Author Topic: Control software of a Quadruped  (Read 3692 times)

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Offline fatal1ty89Topic starter

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Control software of a Quadruped
« on: September 05, 2008, 06:02:10 AM »
I finished my quadruped frame. I used three servos each leg.
I used pic877A in this robot, I acquired 20pwm with 2timer. But I used only 12pwm.(3DOF * 4leg)

The question is that; how can I control this each leg?
I can control each servo  manually by Visual C# from the PC.
But What way do you recommend to me to control legs? May be Inverse kinematic ?

Thanks already now=)
(I'm sorry for my english ;D)

Offline izua

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Re: Control software of a Quadruped
« Reply #1 on: September 05, 2008, 08:47:26 AM »
pololu and sparkfun have some good 8 or 16 servo controller modules. you can try coding one in your pic, but it's pretty harsh.
inverse kinematics is unlikely to be needed, unless you walk on really harsh terrain.

dude, we want pictures :D
Check out my homepage for in depth tutorials on microcontrollers and electronics.

Offline fatal1ty89Topic starter

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Re: Control software of a Quadruped
« Reply #2 on: September 05, 2008, 08:59:33 AM »
I can use 12 pwm with pic, thereis no problem=)
How can I control the legs? Can I preprogrammed the legs? forward-bacward etc... ?

Offline izua

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Re: Control software of a Quadruped
« Reply #3 on: September 05, 2008, 10:53:46 PM »
Yep, preprogrammed motion is the way most guys do it, or what it's called 'gait'. This reffers to hexapods usually, but i'm sure it applies to quadros too.

Check some youtube videos for example motions.
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Offline fatal1ty89Topic starter

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Re: Control software of a Quadruped
« Reply #4 on: September 06, 2008, 05:55:47 AM »

How this robot can walk like that ;D ?


Offline izua

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Re: Control software of a Quadruped
« Reply #5 on: September 06, 2008, 07:19:35 AM »
Well, only one leg is in the air at all time, and they move in a boxed X fashion.

edit: just in case you missed it the last time:
dude, we want pictures :D
« Last Edit: September 06, 2008, 07:24:51 AM by izua »
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Offline fatal1ty89Topic starter

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Re: Control software of a Quadruped
« Reply #6 on: September 06, 2008, 07:29:50 AM »
Dude ok I understand you;D
My Camera data cable isn't here, so I can't transfer photos,Please Wait some day more ;)

Offline izua

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Re: Control software of a Quadruped
« Reply #7 on: September 06, 2008, 07:53:23 AM »
What servos have you used, btw?
Can you control your quadro from something else? Like the computer (using the.. err.. parallel port?)
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Offline fatal1ty89Topic starter

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Re: Control software of a Quadruped
« Reply #8 on: September 06, 2008, 09:51:22 AM »
Futaba S3001 and Towerpro mg995 12kg...
For now I 'm using Visual C#, for communication I 'm using serial port...

On the other hand I'm looking for wireless communication ways, like WIFI. I have a USB wifi dongle, if I can
communcate with an acces point with this dongle, I will try to convert this data to suitable for UART communication...

Offline izua

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Re: Control software of a Quadruped
« Reply #9 on: September 06, 2008, 10:27:16 AM »
Yes, but can you command the whole thing to move from C#? (like sending data to a servo controller). Or you just talk to your MCU, but no servo activity?

If you have a wifi dongle, you can hook it up to an access point, and at the ethernet output, connect an ENC28J60 chip. That chip can talk ethernet, and you can use TCP/IP over it.

TMG995? Those are cool, I got mine (for experimentation purposes). But a single one is expensive as hell, and it visibly offshoots.
How do the S3001 work?
Check out my homepage for in depth tutorials on microcontrollers and electronics.

Offline fatal1ty89Topic starter

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Re: Control software of a Quadruped
« Reply #10 on: September 06, 2008, 11:58:51 AM »
S3001 is cool, but weak , its torque is 3kg/cm....

I can command the MCU to produce the wanted PWM by Visual C#...

By your reccommended chip, how can it communicate with PIC16f877a?

Thanks for your concern  :)

Offline izua

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Re: Control software of a Quadruped
« Reply #11 on: September 06, 2008, 12:54:38 PM »
ENC28J60 is a SPI chip.
Yes, I understood that you can command the MCU. But, do you have software written in the MCU to command the servos? It doesn't matter how, but can they be accessed individually? Like, make each joint move to 0, then make each joint move to +30 degrees?

Well, I'm interested in servos because I've been meaning to build a hexapod for quite some time, but the servo is a difficult issue here, the chepeast one (beeing a lame ripoff, no oem) beeing ~$15.
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Offline fatal1ty89Topic starter

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Re: Control software of a Quadruped
« Reply #12 on: September 07, 2008, 05:14:41 AM »
Yes izua; Each servo accessed individually, you can move each servo what you want...

do you know the towerpro servos are haw much? 12kg servos are 8$...=)

Offline izua

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Re: Control software of a Quadruped
« Reply #13 on: September 15, 2008, 05:39:13 PM »
How do you control all of them? Servo controller, software pwm, individual MCUs with hardware pwm stages?
And, how are the pictures coming? :D
Check out my homepage for in depth tutorials on microcontrollers and electronics.

 


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