A christmass gift desicion

zemkacz

I am going to get quite a bit of servo;s for christamms but i noticed that they could get in really high price ranges, but i saw these servo's on ebay 79.99 for 20 of them, they are sub micro servo's and i was planning to put them into either a walking bipod bot or a hexapod, but i do not know how much power are they gonna use up, and also, what type of servo controller i would use this this, due to the fact that i am going to be using like 15 servo;s at once, and i was planning to use a sub-processor for the sensors such as light, pressure, and eventually when i get enough $$ a cmu cam. I was planning to also somehow use my computer as the "brains of it, but i have no idea on how to attach it to my computer other then using the serial cable from the computer and use the power from the serial cable to power the basic stamp 2, i could learn visual basic quickly, but i do not know how to actually attach it to the computer.

Would sub micro servo's be good for a hexapod / biped robot?
http://cgi.ebay.com/10-pcs-9g-SG90-Micro-Servo-RC-Truck-Plane-Helicopter_W0QQitemZ300173330370QQihZ020QQcategoryZ44028QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
What would yuour opinion be on adding a co-processor, probably a pic?
How to let a computer interfre with the bs2 and be the "brains"?

Mike Green

Can't help you decide whether these would be strong enough or fast enough for your needs. If you're building a small robot, they may be adequate. Don't forget they're called "sub micro" servos and the scale of your robot project would have to match. The eBay page does give the torque and size. The power needs depends partly on the mechanical load, but can be on the order of 1A with a stalled motor.

If you're going to use a lot of servos with a Stamp, get a Parallax Servo Controller (PSC) which can control 16 of them and you can attach two controllers together so they share the same I/O lines from the Stamp. There is a USB version of the PSC which can be directly connected to a desktop/laptop computer. Download the manual from Parallax's web store page for it.

If you use the USB version of the "Board of Education" for mounting your Stamp, you can directly communicate with the Stamp via the same serial port used for programming.

If your computer has a regular serial port, you can get a serial port version of the Board of Education and do the same thing that way.

omgitsaliv55

Mike Green said...
If you're going to use a lot of servos with a Stamp, get a Parallax Servo Controller (PSC) which can control 16 of them and you can attach two controllers together so they share the same I/O lines from the Stamp. There is a USB version of the PSC which can be directly connected to a desktop/laptop computer. Download the manual from Parallax's web store page for it.

I'd have to disagree with you on that one. Even though I general support parallax, I have to say that when it comes to servo control go with lynxmotion. They have the SSC-32 servo controller which is the exact same price as the PSC however it has 32 servo ports. From what it sounds like, you'll want to take out some insurance by getting a servo controller with room for expansion because the moment you decide to pan and tilt to that bot (just an example), you're short one servo header. I use the SSC-32 and it's been a life saver! www.lynxmotion.com/Product.aspx?productID=395&CategoryID=52. They also have a servo erector set that you can use for designing the chassis, plus a powerful visual sequencer to control the ssc-32 visually. With that software, you "build" the basic structure of your bot on the computer and then you directly interact with the structure to manipulate the servos.

An option for the main board is the Bot Board they sell. This is just a carrier board with all the I/O pins connected to servo headers. Of course, it doesn't have a breadboard, but with a biped this is irrelevant; it'd be too messy. You simply connect sensors via the servo headers making them "plug and play". It is fully compatible with the basic stamp 2, however because it can also accommodate a 28 pin basic atom just remember you'll have four empty sockets hence four servo headers that....don't do anything. You can connect the bot board and the servo controller together very easily, but just make sure you read the user manual if you chose to go this route because there are a few jumpers on both boards that you'll need to move around a bit in order to get the serial connection working. Nothing major, might take you about 2 minutes or so if you read carefully.

Now about the servos. I don't think sub micro servos are going to be the option to go with. Those have really low torque and won't fit in many or any servo erector sets...which is what you're going to need to use unless you plan on smelting together your own chassis! Once again lynxmotion offers a wide variety of servos as well as their servo erector set. I'd also take a serious look at some of the bipeds/hexapods they have in kit form already. Most of them come with a SSC-32 servo controller and of course the chassis and servos, but let you add your own micro controller setup. I own a scout biped and have been having a ton of fun with it using the ssc-32 and a basic atom pro on the bot board. Anyway, I hope this helps and post again if you have anymore questions.

-Patrick

Post Edited (omgitsaliv55) : 11/24/2007 7:58:26 AM GMT