Cheap - Mini Home Built

[Enderwiggins]

Hi my name is Ender, I'm brand new to the hobby an I have little to no knowledge in building biped/humanoid robots therefore, I have come up with a plan!

My plan is to build a small robot with a cost in the 100-200 dollar range that has all the basic functionality of the larger KHR type robots (walk, sit, punch, kick) abet at a much slower dumbed down pace.

Now for robots in the 100-200 range I know that Ayu created a perfect example of what I would like to accomplish however the copying of the MR-C3024 is a little daunting so I figured I would use a simple servo controller and run everything from the PC until I gain more knowledge.

This is where I came to a road block. In choosing a servo controller I initially picked the SSC-32 because I've seen it recommended quite a bit, however for such a small robot it's kinda bulky therefore I thought It might be better to stack two or three Pololu Micro Serial 8-servo controllers, this would take up a third of the space but cost about 20 dollars more and control only 24 servos. If anyone has any suggestions or idea's I would love to hear them! (Other controllers or even cheap micro controllers suggestions are welcome too!)

For the brackets I will be hand making my own from aluminum using a dremel and some clamps. ^_^

I haven't began to think about how I will power it, because It probably wont be going too far from my computer so I might look into using continuous power supply, I think a standard battery pack would weigh too much for the poor little robot. Once again suggestions would be appreciated!

Once I have finished I'll make a tutorial on how I did everything so any knowledge, tips, help would be great value!

Link to servos - http://cgi.ebay.com/9-0-Gram-Mini-Servo ... dZViewItem

Link to Ayu's Robot Post - http://robosavvy.com/forum/viewtopic.php?p=15649

March 13, 2009
So, It's been a long time since I last post on my robot, apparently moving upstate with girlfriend and begining university is a stressful and makes for little free time. (Who would have known?) Anyways after talking to one of my professors for awhile he agreed to let me rapid prototype my robot, which means my ugly sharp time consuming metal brackets went flying at super sonic speeds towards the garbage.

So as i said I was gunna detail every step of my journey. Well heres the first leg:

Day One:
I don't know why it never occured to me that people could be in the hobby of making small biped robots, after seeing a khr-1 on youtube i spend my day druelling over countless videos and gawking at the pricetag....

Day Two: I stumbled over RoboSavvy while trying to vicariusly live my new found "hobby" through other peoples robots.

Day Three: Eh Screw this you dont wanna read about my sob story.

*Found Ayu's robot and planned to reproduce it or something similar.
*Begged girlfriend prefusly to go out and buy 24 small 4 dollar servos and a SSC-32 controler before I had any idea of what i was doing.
*Built a "model" of my robot in sketch-up. (Attached at end)
*Began attempting to make metal brackets.
*Moved Upstate
*Began making a new model in solidworks to have prototyped. (Attached at End)


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[limor]

Hi, the Ayu project is definitely admirable.

if you use 3 controlers you will need some way to centrally co-ordinate their activity. How were you thinking of solving this ?

[i-Bot]

If you can fit it in, I would go for the SSC-32. It has the advantage of group moves and also other I/O which are always useful. SSC-32 also will tell you when a move is complete and manages all the servos as one block. The SSC-32 has a strong support community over at Lynxmotion for biped and other configurations.

The Pololu should work OK but you can only set position and speed, and there appears to be no signal back from the controller when move is complete.

The C3024 is probably the most simple controller, but you have to build it if you want to meet your price target.

There are lots of other cheap microcontroller options, but none that I know are so ready for your servo based biped application with good software and support.

[Florent_Lyon]

Hello,
another link to 9g servos:
http://www.hobbycity.com/hobbycity/stor ... roduct=662

they have a 1.6kg.cm torque, but they may be the sames than the ones you propose Enderwiggins...
The shop is great, my RC club use to order to them.
The servos are great also, I've already bought 8 of them and they are powerfull!

regards,
Florent JANIN, Lyon, France

[Enderwiggins]

I might be wrong, but from the documentation I could find on the Pololu controllers you can daisy chain them together and assign different servo numbers to each board and then control them as normal from there.

[Enderwiggins]

Florent_Lyon - more torque, same speed/size, from a real company, AND cheaper! great find! Thanks!

[Enderwiggins]

i-Bot - I will be building my own C3024 in the future, but ATM my electronics skills are even sub-par to my knowledge of biped robots so it will be some time down the road, I did like the amount of support the SSC-32 has, so I was leaning towards it, I also liked the fact you can add the bot board to it, I guess if someone could confirm that it is the same size or smaller than the c3024 it would be a sure go (I couldn't find the c3024's dimensions anywhere), after all its cheaper and I'll probably have more use for it in the future when I plan to make a real robo-one style/size robot

[i-Bot]

I think you are right that the Pololu can be daisy chained which means you can set the speed and position of your 24 servos. What I do not see is any signals coming back from the controller to say when a move is complete. If you set a slow speed, then it is good if the controller tells you when it is done.

More important is the point to point or group move capability of the SSC-32 and the C3024. Here the controller can manage the move of a range of servos and adjust their speeds so that they not only start at the same time, but also end at the same time, even if they move different distances. And it tells you when the move is complete.

The group moves and the move time calculation could be done on the PC, but having the controller do it saves a lot of effort.

[Enderwiggins]

i-Bot - The SSC-32 seems to be an all around better choice, especially with what you just explained which I knew nothing about, unless someone knows of a smaller/comparable controller that can control at least 18 servos, I think I'll go with the SSC-32.

[DocVanThorp]

If you look at most RoboOne robots, the functionality of the arms and legs is typically accomplished with just 16 servos. Probably enough for a "mini" robot.

Has anyone ever attempted a project of this type with gear motors?