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byi
07-11-2010, 09:55 AM
I am buying servos for my mech and I was wondering what servos others recommend. Any help would be great.

iBot
07-11-2010, 10:14 AM
It would help if you could describe your mech, how you will fabricate it and how you will control it.

Also important factor is the state of your savings account and whether it is shared with spouse/partner :wink:

byi
07-11-2010, 11:40 AM
its a quadraped mech with 3 dof legs from lynxmotion. most of the mech will use the SES system from lynxmotion. The head is mounted on a turret. The head contains a lot of components and will be rather heavy.

As for money, I am able to pay for components as long as they are not extremely expensive. For example, I dont think I can pay more than $100 per servo.

RavenW
07-11-2010, 04:17 PM
If you're going with SES then you will need HiTech servos. I would suggest HS-645s at minimum, if they're not enough then you'll have to go for the digital HS-5645s or higher. These are what the SES system was designed for.

RobotAtlas
07-11-2010, 11:19 PM
byi
I was in your shoes about 6 months ago.
So if I may, here are my humble suggestions:

Search this forum for Issy 1/2/3 threads. Watch its walking videos. Try to compare them to the videos of lynxmotion-based robots. Think about where you want to go once you have your Mech. DO you want to make it "smart" and add brains to it?

For quadruped mech you can buy Dynamixel AX-12+ for < $50. But then you have to rethink the whole lynxmotion-based strategy. It is a very important decision though, so take your time. Try not to listen to people from only one company. Especially if they sell it. :)
Also consider the cost over the whole lifespan of your robot.

I know, it's a lot, but you'll learn a lot just from answering these questions.

darkback2
07-12-2010, 12:55 AM
OK...so another mech you could look at is 2nd Amendment. Upgrayde used hitch servos, and the lynx motion SES brackets for the legs. He also implemented Ik. Its the software that makes Bots like this have a smooth gate, not really the hardware.

I would say that you can go either way...especially if you haven't started and have a clean slate.

I personally use HS 5990s in my mech, an investment that I made 2 Years ago, and have made the switch to dynamixel AX-12s in my current humanoid quad hybrid X. I made the switch because I wanted to grow and expand as a builder.

I would suggest if you are just starting out, then at least take a look at the arbotix/ax-12 combo. It was pretty much designed for mech warfare. if you have already started down a path, then I encourage you to consider sticking with it.

good luck.

DB

lnxfergy
07-12-2010, 11:04 AM
I'm going to second a few comments here -- if you haven't spent a dime yet, seriously take a look at AX-12s and the Bioloid. The servos are only a few dollars more than an HS-645MG, we'll avoid the debate over which has more torque and just say they have similar torque right now, but that AX-12 has feedback (very useful for configuring gaits), overtemp shutdown, overload shutdown, etc -- so they're very, very difficult to break. The AX-12s also have their own, very cheap, bracket set. The brackets are way cheaper than SES -- and yes, the white is ugly, but you can dye them nearly any color using RIT dye.

A second note, that nobody here has alluded to, is to take a look at what sort of support you might get, both in developing the mech, and onsite. If you go the Lynxmotion/SES/Hitec route, take a look at the Lynxmotion forums (specifically the threads about the Pheonix or other bots using it's IK, because with all the payload we put on mechs, you really want smooth walking to help your servos out -- and that means IK). The simplest route to an AX-12 quad with IK is probably the ArbotiX route -- and there's several tutorials about AX-12/ArbotiX mechs.

-Fergs

Disclaimer: I'm the creator of the ArbotiX -- and also a co-organizer of Mech Warfare.

byi
07-15-2010, 07:25 PM
Thanks for all the info. I looked at the bioloid building system and the AX12 servos. This looks like a very good option. However, I was wondering if the CM-5 microcontroller is sufficient or if there is another option. I currently know pbasic, perl and vb and can learn java or python. What microcontrollers could I use? Also, what kind of signal does the AX12 servo use? Is it the same as normal servos? Lastly, what exactly is IK and where can I get it? Thanks.

jes1510
07-15-2010, 11:51 PM
The current trend is to pair the Bioloid kit with an Arbotix controller. It's a pretty sweet controller that is programmable from the Arduino IDE. I think Trossen currently sells them.

Finally IK is Inverse Kinematics. I believe the Arbotix board has a system that takes care of the IK for you.
http://en.wikipedia.org/wiki/Inverse_kinematics

Disclaimer: I don't own an Arbotix or a Bioloid kit but I play one on TV.