In the Robosavvy forum, someone pointed out a hexapod kit that uses only three servos, yet can go forward, backward, and turn.
That’s very cool to me – three servos could be a pretty affordable place to start, and it’s a lot more interesting than a pan & tilt rig. Stick some sensors and a controller on that, and you have a real bot!
Then, there’s the three-servo biped made by Robot Force. If that isn’t cool, I don’t know what is.
So. What neat bots can you (yes, you) make out of the SES (plus, say, cut Lexan panels) with only three servos?
Jim, maybe you should hold a contest! The examples above show that there’s plenty of cool stuff that is possible under such a restriction, and the result might be same great new affordable kits for SES newbies.
True, though that’s not an SES kit. It is a neat one, though. Pity they don’t sell it without servos — that would shave $36 off the $100 price for people who already have a few servos, making it a little more palatable. Still not under that magic $50 price point, though.
But I do agree that it’s a better starting kit than most I’ve seen. (What Lynxmotion really needs is two additional kit indexes: one by price, and one by number of servos — in cases where the kit can be bought without servos.)
Speak for yourself! I think they’re very cool. If I could make one for under $50, I’d not only do so, but I’d talk a buddy into doing it too, so they could slug it out.
Yeah, but at $200, it’s out of my range by a factor of 4! That’s why it’d be great to see what small but nonetheless interesting SES designs people can come up with. Then folks on a tight budget (yes, like me for example) could start with those, and gradually build up enough parts to build something like a BRAT.
Oh well, actually, since im waitin for my new Atom (yes Jim I mailed it out ) This will give me a little something to do while I wait. I’ll see what I can create with only 3 servos and some SES brackets, though im sure I won’t get farther than a 3DOF leg
that robot dosent even walk! it woddles, and dosent go in a straight line.
here is something managed to do with 4 servos lynxmotion.net/viewtopic.php?t=934
(its a biped) and its no match against the BRAT, but if you already have servos, well, it dosent cost that much to buy just the SES parts… with three servos you cant realy make a biped with the SES, you will need bones (i think thats what its called…) so one servo will control more than one joint, and there it guets more complicated for the design… exept for a pan and tilt, I dont know what you could do, surely a lot but i didnt think about it and Im tired…
Sure it waddles, but so do most robot bipeds. But this one can also get up from a prone position, either on its front or its back, and strike (swing) with its arms… can a BRAT do that?
Now that is very cool! Jim, whatever happened to that “Brat Jr.” idea? Seriously, there is a severe shortage of low-end kits for getting started with the SES, and something like this would be a great addition (especially if you can buy it without the servos — many of us have a handful fo servos already).
Do you have any more views of this robot, that a newbie like me could use to help build one?
Yeah, you’d need linkages… zoomkat suggested having one servo control both ankles, and that seems like a reasonable idea. But I agree that it would get a lot more complex to design.
Thanks for pointing this out — even if it is four servos, it looks like a great place to begin, and is well within the spirit of my question.
Here’s a parts list:
All numbers are the actual number of brackets necessary.
Many brackets are purchased in pairs, so be sure that you keep that straight.
All the * are potentially unecessary, for the following reasons:
ASB-06: not needed if you’re willing to drill holes into the bottom of the hip ASB-04’s
SSC-32: not needed (but still nice to have) if you use a micro to control the servos
DB9: not needed if you use a micro; also, you may need a DB9-USB cable instead if your PC doesn’t have free serial ports.
I’d suggest using two ASB-16 brackets in place of two of the ASB-04, two ASB-06, and two ASB-09.
The ASB-16 would fit in exactly where the other three types are in that video, which saves you quite a buck.
Sounds great! Please offer a no-electronics, no-servos version. I’m looking for something I can buy for under $50… and the servos alone would cost $48 (assuming HS-422s at $12 each). And of course, if you need a beta tester, you know who to call!
I priced this out, and just in case there are any other tightwads here, here are the results:
As spec’d by Nick, using the USB-16s, the total is $56.75 (plus probably about $8 shipping). (That’s 2x ASB-16, 1x ASB-503B, 1x ASB-04, and 1x ARF-01.)
However, a large chunk ($18) of that is the feet. I’m inclined to make my own feet, especially since I want to experiment with putting the batteries down there. So, without them, it’s only $38.80. That’s not bad at all!
Just for the sake of completeness, if one were inclined to replace the brushed aluminum channel (hey, if you’re making your own feet you may as well make your own chassis too), then it’d be $31.85.
Well bad news. Building the 4 servo biped using the ASB-16’s will not work. At least not with off the shelf components. The legs are too close together to be able to rotate at the hip and the stride length is really short. The legs are really short too, which makes it impossible to lean enough to lift one leg. The way Sam did it the legs were about 1" farther apart and taller. Of course if your going to make your own feet and U channel then you may be able to overcome some of these problems. I will go back to Sams original design for BRAT Jr.
I had been operating under the asumption that there would be insignificant difference in overall height with the swap.
But, looking back at the videos, I now see the gap that the 3 seperate brackets provides.
I think they’re very cool. If I could make one for under $50, I’d not only do so, but I’d talk a buddy into doing it too, so they could slug it out.
that robot dosent even walk! it woddles, and dosent go in a straight line.
wow 