servos aren't quite up to the job you can get more power from the motors by giving them more juice than their rated for. note that this is actually safe as long as your careful. you can run a servo on up to 12 volts but the motor will get warm pretty fast and i would not recommend running them more than 4-6 min on a high voltage (and yes this will lower the milege of your motors but the speed and power increase is worth it).

[tiffany34990]

wow!! that's really nice!! great job... what exactly do you want this bot to do???

[sanddrag]

I think that's a lot of load for those servos to handle at the top, but it does look like it will be cool once it gets moving. It will never outrun anything with wheels, but it definitely scores in the articulation category.

[[527]phil]

yeah I'd like to see a wheeled robot do a back flip, lol. But if you could provide any code examples it would be nice. I'm not much of a programmer.

[mechanicalbrain]

sanddrag makes a valid point but i think you are going to see more motor problems at the bottom. if you can run different amounts of current to different motors run about 8 volts to the bottom motors.

[[527]phil]

I figured out one major problem with the legs, i need to take out one servo from each leg, not only will this make it more stable, it'll make it easier to program.

[sanddrag]

run about 8 volts to the bottom motors. I think 8v is far too high for most hobby servos. I think about 6v is the max.

[Mike AA]

phil']I figured out one major problem with the legs, i need to take out one servo from each leg, not only will this make it more stable, it'll make it easier to program.

I was beginning to wonder why you had some many servos. You should only need 3 per leg (just like human legs) including ankles. It would definatly make things easier.

-Mike

[mechanicalbrain]

i like the idea too often i see robots bound by the constraints of biology. make biology the base and then improve!

[Gdeaver]

If I remember your past post about the atom, there was a problem with your use of the servo command. Look at the docs on the servo command.
Servo 1,5 will repeat this command 30 times by default which takes about 1 second to execute. Try servo 1,5,1 This will take about 30 ms to execute.
To control that many servos you going to need a servo board. Most servo boards are serial or I2C controlled. Serial is probable easier, I2c is most likely faster.

[mechanicalbrain]

I think 8v is far too high for most hobby servos. I think about 6v is the max.
you can run the Hitec and Futaba servos on 12 volts DC even though its rated for 6 volt. also you can run almost any servo on roughly 8 volts.

[[527]phil]

http://fs4.picjar.com/ki/MGZdWLjjoOXmkOdDWWWxsZVbeLVaD/D-DSC00002.JPG

this is robo-one legs 2.0. I took off the knee servos and not only is it shorter, it's much more stable. :D

[mechanicalbrain]

hehe he's stubby!

[John Gutmann]

I was beginning to wonder why you had some many servos. You should only need 3 per leg (just like human legs) including ankles. It would definatly make things easier.

-Mike

you should need 4 servos per leg cuz the leg has to rotate 3 ways(forward/back, left/right, and to rotate the whole leg) that way you can turn

[mechanicalbrain]

ive been compiling info to write a whitepaper on bipedal walking so tell me how this turns out. one of the things i want to see and i think would be extremely usefull to a better system would be the addition of bending toes and able to lean side to side. both of these are extremely important to human balance. if you don't believe me try walking without bending your toes or shifting weight from side to side.

[[527]phil]

It's having a weee bit of trouble walking, but it's not because of my designs it's because of my programming, I still haven't mastered the HSERVO command, + I've been searching for a Pentium 3 laptop, kinda like an IBM think pad or a dell latitude, but alas i keep getting overbid :mad: .

what happened to the pic of legs 2.0?

[mechanicalbrain]

but can it actually move?

[[527]phil]

Yes he can move. all servos work perfectly and I calibrated the servo horns so they are at the 0 position (or almost). I can move single servos or multiple ones. It's just in order for it to walk on it's own i have to find the exact placement of each servo so it won't fall over. But it's alive!!!, lol :D